book of abstracts - wur edepot

EUROPEAN SOCIETY FOR AGRONOMY

BOOK OF ABSTRACTS

VOLUME II: Theme 2

Agroforestry Session Divisions

Editors: M.K. van Ittersum G.E.G.T. Venner S.C. van de Geijn

T.H. Jetten

FOURTH CONGRESS 7-11 July, 1996

Veldhoven - Wageningen THE NETHERLANDS

H V h

I

Published by ESA Congress Office AB-DLO P.O. Box 14 NL-6700 AA Wageningen The Netherlands

Additional copies are availble from:

European Society for Agronomy (ESA) BP 52 68000 Colmar Cedex FRANCE Tel: +33 8972 4986 Fax:+33 8972 4933

© European Society for Agronomy 1996 ISBN 90-73384-44-3

Cover designed by Ruud Verkerke

Fourth Congress of the

European Society for Agronomy

Chairman Dr. Hubert Spiertz (Chairman)

Scientific Secretariat

Dr. Siebe van de Geijn (Chairman) Dr. Martin van Ittersum

Dr. Theo Jetten Dr. Kees Rijniersce Ir. Guido Venner Ruud Verkerke

Corresponding Address: AB-DLO

P.O. Box 14 NL-6700 AA Wageningen THE NETHERLANDS Tel:+31 317 475700 Fax:+31 317 423110

Fourth ESA-Congress Board

Dr. Hubert Spiertz (Chairman) Prof. dr. Louise Fresco Dr. Siebe van de Geijn Prof. dr. Rudy Rabbinge Dr. Kees Rijniersce

Organising Institutes:

Research Institute for Agrobiology and Soil Fertility (AB-DLO)

CT. De Wit Graduate School for Production Ecology (WAU-PE)

Research Station for Arable Farming and Field Production of Vegetables (PAGV)

The editors are grateful to Nicolette Matulessy, Loes Helbers, Martin van Zandvoort, Erika van Harten and Armanda Versluijs for their assistance.

Contents Volume II I

Contents volume II

Plenary introduction of Theme 2: Integrated and ecological agriculure. 403 P. Vereijken

A methodical way of prototyping integrated and ecological arable farming systems (I/EAFS) in interaction with pilot farmers. 404

Session 2.1: Designing farming systems: methodological aspects. 407 Introduction: J.M. Meijnard, W.A.H. Rossing

Methodology for designing sustainable farming systems: prototyping and model-based explorations in a participatory research setting. 408

H. Bürgi, W. Richner, A. Soldati, P. Stamp Minirhizotron and soil monolith comparison of root distribution in pure and mixed stands of maize and Italian reygrass. 410

N. Babich, I. Grichanov Ecological basis for sustainable pest management system. 412

C. Bockstaller, P. Girardin Use of agro-ecological indicators for the evaluation of farming systems. 414

CS Butcher, K.B. Matthews, A.R. Sibbald The implementation of a spatial land allocation decision support system for upland farms in Scotland. 416

C. David, B. Fahre A model of on-farm agronomic monitoring applied in organic farming. 418

CA. He lander Arable farming system research project Logârden. 420

H. Hengsdijk, M.K. van Ittersum Towards sustainable land use in the rural areas: the need for designing new systems and technology. 422

F. Herzog, M.J.C. Brownlow Re-integrating perennials into agricultural landscapes - a conceptual approach. 424

T.J. Koeijer, G.A.A. Wossink Farmer specific prototyping of sustainable production systems: a conceptual framework. 426

E.A. Lantinga, R. Rabbinge The renaissance of mixed farming systems: a way towards sustainable agriculture. 428

J. Nocquet, C. David, Y. Gautronneau A farming system environmental assessment applied on organic farms and farms in conversion. 430

B.M. Somers Learning for sustainable agriculture. 432

A.M. Triboi, E. Triboi, B. A le ton Nitrogen dynamics and efficiency in cropping systems with different input levels: agronomical, economical and environmental considerations. 434

M.K. van Ittersum, R. Rabbinge Production ecological concepts for the analysis and quantification of input-output combinations. 436

P. von Fragstein Organic arable farming - a contradiction? 43 8

II Book of Abstracts 4th ESA-congress

F.G. Wijnands Environment exposure based pesticides selection. 440

Session 2.2: Resource use at cropping system level. 443 Introduction: P.C. Struik, F. Bonciarelli

Resource use at the cropping system level. 444

M.L. Bartosova, S. Kosovan Preliminary evaluation of EPIC in simulating cropping systems at one Slovakian location. 446

A. Canarache Soil physical properties - soil management interactions in a suitable farming system. 448

A. Castrignanô, G Convertini, D. Ferri, P. Greco Simulation of durum wheat yield and N dynamics by CERES/wheat model in a alfisol of southern Italy. 450

A. Castrignanô, G. Convertini, D. Ferri, V. Rizzo, M. Rinaldi Grain sorghum in southern Italy: dynamic growth and nitrogen simulation by CERES/sorghum model. 452

E. Ceotto, M. Donatelli, R. Marchetti, P. Spallacci Nutrient balance at farm level for cropping systems in the Po Valley, Italy. 454

N. Colbach Modelling the influence of cropping system on infection cycles and disease build-up for eyespot. 456

N. Colbach, J.M. Meynard Modelling the influence of cropping system on gene flow from herbicide resistant rapeseed. Presentation of model structure. 458

K. Debreczeni Responses of winter wheat and maize to NPK nutrient levels in long-term fertilization trials. 460

J.-E. Delphin The use of porous cups for estimate the impact of cropping systems on the ground water quality. 462

S. V. Garibay, B. Feil Maize production in a living grass mulch system. 464

P. Greco, G. Manzi Introduction of a catch-crop of soybean in a biennal oriental tobacco-durum wheat rotation. 466

F.C.T. Guiking, D.M. Jansen The role of mulching in cropping systems - synchronizing the release of nutrients and crop requirements. 468

M. Jedruszczak, M. Wesolowski, K. Bujak Soybean yield and canopy weed infestation under different crop rotation systems (introductory investigations). 470

J. Kolodziej, K. Liniewicz The influence of the cover of different cultivated plants on the ground water reserve (1981-1995). 472

J. W.A. Langeveld, G.B. Overbosch Nitrogen use and losses at (sub-)farm level in Poland. 474

P. Misa Energy balance of cropping systems in the sugar beet-growing region of Central Moravia. 476

Contents Volume II III

G. Mikkelsen Ecological and integrated systems in Denmark. Internal resources in different systems and their potentials for use. 478

K. Petö Water and nitrogen interaction in different cropping systems. 480

F. Piro, P. Greco Effect of rotation with wheat and catch-crops on physical traits of Xanthi tobacco. 482

E.K. Pisulewska, T. Zajac, R. Witkowicz Intercroppping spring triticale with N-fixing legumes as a component of sustainable farming. 484

A. Pucaric, B. Varga Maize response to fertilizer nitrogen in monoculture and rotation systems on vertic amphygley in Upper Sava Valley. 486

G. Richard, H. Boizard Modelling workability of loamy soils for seed bed preparation. 488

G.M. Richter, A.J. Beblik, J. Richter Optimizing N fertilizer demand of winter rye through quantitative modelling - calibration and practical application. 490

P. Spallacci, E. Ceotto, R. Rapini, R. Marchetti Lucerne as a "nitrate scavenger" for silty clay soil manured with pig slurry. 492

V. Stefan, I. Savulescu, H. V. Halmajan Cultivar mixture study on wheat yield in Romanian conditions. 494

E.A. Stockdale, A. Agarwal, K.W.T. Goulding, S.C. Jarvis Quantification of nitrogen dynamics in ecological mixed farming systems. 496

C. O. Stockte, M. Cabelguenne, P. Debaeke Validation of CropSyst for water management at a site in south-western France. 498

S.A. Tarawali, J. W. Smith, M. Peters, L. Muhr, R. Schultze-Kraft, G. Tarawali Optimising land productivity in crop-livestock systems by integrating legumes in the lowland moist savannes of west Africa. 500

A.M. van Dam, J. Vos, J. Wolfert, E.A. Lantinga, P.A. Leffelaar Growth and nitrogen accumulation of winter rye as a catch crop: model and experiment. 502

F.K. van Evert, J.M. Baker CropSyst-with-objects 3.0:geared for comparison of component models. 504

D. Ventrella, M. Rinaldi, V. Rizzo, F. Fornaro Water use efficiency of nine cropping systems in a water limited environment. 506

A. Wozniak Importance of underplant crop and farmyard as manures in monoculture of winter triticale. 508

K.D. Sayre Development of a sustainable bed-planting technology to allow reduced-tillage and crop residue management in furrow-irrigated wheat production systems. 510

Session 2.3: Resource use at crop level. 511 Introduction: A.J. Haverkort, M.J Minguez

The efficient use of water and nitrogen in arable farming in Europe: is there scope for improvement? 512

IV Book of Abstracts 4th ESA-congress

A. A bad, J. Lloveras, A. Michelena Effect of soil nitrate and N fertilization on bread and durum wheat yield and quality and on residual N-NO3 concentrations under irrigation in Ebro Valley (Spain). 514

L. G. Angelini, M. Mazzoncini, L. Ceccarini Changes in photo synthetic capacity associated with soil water depletion in maize grown under conventional and minimum tillage. 516

M. Aydin Response of cotton to nitrogen and water in a subtropical environment. 518

P. Barberi, M. Ginanni, S. Menini, N. Silvestri, M. Mazzoncini Effect of tillage systems on weed presence and diversity in a continuous maize cropping system. 520

R.J. Bryson, W.S. Clark, N.D. Paveley Explaining the yield response of winter wheat due to fungicides by the effects on green leaf area duration and radiation interception. 522

A.M. Castelao, M.J. Sâinz, M. Bujân Variation of the soil humidity in an ecological culture of asparagus (Asparagus officinalis L.) in Galicia (N.W.Spain). 524

P. Castillon, A. Bouthier Correction of zinc and copper deficiencies on maize crops. 526

B. Chauvel, C. Angonin, N. Colbach Black-grass (Alopecurus myosuroides Huds.) development and seed production in wheat. 528

B. Colomb, G. Fayet, C. Villette, M. Gigout, P. Dubrulle, D. Baudet Soil analyses and fertilizer recommendations. Software for soil test laboratories and extension services. 530

Z.M. Copchyk, A. Y. Maruhnyak The reaction of cultivars spring barley to fertilisers and sowing rates of the seed under condition of West Region of Ukraine. 532

F.J. De Ruijter, A.J. Haverkort Potato crop growth and nutrient concentration as influenced by soil-pH and potato cyst nematodes. 534

G Deffune, A.M. Scofield, H.C. Lee, J.M. Lopez-Real, P. Simünek Influences of bio-dynamic and organic treatments on yield and quality of wheat and potatoes: the way to applied allelopathy? 536

S. Demotes-Mainard, M.H. Jeuffroy Effects of nitrogen deficiencies on grain set in wheat. 538

K.J. Doughty, C. Lewis, H.A. McCartney, G Norton, E.J. Booth, K. Walker Oilseed rape oil yield and quality in relation to fungal disease. 540

M. Durkic, M. Knezevic, I. Juric Relationship between weed level and leaf area in inbred maize lines. 542

JE. Fernandez, J.M. Murillo, F. Moreno, F. Cabrera, E. Fernandez-Boy Reducing fertilization for maize in south-west Spain. 544

J. Fismes, P.C. Vong, A. Guckert Ammonium thiosulphate (ATS) as an environmentally friendly tool for N and S nutrition ofrapeseed (BrassicanapusL). 546

E. Fotyma, M. Fotyma Water and nitrogen budget of spring barley field. 548

M. Fotyma, E. Fotyma Water and nitrogen budget of winter wheat field. 550

Contents Volume II V

M. Galan, N. Lisova High-yield varieties of winter vetch and use of variey-strain technology for their growing. 552

M. Guiducci, P. Benincasa, M. Migni Effect of nitrogen fertilisation on leaf photosynthesis and light absorption in tobacco. 554

M. Jolânkai, Z Szentpétery, T. Szalai Variety specific weed tolerance - a key to non chemical weed control. 556

M. Knezevic, I. Zugec, I. Juric, M. Durkic Soil tillage as an important measure in weed control for winter wheat (Triticum aestivum L). 558

J. Kren Possibilities of using modular growth and plant hierarchical structure to evaluate resource use in cereal growing. 560

J. Kren Comparison of ecological and conventional cropping practices of cereals under fertile conditions in Central Moravia. 562

M. Kruse, W. Aufliammer Evaluation of alternative grain crops in south-west Germany: nitrogen economy. 564

B. Kulig, W. Ziólek Productivity of horse bean in relation to the nitrogen fertilization. 566

A. Lange, H. W. Scherer Effect of sulphur nutrition on the activity of nitrogenase and enzymes of the C- and N-metabolism of Vicia faba minor and Pisum sativum. 568

F. Lasserre, B. Jouan, R. Rivoal Optimal use of resistance for an integrated management program of cereal nematode populations. 570

N. Lisova, M. Galon, V. Patyka, M. Bezdushny, A. Pogorecky Use of associative diazotrophs for nitrogen nutrition of gramineous crops. 572

N. Losavio, N. Lamascese, F. Serio, A. V. Vonella Estimated radiation use efficiency on alternative crops under typical mediterranean conditions. 574

M. Maiorana, R. Colucci, D. Ventrella Crop residues and soil tillages management: effects on soil strength. 576

E. Nâdasy Study on the effect of N-fertilizers on total nitrogen and nitrate content of green pea and garlic. 578

J. Nagy, L. Huzsvai, J. Tamos, G.J. Kovâcs, I. Mészâros The effects of irrigation, fertilization, tillage and plant density on corn {Zea mays L.) yield. 580

L. Neudert, J. Kren Energetic analysis of European winter wheat management practices compared at the DLG-Feldtage in Germany. 582

D.J. Pantone, J.R. Kiniry Integrating weed-crop competition into a process-oriented crop growth model: Evaluation of cocklebur competition with soybean. 584

F. Promayon, C. David Nitrogen nutrition management in winter wheat in organic farming. 586

R. Reau, C. Colnenne, D. Wagner Nitrogen fertilization needs of rapeseed in autumn. 588

VI Book of Abstracts 4th ESA-congress

R. Richter, Z. Poulik, J. Rihmovâ Efficiency of different technologies for the application of fertilizers to cereals. 590

J. Rozbicki, W. Madiy, M. Kalinowska-Zdun, Z. Wyszynski Yielding of winter triticale var. Presto under low input and intensive methods of crop management. 592

K.D. Sayre, C. van der Wilk Lower yield loss due to diseases in newer wheat varieties. 594

J. Schouls, G.O. Nijland Input, output and residue of nutrients. 596

L.P. Simmonds, C.C Daamen, C.J. Pilbeam Factors influencing crop water use efficiency. 598

CO. Stockle, P. Debaeke Modelling crop N requirements: a critical analysis. 600

F. Tei, A. Onofri, M. Guiducci Relationship between N-concentration and growth in sweet pepper. 602

A.J. Valentine, B.A. Osborne, D. T. Mitchell Effect of mycorrhizal infection on photosynthetic metabolism. 604

R. van den Boogaard, K. Thorup-Kristensen Effects of defoliation on growth of cauliflower. 606

P.E.L. van der Putten, G. Posca, J. Vos Effect of nitrogen supply on leaf growth and photosynthetic capacity in potato. 608

M. Volterrani, M. Gaetani, N. Grossi, G. Pardini, S. Miele, G. Scalabrelli Ground cover in vineyards with grass and legume species in pure and mixed stands. 610

M. Wesolowski, M. Jedruszczak Yield of sugar beet using alternatives for farm yard manure. 612

W. Ziólek, B. Kulig Effects of foliar fertilization with nitrogen and microelements on seed yield of peas. 614

Agroforestry Session 617

D. Auclair Alternative agricultural land use with fast growing trees: scientific bases and model for European agroforestry. 618

H. Breman, J.J. Kessler The potential of agroforestry for Sahelian countries. 620

J.G. Conijn Simulation of long term carbon dynamics and nitrogen yield of an agroforestry system in a semi arid region. 622

J. Dauzat, M. Eroy, M.L. Girard Radiative climate modelling on virtual cococuts stands for predicting the light regime in coconut based farming systems. 624

A.M. Heineman On station evaluation of Leucaena, Calliandra, Gliricidia, Sesbania, Senna and Erythrina species in alley cropping with maize in western Kenya. A long term experiment: 1988-1994. 626

Contents Volume II VII

A.M. Heineman Seasonal and long term effects oîLeucaena leucocephala hedgerows and inorganic sources of N and P on the productivity of maize - bean systems in western Kenya, with comparative nutrient use efficiencies of different fertiliser alternatives. Along term experiment: 1988-1994. 628

GM. Hoppe, A.R. Sibbald, J.H. McAdam, W.R. Eason, M. Hislop, Z. Teklehaimanot The UK national network silvopastoral agroforestry experiment - a co-ordinated approach to research. 630

J.E. Lott, CR. Black, CK Ong The physiological constraints on crop growth in dryland agroforestry. 632

J. Park, S.H. Newman Tree-soils interactions in poplar-arable agroforestry systems. 634

M. van Noordwijk Below- and above ground resource capture in agroforestry systems. 636

Division 1: Crop physiology, production and management. 639

A.S. Alexieva, M. Kilifarska Investigating the air humidity in the environment of plants by using an electric thermal measuring transducer. 640

S.J. Crafts-Brandner, R. Hölzner, U. Feller Stromal enzymes in N-deficient wheat: mRNA and protein quantities. 642

T. Gebbing, H. Schnyder Is immobilzation of pre-anthesis reserves reflected in dry matter loss from vegetative plant parts of wheat? 644

T. Gebbing, H. Schnyder, W. Kühbauch Contribution of pre-anthesis reserves to grain filling of spring wheat: assessment by steady-state 13C02/

12C02 labelling. 646 M.P. Guinchard, Ch. Robin

Contribution of carbohydrates to winter survival and spring regrowth of white clover ( Trifolium repens L. ). 648

H. Lipavskä, L. Nâtr Contribution of in vitro plant cultures to the study of mineral nutrition. 650

R. Maciorowski, S. Stankowski, G Podolska, A. Pecio Application of different functions to the description of growth of buckwheat (Fagopyrum esculentum Moench). 652

I. Maurice, F. Gastal Anatomical and biochemical changes of grass leaves during development. 654

N. Mladenov, N. Przulj, N. Hristov, Y. Yan, S. Prodanovic, S. Vuckovic Studies on the accumulation of gliadin proteins during wheat grain development. 656

R. Mosquera, E. Corral, A. Castelao, E. Lopez, C Moirón, A. Rigueiro, J. Villarino Comparison of two destructive methods in the estimation of grassland production. 658

R. Mosquera-Losada, A. Gonzalez-Rodriguez Study of non destructive method of dry matter yield estimation in dairy rotational system. 660

J. Pawlowska, D. Dietrych-Szóstak, A. Pecio Response of buckwheat varieties grown on different soils to dimetipin. 662

R. Pfarrer, U. Feller Influence of inorganic nitrogen on senescence and protein remobilization in flag leaves of maturing wheat grown on waterlogged soil. 664

VIII Book of Abstracts 4th ESA-congress

K. Streiff, A. Blouet, A. Guckert Water deficit and pollination potential of wheat (Triticum aestivum L) . 666

Division 2: Agroclimatology and modelling. 669

V. Magliulo, F. De Lorenzi, L. Lustrini, A. Pitacco Estimating zero plane displacement and roughness parameters in a sunflower crop. 670

Division 3: Plant-soil relationships. 673

A.S. Alexieva Results from an investigation on the heat flux density in soil on the base of thermoelectric and conductometric transducers. 674

N.P. Buchkina, T.S. Zvereva Relations between stability of tundra soils affected by mechanical impacts and plant community composition. 676

M. Bzowska-Bakalarz Factors determining the values offerees needed for pulling out sugar beet roots from the soil. 678

H. V. Halmajan, L. Ungurean, A. Dobrescu, V. Stefan, I. Savulescu Effect of soil compaction on nodule structure in soybean. 680

J. Matula Evaluation of potassium status of soils. 682

M. Mazzoncini, E. Bonari, M. Ginanni, S. Menini, F. Sancarlo Earthworms presence as affected by tillage system in clay soil. 684

L. Szabó Effect of toxic metals on the germinating ability of winter wheat. 686

L. Szabó Trace elements supply of the arable land in Hungary. 688

Division 4: Crop quality and post-harvest physiology. 691

F. Borowiec, E. Pisulewska, K. Furgal Mixed cereal-vetch forage as a silage crop in sustainable farming. 692

J. Crnobarac, B. Marinkovic Effect of environmental factors, genotype and period of harvest on post-harvest ripening of sunflower. 694

M. Malesevic, Lj. Starcevic, D. Bogdanovic, N. Przulj Relationship between soil nitrate content and grain protein content in malting barley {Hordeum sativum ssp. Distichum). 696

I. Pâlinkàs Examination of the organic growth of five silage maize varieties by applying statistical approaches. 698

V.J.H. Sewalt, J. W. Blount, R.A. Dixon Metabolic engineering of lignin through flux control in the phenylpropanoid biosynthetic pathway. 700

Contents Volume II IX

Division 6: Agriculture-environment relationships. 703

J. Balik, P. Tlustos, J. Szakova, V. Vanek The effect of different forms of nitrogen fertilizers on the accumulation of cadmium and zinc in plant tissues. 704

L. Fodor Effect of toxic elements on the winter wheat on brown forest soil. 706

N. Kharitonov, M. Bulgakova, V. Pashova, I. Onuphrieva Growing the plants on the soil polluted by heavy metals. 708

D. Pavlikova, V. Vanek, J. Szakova, J. Balik The accumulation and distribution of cadmium, zinc and arsenicum by poppy. 710

V.A. Pozdnyakov, A. Kudums, I. Drizhachenko Heavy metals and differentiation of perennial grasses in the pathogen resistance character. 712

P. Tlustos, J. Balik, J. Szakova, D. Pavlikova The effect of soil remediation treatments on plant uptake of cadmium, zinc and arsenic. 714

H.M.G. van der Werf, C. Zimmer Evaluating the impact of pesticides on the environment using an indicator based on fuzzy coded variables. 716

Author index 719

Subject index 727

National representatives 734

ESA Executive committee 736

Plenary introduction of Theme 2

Integrated and ecological agriculture.

404 Book of Abstracts 4th ESA-congress

A METHODICAL WAY OF PROTOTYPING INTEGRATED AND ECOLOGICAL ARABLE FARMING SYSTEMS (I/EAFS) IN INTERACTION WITH PILOT FARMS

P. Vereijken, AB-DLO, P.O. Box 14, 6700 AA Wageningen, The Netherlands

Introduction The European Union (EU) is facing an agricultural crisis with two major symptoms: deterioration of rural income and employment and deterioration of environment, nature and landscape. The basic mechanism is a never ending intensification causing surplus production and price fall on the one hand and ecological deterioration on the other hand. Therefore, a crucial question for the Common Agricultural Policy (CAP) is to alleviate the symptoms of intensification on the short term and to find a sustainable solution on the long term. In the early nineties, various EU-countries started promoting Integrated Farming Systems to alleviate the agricultural crisis, when drastic reductions in inputs of pesticides and fertilisers were achieved with initial prototypes on experimental farms. Subsequently, in 1993 the EU-Commission invited the author to act as coordinator of a network of research teams on Integrated Arable Farming Systems (IAFS). The setting up of the network should be combined with development and standardisation of the methodology in a concerted action within the third EU framework programme for agricultural research called AIR. Most research teams joining the network develop IAFS prototypes feasible for the main group of farms. This group must try to be competitive on the world market, based on high and efficient production, and this gives only limited scope for pursuing non-marketable objectives such as environment, nature/landscape and sustainability of food supply. Therefore, a more consistent integration of objectives is needed for a sustainable solution of the agricultural crisis. Consequently, many research teams also or exclusively develop an IAFS for the long term, albeit that this IAFS is as yet only feasible for pilot groups of farms. Contrary to short-term IAFS, these long-term IAFS place income/profit subordinate to environment, and rely on ecologically-aware consumers willing to pay premium prices for food products with high added value and a credible label. The latter implies the sharing of responsibility by producers and consumers for a multifunctional and sustainable management of the rural areas. Social conversion to this market model seems the only sustainable solution to end intensification and replace it by a socially controlled and ecologically responsible technology development, notwithstanding a free world market. In the long-term IAFS, Chemical Crop Protection is fully replaced by a package of non-chemical measures, to achieve ambitious objectives in environment, nature/landscape and quality and sustainability of food supply. So, long-term IAFS are based more on ecological awareness and knowledge than short-term IAFS. Therefore, our prototypes of long-term IAFS are simply called EAFS (Ecological Arable Farming Systems), and short-term IAFS are referred to as IAFS. However, it should be explicitly stated that EAFS are not the same as the organic farming systems that currently feature under an official European label. Organic systems can be considered to be a forerunner of EAFS, but they have no quantified objectives in environment and nature/landscape and as a result, they need to be considerably improved to become acceptable to the majority of consumers. Nevertheless, organic farming has a strategic significance to Europe because it is the first example of the market model of shared responsibility of consumers and producers for the rural areas. Therefore, many research teams are collaborating with a pilot group of organic farms which have primarily been selected for their willingness to achieve more than is required by current minimal guidelines of the EU organic label. Selected on a set of general and specific criteria, 22 research teams from 14 EU and 3 associated countries have been brought together into the network, since the start in 1993. Together they invest more than 30 scientist years per annum in prototyping. This paper focusses on a methodical way of 5 steps we have developed within the network as a common frame of reference for prototyping I/EAFS. The consecutive steps will be presented and illustrated by the state-of-the-art of the author's own project on EAFS with a group of pilot farms (NL 2).

Methodical way of prototyping I/EAFS (5 steps) Building on initial experience with an experimental farm at Nagele (Vereijken, 1992) and the input of the research leaders from the network, prototyping of I/EAFS has been elaborated in a

Plenary introduction of Theme 2 405

methodical way of 5 formal steps (Vereijken, 1994, 1995), (Outline 1). The outcome of these 5 steps is expressed in parts of an identity card for the prototype to facilitate the cooperation within the team and the exchange with the other teams in the network. In the full paper the 5 steps will be explained in more detail and illustrated by the various parts of the identity card of our prototype EAFS for the central clay region in The Netherlands (NL 2).

Outline 1. Methodical way of designing, testing, improving and disseminating prototypes of Integrated and Ecological (Arable) Farming Systems (I/EAFS).

(1) Hierarchy of objectives: making a hierarchy in 6 general objectives, subdivided into 20 specific objectives as a base for a prototype in which the strategic shortcomings of current farming systems are replenished (Part 1 of the identity card of a prototype).

(2) Parameters and methods: transforming the major (10) specific objectives into multi-objective parameters to quantify them, establishing the multi-objective methods needed to achieve the quantified objectives (Part 2 of the identity card).

(3) Design of theoretical prototype and methods: designing a theoretical prototype by linking parameters to methods (Part 3 of the identity card), designing methods in this context until they are ready for initial testing (Multifunctional Crop Rotation as major method and Part 4 of the identity card).

(4) Layout of prototype to test and improve: laying the prototype out on an experimental farm or on pilot farms in an agro-ecologi-cally appropriate way (Part 5 of the identity card), testing and improving the prototype in general and the method in particular until (after repeated laying out) the objectives, as quantified in the set of parameters, have been achieved. (Part 6 of the identity card).

(5) Dissemination: disseminating the prototype by pilot groups (< 15 farmers), regional networks (15-50 farmers) and eventually by national networks (regional networks interlinked) with gradual shift in supervision from researchers to extensionists.

References Anonymous (1977). An approach towards integrated agricultural production through

integrated plant protection. I0BC/WPRS Bulletin no. 4, 163 pp. El Titi, A., Boiler E.F. & J.P. Gendrier (1993). Integrated production, principles and technical

guidelines. Publication of the Commission: IP-guidelines and endorsement. IOBC/WPRS Bulletin no. 16, 96 pp. ISBN 92-9067-048-0.

Geier, B. (1991)(Ed.). IFOAM basic standards of organic agriculture and food processing, 20 pp. Oecozentrum Imsbach, D-66696 Tholey-Theley (Germany).

Gibbon, D. (1994). Farming systems Research/Extension: background concepts, experience and networking. In: Dent J.B. and M.J. Mc Gregor (Eds.) Rural and farming Systems analysis. European perspectives. Proceedings of the first European Convention on Farming Systems Research and Extension, Edinburgh 1993:3-19. AB International. ISBN 0851989144.

Rohling, N. (1994). Interaction between extension services and farmer decision making: new issues and sustainable farming. In: Dent J.B. and M.J. Mc Gregor (Eds.) Rural and farming Systems analysis. European perspectives. Proceedings of the first European Convention on Farming Systems Research and Extension, Edinburgh 1993: 280-291. AB International ISBN 0851989144

Vereijken, P., C.A. Edwards, A El Titi, A. Fougeroux & M. Way (1986). Report of the study group: Management of farming systems for Integrated Control. IOBC/WPRS Bulletin no. 9. ISBN 92-9057-001-0.

Vereijken, P. (1992). A methodic way to more sustainable farming systems, Netherlands Journal Agricultural Science (40):209-223.

Vereijken, P. (1994). Designing prototypes. Progress report 1 of the research network on Integrated and Ecological Arable Farming Systems for EU and associated countries, 90 pp. AB-DLO Wageningen (Netherlands).

Vereijken, P. (1995). Designing and testing prototypes. Progress report 2 of of the research network on Integrated and Ecological Arable Farming Systems for EU and associated countries, 90 pp. AB-DLO Wageningen (Netherlands).

Session 2.1

Designing farming systems: methodological aspects.


METHODOLOGY FOR DESIGNING SUSTAINABLE FARMING SYSTEMS: PROTOTYPING AND MODEL-BASED EXPLORATIONS IN A PARTICIPATORY RESEARCH SETTING

J.M. Meynard1 and W.A.H. Rossing2

1 Unité d'Agronomie INRA-INA PG, F-78850 Thiverval-Grignon, France 2 Dept. Theoretical Production Ecology, WAU, PO Box 430, 6700 AK Wageningen, the Netherlands

Introduction In many parts of Europe, agriculture has been very successful in increasing yields per unit of area. At the same time, the production techniques that have been employed, have resulted in unwanted side effects: emissions of pesticides and plant nutrients, (in)organic waste, high energy consumption. Public concern is reflected in a suite of national and international policy statements. More sustainable agricultural land use requires production systems which, in addition to economic objectives, cater to objectives in areas of environment, public health, rural scenery and nature. Since these objectives are at least partially conflicting, development of sustainable farming systems is equivalent with searching for acceptable compromises between objectives using all technology available. What ensues is a process of negotiation about objectives and learning about production techniques and their interaction with objectives. The challenge for agricultural research is to develop methodology to facilitate these processes and help to develop technologies and systems that enable combination of, to date, conflicting objectives. During the last decade, prototyping and model-based exploration have emerged as promising approaches in sustainable farming systems research. Prototyping involves application-oriented development of sustainable farming and cropping systems in collaboration with commercial farmers or at experimental farms according to a methodical approach (Vereijken, 1992). Model-based explorations have been conducted at the field level and at the farm level, improving decision making (Meynard & Girardin, 1991) and exploring bio-physical possibilities for achieving economic and environment-oriented objectives (Rossing et al., 1996). From the case studies available to date, four phases emerge in development of sustainable farming systems: diagnosis, design, testing and improving, and dissemination. We will discuss methodical aspects of each phase and emphasize the distinct and complementary role prototyping and model-based explorations play. Two illustrations will be provided, one on cereal crops in France, the other on flower bulb dominated rotations in the Netherlands.

Phase 1 - Diagnosis In contrast to adoption of traditional, discipline-driven, tactical innovations in the production process, a change towards more sustainable production systems usually involves a turnaround in the entire farm operation. Such strategic innovation is only possible when farmers and their social environment are aware of current constraints and motivated towards change. Operating in a network as a means to deal with uncertainties associated with major changes in farming practice often appears essential. Often, registration and comparison of farm activities by farmers constitutes an important method to increase awareness. Research may enhance the diagnosis phase by analysis of existing production methods at two levels. At the field level characteristics of the cropping systems are identified which determine yields, quality, and environmental aspects (Doré et al., 1996). At the farm level agro-ecological and economic indicators are used to indicate opportunities for change. The diagnosis phase results in a strategic alliance of "stakeholders" with

Session 2.1 409

a common motivation to explore alternative ways of agricultural production.

Phase 2 - Design The products of the design phase are a number of theoretical prototypes of sustainable cropping and farming systems. The process follows the steps of industrial design, starting with identification of the objectives including units in which the design is to be evaluated, followed by appraisal of production techniques in terms of these objectives, and searching for blends of production techniques which satisfy the objectives. The result is a perspective on development options based on the trade-off between e.g. economic and environmental objectives, which provides a basis for selection of promising theoretical prototypes. Tools in this phase range from interactive simulation systems, to expert systems and multiple goal linear programming models and are used as part of workshops. Research has a synthesizing role, providing information on production techniques and their relation to objectives in an educational setting aimed at stimulating the design process.

Phase 3 - Testing and improving The theoretical prototypes that emerged from the design phase are evaluated and improved with respect to comprehensiveness, acceptability, workability, and effectivity. Evaluation may be executed on experimental farms, commercial pilot farms, or in decision rule based cropping systems experiments. While an experimental setting enables comparison between alternative prototypes, important constraints on commercial farms may be disregarded. Cropping systems experiments in which production methods are tested subject to constraints and decision rules prevailing on commercial farms, contribute to improving prototypes (Meynard & Girardin, 1991).

Phase 4 - Dissemination Dissemination of the regionally adapted prototype requires processes and tools similar to those of testing and improving, since in this phase the regional prototype is adapted to local conditions and individual constraints. Results of the diagnosis phase reveal the diversity of farm constraints the prototypes have to be adapted to, and provide support in the dissemination phase. Approaches range from guided implementation of integral prototypes to introduction of components, such as integrated nutrient management. While in the process agronomic uncertainties have been made manageable, psychological and social uncertainties appear to be still large in this phase. Thus, in addition to technical monitoring, sustained attention for facilitating learning processes is needed.

Conclusion Despite the general distinction of four phases, we observe important differences in approaches between countries, both regarding the nature and the role of agronomic research. It will be necessary to increase methodical comparison and reciprocal enrichment in order to improve methodology for designing new and sustainable farming systems.

References Doré, T., et al, 1996. A diagnosis method on regional crop yield variations. Submitted to Agricultural Systems. Meynard, J.M. & Girardin, P., 1991. Le Courrier de l'Environnement de l'INRA 15:1-19. Rossing, W.A.H., et al, 1996. Between market and environment: exploring options for environmentally friendlier flower bulb production systems. Submitted to European Journal of Plant Protection. Vereijken, P., 1992. Netherlands Journal of Agricultural Science 40:209-223.


MINIRHIZOTRON AND SOIL MONOLITH COMPARISON OF ROOT DISTRIBUTION IN PURE AND MIXED STANDS OF MAIZE AND ITALIAN RYEGRASS

H. Bürgi, W. Richner, A. Soldati, P. Stamp

ETH Zürich, Institute of Plant Sciences, ETH-Zentrum, CH-8092 Zürich

Introduction

The minirhizotron technique has often been used to non-destructively analyse plant root growth and dynamics, because it is less labour-intensive than destructive methods and allows the roots to be repeatedly observed over longer periods of time. However, numerous studies with minirhizot-rons buried at an angle to the soil surface have shown that a universally applicable calibration of minirhizotron root counts with root length density is not possible (Smit et al, 1994). Fewer calibration experiments have been carried out with horizontally buried minirhizotrons. Therefore, we compared root distributions determined using horizontally installed minirhizotrons and soil monoliths in both pure and mixed stands of maize (Zea maize L.) and Italian ryegrass (Lolium multiflo-rum L.). The latter system, Le. sowing maize into living ryegrass sods (Garibay and Feil, 1996), is propagated in Switzerland because it may alleviate problems associated with traditional cropping of maize such as soil erosion and nitrate leaching.

Methods Plants were grown in a greenhouse in boxes of 75 cm length, 55 cm width and 90 cm depth, which were filled with sandy loam soil to a bulk density of 1.2 Mg m""3. During filling, minirhizotrons were installed horizontally at depths of 10, 20,40, 60, and 80 cm. Corresponding to a planting density of 10 plants m~2, maize was sown in a row perpendicular to the minirhizotrons. The ryegrass was sown at a density of 3 g m-2, covering the entire soil surface. After establishment of the ryegrass stands, a 30 cm wide strip in the middle of each box was killed off using Roundup®. For the mixed stand treatment only, maize was sown in the resultant strip of exposed soil ten days after killing of the swards. To alleviate competition with the maize crop, ryegrass regrowing in the strip was cut three times during early growth of the maize. Plants were harvested at the time of maize silking. When the recording of the upper sides of the minirhizotron tubes with a Bartz® camera system was completed, soil samples (7.5 cm length, 6 cm width, 5 cm height) were taken from directly above the minirhizotron tubes to determine volumetric root length density. There were three replications.

Results Root length density was greatest in the mixed stands in both the row and inter-row regions for all soil depths except 60 cm and smallest in the row region under maize to a depth of 40 cm. At greater depths, maize rooting density was comparable to that of mixed stands in both row and inter-row regions due to the more shallow root system of ryegrass (data not shown). These vertical distributions of root length densities were poorly represented by minirhizotron root numbers, especially in maize and mixed stands of maize and ryegrass (Fig. 1). Rooting density seemed to be significantly underestimated in ryegrass at 10 cm depth, and in maize and the maize-ryegrass mixture at depths from 10 to 20 cm and below 60 cm. In similar fashion, Andren et al. (1993) found an underestimation of root growth using horizontal minirhizotrons in the topsoil (0 -30 cm) under barley.

Session 2.1 411

Inter-row region Row region

10 cm 20 cm 40 cm

EX3 60 cm ^ 3 80 cm

M MR Maize -

Ryegrass

M MR

Ryegrass

M MR

Maize Maize -

Ryegrass

Figure 1. Depth distribution of root length density from soil monoliths (M) and minirhizotron root numbers (MR) in the row and inter-row regions of pure and mixed stands of maize and Italian ryegrass at the time of maize silking.

In agreement with the relationship between depth profiles of root length density and minirhizotron root numbers, there was a close overall correlation between these two parameters in ryegrass only (r=0.92) (Fig. 2). The same relationship was weak in maize, and, corresponding to the closer correlation in ryegrass, slightly better in the mixed stands. Poor correlations between monolith and minirhizotron data in maize were also found by Majdi et aL (1992). A more regular horizontal distribution and a more uniform growth direction of the highly branched ryegrass roots in the soil may have been responsible for the better correlation between root length density and root numbers in ryegrass, but this hypothesis and the lack of correlation in maize need further investigation.

f : *• ? * Î 3 f 2 .2

i '

Ryegrass

• /

f m

0 1 2

number of roots (cm -2)

Maize

•

* • j i r

~y^, ' • ) 1 2

number of roots (cm"2)

Maize - Ryegrass

• X

• '. - y* • X • X

• X • Xm

./ •

) 1 2 3

number of roots (cm -2)

Figure 2. The relationship between minirhizotron root numbers and root length density in adjacent bulk soil in Italian ryegrass, maize, and the mixture of both species. The regression lines forced through the origin are shown.

Conclusions Horizontally installed minirhizotrons did not reliably reflect the vertical root distribution. As with minirhizotrons installed at an angle, there was an underestimation of rooting density in the topsoil using horizontal minirhizotrons. Overall, correlation between root length density and minirhizotron root numbers was much closer in Italian ryegrass compared with maize and the mixture of both species.

References Andren, O. et al., 1993. Swedish Journal of Agricultural Research 23: 115 - 126. Garibay, S.V. and Feil, B., 1996. This Book of Abstracts. Majdi H. et al., 1992. Plant and Soil 147: 127 - 134 Smit AL. et aL, 1994. Plant and Soil 161: 289 - 298


ECOLOGICAL BASIS FOR SUSTAINABLE PEST MANAGEMENT SYSTEM

N. Babich and I. Grichanov

All-Russian Plant Protection Institute, Sh. Podbelskogo 3, St.-Petersburg-Pushkin 189620 Russia

Introduction Basis for sustainable pest management system is in agroecology - the applied field of ecology, that study influence of environmental factors (biotic and abiotic) on crop productivity, on structure and dynamics of arable land associations and their feedback. Pest outbreaks are a regular feature of agricultural ecosystems (Southwood and Way, 1970). Plant-herbivore interactions are an important component within agricultural ecosystem as herbivore animals become agricultural pests. Herbivores represent part of the consumer component of the ecosystem.

Nevertheless, human-controlled agricultural ecosystems still develop under natural climate and weather conditions in accordance with basic ecological laws.

Overview 1. Influence of the weather. Only certain weather conditions are favorable for herbivore

population growth, though it usually explains about 70% of variability, as in our research on dynamics of common vole populations in North Caucasus region (Babich 1991). Climatic factors for all organisms work as regulators of their life cycles and activity rhythms. The phyto sanitary forecasts still can not be based on weather forecast, as its accuracy is not sufficient. The weather forecast mistake will be multiplied in phytosanitary forecast. So climatic factors are used not in the form of weather forecast values, but as analyses of up-to-date situation. This approach assumes that vitality of any organism is formed during its ontogeny, under impact of the environment, including climatic factors . 2. Plant-herbivore interactions. Interactions between grazing animals and their food plants are known to involve: (1) response of feeding rate to the structure of the vegetation; (2) transfer of plant material to saprophages in the form of faeces; (3) selective use of different plant species by the grazers; (4) effects of canopy structure on photosynthesis rate; (5) differences between plant species in their response to grazing, (Newman E. 1993 ) (6) selection of plants specimens on earlier phenological phase by grazers (Bashenina, 1962; Abaturov, 1984 ; Babich 1994). 3. Population cyclicity. Most of phytophages' populations in agricultural ecosystems show cyclicity, that means seasonal and annual fluctuations in population density. Population dynamics of pest species is a result of phenotypic variability, caused in certain periods of a life cycle. This variability is caused by climatic factors and energy resource. Sometimes it is adaptive, but with the same probability it will not be adaptive for future season. That is why population dynamics depend on past conditions - when development occurs, and on future - were population will get (Poliakov, et al. 1995).

Results of field experiments For a couple of years common vole (Microtus arvalis Pall.) - a rodent pest has been studied. Its impact is most serious on winter wheat crops. It could be adopted that the most severe is those damage, that is registered on inhabited through the summer voles colonies, or noticeable spots of thinned out crops. Following calculation show how to make rough estimate of colony's density per 1 hectare of crops, brining to economical significant winter wheat crops loss. According to our preliminary data crops loss per one colony (L\k) -equals 70% in average. Square of colony {S\k ) o n phase of depression equals 10 i2 in average. So we can try to

Session 2.1 413

estimate critical density of colonies per 1 hectare(£) ) that will lead to economically significant crops loss (Ls) - let it be 10% per hectare.

= SyrLA = 1 2 ^ i ^ i = i 4 2 . 8 colonies/hectare, L\k 70%

where D - critical density of colonies per 1 hectare ',S\k~ average square of 1 colony;

Ls - economically significant crops loss (%);L\k - crops loss per one colony (%). When crops loss from one colony is determined we can estimate crops loss from the field:

L\k-Dha f S ik

where Lf- crops loss from the field; L\k - crops loss per one colony;

Dha' density of colonies per 1 hectare; S\k ' average square of 1 colony.

Conclusions Ecological basis for sustainable pest management system is in understanding of nature of phytophages' populations in agricultural ecosystems. The vitality of organism is formed during its ontogeny, under impact of the environment, including climatic factors . Pest populations dynamics depend on past conditions - when development occurs, and on future - were population will get. In pest populations monitoring the climatic factors are used not in the form of weather forecast values, but as analyses of up-to-date situation. The preliminary results suggest that severity of common vole damage in winter wheat crops, should not be overestimated. Economically significant losses will bring pest attack, when rodent's population density exceed 100 colonies per 1 hectare. The main goal of the future study will be improvement of existing models of damage of common vole, that should consider phase of population cycle, characteristics of wheat varieties in response to grazing and preceding crops in crop rotations and impact of climatic factors. We look forward to create a computerized version for the estimation of economical threshold of damage.

This work has been supported by a grant from the Department of Environmental Sciences and Policy of the Central European University and the Higher Education Support Program.

References AbaturovB. D., 1984. Mlekopitajushie kak element ekosistemy. M. Nauka, 280 s (in

Russian) /Mammals as the element of ecosystem. M. Nauka, 280 p Babich N. V., 1991 Proc. of Conf. Agrometeorological resources and production processes,

Kiev, (in Russian) pp. 21-23 Babich N.V., 1994 Proc. of 75th, Anniversary American Mammology Society Meeting,

Washington D C , pp. 14-15 BasheninaN. V., 1962 Ekologiya obyknovennoi poliovki, M. 310 s. Newman E., 1993. Applied Ecology, by Blackwell Scientific Publications, 328 p Poliakov I. Ya. , Levitin MM., Tansky V.l., 1995. Phytosanitarnaya diagnostika v

integrirovannoi zashite rastenii. Moskva, "Kolos", 208 c. Southwood R. and Way 1970. Concepts of pest management, Rabb & Gurthrie (eds)

N.C.St. Univ., Raleigh, pp. 110-120


USE OF AGRO-ECOLOGICAL INDICATORS FOR THE EVALUATION OF FARMING SYSTEMS

C. Bockstaller ] , P. Girardin 2

1 Association pour la Relance Agronomique en Alsace (ARAA), INRA, Laboratoire d'Agronomie, BP 507, 68021 Colmar Cedex, France. 2 INRA, Laboratoire d'Agronomie, BP 507, 68021 Colmar Cedex, France.

Introduction For the development of Integrated Arable Farming Sytems (LAFS) tools are needed to evaluate the achievement of agronomic and environmental objectives, in order to optimize the system (Vereijken, 1992). Measurements, (e.g. nitrate content in ground water) are time consuming and costly, whereas models are often not adapted for use at farm level (Sharpley, 1995). Another solution is to use indicators, which help to interpret a complex system (Girardin et al., 1996). We propose a set of agro-ecological indicators (AEI) as decision aid tools, to help the farmers to adapt their cultivation practices to IAFS requirements.

Methods The AEI values range from 0 to 10. The value 7 is arbitrarily chosen to represent the achievement of "realistic" IAFS requirements. A value below 7 indicates that these IAFS requirements are not achieved and a value above 7 indicates that the fanner does better than the "realistic" IAFS requirements. The AEI are calculated with the data available on the farm (cultivation pratices recorded by the farmer, soil analyses, steady data such as field size, slope ...). Most of them are calculated at the field level and then weighted by the field size to obtain a mean value at the farm level. The calculation of most of them is based on the comparison of the farmer's cultivation practices with IAFS recommendations. An example is given in Bockstaller et al. (1996). Several of the IAE can also be used to estimate the impact of the farming system on the environment. We assume that, in general, the less IAFS requirements are met, the greater the negative impact on the environment will be.

Results So far, six indicators have been elaborated for the evaluation of: crop diversity, crop succession, nitrogen, phosphorus, organic matter and irrigation management. Indicators for: pesticide, energy, ecological structures are being tested. The elaborated indicators were calculated in 1994 and 1995 with data from a network of 17 commercial arable farms. Figure 1 shows a presentation which gives an overview of the results at the farm level, showing the weak and strong points of arable farming systems as assessed by IAFS requirements. For each indicator, results at the field level are available to help the farmers take into account the differences between the fields. This kind of indicator can be used by decision makers to follow up the evolution of cultural practices and the influence of a agri-environmental policy as shown in Figure 2 for the nitrogen management indicator. The reliability of the AEI is tested by means of a probability test (Girardin et al., 1996): the relationship between an EAI and an environmental parameter is expected to be in the form of a probability area, delimited by a boundary line. Thus, the EAI reflect a potential environmental impact of the farming system. This is shown by Figure 3 in the case of the nitrogen management indicator. Girardin et al. (1996) emphasize that it is also necessary to validate the indicator by assessing the reaction of the potential users. The reactions of the farmers of the network were positive: 67% found them easy to understand.

Session 2.1 415

Crop diversity IC

OM management

P management

Crop succession

N management

Farm value in 1994

-Farm value in 1995

Recommended value

Figure 1. Example of use of the agro-ecological indicators at the farm level (90 ha: grain maize, sugar beet, winter rape, winter wheat ).

T3

7 8 9 10 11 12 13 14 15 16 17

Farm number

Figure 2. Value of the nitrogen management indicator in 1994 and 1995 for the 17 farms of the network (1 to 13: France; 14 to 17: Germany).

Boundary line Probability area A Sugar beet D Winter wheat O Winter rape • Grain maize XSoybean

20 30 40 50 60 70

Nmin before winter (kg.ha1)

90

Figure 3. Probability test of the nitrogen management indicator: relation of the indicator to the mineral nitrogen content in soil before winter (— : boundary line of the probability area (below)).

Conclusion and perspectives The agro-ecological indicators presented in this paper are first of all aimed at helping farmers to adapt their cultivation practices to the IAFS requirements. For other production systems with livestock or vine, our indicators should be probably adapted and specific indicators developed.

References Bockstaller, C. et al., 1996. An example of an agro-ecological indicator: the organic matter management indicator. Book of Abstacts of the fourth ESA Congress, 7-11 July 1996, Veldhoven, The Netherlands.

Girardin, P. et al., 1996. Submitted for publication to Agriculture Ecosystems & Environment. Sharpley, A., 1995. Journal of Environmental Quality 24:947-951. Vereijken, P., 1992. Netherlands Journal of Agriculture Science 40:209-223.


T H E I M P L E M E N T A T I O N OF A SPATIAL L A N D ALLOCATION DECISION S U P P O R T S Y S T E M FOR U P L A N D FARMS IN S C O T L A N D

CS.Butcher1 , K.B.Matthews2, A.R.Sibbald2

1 Overseas Development Administration, c/o FCO (Yaounde), King Charles Street, London. 2 Land Use Division, Macaulay Land Use Research Institute, Aberdeen, AB9 2QJ, UK.

Introduct ion Upland farming systems form the interface between lowland farming areas, where agricultural land use decisions are dominated by economics, and hill areas where land use options are highly constrained by bio-physical limitations and nature conservation pressures. The importance of these upland areas is further emphasised by the increasing shift of UK and EU policy goals away from maximising agricultural production towards integrated economic, social and environmental goals. This policy shift provides incentives to alter patterns of land use in the uplands and places great importance on the study of land use options for upland farming systems to allow conflicting goals to be reconciled.

The computer based spatial land allocation decision support system (LADSS) being developed at MLURI has two roles. First it provides decision support for land managers by testing land allocation scenarios and suggesting possible combinations of land uses to meet their goals. Second it permits the analysis of farm scale land manager responses to policy change at UK and EU level. In both cases the land manager is the focus of the system.

LADSS specification and methods LADSS is implemented as a series of knowledge bases within Gensym's G2 real-time application development environment. LADSS thus has a modular structure, with data management, land use, impact assessment, and user interface modules. This structure facilitates the growth of LADSS capabilities by the addition of further land uses and impact assessments, or the substitution of existing modules by those developed within ongoing research. It also enables the customisation of the users' view and interaction with LADSS.

A LADSS spatial bio-physical database was collected for a MLURI Research Station in central Scotland. The database includes topographic, climatic and soil variables. The climatic parameters are derived from climate maps (Matthews et al., 1994). The topographic and soil data were field surveyed on a 100m sampling grid. The sample point is assumed to characterise the surrounding 1 ha area and leads to the grid based spatial representation currently used. In addition to these data further data were collected based on the perceptions of the manager of the Research Station. The fiscal data, market prices, grant rates and management costs required for the model were derived from standard UK sources (Hart, 1991; SAC, 1995).

The land use modules estimate for each land block the suitability, productivity and financial returns for each of ten land uses based on the bio-physical resources, management and grant regimes. These land uses are spring-barley (Dyson, 1992; Eagle et al., 1976; Sparrow et al., 1979), upland-sheep (Maxwell et al., 1993), suckler-cattle (Wright et al., 1996), two conifer and five broad-leaved tree species (Allison et al., 1994; Edwards et al., 1981; Pryor, S.N. 1988). In all cases the estimation of site suitability uses fuzzy membership functions (Burrough, 1989) to estimate the degree of suitability for the range of site factors. The functions are derived either from individual models or taken from the

Session 2.1 417

MLURI LCA guidelines (Bibby et al., 1982). Existing data available for any location in the uplands or data easily derived from field survey have guided the choice of models used within LADSS. Fiscal returns are estimated on a revenue basis optionally including those grants available.

Allocations of land uses to individual land blocks may be made by the user directly and their parameters accessed. Otherwise the user may choose from the palette of available land uses and allocate user-defined percentages of the farm to land uses based on a hierarchy of priorities. The allocations made by the user or the rules are currently evaluated in financial terms. Net present value is used to integrate the expected returns from annual enterprises with those from forestry. The interest rate and the period over which the NPV is calculated are defined by the user.

Individual land use modules within LADSS have been verified as part of their development. Within LADSS each is further sensitivity tested to establish both the absolute sensitivity and relative importance of each input parameter. This analysis begins to allow the estimation of uncertainty associated with predictions made by the land use modules and prioritises data collection requirements for the operational use of LADSS.

Results LADSS has been used to demonstrate the potential role of the grant system in locking-in land use systems on a Scottish upland farm. A comparison of allocations made on the basis of a farmer perceived resource description and the objective surveyed using identical rules has also been made.

Future developments Ongoing developments include: rapid site characterisation methodologies based on remote sensing, ground survey and geostatistics; the use of a linked geographical information system to provide a full range of spatial data representations and analysis; an extended range of land uses; social and environmental impact assessments; and the implementation of explicitly goal driven land use allocation strategies.

References Allison, S.M. et al., 1994. Canadian Journal of Forest Research. 24:2166-2171. Bibby, J.S. et al., 1982. Land Capability Classification for Agriculture. MLURI, 75 p. Burrough, P.A., 1989. Journal of Soil Science 40:477-492. Dyson, P.E., 1992. Personal communication. SCRI. Eagle, D.J., et al., 1976. Using response curves to estimate the effect on crop yield and

profitability. MAFF Technical Bulletin on Agriculture and Water Quality, 355-370. Edwards, P.N., et al., 1981. Yield models for forest management. FC Booklet 48, 32 p. Hart, C , 1991. Practical Forestry, 3rd ed. Alan Sutton Publishing Ltd. Matthews, K.B., et al., 1994. Climatic Change 28:273-287. Maxwell, T.J. et al., 1993. Grass and Forage Science. 49:73-88. Pryor, S.N. 1988. The silviculture and yield of wild cherry. FC Bulletin 75, 23 p. SAC, 1995. Farm management handbook. SAC, Edinburgh. Sparrow, P.E., et al., 1979. Journal of Agricultural Science 92:307-317. Wright, I.A., et al., Submitted 1996. The effect of grazed sward height and stocking rate

on animal performance and output from beef cow systems. Grass and Forage Science.


A MODEL OF ON-FARM AGRONOMIC MONITORING APPLIED IN ORGANIC FARMING

C David, B Fabre

ISARA, 31 place Bellecour, 69288 Lyon cedex 02, France

Introduction The market for organic produce appears to be expanding but it is to some extent limited by supplies. Although organic farming is profitable, the conversion from a non-organic farming system is a period of technical, social and financial stress. A EU programme « Conversion to organic stockless systems. On-farm research in South East France » was designed to appraise and resolve technical problems during conversion to organic farming This paper presents an experimental model based on on-farm monitoring and mainly develops the methodological approach

Methods This experimental model is based on different hypotheses: 1. The agricultural production depends on numerous factors as environment, fanning and cropping system. The generalization of a new technique should be adapted to this complexity. 2. The improvement of techniques is relevant only if they are adopted by the farmers and adjusted to their situation (Lefort, 1988). Consequently, it is necessary to take into account the farmers' opinion as well as the researchers' and the advisers'. This is why an on-farm experiment approach has been implemented. This experimental design disseminated in various spots, since various circumstances will provide adapted models (Sebillotte, 1989). It is important to combine this type of on-farm experiment with station experiments which allows the understanding of the biological processes (Debaeke et al, 1996). 3. The on-farm monitoring requires a pluriannual scheme to consider the climatic variation and the time needed to adapt a new technique. The appraisal of the problems during the conversion requires a minimum of three years to obtain a set of references.

We mixed sociological, economical and technical approaches to assess the feasibilty of a technical improvement by using a method similar to the farming system research and development (Billaz et al, 1983). The on-farm experiment is represented (scheme 1) by the model developed by Triomphe (1988). Three networks are interrelated: 1. A farm network where the farming systems' changes are studied. 2. A field network included in the farm network where the main agronomic problems are considered. Two levels were distinguished, the cropping system and the wheat crop. 3. On selected fields, trials were set up to test relevant practices on winter wheat, concerning nitrogen nutrition and weed control. In a « social survey », we analyse the attitude of farmers towards conversion. The technical and economical monitoring provides information on barriers during conversion on farm level. Moroever, a study of the organic cereal market was carried on a regional level to appraise the potential of expanding.

Session 2.1 419

Adoption of techniques

Scheme 1 : Organic farming diagnosis in Drome

Type of problems

Agronomical

Network 1

Network 2 Farm diagnosis

/ Technical and economical monitoring

"Social survey"

Field monitoring on

Cropping

systems

Winter

wheat

Network_3_ Experiment

on weeds and __ niJrog_en_

Organic cereal market

Inquiries on Farm and

cooperatives

Proposal for the improvement of the conversion

Proposal of techniques and decision support tools

Actions on organic farming development

Conclusion From the results provided by the different networks, it can be concluded that this on-farm model is relevant. Several techniques tested in our network were spread to other farms. For instance, a new model for nitrogen management is now being used (Promayon and David, 1996). The number of conversions to organic farming has increased in this region since the programme started. Some of the references are already being used by advisers to facilitate the development of the organic farming.

References Billaz, M et al., 1983. Les cahiers de la Recherche-Développement, 1: 12-16 Debaeke, P et al,. 1996. DERF-APCA Comité potentialités, 87-98 Lefort, J.,. 1988. Les cahiers de la Recherche-Développement, 17: 1-10 Promayon, F. and David, C , 1996. 4th congress European Society of Agronomy Sebillotte, M , 1989. Approaches of the on-farm agronomist. Kasetsart University, Thailand. Triomphe, B , 1988. Les cahiers de la Recherche-Développement, 17: 11-20


Experimental farm Logârden ( S-l )

D D

ARABLE FARMING SYSTEM RESEARCH-PROJECT LOGÂRDEN

CA. Heiander

Agricultural Society, P.O. Box 124, S-532 22 Skara, Sweden

Introduction A large scale farming system research project started 1991 at the research farm Logârden, Grästorp, (58° N, 12°0) Sweden. The main emphasis is on development of an Ecological Arable Farming System (EAFS) and of an Integrated Arable Farming System (IAFS). The total area for the experiment includes 60 ha of arable land, the size of each field is between 2.5 and 4.0 ha, see map of the farm below.

Methods The farming system project at Logârden follows the methodology for farming systems research elaborated by a European research network in a EU Concerted action (Nilsson, 1994;Vereijken, 1994; 1995). The aim of the project, the main objective, is a sustainable and productive food supply in combination with a minimum of negative inpact on the abiotic environment. The management of the heavy clay soil (40-50 % clay) is central, aiming at optimum structure and biological activity in the topsoil. A further aim is minimum input of external energy by maximum use of farm-produced bio-energy (fuel from rapeseed) and self-sufficiency in feed-stuffs (mixed farm). The methods used follow the european shortlist (Vereijken, 1994). They are used in the following order: 1. Multifunctional Crop Rotation (MCR) 2. Integrated/Ecological Nutrient Management (INM/ENM) 3. Minimum Soil Cultivation (MSC), only IAFS 4. Ecological Infrastructure Management (EIM) 5. Integrated Crop Protection (ICP), only IAFS 6. Farm Structure Optimisation (FSO).

EAFS (22 .0ha)

IAFS (28.0ha)

CAFS (12.0ha)

I-VinCrop rotation blocks

a-b Rotations with 75-50% cerials

M Ecological infrastructure

Figure 1. Map of Logârden showing the design of the farming system research project.

Table 1. The Multifunctional Crop Rotation at Logârden Year Conventional Ecological Integrated a) Integrated bt 1 2 3 4 5 6 7 8

peas w-wheat oats w-wheat s-rape w-wheat oats w-wheat

peas w-wheat set-aside rye fieldbeans oats set-aside w-rape

peas w-wheat oats (undersown) w-wheat s-rape w-wheat oats (undersown) triticale

peas w-wheat set-aside (grass/lucerne) set-aside (grass/lucerne) w-rape w-wheat oats (undersown) triticale

Session 2.1 421

The three different parts of the farm, Conventionel (CAFS), Ecological (EAFS) and Integrated (IAFS) have different crop rotation (see Table 1) using the Multifunctional Crop Rotation (MCR) Concept (Vereijken, 1994). Table 2 gives the percentage of ecological infrastructure in the different systems.

Table 2. Percentage ecological infrastructure Conventional Ecological Integrated a) Integrated b)

0% 6% 6_% 6_%

The evaluation of the systems is planned to use 11 (EAFS) or 12 (IAFS) of the multi-objective parameters on the European list (Vereijken, 1994). So far 8 of these actually have been used in the yearly evaluations.

Results Many of the results from the last year are still under evaluation. The most interesting results will be presented at the conference. As an example the results from the analyses of available Nmj„ at the start of the leaching period (nov.-dec.) in the reference areas are given in Table 3.

Table 3. Nitrogen Available Reserves (NAR) in kg ha" , after the indicated crop, at start of the leaching period Year Conventional Ecological Integrated

NminSoil Crop NminSoil Crop NminSoil Crop 1992 1993 1994 1995

39,8 57,9 63,7 34,7

w-wheat s-rape oats w-wheat

75,9 50,8 42,3 41,2

green manure rye field beans w-wheat

55,9 31,3 43,3 36,9

s-rape w-wheat oats triticale

Conclusions In the Ecological Arable Farming System (EAFS) there has been a lower yield level than expected. This is probably caused by a lack of nitrogen during especially the early part of the growing season. The low level of available nitrogen is, at least partly, connected with a very compact soil and thereby a low microbial activity. The compact soil can also cause losses of nitrogen by denitrification under very wet conditions (as during June -95). Weeds, insects and diseases have been a smaller problem than expected, the use of mechanical weed control has been quite successful. The use of external inputs (pesticides and chemical fertilisers) in the conventional farming in Sweden is very low compared to many western European countries. This means that there is not much room for reduction of for instance the pesticide use. At Logârden hardly any fungicides or insecticides have been used in the conventional part. The most obvious reduction has been in the use of nitrogen fertilisers and in the use of fuel for soil preparation. It is also very important to realise that some of the positive effects that are expected from a change of the farming system, into an ecological or into an integrated, are still to come.

References Nilsson, C, 1994. Integrated farming systems research at Alnarp. Proceedings NJF symposium

'Integrated systems in agriculture', 1-3 December 1993 Norway: 65-70. Vereijken, P., 1994. 1. Designing Prototypes, Progress Reports of Research Network on

Integrated and Ecological Arable Fanning Systems for EU and associated countries. AB-DLO, Wageningen, 87 p.

Vereijken, P., 1995. 2. Designing and Testing Prototypes, Progress Reports of Research Network on Integrated and Ecological Arable Farming Systems for EU and associated countries. AB-DLO, Wageningen, 90 p.


TOWARDS SUSTAINABLE LAND USE IN THE RURAL AREAS: THE NEED FOR DESIGNING NEW SYSTEMS AND TECHNOLOGY

H. Hengsdijkl and M.K. van Ittersum^» 3

1 Research Institute for Agrobiology and Soil Fertility, P.O. Box 14, 6700 AA Wageningen, The Netherlands 2 Department of Theoretical Production Ecology, Wageningen Agricultural University, P.O. Box 430, 6700 AK Wageningen, The Netherlands 3 CT. de Wit Graduate School for Production Ecology, Wageningen, The Netherlands

Introduction Environmental problems, a growing population density and an increasing demand for non-agricultural functions (recreation, nature, drinking water supply, etc.) in the rural areas call for drastic changes in land use in the Netherlands. Aims of such 'sustainable' type of land use are an improved quality of both agricultural products and production methods and scope for non-agricultural functions. This process can be moulded and steered by a combination of rearranging land use and other resources at regional and farm level (so called systems designs) and new technologies to solve problems at field, crop or animal level. In the present study such systems designs and technologies at three levels of scale, - region, farm and field - are identified to realise particular land use aims. The study has been carried out for the intergovernmental research programme 'Sustainable Technological Development'.

Multifuntional land use and environmental pollution: conflicting aims The multifunctional character of land use and the different types of environmental problems (e.g. emission of biocides and nutrients) require priority setting of goals. Moreover, expression of environmental pollution in different dimensions results in conflicting information as illustrated in Figure 1 in which the N-supply in relation to the N-output and N-surplus for different arable farming systems is analysed. The N-surplus is defined as the difference between N-supply and the removal of nitrogen from the system (N-output) and equals N-emissions and N-accumulation in the system. Below a certain critical N-supply the production (in terms of N-output per ha) decreases strongly. Simultaneously, the N-surplus expressed per hectare still decreases while the N-surplus expressed per kg of N-output increases.

Figure 1. N-output (—•— ), N-surplus per ha (•••D...) and N-surplus per N-output (--o— ) in relation to N-supply for different farming systems. EC=ecological farming system, IN=integrated farming system and COI, C02 = conventional farming systems.

250

200

150

100

50

'C02

P . 1

0.75

. 0.5

0.25

a. 3 in

z 3 Q.

* J 3 O

150 200 250 300 350

N-supply (kg N/ha/yr)

400

This example shows that expression of environmental pollution in two different dimensions, per unit of area or product, results in paradoxes. Optimalisation of land use for one aim, e.g. reducing the emission per unit of area, may have implications for other aims, e.g. reducing the emission

Session 2.1 423

per unit of product. In the search for new systems and technologies it is important to explicitize their consequences for various aims related to a multifunctional and environmental friendly land use. For operationalization of sustainability a distinction between levels of scale is required so that repercussions of intervention at one level of scale for other levels of scale can be disentangled. The use of organic waste products from cities or farms as fertilizer can e.g. reduce nutrient surpluses at farm and regional level, but at the field level emissions might increase because organic fertilizers are less efficient than chemical alternatives.

Systems designs and technologies In a rapid appraisal systems designs and technologies at regional, farm and field level are identified that can contribute to the realization of different land use aims. Seven prospective systems designs and technologies are identified that can potentially contribute to lower environmental pollution levels and realisation of non-agricultural functions in the rural areas: Region: 1. Recirculation and reuse of manure and organic waste as animal feed or

fertilizer can reduce regional nutrient surpluses. Farm: 2. The use of renewable energy sources and energy management can reduce

the dependency of agriculture on fossil energy sources. 3. Expert- and management supporting systems can gain insight in the effect

of operations on growth and development of crop and animal, natural resource use, and attainment of non-agricultural functions (e.g. nature).

Field: 4. Sensor-and information technology for location specific management to reduce fertilizer and bioicide use.

5. Upgrading of organic fertilizers to ensure a reliable working of nutrients and to harmonise the mix of nutrients with the crop requirements.

Region/farm/field: 6. Monitoring systems to measure and evaluate the environmental pollution of functions of rural areas at various temporal and spatial levels of scale.

7. Planningstechnology in which different information flows are integrated to support the decision-making processes concerning rural land use.

Current limited application of these systems designs and technologies must be attributed to (i) the fact that cultural and economic boundary conditions are not fulfilled, (ii) uncertainties about the implications of their application, and (iii) the lack of operational techniques at field level. Therefore, the following research agenda is proposed.

Research agenda The consequences of the identified systems and technologies should be explicitized in an integrated framework so that interactions of various types of pollution and functions at different scales can be analysed. A framework is proposed in which step by step consequences and uncertainties of the identified systems designs and technologies can be assessed on basis of the land use aims pursued. Two case study areas differing in biophysical and socio-economic characteristics are used as a benchmark. The framework includes (i) a quantitative exploration of new systems and technologies at various levels of scale, (ii) communication of results of step (i) with stakeholders, (iii) development of systems and technologies with stakeholders, (iv) introduction and implementation of systems and technologies and (v) monitoring and evaluation systems and technologies.

References Duurzaam landgebruik, definitiestudie, 1996. AB-DLO, PE-LUW, MiBi-RUL & Heidemij Advies B.V., DTO-werkdocument VDO (in prep.).


RE-INTEGRATING PERENNIALS INTO AGRICULTURAL LANDSCAPES A CONCEPTUAL APPROACH

F. Herzog', M. J. C. Brownlow2

'UFZ Centre for Environmental Research, PF 2, D-04301 Leipzig "Institut für Agrarökonomik, Universität für Bodenkultur, A-l 190 Vienna

Introduction The mechanisation and intensification of agriculture in Europe have lead to a massive removal of trees and shrubs from agricultural landscapes. This has negative (agro-)ecological, aesthetic and cultural effects: loss of biodiversity and decrease of system stability, diminished attractiveness for recreation, destruction of landscapes which were part of our cultural heritage. At present, there is considerable economic and environmental pressure to explore alternative nonfood uses for agricultural land. In re-integrating perennials into landscapes, farm production can be diversified while positive environmental effects can be obtained. By deliberately combining annual and perennial crops in agroforestry. modern sustainable land use systems can be developed.

Properties of agroforestry systems for industrialised countries Whereas tropical agroforestry aims at a sustainable intensification of production, agroforestry in industrialised countries must be designed to generate environmental benefits, reduce the socioeconomic burdens associated with agriculture and maintain the income of the farmer. Land use systems must be judged according to their ecological, economic and socio-cultural properties (Lefroy et al, 1993). In the figure, these properties are given for agroforestry when compared to monocropping - agronomic properties are also included.

Ecological properties higher stability through diversity habitat for wildlife C02-fixation local cycling of water and nutrients more ecological benefits

Agronomic Properties interactions between trees and crops can be manipulated less flexible rotation some knowledge on trees is required

• more sophisticated / demanding management

Agroforestry compared to

monocropping

Economic properties • diversification • lower „private efficiency" • higher „social efficiency"

• widespread viability only when ecological benefits are financially rewarded / ecological losses are penalised

Socio-cultural properties high aesthetic value of trees in landscapes cultural value of trees public acceptance, good „image" of trees

• no more „throw away" landscapes

Properties of agroforestry systems in industrialised countries

Session 2.1 425

This simplified list is based on the fundamental properties of complex systems compared to monostructural ones. However, the specific properties of any one agroforestry system depend on the design of the system, since the term agroforestry covers a wide range of possibilities. The selection of the agricultural and tree components, and their combination in space and time are particularly crucial. The net environmental, social and economic characteristics of these systems are then dependent on the subsequent interactions between the system components. Under the current policy in the EU, agroforestry tends to offer environmental and social benefits, but usually (although not always) at the expense of financial viability. These characteristics must not only be compared to existing monocultures, but also to other alternative land uses (both proposed and practised), such as fallows, non-food agricultural crops, afforestation, etc., in order to properly understand the relative worth of agroforestry in solving the problems of agriculture.

Candidate systems for Western Europe Agroforestry was widespread in Europe until the 19th century (e.g. Beil, 1839). Most of the systems were abandoned as a result of changing economic conditions and agronomic progress (e.g. fertilisation, mechanisation) (Brownlow, 1992). Remaining systems are mostly restricted to mountain regions and to the Mediterranean, some exist in western Europe as well. They form some of the most precious landscapes in Europe and their preservation is a priority. Modern systems, however, have to address prevailing land use problems and take into account modern practices and conditions. This practically excludes fruit production with high growing trees, the tree component must rather be oriented towards wood production. The most promising systems are: • silvopastoralism (trees and livestock): Trials, predominately in the UK and France, are being

carried out using hardwoods (e.g. Prunus avium, Pyrus communis, Gleditsia triacanthos, etc.) on pasture at densities between 50 and 400 trees/ha (e.g. Dupraz et al., 1994).

• silvoarable systems (trees and crops): Alley cropping with hardwood trees is also tested in the UK and France. An EU demonstration project „Farming with Poplars" seeks to spread this technology to other European countries. Silvoarable systems might be particularly valuable in reintroducing trees into areas dominated by arable farms such as the cereal producing regions in France and the large arable co-operatives in eastern Germany.

Conclusions Agroforestry systems are a potential means for re-integrating trees into agricultural landscapes. This could bring considerable environmental and social benefits in comparison with monocrop-ping, but the financial viability of such systems is currently poor. Their adoption therefore depends on future comparisons of production systems being based on „social efficiency" (Barbier, 1990), where external costs and benefits are internalised and environmental products/services are rewarded financially.

References Barbier E. B. (1990) in Prinsley R. T. (ed.) Agroforestry for sustainable production. Common

wealth Science Council, London, 389 - 404. Beil A. (1839) Aphorismen über die Verbindung des Feldbaues mit dem Waldbaue oder Röder

und Baumfeldwirtschaft. Frankfurt a.M., Andreaische Buchdruckereien, 89 p. Brownlow M. J. C. (1992) Quarterly Journal of Forestry 86(3), 181 - 190. Lefroy E. C. et al. (1992) in Hobbs R. J et al. (eds.) Reintegrating fragmented landscapes. New

York, Springer Verlag, 209 - 244.


FARMER SPECIFIC PROTOTYPING OF SUSTAINABLE PRODUCTION SYSTEMS: A CONCEPTUAL FRAMEWORK

T.J. de Koeijer1, G.A.A. Wossink2

'Department of Ecological Agriculture, WAU, Haarweg 333, 6709 RZ Wageningen, The Netherlands department of Farm Management, WAU, The Netherlands

Introduction In the near future Dutch agriculture must realise a strong reduction in the use of environmentally damaging inputs in order to become more sustainable. Although the term "sustainable" has become popular, defining the term precisely and unambiguously is far from easy. Definitions abound, varying within context (Pandey et al., 1995). Hardaker (1995) gives five categories of sustainability in farming systems: technical performance; economic performance; quality of the natural environment; system resilience and adaptability; and human welfare and equity. One of the key elements for an optimal technical and economic performance and for curbing environmental stress, is an efficient production practice in order to reduce the amount of environmentally harmful inputs. For designing these efficient, sustainable production systems technical, economic and sociological insights must be combined. This paper presents a conceptual framework for addressing this issue.

Efficiency For a fruitful cooperation between different disciplines, knowledge of each others concepts of sustainability and efficiency is needed. In economy as well as in production ecology, an "increase in efficiency" means that a certain objective can be reached with less or cheaper inputs. Efficiency is a relative criterion and is expressed by the ratio between a desired or attainable productivity and the actually realized productivity. Productivity, indicates the amount of output which is produced with a certain amount of input. Efficient use of inputs can be looked at from different points of view: agronomically, ecologically and economically. Efficiency in the agronomical point of view can best be indicated as resource-use-efficiency, a term derived from De Wit (1992). It is measured in kg input per kg output. The ecological efficiency of crop production is based on the use of renewable resources. Here, the self regulating capacity of natural systems is the central issue (Goewie et al., 1995; Lampkin et al., 1994). In this concept of efficiency the environmental burden is the main point. Because the environmental burden depends on all kinds of eco-physiological processes, the ecological efficiency is difficult to measure. According to Goewie et al. (1995) ecological efficiency should be expressed in kg input per unit of area. These authors state that low concentrations of artificial inputs per hectare refers to better chances for restoration of natural resources such as good soil fertility, soil structure and biodiversity (predators versus harmful organisms). However, in all agricultural production systems it is important to realize maximum profit. Maximum profit is realized when marginal costs equal marginal return. Hence, for economic efficiency the price ratios of in- and outputs are decisive.

Conceptual framework The design of sustainable cropping systems which meet farm economical, agricultural and environmental objectives, requires insight into (a) the relations between cropping measures, environmental burden and the farmer's income and (b) the combination of economic, production ecological and sociological approaches.

Session 2.1 427

The identification of new input-output combinations, which may contribute to a more sustainable agriculture, calls for the application of production ecological knowledge and insights which is derived from a combination of experiments and system analysis (Rabbinge et al., 1994). Therefore the first step in the design process is to assess input output combinations for a given production situation based on production ecological insights. In the second step, these "potential" production sets are combined with farm economic considerations. These considerations include (a) profit maximization as the main objective, i.e. price ratio of outputs and inputs and marginal returns are decisive instead of average physical output input ratios, b) farm structural restrictions regarding labour and machinery, and c) uncertainty due to the variability of the natural environment. It is obvious that variability in agro-ecosystems plays an important role in practice and on farm level compared to controlled experiments and experimental plots. Sources of variation a farmer has to deal with in practice are found in the biotic and abiotic environment and in genetic resources (Almekinders et al., 1995). The result of the second step is a normative set of production techniques appropriate for a given production situation. Thus far the approach is normative: farmers are considered as a group of similar decision makers. The third step focuses more precisely on differences among farmers. Starting from insights from sociology and behaviourial economics the technology set as observed in practice is analyzed. In the normative approach it is assumed that (a) all farmers strive for profit maximization and (b) that all farmers have complete knowledge of prices and technical possibilities. In practice this is not the case, while in practice risk aversion or spare time also play a role and while farmers' knowledge will never be perfect. The three steps will result in differing levels of production. The highest level is the "laboratory" set resulting from the production ecological approach. The "blue print" set from the normative economic approach is the next lower level. Finally, from the third step the "best practice" set of production techniques and the "average" set can respectively be assessed. By measuring the differences between the levels followed by an explanation of these gaps, insight can be gained in what will be possible in practice and what the reasons are for not realising the potential level. With this knowledge of the four mentioned productivity levels and the explanation for the differences between them, optimal and in practice attainable production systems can be designed.

References Almekinders, C.J.M. et al., 1995. Netherlands Journal of Agricultural Science 43: 127-142. Goewie, E.A. et al., 1995. Hoe ecologisch kan de landbouw worden? AB-DLO Thema's 3, Wageningen.

Hardaker, J.B., 1995. Farming systems perspectives on policy making and planning for sustainable agriculture and rural development, Rome: FAO (manuscript)

Lampkin, N. et al., 1994. The economics of organic farming, an international perspective, CAB International, Oxon, UK.

Pandey, S. et al., 1995. Agricultural Systems 47: 439-450. Rabbinge, R. et al., 1994. In: Rajan, A. and Y. Ibrahim (eds) Proceedings Fourth Int. Conference on Plant Protection in the Tropics, Malaysian Plant Protection Society, pp. 25-46.

Wit, CT . de, 1992. Agricultural Systems, 40: 125-151.


THE RENAISSANCE OF MIXED FARMING SYSTEMS: A WAY TOWARDS SUSTAINABLE AGRICULTURE

E.A. Lantinga and R. Rabbinge Department of Theoretical Production Ecology, Agricultural University, PO Box 430, 6700 AK Wageningen, The Netherlands

Introduction During the last decades agricultural production systems have developed in North-western Europe that waste inputs and are suboptimal in biotechnical and environmental terms. In the near future this will lead to unacceptable environmental and ecological, but also economical and social effects (Rabbinge, 1992). Therefore, there is a need to develop and test alternative systems, which are acceptable in the long term. One of the possibilities to reduce the negative effects of the increased specialisation and intensification, characterized by too narrow crop rotations and an overuse of external inputs like fertilizers and biocides, is a renaissance of mixed farming systems at farm or regional levels in which products and services are exchanged between the different production branches. The main advantages of mixed farming systems are:

- reduction of use of external inputs and increase their efficiency through (i) use of homegrown concentrates (less purchased concentrates), (ii) more efficient application of animal manure (less waste of nitrogen and minerals), and (iii) broadening the crop rotation (less use of biocides and higher yields due to less problems with soil-borne pests and diseases);

- better utilization of the available labour and spreading of income risks.

Methods On the Minderhoudhoeve, the experimental farm of Wageningen Agricultural University in Oostelijk Flevoland, two different prototypes of mixed farming systems are developed, optimized and tested: an integrated farm (135 ha; 90 dairy cows, 60 young cattle, 60 sheep) and an ecological farm (90 ha; 55 dairy cows, 60 young cattle and bulls, 40 sheep, 200 laying-hens). Both farms have their own sets of goals and constraints. The production target per ha at the ecological farm is 80% of that on the integrated farm as an average for milk, potatoes and cereals. The location is characterized by a good loam soil with a high nutrient use efficiency and low irrigation needs. Measurements at farm level will start in autumn 1996 when both farms are fully operational. In the foregoing years the two prototypes were designed and the transition to the present farms was initiated. The integrated type is described here according to its targets and constraints. Nitrogen surplus is used as an example for its perspectives.

Main targets and constraints on the integrated mixed farm 1) minimization of the nitrogen (N) surplus per unit product; 2) minimization of the use of biocides per unit product under the fertilization regime resulting

from target 1 and with the constraint of a good product quality at harvest; 3) in the system there is a variety of crops more or less corresponding with the 'average'

Dutch cattle and arable farms: grassland, maize, seed and ware potatoes, sugar beets, winter and summer cereals, vegetables (onions, peas, green beans, etc.);

4) no bare fields until late autumn to prevent nitrate leaching;

Session 2.1 429

5) cultivation of potatoes and sugar beets on a certain field up to a maximum of only once in every six years to reduce the risks of soil-borne pests and diseases;

6) application of slurry only between late winter and mid-summer to reduce nutrient losses; 7) amount of purchased concentrates less than 0.10 kg per kg milk, i.e. less than about 800

kg cow"1 yr *, to restrict nutrient inputs under the constraint of a milk production of about 8 000 kg cow-1 y r1 and about 11 000 kg per ha of forages (grass, clover, maize, wheat);

8) with the exception of 4 ha permanent grassland surrounding the farm buildings, the grass in rotation is ploughed after two or four years to prevent nutrient accumulation in the soil;

9) a stock of 60 ewes is kept to increase pasture utilization and condition (consumption of grass rejected by dairy cows, winter grazing, 'biological' weeding in sown pastures);

10) sufficient phosphorus (P) status of the soil (Pw-value about 25); 11) weeding in principle first through mechanical measures.

Results The N and P surpluses per unit of acreage and the N surplus per ton of milk are shown in the Table. It illustrates the possibilities of mixed farming to decrease environmental side effects and to increase profit. This was also concluded by De Koeijer et al. (1995) in an environmental-economic analysis of mixed crop-livestock farming. The contribution on a country level is considerable as the dairy sector is responsible for about two-thirds of the N surplus in Dutch agriculture. The negative P balance is due to the aim to achieve a sufficient P status of the soil. Current fertility in most of the fields is far beyond this level.

Table. Calculated nitrogen and phosphorus surpluses excluding deposition on the integrated mixed farm (1996-2000; 50% forage land) compared with the reference year 1993 (56% forage land) and the average of Dutch cattle and arable farms, 1985/1986 (65% forage land).

The Netherlands (1985/1986) Minderhoudhoeve (1993) Integrated mixed farm (1996-2000)

Conclusions The calculated results illustrate that nutrient losses per unit product and per ha may be reduced considerably by a sound integration of the different production branches. It is interesting to note that when the results are translated to the Netherlands as a whole, total milk production is almost the same as the current Dutch production volume (11 million tonnes on 2 million ha agricultural land, i.e. 5 500 kg per ha). On the integrated mixed farm, the milk quotum equals 5 300 kg per ha farmland of which only 50% is used for growing forages. This confirms both the good production situation at this site and the perspectives for mixed farming systems.

References De Koeijer, T.J. et al., 1995. Agricultural Systems 48: 515-530 Rabbinge, R., 1992. Proceedings IOBC/WPRS Conference, p. 211-218. Pudoc, Wageningen

Kg N ha-1 y r1

217 124 33

Kg P ha"1 y r 1

11 10

-12

Kg N ton-1 milk 37 25 6


A FARMING SYSTEM ENVIRONMENTAL ASSESSMENT APPLIED ON ORGANIC FARMS AND FARMS IN CONVERSION

J Nocquet, C. David, Y Gautronneau

ISARA, 31 place Bellecour, 69 288 Lyon Cedex 02, France

Introduction Organic farming is characterised by a larger consideration of the environment. In a EU research program « Conversion to organic stockless systems. On-farm research in Southeast France », a farm network has been set up in various organic farms and farms in conversion (Gautronneau et al, 1994). One of the aims of the project is the conception of a farming system environmental assessment. The principal goal is to evaluate the impact on environment by organic farms or farms in conversion.

Methods The environmental assessment of the farming system demands a thematic approach in order to evaluate the holistic qualities of durable farms (Nocquet et al, 1994 , Nocquet, 1995). Two themes are formalised in reply to the environmental case-studies of the region : - land management : landscape quality and maintenance of the biodiversity , - control of pollution risks : diffuse pollution (nitrates, phosphates) and point pollution (animal waste storage) The method is based on fast, on-the-spot surveys and expert opinion (half a day per farm). A limited number of quantitative and qualitative indicators is denned, according to the environmental case-studies and farming system components. The farming system is divided into different sub-systems : the economic system, the livestock farming system, the forage system, the cropping system, the fixed production factors and the decision-making system.

Results The results are presented in Tables 1 and 2. The environmental assessment of each farm is based on the synthesis of the indicators. The mark is the sum of the values of all the indicators. It gives a level of environment-friendly practices.

Conclusions This method is easy to apply on site. The strengths and weaknesses of the farming system can be detected rapidly. In this survey, it has been concluded that : - In general, organic farms had good practices for landscape management and the control of pollution risks. Only one farm (1) was found to have more problems than the other farms concerning land management. - On the other hand, the environmental assessment of the farms in conversion is more diversified. Two farms (9 and 14) had environment-friendly practices with land management and all the farms more or less had problems with the control of pollution risks.

References Gautronneau, Y. et al, 1994 Contrat AIR 3 CT 93 0852, CEE DG VI / CEREF-ISARA, 42 pp Nocquet, J. et al, 1994. Cahiers Agricultures 3: 39-50. Nocquet, J , 1995 Annales de zootechnie 44, Suppl, 338.

Session 2.1 431

Table 1 Control of pollution

Indicators

Livestock farming system : - organic nitrogen pressure - animal waste storage Cropping system : - N fertilisation - N leaching risks - P fertilisation - pesticides - toxic waste Equipment : type and state Land structure Decision-making system : - environmental consideration - practices planning

ASSESSMENT (points)

risks

6

+

+ + + +

=/-+

+ + + (8)

3

+

+ + + + +

:

+ + + (7)

Organic farms

7 10 2

+ + +

H ii

+ ii

+

ii +

ii •

+

+ +

+ ' +

+ + +

+ + + + + + +

(6) (5) (4)

4

=

+ +

+

+

(1)

1

+

+

=/-

+/= +

-

(-1)

Farms in conversion

9

+

_

=/-

+ +

(3)

14 13

+ + +

= +/=

=/- = +/= + +

+ +

(3) (2)

15 17 16 12

+ + + -

+

+ = +/= + + - - -

-

(0) (-2) (-6) (-9) Legend: + : good (1 point), = : medium (0 point), - : problem (-1 point)

Table 2. Land management

Indicators

Economics involment in maintenance of field pattern Forage system : - valorization of grassland - valorization of shrubland Cropping system : - crop diversity - erosion risks - biodiversity Farm buildings and farmland : - integration of farm in the landscape - maintenance of farm buildings - maintenance of farmland Decision-making system : - knowledge of environmental policies - consideration of landscape quality

ASSESSMENT (points)

6

+

+ =

+/=

+

+

=

+

+

+ (8)

3

+

+ +

+ = +

+

=

+

+

+

+ (9)

Organic i

7 10

=

= =

+

=/- +

+ =

+

+

+ +

+

+ (-1) (5)

arms

2

-

+ +

+ =

+/=

+

+

=

+

+

+ (7)

4

+

+ +

+ = +

=

=

+

=

+

+ (7)

1

-

-

=/-

-

=

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LEARNING FOR SUSTAINABLE AGRICULTURE

B.M. Somers

free-lance social researcher, Hoofdweg 3, 3233 LH Oostvoorne, The Netherlands

Introduction Designing sustainable farming systems is one thing, farmers practising sustainable agriculture is another. For extensionists, the work of Rogers (1983) has long been a guide for understanding the speed and extent to which innovations are put into practise. Also for sustainable agriculture, conceivable as a combination of novel technologies and farming methods, Rogers' work provides for a checklist of factors that influence the process of diffusion among farmers. Some of these factors point to the economic prospects and perceived risks inherent in the innovation. Extensionists and policy makers are searching for means to speed up the rate of adoption of sustainable agriculture. However, sustainable agriculture is a complex innovation that seemingly lacks points of impact for intervention. Compared to other types of innovations, the turn-over to sustainable farming systems bears risks on many terrains. There is the economic risk of cut-backs in yields and inappropriate marketing strategies; there are problems with pest and disease management; on many aspects there is a lack of knowledge. Moreover, the actual and perceived risks are not confined to economic and technological aspects. There are also social and political risks. The seriousness and sources of the environmental problems are constantly contested, which is also the case with norms and penalties to fight the problems. Forerunners in sustainable agriculture risk the distrust of colleagues who fear that proofs of low input agriculture will be raised till political norms. The social and political risks that are inherent in a turn-over to sustainable agriculture form strong impediments for its introduction. However, in this contribution I will rather not focus on the problems, but on practical solutions that have already been found.

Conceptual background Studies in innovation processes in general and in sustainable farming systems in particular, have taken place in an interpretative anthropological tradition as well as by methods that aim at finding statistical evidence. Somers and Röling (1993) found that the introduction of sustainable farming systems differs from an adoption-of-innovation perspective. Because of the complexity of sustainable farming and the lack of practical knowledge, the introduction of it can better be described in terms of learning processes. Also Bayes points to the importance of learning processes in adoption of innovations (Leathers et al, 1991; Lindner et al, 1990). The so-called Baysian learning model is an adaptive learning model. Crucial is the notion that the perceptions of farmers will change when they gain experience with a part of the innovation. This means that farmers have the possibility to try out one or more modules of the system, to try out the new methods on a part of their farm, or have a choice concerning the level of input of a certain innovation. By trying out, the farmer gains extra information by which he can adapt his original perceptions about the risks of applying the innovation. He also experiences whether the information he got from researchers or extensionists is relevant for his own farm situation. The notion of reducing perceived risks by doing coincides with Kolb's ideas about learning by experience (Kolb, 1984). Kolb's theory is incorporated in many modern management theories about 'learning organizations'. Relevant is the notion of interaction between cognitive processes and acting. By shifting the perspective from a (top-down) adoption process to a (bottom-up) learning process, also the patterns of interaction and roles of actors involved will change. Applying this notion to the agricultural knowledge network, we will find that roles, attitudes and

Session 2.1 433

skills of all actors change when learning processes and supporting learning processes become the point of departure.

Environmental co-operatives as a case This shifting perspective is well illustrated by five experiments in Dutch agriculture, so-called environmental co-operatives. Environmental co-operatives are local groups of farmers who search for ways to realize environmental goals that are specific for their own locality and for their type of fanning. Often, they hold on-farm experiments in order to gain knowledge about environment, nature and landscape. Their aims vary from achieving measurable values of nature to minimize the input of fungicides. In my contribution I will highlight the experiences of one of such groups, the working group soil-based horticulture under glass. Especially soil-based horticulture under glass is threatened by policy measures. Moreover, over the years the agricultural research for soil-based horticulture was minimized in favour of horticulture on artificial substratum. Soil-based growers experience that they loose space for manoeuvring and searching for solutions. They think it of importance to quickly help develop new methods and technologies under 'practical circumstances'. By means of experiments they will - together with researchers - search for environmental parameters that are specific for their situations and gain knowledge on practical methods and technologies. For researchers in order to support this learning process, they must have an open mind for knowledge other than scientific knowledge: the researcher must gain experience in learning systematically from innovations that take place in practice already. They also must develop a feeling for the policy restrictions and risks farmers are working under.

Conclusions A growing number of experiments show that farmers are willing to contribute to a more sustainable agriculture when the necessary conditions are created that facilitate learning processes. Conclusions are among others that: a) The introduction of sustainable farming systems is encouraged when the systems bear the possibility of learning by doing. A modular construction of new technologies and methods will increase the willingness of farmers to take risks; b) A greater interaction between researchers, extensionists and farmers is needed by taking into account valuable practical experiences of farmers - this requires a more systematic apprehension by researchers of farmers' experiences; c) Because of the social and policial impediments, the development of sustainable farming systems will benefit from 'social' learning: groups of farmers setting their goals and finding ways to realize these together.

References Kolb, DA., 1984. Experiential Learning. Englewood Cliffs, New Jersey: Prentice Hall, Inc. Leathers, HD. et al, 1991. A Baysian Approach to Explaining Sequential Adoption of

Components of a Technological Package, American Journal of Agricultural Economics 73(3): 734-742.

Lindner, R. et al, 1990. A test of Bayesian Learning from Farmer Trials of New Wheat Varieties, Australian Journal of Agricultural Economics 34(1): 21-38.

Rogers, EM., 1983. Diffusion of Innovations (third edition). New York: The Free Press. Somers, B.M. et al, 1993. Kennisontwikkeling voor duurzame landbouw (Knowledge development for sustainable agriculture). The Hague: NRLO.

Somers, B.M., 1994. Zoek- en leerprocessen bij innovaties op het primaire agrarische bedrijf (Learning processes and innovations on primary agricultural firms). The Hague: Ministry of Agriculture, Nature and Fisheries

Somers, B.M. (1995). Plan van Aanpak Werkgroep Telen in de Grond (Project soil-based glasshouse horticulture). Honselersdijk: Dutch Federation of Horticulture Study groups.


NITROGEN DYNAMICS AND EFFICIENCY IN CROPPING SYSTEMS WITH DD7FERENT INPUT LEVELS: AGRONOMICAL, ECONOMICAL AND ENVIRONMENTAL CONSIDERATIONS.

A.M. Triboi1, E. Triboi1, B. AletQn2

^Station d'Agronomie INRA, 12 avenue du Brézet, 63039 Clermont-Ferrand, France. ^Chambre Départementale d'Agriculture 63, France.

Introduction Nitrogen is the most important nutrient involved in growth and yield formation, in system productivity and in environmental variations. The adjustement of N supply to crop growth by N fertilizer and the efficiency of N use may be variable according to the level of desired performances of the system and of the degree of uncertainty of environmental conditions (weather).

Methods Dynamics of mineral N (NO3) in the soil profiles and total nitrogen in the aboveground plants were analysed during two years : 1993 (year 1) and 1994 (year 2), in relation to crop growth and yield elaboration, on a rapeseed (Rs), wheat (Wh), sunflower (Sf), wheat (Wh) crop succession. One crop rotation at different stages was studied : Rs-Wh-Sf-Wh, Wh-Sf-Wh-Rs, Sf-Wh-Rs-Wh and Wh-Rs-Wh-Sf. Three input levels defined by yield objective were applied: a) an Intensive (I) or High-Input System to approach the potential yield ; b) an Adjusted (A) or Recommended System with inputs determined according to an actual crop potential ; c) an Extensive (E) or Low-Input System. To compare the N use efficiency (Huggins & Pan, 1993) among cropping systems, some agronomical, economical and environmental indices were calculated.

Results Results are presented in the Table.

Table. Analysis of nitrogen efficiency at 3 input levels (I, A or E). Values are means (n = 4 crops per year or n = 2-4 values per crop).

I A E

1=N(F) N Fertilizer kg ha"1 year"

145 108 63

2=Y Yield %

1 (4 Crops) year 1 100 86 77

. year 2 100

93 75

3=N(G) Grain N-uptake kg ha"1

year 113 91 81

1 year 2 142 120 88

4=N(R) 1 Non-Harvested

5=CSN(H) Crop-Soil-N

N-Crop Residues at Harvest, kg ha"1

year 1 61 47 35

year 2 50 42 29

year 1 253 218 175

year 2 231 193 141

I A E

6=CN(W) Winter CropN Wh Rs 55 99 49 64 28 60

7=FUE 8=G-FUE Fertilizer Uptake

Efficiency Crops 1.26 1.39 1.85

Grains 0.88 0.97 1.34

9=Nm(W)= Winter Soil Nm year 1

(62) (66) (62)

year 2 after

Wh Rs 33 125 29 73 28 66

Sf 45 40 45

under Wh Rs 69 27 61 22 60 21

Bare Soil 51 52 30

Session 2.1 435

10=Nm(PH) max Postharvest (Autumn)Soil Nm Wh R s S f

11=NM N Mineralization under Bare Soil(Sf) before 15 April

12=NL(A)orNM Autumnal Leaching (-) or Mineralization (+) Wh Rs Bare soil

13=%N(G) Grain N-conc 2 years Mean Wh Rs Sf

I 103 128 60 A 68 94 76 E 71 75 52

43 yearl 33 year2 45- 23 55 29

+ 17 +22 -66 + 13 + 1 -19 + 18 + 9 -30

2.35 3.59 3.24 2.18 3.33 3.12 2.12 3.32 2.94

Three input levels were compared. The annual mean fertilization for the 4 crops (4 different crops the same year : Wh after Sf, or Rs, or Wh after Rs, or Sf) was respectively 63-108-145 kg N ha"1 per year (1). The mean relative yield (2) was 76-90-100% and the Grain N-uptake 85-105-127 kg ha"1 per year. The nonharvested crop Residues N (4) were 32-44.5-55.5 kg ha"1

per year. The Fertilizer Uptake Efficiency (7 and 8) (or FUE, defined by Jenkinson et al, 1985 as the percentage of applied N taken up by the plants) was calculated for the total crops ((3+4)/l) and for the Grains (3/1). The low input system (E) gives the highest efficiency : FUE or G-FUE. The 1.34 Grain FUE value indicates that the N exported by grain in this extensive system exceeded the N fertilizer rate. The amount of mineral N (Nmin) in the soil profiles varies through the year. Some values seem to be interesting to point out : - Winter Soil Nm (9) was measured in January before the beginning of growing period and before N fertilization (Remy & Viaux, 1982). This Nm(W) depends on proceeding crop (Rs gives the highest values), and it depends also on the present crop : under Rs the lowest value was observed. Simultaneously, the Winter crop N (6) was determined, thus 9+6 gives the Winter Crop-Soil-Nitrogen (Appel, 1994 ; see 12). - Maximum postharvest (autumn) Soil Nm (10) is a good indicator of the decomposition and mineralization of crop residues (Muller & Mary, 1981). This Nm(PH) is higher for Rs (with about 80 kg N ha"1 from the leaves, unpublished results), than for Wh and Sf. - From the data obtained under bare soil until 15 April (sunflower is sown late), the N mineralization was estimated : 40-50 kg N the 1st year and 25-30 kg the 2d year. - The difference between the Nm(PH) and the Winter Crop-Soil-Nitrogen can indicate 2 distinct mechanisms : under bare soil, the negative values show the Leaching of Nitrogen during autumn (with rain) ; under Rs or Wh, the positive values indicate that the Mineralization is higher man Leaching. Probably, the N leaching rate during the autumn period decreased in the order bare soil > wheat > rapeseed, because the mineral N amount in soil was reduced due to plant uptake (rapeseed > wheat) over autumn-winter period.

Conclusions The intensive system has the highest yield and Grain N-concentration (13) but the lowest N efficiency and the highest risk of leaching. The adjusted and extensive systems are superior in terms of economic returns (non presented results) and environmental considerations. The extensive system presents the highest N productivity but the lowest grain quality. To improve efficiency of the cropping system, a better management of intercropping period and control of yield reducing factors (pests, diseases) are necessary.

References Appel, T., 1994. Zeitshrift fuer Pflanzenernährung und Bodenkunde, 157: 407-414. Huggins, D.R. and Pan, W.L., 1993. Agronomy Journal, 85: 898-905. Jenkinson, D.S. et al, 1985. Journal of Soil Science, 36: 425-444. Muller, J.C. and Mary, B., 1981. CR Académie des Sciences, France, 67 : 808-902. Remy, J.C. and Viaux, P., 1982. 'Symposium on fertilisers and intensive wheat production in

the EEC', London, 10 December 1982: 67-92.


PRODUCTION ECOLOGICAL CONCEPTS FOR THE ANALYSIS AND QUANTIFICATION OF INPUT-OUTPUT COMBINATIONS

M.K. van Ittersum & R. Rabbinge

Department of Theoretical Production Ecology, Wageningen Agricultural University, P.O. Box 430, NL-6700 AK Wageningen, The Netherlands

Introduction Agriculture can be defined as the human activity in which energy from the sun is used for the production of sugars by using a set of inputs. This activity results in desirable outputs, such as grain or potatoes, and, inevitably, in undesired outputs, such as nutrient emissions. Numerous combinations of inputs and outputs are practised and possible in agricultural production systems. Production ecology studies the way agricultural production systems function and may function in relation to physical constraints and environmental factors. Important aims of production ecology are: i) the analysis of the relative importance of several growth factors and inputs to explain actual yield levels and resource use efficiencies and to open ways for improvement; ii) to quantify new input-output combinations for developing sustainable production systems. The basis of such analysis and quantifications is knowledge of basic processes at soil, field, crop and animal level. For a systematic analysis and quantification of agricultural input-output combinations various production ecological concepts have been developed.

Production level - desired output per unit area (Figure 1) Potential, attainable and actual production levels can be distinguished according to three groups of production factors: growth defining, growth limiting and growth reducing factors. Growth defining factors include factors that, at optimum supply of all inputs, determine growth and production from a plant's point of view: C02-concentration, radiation, temperature and crop and cultivar characteristics. Growth limiting factors comprise the essential abiotic resources water and nutrients; they are taken up, and some are incorporated in the plant. Growth reducing factors include weeds, diseases, pests and polluting substances.

Production situation - physical conditions at which production takes place (Figure 1) Input-output combinations are location specific. The location can be characterized by the production situation, i.e. the climate and soil conditions. The production situation is hard to manipulate and affects the potential production level or the required inputs to realize a particular production level. The other way around, agricultural activities hardly affect the production situation; only in the long run changes may occur (e.g. in organic matter content).

Target-oriented approach - adjustment of inputs to realize a particular output On the basis of knowledge of bio-physical processes the inputs for the realization of a certain output in a particular production situation can be quantified. This so called target-oriented approach is an important concept in exploring new land use options. Input-output combinations quantified with this approach discriminate between bio-physical and technical opportunities and socio-economic constraints and objectives.

Production techniques - complete set of agronomic inputs Production technique stands for the inputs and the way the inputs are applied to realize a particular production level in a certain production situation. Since substitution is possible between some inputs, for instance between labour, mechanization and herbicides, a production level in a particular production situation can be achieved with various production techniques.

Session 2.1 437

Production orientation - aim of production activity that directs output and inputs The production orientation directs the output and input levels. Orientations for production activities could be a high soil productivity, high resource use efficiencies, low emissions per unit product and low emissions per unit area.

Example Table 1 gives an example of four input-output combinations (production activities) for growing a crop rotation in a particular production situation. The production activities are characterized by two production levels and two production orientations and were quantified with the target-oriented approach. They were used in an exploration for future land use options in the European Union (Rabbinge & Van Latesteijn, 1992; De Koning et al., 1995).

, .production level

: limited :

actual

actual

Defining factors -CO* - radiation - temperature

' - crop characteristics

! Limiting factors I - water

- nutrients

: Reducing factors : - weeds

- diseases ; - pests ' - pollutants

actual

bad production situation (bad climate / bad soil)

bad production situation (good climate / bad soil)

good production situation (good climate / good soil)

Figure 1. Production situation, production levels and associated principal growth factors.

Table 1. Example of four input-output combinations characterized by two production orientations and two production levels for growing the rotation 'potato-wheat-sugar beet-wheat' in a region in the Netherlands. Inputs are quantified with the target-oriented approach.

Outputs (fresh tons hd'yf') Wheat Potato Sugar beet

Inputs (ha'yr') Irrigation water (106m3) Nitrogen application (kg) Pesticide (kg a.i.) Labour (h) Machines (ECU)

Yield-oriented agric.

Potential

9.8 63 76

0.47 296 6.2 38 489

Water-limited

8.0 54 66

273 5.6 30 489

Environmental-oriented agric.

Potential

7.5 46 67

0.30 223 1.6 35 493

Water-limited

6.6 40 58

214 1.6 30 493

Production technique

References De Koning, G.H.J, et al., 1995. Agricultural Systems 40: 125-151. Rabbinge, R. & H.C. van Latesteijn, 1992. Agricultural Systems 40: 195-210.


ORGANIC ARABLE FARMING - A CONTRADICTION ?

P. von Fragstein

University of Kassel Faculty of Agriculture, International Rural Development and Ecological Environmental Protection Department of Ecological Agriculture Nordbahnhoftstr. la D-37213 Witzenhausen

Introduction Ecological Agriculture is a growing system in which the farm is considered as an organism of nearly closed cycles (Köpke 1995). Although severely critized by Koepf (1980): "The separation of domestic animal and clod was one of the most momentous steps in the development of modern agriculture although it was not the only one that influenced soil fertility in a negative way. " (p.55: "Die Trennung zwischen Haustier und Scholle..."), new tendencies in ecological agriculture clearly indicate a high interest of farmers for specialized, animal-independent organic farming systems. A successful crop growing in organic farming cannot be managed without the cultivation of legumes because of distinct restrictions for the N input through composts and organic fertilizers. The dependence on the functioning ofthat leguminous nutrient cycle is of extreme importance for the whole system. N-fixation and N-losses by volatilization or leaching have greater influence upon the stockless system compared to a mixed system. The crop rotation is the essential basis for an ecological growing system because it has to contribute to a satisfactory regulation of the wild flora, an equilibrated humus balance and an optimized nutrient management (Heß 1990).

Ecological stockless Farms A questionnaire to the main organisations of Ecological Agriculture in Germany - a response of the East German GAA could not be obtained - revealed astonishing results • • The biodynamic organisation (DEMETER) that strictly requires animal husbandry as part of

biodynamic farms allows vegetable growing enterprises as stockless systems. Contracts must assure the import of farmyard manure that has to be composted and biodynamically prepared before use.

•> There are three organisations - ANOG, NATURLAND, and BIOLAND - in which 20 to 40 % of all farms represent stockless systems. The North German Extension Service -ÖKORING - is close to 50 % of all farms practicing arable farming.

• • The organisation specialized for wine growing and vine making - BOW - includes approximately 100 % of stockless growing systems that is very typical for special crops like fruits and grapes.

It is obvious that East German organic farms tend to systems without stocking or very low stocking rates because of the big farm size, very often bigger then 500 ha. Spohn (1993) interviewed nine stockless organic farmers and asked among others for their motivation to work in that system. He found five dominant aspects:

1. main interests in crop growing, 2. no animal housings at the place, 3. low rentability, 4. high (continuous) labour input, 5. ethic reasons.

Session 2.1 439

Conclusions Regulation of weeds • The cultivation of forage crops cannot be given up due to the weakening effect to root

weeds like thistles by the repeated cuttings during the growing season. Humus management • Organic fertilizers, especially off-farm composts can be essential for the necessary recycling

of stable organic compounds in order to maintain sustainable soil fertility (provided that continuous quality controls are made concerning unwanted concomitants).

N-Management • Seed and forage legumes are capable to provide sufficient N-reserves for a crop rotation or

rotational segments either by crop residues or by the total biomass (Hagmeier 1986), • that potential can only be benefical if site and growing conditions suit the requirements of

the cultivated legumes, • strategies have to be developed and applied in order to minimize nutrient losses (Heß 1990,

Justus et al 1990). General remarks •> It is obvious that arable growing systems are also determined by essential elements of crop

cultivation in mixed systems, namely the forage crops (Hagmeyer 1986), •> There is no doubt about the special importance of farmyard manure or composted FYM

towards the maintenance of soil fertility. Off-farm composts are able to replace their function in arable systems (Fragstein et al 1994, 199S).

• • There is an increasing tendency towards arable cropping systems, actually favoured by the financial supports for conversion as part of the EU-wide set-aside programme (Spohn 1993).

-> Farms of intensive crops, i.e. vegetables, fruit trees or vine, traditionally belong to stockless systems. Even in biodynamic farms that practice is continued regardless the requested animal husbandry on agricultural farms.

The contradiction in question is not caused by the existence of organic arable farming, but by the contrasting strategies of organisations which permit stockless organic gardening, but exclude organic arable farming.

References Fragstein, P. von and H. Schmidt, 1994, 1995. N management in an organic stockless crop

rotation. Annual Report I and U of EU-Project AIR3-CT93-0852, "Development and evaluation of organic farming systems: The role of livestock and agroforestry", 60 p. & 66 p.

Hagmeier, H.U., 1986. Über die Stickstoffversorgung von Winter-Weizen und Winter-Roggen durch Leguminosenvorfrüchte, dargestellt anhand von Experimenten auf einem viehlos bewirtschafteten organisch-biologischen Ackerbaubetrieb auf der Schwäbischen Alb. Dissertation Universität Hohenheim, Stuttgart, 119 p.

Heß, J., 1990. Mitteilungen der Deutschen Gesellschaft für Pflanzenbauwissenschaften. 3: 241-244.

Justus, M. and U. Köpke, 1990. Mitteilungen der Deutschen Gesellschaft für Pflanzenbauwissenschaften. 3: 187-190.

Koepf, H.H., 1980. Landbau - natur- und menschengemäß - Methoden und Praxis der biologisch-dynamischen Landwirtschaft. Verlag Freies Geistesleben, p.55 (quotation)

Köpke, U., 1995. Warum organischer Landbau? In: Tagungsband 3. Wiss. Fachtagung zum Ökologischen Landbau, (Hrsg) SÖL und FG Ökologischer Landbau der Universität Kiel., p. 13-19.

Spohn, L., 1993. Viehloser Ökologischer Landbau. Diplomarbeit FH Kreuznach, 117 p.


ENVIRONMENT EXPOSURE BASED PESTICIDES SELECTION

KG. Wijnands

Research Station for Arable Farming and Field Production of Vegetables, P.O. Box 430, NL 8200 AK, Lelystad, the Netherlands

Introduction The use of pesticides in current farming systems is extremely high due to the almost exclusive choice of pesticides to correct for structural problems in the farm management such as insufficient crop rotation, susceptible varieties and high nitrogen inputs. This is only one, however a major one, of the complex of problems that current farming is involved in. In reaction to these problems, Integrated Farming Systems (IFS) have been developed as a coherent new vision on agriculture alongside other concepts as ecological farming (EFS). Over the last 15 years these I/EFS systems that integrate potentially conflicting objectives concerning economy, environment and agronomy are being developed on experimental farms all over Europe. In the last 5 years this even has been done in co-operation with commercial farms; innovative pilot farms. The development of these systems is presented as a coherent methodology called prototyping (Vereijken 1994, 1995). Appropriate farming methods (comprehensive strategies built on different techniques) need to be developed or redesigned. Top priority is given to the design of a multifunctional crop rotation followed by the nutrient management, the soil cultivation and the ecological infrastructure. All these methods are aiming at sustaining quality production with minimum external inputs and environmental hazards. Based on prototyping research on experimental farms (Wijnands and Vereijken, 1992) and pilot farm (Wijnands, 1992) in the Netherlands it is shown what the role of crop protection is in these systems and an innovative approach towards selection and evaluation of pesticides use is presented.

Methods The role of crop protection in an integrated system is to sustain quality production by efficient control of the residual harmful species, with minimal use of well selected pesticides, giving priority to all non-chemical control options available. The selection of pesticides must be based on a quantitative appraisal of their impact on the environment, since the overall aim of sustainable farming systems is to minimise the exposure of the environment to pesticides in order to prevent short- and long term adverse effects on all species overall the biosphere. The Exposure of the Environment to Pesticides (EEP) is quantified by relating the active ingredient properties Vapour Pressure, Half life time (DT50) and Kom (exchange coefficient water-organic matter) to the amount used. These properties are known under standardised conditions, since they are required values for the approval procedures (Linders et al., 1994). EEP quantifies the maximum risk of environment exposure to pesticides for the different compartments of the abiotic environment: water, soil and air. It can be used to evaluate pesticide use or to select pesticides. EEP by farm should targetedly be improved by a) substitution of the highest ranking compounds by non-chemical measures or lower ranked pesticides or b) by reducing the used amount by a more appropriate dose or band-spray or spotwise treatments.

Session 2.1 441

Results Over the period 1986-1990 the input of pesticides in the integrated farm at Nagele (Development of Farming Systems experimental farm) was reduced with 60%, excluding nematicides and by 90% if nematicides are included, in comparison to the conventional system. The reduction was a result of the Integrated Crop Protection strategy (no major changes in available pesticides during this period). The integrated system in 1992 reduced another 70% of the active ingredient use of the integrated system during 1986-1990. This was for the larger part due to substitution of old pesticides by "new" low active ingredient compounds. From the conventional system in 1988 (representative for 1986-1990) to the integrated system in 1992 (representative for 1992-1995) the active ingredient use and EEP-air, -water and -soil were respectively reduced by factors of 43 106, 215 and 254.. For active ingredients this means in terms of reduction %, 98% reduction if nematicides are included. The selection of pesticides based on EEP obviously multiplied the effect of the ICP (reduced use). The pilot farm Central clay group (9 pilot farms in the same area as the Nagele farm) reduced the input of pesticides in kg active ingredient and in EEP, like at Nagele, strongly. In 1993 the active ingredient input and the EEP was, in comparison to the farm-specific reference years 1987-1989, reduced by respectively factors of 6.5, 106, 3 and 5. For active ingredients this means in terms of reduction %, 85% reduction if nematicides are included.. It is shown that the quantitative EEP (Environments Exposure to Pesticides) parameter is an excellent evaluation and selection tool for pesticide use.

Conclusions IAFS prototypes as designed, tested and improved in the Netherlands on experimental farms for region-specific conditions showed economically and technically feasible possibilities to reduce the input of pesticides drastically and to almost minimise their environmental impact whilst maintaining soil fertility, minimising P/K/N mineral fertiliser input and controlling leaching of N. The economic perspectives were equal to those of the "conventional" farming systems. The prototypes thus were ready for a test and improvement phase with a limited number of well-motivated practical farmers (38 farms from 1990 till 1993).. Similar results as on the experimental farm were obtained. In 1993 the pre-requirements for large scale introduction were fulfilled and a new, large scale dissemination project, involving 450 farmers was started.

References Linders, J.B.M.J, et al. Pesticides: Benefaction or Pandora's box, a synopsis of the environmental

aspects of 243 pesticides. Report no 6791014. National Institute of Public Health and Environmental Protection, Bilthoven Netherlands, 201 pp

Vereijken, P., 1994. 1. Designing prototypes. Progress reports of research network on integrated and ecological arable farming systems for EU- and associated countries (concerted action AIR3-CT927705). AB-DLO, Wageningen, Netherlands 87 pp.

Vereijken, P., 1995. 2. Designing and testing prototypes. Progress reports of research network on integrated and ecological arable farming systems for EU- and associated countries (concerted action AIR3-CT927705). AB-DLO, Wageningen, Netherlands 76 pp.

Wijnands, F.G., 1992. Netherlands Journal of Agricultural Science 40(3): 239-250.. Wijnands, EG. and P. Vereijken, 1992. Netherlands Journal of Agricultural Science 40(3): 225-

238.

Session 2.2

Resource use at cropping system level.


RESOURCE USE AT THE CROPPING SYSTEM LEVEL

P.C. Struik1, F.Bonciarelli2

1 Department of Agronomy, Wageningen Agricultural University, Haarweg 333, 6709 RZ Wageningen, The Netherlands 2 Istituto di Agronomia Generale e Coltivazione Erbacee, Universita' di Perugia, Perugia, Italy

Introduction The basis of sustainable agriculture is a good crop rotation, adequate soil and water management, and proper husbandry of the different crops in the rotation. Agronomically, farmers should aim at the minimum input of each production resource required to allow maximum utilization of all other resources. Consequently, above a certain minimum, higher inputs of a resource result in higher yields per unit area and are associated with higher efficiencies (expressed as output per unit of input) of other resources, but at the same time might cause large residues or emissions per unit area. Many processes relevant to resource-use efficiency (RUE) are so slow or long-lasting that they also have effects at the time scale of an entire rotation. This paper focuses on these processes.

Crop rotation Crop rotation is a more or less fixed pattern in the succession of crops on a certain field and thus a more or less fixed pattern of management and inputs. RUEs at the crop rotation level are not only determined by short-term efficiencies of component crops but also by long-term processes influenced by tillage, the different crops in the rotation and their management. The physical fertility is affected by each crop, the type and timing of cropping practices in each crop, and the measurements taken during fallow periods to improve the physical fertility. Chemical soil fertility is affected by fertilizer application; the effects of crops on nutrient fixation and mobilization, mineralization and losses of nutrients; the amount and quality of crop residues; and their rate of degradation. The higher the frequency of crops sensitive to soil-borne diseases or other biological stresses, the higher the need for crop protectants to control them. In contrast, the higher the frequency of crops with positive effects on beneficial organisms, the lower the need for crop protectants. It is difficult to set out general rules for a good crop rotation but alternating crops with contrasting effects on the physical, chemical and biological soil fertility is usually advisable.

Management strategies at the cropping system level (illustrated by a balanced N-supply) Differences among crops and their cultivars in recommended (economically optimal) applications and nitrogen use efficiency are large; residual N is therefore very variable. Residual N will be lost or will have after-effects later in the rotation. At the cropping system level the efficiency of nitrogen is determined by the level of input, the form and timing of input, the efficiencies of utilization by the different component crops and the degree to which N remaining in the soil or in crop residues can be kept within the boundaries of the cropping

Session 2.2 445

system and can be utilized by later crops. Efficiency is optimal when the following aims are met: i. maximum use of the nutrients supplied by adjusting the amount supplied to the demand, by synchronisation of supply and demand, and by synlocalisation (the nutrient is available where it can be taken up); ii. optimal use of crop residues, for example by maintaining the proper C:N ratio in the soil; iii. maximum reduction of emission during the periods between the main crops, e.g. by growing catch crops or by incorporating straw. Microvariability in plant and soil characteristics and their interactions is crucial for a proper management of nutrients. Part of the variability may persist, increase in time and interfere with other aspects of crop management. Managing variation is therefore crucial for sustainable resource management at the cropping system level.

Management strategies per link in the crop rotation (illustrated by a balanced N-supply) For nitrogen efficiency two crop types can be distinguished: crops without change in N-recovery with an increase in N-supply until the agronomically optimal level and crops with an decrease in N-recovery with an increase in N-supply. Beyond the agronomically optimal supply the recovery decreases with an increase in supply for both types. In all cases nitrogen residues are unavoidable. The type of fertilizer is relevant to the magnitude of and variation in the losses. The dynamics of N availability cannot be accurately predicted, not in time and not in amount whereas also crop growth and amounts of N in crop residues are still unpredictable to a large extent. Crop residues will affect the soil fertility. Depending on their C:N ratio, soil characteristics, tillage and cropping practices, and weather the proportions of N lost or carried over to the next growing season vary considerably. The emissions can be reduced, albeit not to zero. If nitrogen emissions are kept extremely low, usually the chemical soil fertility is reduced in the long term. This may not be true for other nutrients.

Use of special crops to improve sustainability Growing of legumes (improving nitrogen and phosphorus availability); green manure crops (physical, chemical and biological soil fertility); lure, catch, trap and killing crops (biological control or suppression), cover crops (preventing soil erosion); and nutrient catch crops (keeping nutrients available for subsequent crops) can help to improve the sustainability of the cropping system. They have to fit in the sequence of main crops and should not interfere with necessary soil tillage. Especially their response to light and temperature in dependence of sowing date and their effects on water availability need further research to optimize their use.

Final remarks Tools for analytical study of and decision support on the effects of cropping system management on the productivity of each crop in the rotation, of the environmental risks and of the sustainability of the cropping system are strongly needed. Investigations into options to maintain a short rotation of a crop with low self-tolerance by making use of non-chemical strategies to avoid yield-reducing conditions are also required. In practice, variation in RUE is strongly influenced by differences in "farming styles" among farmers, even under similar environmental conditions and financial returns.


PRELIMINARY EVALUATION OF EPIC IN SIMULATING CROPPING SYSTEMS AT ONE SLOVAKIAN LOCATION

M. L.- Bartosova, S. Kosovan

Department of Agricultural Systems, University of Agriculture, 949 76 Nitra, Slovakia

Introduction Agriculture is commonly considered as one of the most important non-point sources of ground water pollution in Slovakia. Very little measured data are available to quantify the impact of agricultural management on water pollution. Simulation models are research tools which can be used to assess both the impact of agricultural management on the environment and the agronomical outcome of different managements. Models must be evaluated in each specific environment before using them in simulation studies. As a first approach to model validation, we compared data collected on an on-going cropping systemexperiment with simulations run using the EPIC model.

Methods The experiment was laid out at the research station of Dolna Malanta (Nitra, Slovakia). The data used refer to the years 1991-95. The rotation studied is a 8 years rotation, alfalfa - alfalfa -winter wheat - sugar beet - spring barley - common pea - maize - spring barley. Each phase of the rotation was sown every year in a randomized block design with four replicates. Fertilizers applied were the amounts per ha commonly used in the area until 1993, the treatment no fertilization was added in the years 1994-95. Weeds and pests were controlled by using pesticides. Meteorological data were collected at a local university weather station. Soil input parameters were estimated by measurements on site. The EPIC model, version 3090, was used to simulate the cropping systems during the years 1991-95, without reinitializating soil variables.

Results The location of Dolna Malanta is characterized, with respect to rainfed agriculture, by the amount of average yearly rainfall 533 mm and by the value of average monthly windspeed 4.8 m/s. In these conditions, the proper estimate of both potential évapotranspiration and water use by the crops is extremely critical to simulate the water budget. Data available allowed only a partial description of the system under study. Nonetheless, the data available were the only ones to make a first approach to cropping system simulation by EPIC, looking mostly at model capability to adequately estimate year-to-year variability of grain yields. Calibration of crop parameters, because of lack of data, was restricted to total heat units, in order to set the proper length of the biological cycle for each crop.

Maize- grain yield ( t.ha ') Maize-above ground biomass (t.ha'1)

• HO

• /

/ •

& s^

- -• 91 • 92 A 93 1194 O 95

• 94n

+ 95n

of

of ]

T3 4)

13

U

I L

16

14

12

10

8

6

Measured yield

A

s' a -

//

/ 4 6 8 10 12 14

Measured yield

16

• 91 A 92 A 93 X 94 X 95 • 94sil + 95sil - 94nof

• 95nof • 94silnof • 95silnof

Session 2.2 447

Winter wheat yield (t.ha'1) Spring barley yield (t.ha'1)

2 4 6 Measured yield

2 6 a

•o S 4 o

2 , 0. 2

n

x / / m

/ / Û

/ ^ /" •

• 91

• 92

A 93

X 9 4

X 9 5

' • 9 5 n o f

2 4 6 Measured yield

Alfalfa yield (t.ha1) Sugar beet yield (t.ha ' )

0 2 4 6 8 10 12 14

Mesured yield

2 14 -

> 12 -•a s io -u TJ 8 -£ 0. 6 -

4 -

/k

~—\ \

x '~7 O y /

/ m «

a •

i i

4 6 8 10 12 14 16

Measured yield

• 91

D 9 2

A 93

• 94

x 95

• 94nof

O 95nof

Figure 1. Predicted vs. measured yield data (t.ha" ) for crops grown in the rotation. Legend: nof : no fertilization; $: first year of alfalfa; sil: maize for silage

The underestimated yields of sugar beet, winter wheat and spring barley (Fig. 1 ) were affected by water stress (low rainfall). Unacceptable results are the predicted maize and winter wheat yields in the year 1995 for no fertilized conditions.

Conclusions The discrepancies between predicted and measured data suggest that the default values of EPIC parameters are not fully adequate for Slovakian conditions, so measurement to estimate model input parameters are needed to allow evaluating model capability to simulate cropping systems in the conditions under study. It must be pointed out that the model estimates show often an overestimate of water stress, whereas some validation studies conducted in different areas of Europe showed that EPIC tends to underestimate water stress.

References Cabelguenne, M. et al, 1988. Agronomie, 8 (6):549-556 Cabelguenne, M. et al., 1988. EEC, Brussels, 24-25 November 1988 Ceotto, E. et al, 1993. Agricoltura Ricerca, 151-152:209-228 Williams, J. et al., 1994. 1984. Transact. ASAE, 27 (1):129-144 Williams, J., 1994. The EPIC model, U.S.A., U.S. Dept. Agric, ARS/ SWRL, 114 p.


SOIL PHYSICAL PROPERTIES - SOIL MANAGEMENT INTERACTIONS IN A SUSTAINABLE FARMING SYSTEM

A. Canarache

Research Institute for Soil Science and Agrochemistry, Bd.Marasti 61, 71331 Bucharest, Romania

Introduction Soil physical properties are recognized as one of the major factors determining soil productivity, crop yields, and sustainability of farming systems Results of determinations of soil physical properties in long term-field experiment are presented here.

Method Several long-term experiment fields, organized by various research institutes and research stations in this country have been investigated. Undisturbed soil samples were collected. Bulk density, total and aeration porosity, saturated hydraulic conductivity, standard resistance to penetration, aggregate water stability, and dispersion were determined using classical analytical methods. Infiltration rate was determined in the field using a single-ring infiltrometer. A synthetic "agrophysical index" (Canarache, 1978), which is the average of the normalized data for 10 individual soil physical characteristics, has been calculated. Results were fit in a conceptual model (Canarache, 1987, 1994) describing mechanisms of changes and interrelationships with some soil chemical properties and with crop yields. Regression analysis, linear and quadratic, as well as single and multiple, was used to quantify the different mechanisms involved.

Results As shown in the Figure, five main types of mechanisms are considered to be involved in the changes affecting soil physical properties under long-term management techniques. A sixth mechanism represents the feedback effects of changed soil physical properties on crop yields.

Direct effects of management on soil physical properties (No. 1 in the Figure) result mainly from tillage practices and from traffic. As an example, in a long-term experiment conducted at the Marculesti Research Station on a vermi-calcaro-calcic Chernozem, grain maize being the crop (Canarache et.al., 1979), with various ploughing depths and reduced tillage, continuous or alternating from year to year, the following regression was obtained: BD = 1.36 - 0.0023*Tcy - 0.0013*Tpy - 0.000022*Tcy

2

- 0.000022*Tpy2 +0.00013*Tcy*Tpy (R2 = 0.93*)

where: BD - bulk density (g.cm"3), Tcy - tillage treatment current year, Tpy - tillage treatment preceding year (T representing the depth of ploughing in cm, with zero conventionally used to describe no-ploughing treatments). Other results referring to deep loosening of compact subsoil, zero-tillage, cultivation, as well as to man-made compaction, are available.

Indirect effects of management on soil physical properties through the path management - soil chemical properties - soil physical properties (No.2+3 in the Figure) are often noticed when fertilizers are applied. They are illustrated here with results from the Fundulea Research Institute for Cereal and Industrial Crops (haplic Phaeosem), for silage maize as a crop (Moga et al, 1986). The regression equations are: H =2.91 + .0060*M-0.076*N-0.0025*M2 + 0.022*N2 + 0.0011*M*N (R2 = 0.99**) AI = -5.3+3.54*H-0.54*H2 (R2 = 0.50*)

Session 2.2 449

where: H - humus content (percent), AI - agrophysical index, M - manure (t.ha" ), N - nitrogen (kg. ha"1). There are many results of this type, for different soils, crops, and fertilizers.

—»

<-

<-

i Crop growth

and yield

6b

Management techniques

4

5

I

1

6a

i I Soil physical prop erties

2

3

i Soil chemical

properties

Figure. Conceptual model of management - soil - crop interactions (see text for explanations)

Indirect effects through the path management - crop growth - soil physical properties (No. 4+5 in the Figure) is a mechanism less studied. We explain this effect through a better root development caused by adequate soil management, and by the effects the root system have on soil structure and on other soil physical properties. Crop rotation is one of the management practices usually showing this mechanism. Results from an experiment with potatoes on a haplic Phaeosem at the Secueni Research Station (Canarache et al., 1984) are presented here: Y =22.3 + 1.20*R + 3.90*F-0.38*R2-0.34*M*F (R2 = 0.96**) AI = 0.78 - 0.0021 *Y + 0.00037*Y2 (R2 = 0.48*) where: Y = yield (t.ha"1), AI - agrophysical index, R - crop rotation (number of years with other crops than potatoes), F - fertilization (conventional figures used: zero for non-fertilized, 1 for complete NPK fertilization). Other experimental data are available on different soils describing similar effects of preceding crops and of crops with specific improving effects.

Conclusion Data presented in this paper, and many similar data available, describe possible positive and negative effects of soil management on the soil physical status, some of the mechanisms involved, and could contribute to a sustainable soil management system.

Literature Canarache, A. , 1978. Stiinta Solului, 1: 33-43. Canarache, A., 1987. Dum Techniki CVSTS, Tabor (Czechoslovakia), pp. 106-117. Canarache, A., 1994. In: Trans. 15th World Congress of Soil Science, Acapulco, 6a: 142-143. Canarache, A. et al., 1979. In: 50 Ani de Activitate Stiintifica in Baraganul de Sud-Est, Marculesti

(Romania), pp. 168-204. Canarache, A. et al., 1984. Technical Report, Institutul de Cercetari pentru Pédologie si

Agrochimie (unpublished). Moga, I. et al., 1986. Analele Institutului de Cercetari Céréale si Plante Tehnice, 53: 211-236.


SIMULATION OF DURUM WHEAT YIELD AND N DYNAMICS BY CERES/WHEAT MODEL IN AN ALFISOL OF SOUTHERN ITALY.

A. Castrignanô1, G. Convertira1, D. Ferri1, P. Greco2.

1 Istituto Sperimentale Agronomico. Via C. Ulpiani, 5. 70125 BARI, Italy. 2 Istituto Sperimentale per il Tabacco. Via F. Calasso, 3. 73100 LECCE, Italy.

Introduction Nitrogen fertilizers should be annually applied and well adapted to crop needs as well as to soil and climatic conditions. However, to predict the precise crop N requirements, crop growth and development processes in relation to water and N balances should be estimated. Simulation models are particularly useful to provide some insights into fertilizer responses in different environments and they are of great help for optimizing long-term management strategies. To simulate N dynamics adequately, a model capable of describing the major soil and plant transformations is required. The CERESAVheat model was chosen, as it simulates growth, phenology, water and nitrogen balance, and yield; moreover it has widespread applicability (Godwin and Vlek, 1985).

Methods A field trial was conducted from 1988 to 1991 on a sandy soil (Haploxeralf) at the Tobacco Experimental Institute, Lecce-Itary. The main soil characteristics are: 70% sand; 13% clay; 1.3% o.m.; 0.7 g kg"1 N , pH (H20): 8.2; C.E.C.:13 meq/100 g, NaHC03-extractable P: 20 mg kg"1. Among five rotations in comparison, the biennial tobacco-durum wheat rotation without soybean as catch crop, fertilized, irrigated and managed according to two treatments (high input and low input) was used to validate CERES model for wheat crop in two cropping seasons (1986-87; 1988-89). The climatic conditions during the trial period were reported by Greco et al (1994). Monthly soil samples were taken at two depths along the soil profile (0-15; 15-40 cm). Each sample was subsampled for moisture determination by drying in an oven at 105° C and placed in an extracting solution (1 M KCl) at 1:5 sou solution ratio for 2 h; filtered extracts were analyzed with a Technicon Autoanaryzer, series II for N-NO3 and exchangeable N-NH, measurements according to standard methods.

Results With regard to phenology the observed maturity dates (Table 1) were always later than the predicted ones, even in the 1986-87 season when the high input treatment data were used to calibrate wheat genetic coefficients. That probably results from a weakness of CERES/Wheat model (in particular, the genetic coefficient PS) to simulate the phenology of durum wheat in hot-dry conditions, typical of southern Italy. On the contrary, as for anthesis date matching between observed and predicted values was very good in the 1986-87 season, and the predicted date was later in the 1988-89 season. From the estimation of the model stress coefficients, that might be caused by nutritional and water stresses, occurred at the beginning of cropping cycle and at grain filling stage, respectively. The prediction of grain production values was always quite good but in the 1986-87 season a severe lodging (70 percent of plants), due to the particular size of the used durum wheat genotype, selected in our environment and characterized by an even yield during the years, caused a loss in grain yield. Thus the simulated values were reduced because the model does not consider other limiting factors than temperature, water and nitrogen. The observed grain yields (Table 1) were not statistically significant between the two treatments, because of the more severe loss of production due to the lodging in the "high input" treatment.

Session 2.2 451

N grain content (%) was also estimated fairly well (Table 1) but an overestimation (except in 1986-87 season for high input data used for calibration) of the model was observed for the "low input" treatment, probably caused by nutritional and water stresses occurred at the beginning of ear growth and during the grain filling. The fitting of grain N uptake (kg ha" ) was also very good for both treatments and in both years, whereas the significant overestimation of total N uptake was very likely produced by an overestimation of total biomass. In Figure 1 the observed and simulated values of N percentage in plant tops are compared. It appears that the model overestimates.

Table 1 - Comparison of predictions of the CERES/Wheat model with averaged observed data from experiments.

Anthesis date Maturity date Grain yield ( kg ha" Kernel weight (g) Grains per sq metre Grain per ear N Grain (%)

')

Tot. N uptake ( kg N h a - 1

Grain N uptake

z CO 0 -

0 r -

" 0 0)

£ <D 0)

0

)

6 5 4

3

2 1

0

High level Input 1986-87

Predicted 121 160

3446 44.357 11952 30.18 2.23 149.6 97.1

Observed 121 178

3106 48.000 12000 30.00 2.65 102.9 94.6

1988-89 Predicted

120 164

3251 40.283 9171 12.92 2.44 157.0 90.2

. . • * /

.^ *"

1 1

Obseived

R = 0.69

i

Observed 107 175

3236 52.000 9840 30.00 2.48 121.8 92.3

Low level input 1986-87

Predkted 121 160

3411 44.371 11825 25.40 2.23 126 76.1

1988-89 Observed Predkted

121 178

3089

120 164

3210 52.000 42.809 10500 8242 28.00 2.17 103.0 77.0

t

= 2.41 + 0.73 * Simulated

• 1 1

10.51 2.30 107.2 73.8

Observed 107 175

3180 57.000 9660 28.00 2.04 96.6 74.5

0 1 2 3 4 5

Simulated TOPS N (%)

Figure 1. Observed versus predicted plant top N (%). The 1:1 fine and the regression une (observed vs simulated) are given.

Conclusions The results show that CERES/Wheat model should be better calibrated and eventually modified to adapt it to hot-dry conditions in southern Italy. Nevertheless, it already proves a valid tool for optimizing fertilization and water management, because the experimental results showed the possibility to reduce the agrotechnical inputs.

References Godwin, D.C. et al., 1985. Simulation of Nitrogen dynamics in wheat cropping systems. In:"Wheat growth and modeling".W. Day and R.K. Atkin (Eds). Series A: Life Sciences . New York, 86, 311 - 330; Greco, P., et al., 1994., Proc 3rd ESA Congress, 696 - 697.


GRAIN SORGHUM IN SOUTHERN ITALY : DYNAMIC GROWTH AND NITROGEN SIMULATION BY CERES/SORGHUM MODEL

A. Castrignano, G. Convertira, D. Ferri, V. Rizzo, M. Rinaldi.

Istituto Sperimentale Agronomico. Via C. Ulpiani, 5 70125 BARI, Italy.

Introduction Grain sorghum is a C4 species with very high photosynthetic efficiency, suitable to be cropped in the environments of South Italy, characterized by intense radiation levels. High grain yields were obtained both in irrigated farms and even during long dry seasons (Quaranta et al., 1987), probably because of root morphological and physiological characteristics that make grain sorghum quite resistant to drought (Mariani and Donatelli, 1983). To get more insights in yield potential and N dynamics of sorghum cropped in southern Italy, the experimental results of a long term trial were compared with the predictions of the CERES/Sorghum model ( Virmani et al., 1989).

Methods The silty-clay soil (Typic Chromoxererts) of the trial had the following characteristics: 40% clay, 27% sût, 2% O.M., 1.2 g kg"1 N, 75 mg kg'1 NaHC03-extractable P, 1000 ppm NILOAc-extractable K, 37 meq/100 g C.E.C., pH=7. Monthly soil samples were taken in three layers along the profile (0-20; 21-40; 41-60 cm) at Foggia (southern Italy) during the cropping seasons: 1989 and 1991. Each soil sample was subsampled for estimating water and nitrate contents checked by extraction with 1 M KCl and analyzed by automatic standard methods. In 1989 also weekly plant samples were collected for growth analysis. The trial consisted in the comparison among different cropping systems combined with two agrotechnical input levels, concerning soil tillage, fertilization and water management (conventional management as high level and low-input management as low level). In this work only grain sorghum data (cv. NK 180), submitted to the two input treatments and sown in May in the two trial years, were utilized for simulation. The 1989 data for high input level were used to calibrate the model genetic parameters, whereas the remaining three data sets were used for validation.

Results The results of the simulations are presented in Table 1. The best goodness-of-fit was obtained for anthesis and maturity dates in both years. The differences between predicted and observed sorghum grain yields were about the same in both years (12-15 %), but in the first one the model overestimates, whereas in the second one it underestimates in both treatments, as a consequence of the underestimation of the kernel weight. The different performances of the model in the two years of simulations is probably determined by different rainfall patterns: i. e. the second year was characterized by drier meteorological conditions (360 vs. 280 mm on average of water supply in the two cropping seasons, respectively). As regards N balance, it appears clear from Table 1 that the model tends to overestimate both grain N (%) and grain N uptake and underestimate total N uptake, except in 1989 for "low input" treatment. An improvement of model prediction as a whole could be obtained by increasing goodness-of-fit of above-ground biomass. On the contrary a quite good matching between observed and predicted values of growth analysis (leaf area index "LAT', stem and leaf dry weight and above-ground biomass "DM") was obtained with determination coefficients always greater than 0.97. As an example, in Figure 1 the comparison between observed and predicted LAI and DM values for the two treatments is shown. It appears clear that the model tends to overestimate above-ground biomass, mainly in the low input treatment and during the final part of the crop cycle.

Session 2.2 453

Table 1. Comparison of predictions of the CERES/Sorghum model with averaged observed data. 1989 1991

High level Low level High level Low level Predicted Observed * Predicted Observed Predicted Observed Predicted Observed

Anthesis date Maturity date Grain yield ( kg ha"1) Kernel weight (g) Grains per sq meter Grains per ear Biomass yield (kg ha"1) Grain N (%) Tot. N uptake ( kg N ha ~l) Grain N uptake " * Used for calibration

203 237 8097 0.024 33574 1119.13 19162 1.94 198.4 157.5

202 240 7668 0.023 33750 1277.00 20159 1.67 209.0 149.0

203 237 8000 0.024 33647 1121.57 19081 1.89 191.9 151.0

202 240 7041 0.024 28739 1150.00 16361 1.50 162.0 123.0

203 236 5026 0.015 33504 1164.81 15448 2.88 183 144.7

207 238 5911 0.020 30359 912.00 14281 1.90 222.0 131.0

203 236 4657 0.015 31048 1034.93 14750 2.70 162.3 125.5

207 238 5298 0.017 31031 1015.00 18931 1.77 196.0 109.0

DM (g ntf)

2000

LAI

e

1600

1200

800

400

0

S

4

3

2

1

0 190 180 200

Ju««) day Julian day

Figure 1. Comparison of predicted and observed LAI and above-ground biomass during the crop cycle for each treatment (high and low input level).

Conclusions The results of the work show that CERES/Sorghum model is able to explain most of the observed variation in phenologjcal dates, yield and other growth variables. However, further studies and validations in relation to soil and plant components of N balance are required to improve the model performance.

References Mariani,G, Donatelli, M , 1983. LTnf. Agr., 39, 11, 24991 - 24999. Quaranta, F., et al., 1987. LTnf. Agr, 43, 14, 37 - 41. Virmani, S.M. et al., 1989 (Eds). Modeling the Growth and Development of Sorghum and Pearl Millet. Research Bulletin n° 12. (ICRISAT). Patancheru, A.P. 502324, India.


NUTRIENT BALANCE AT FARM LEVEL FOR CROPPING SYSTEMS IN THE PO VALLEY, ITALY

E. Ceotto, M. Donatelli, R. Marchetti, P. Spallacci

Istituto Sperimentale Agronomico, Sezione di Modena, Viale Caduti in Guerra 134, 41100 Modena, Italy

Introduction The accumulation of nutrients is one of the main environmental problems in areas of intensive farming and livestock activities (Ivens et al., 1992; Loomis and Connors, 1992). In Northern Italy planes this problem is twofold due to the concentration of pig livestock and to the high amount of mineral fertilizers often applied. Manure constitutes a serious waste problem, due to the uneven distribution of livestock facilities and suitable crop areas. A proper choice of crop rotation on the one hand, and level of fertilizers applied on the other hand, leads to more sustainable land use. In order to gain a first insight on the possible environmental side effects of several cropping systems a nutrient balance at farm level was performed. Although these simplified balances are largely incomplete for a proper quantification of pollution determined by the systems, they help in identifying unacceptable situations.

Methods A cropping system trial started in 1993, at location S. Prospero (Modena), Low Po Valley, to assess the environmental impact of cropping systems denned by five crop rotations and three input levels. The crop rotations compared were: - Sugarbeet-Wheat - Sugarbeet-Sorghum-Wheat - Sugarbeet-Maize-Maize-Wheat - Maize-Maize-Wheat - Soybean-Barley+Sorghum late sowing Crop rotations are both in time and in space so each phase of crop sequences is present every year. Sugarbeet-wheat rotation is quite common in the area due to high income of the first crop, but it is not suitable to use pig slurry. The introduction of maize and sorghum in the rotation leads to increased possibilities for spreading animal wastes. The highest input level (A) is the one often applied by the farmer, in which mineral fertilizers (nitrogen and phosphorus) are supplied in addition to pig slurry. The reduced input level (B) relies on pig slurry, mineral nitrogen supply is reduced, and no mineral phosphorus is supplied. With the minimal input level (C) only a limited amount of mineral nitrogen and phosphorus fertilizers is applied. Nitrogen and phosphorus content in the harvestable products and in the aboveground residues were measured in the year 1994. The animals are here considered being beyond the boundaries of the systems, so pig slurry is an input just like mineral fertilizers. Crop residues are recycled within the systems so harvested products are the only outputs of nutrients.

Results The yield levels, and consequently the nutrient uptake of the crops for the year 1994, can be considered on the average for this environment. Due to the initial condition of good soil fertility, the yields obtained from input C were close to the ones obtained with the higher inputs. Situations ranging from trends of accumulation to trends of depletion are presented in Table 1.

Session 2.2 455

Table 1. Nitrogen and phosphorus balances (kg ha'1 year"1 ) of the compared cropping systems.

Rotation Sugar beet-wheat

Soybean-barley+

sorghum late sowing

Sugar beet-sorghum-

wheat

Maize-maize-wheat

Sugar beet-maize-maize-wheat

Input levels B B B B B

N applied Mineral fertilizers Manure Total N(T) Crop uptake YieldN(Y) 131 125 122 231 228 220 138 135 122 139 135 107 131 128 109 Aboveground residues N 67 69 76 106 97 73 97 101 93 69 72 49 71 78 65

140 80 40 90 58 25 133 73 53 147 90 80 130 78 60 0 0 0 125 125 0 83 83 0 167 167 0 125 125 0

140 80 40 215 183 25 217 157 53 313 257 80 255 203 60

T minus Y 9 -45 -82 -16 -46 -195 79 22 -69 174 122 -27 124 74 -49

P applied Mineral fertilizers Manure Total P (T) Crop uptake Yield P (Y) Aboveground residues P

T minus Y

55 0 55

24 9

31

33 0 33

25 10

8

33 0 33

28 9

5

44 70 114

34 17

80

0 70 70

32 14

38

22 0 22

22 8

0

52 46 98

25 16

73

0 46 46

27 17

19

22 0 22

27 13

-5

44 93 137

27 9

110

0 93 93

26 11

66

22 0 22

22 7

0

49 70 119

26 9

93

0 70 70

26 12

43

17 0 17

24 9

-8

* Negative values for this rotation are due to N fixed by leguminous crop.

Conclusions The amount of fertlizers often applied in the area (input A) leads to an accumulation of nutrients for most of the cropping systems under study. A reduced mineral nitrogen fertilization together with no phosphorus fertilization (input B) seems to be profitable when manure is applied. The limited nitrogen fertilization (input C), if applied in the long term, would inevitably lead to a lower levels of both yield and soil fertility. Some of the rotations seem to be a feasible possibility for an eco-compatible use of organic manure. The nutrient quantities recycled within the system indicate that an alternative use of crop residues (i.e. for animal feeding) would allow the distribution of higher amounts of animal wastes. Investigations are in progress for the quantification of nitrogen lost by volatilization and gained by rainfall in this environment, in order to enhance the precision of the nutrient balances.

Acknowledgements PANDA Project, Subproject 2, Series 2, Paper No. 39.

References Ivens, W.P.M.F. et al., 1992. World Food Production. Herleen: Open Universiteit, 2: 247 p. Loomis, R.S. and Connor, D.J., 1992. Crop Ecology: productivity and management in

agricultural systems. Cambridge University Press, 538 p.


MODELLING THE INFLUENCE OF CROPPING SYSTEM ON INFECTION CYCLES AND DISEASE BUILD-UP FOR EYESPOT

N. Colbach

Station d'Agronomie, INRA, 17 rue Sully, BV 1540, 21034 Dijon Cedex, France

Introduction Eyespot (Pseudocercosporella herpotrichoides (Fron) Deighton) is a major component of the foot and root disease complex of wheat. The fungus infects the stem bases. The models presented here, express the influence of cropping systems on infection cycles and on disease build-up during wheat growth. They contribute to choose cropping systems which minimise disease risk.

Methods The first trial design combined several previous and "pre-previous" crops and two soil tillage tools (one inverting soil, the second not); it was repeated on two sites. The first site comprised 6 "pre-previous crop*previous crop*soil tillage" combinations in a 2-block-design; the second 4 combinations in a 4-block-design. The second trial combined sowing date, sowing density, total nitrogen quantity and nitrogen fertiliser form (high vs. low ammonium content). This design was repeated on four sites; each "sowing date*density*nitrogen quantity*nitrogen form" combination was replicated in a 3 or or 4-block-design. On each plot, winter wheat was assessed for eyespot at four growth stages. For each of the 74 "site*cropping system" combinations, the following kinetic equation was then fitted to disease data:

, _ 1 e y =percentage of diseased plants Cj=importance ofprimary cycle 1 + ™ • e~(c'+'2 )" t=sum of degree-days since sowing c2=importance of secondary cycle

This equation was developed by Colbach and Meynard (1995). It estimates disease frequency as a function of thermal time and the importance of two parameters associated to the primary (from infectious crop residues) and secondary (from living diseased plants) infection cycles for each experimental treatment. For each disease infection cycle, the following multiplicative model was then tested to estimate parameter value as a function of environment and cropping system:

£(c,)= EN•(SUxST)'SD" *TPb » Nc •NFd (E) E(Ci) = expected mean of parameter c,=ci or c2 January=end of autumn infection period). EN = effect of environment (=location*year). TP = tillers per plant SUxST = effect of the interaction of crop succession (pre-previous N = total nitrogen (kg/ha)=soil nitrogen + crop, previous crop) and soil tillage (inversion or non-inversion of mineralisation + nitrogen fertiliser soil layers). NF = form of nitrogen fertiliser ( percentage SD = sowing date (sum of degree-days from sowing to 31s' of ammonium nitrogen).

Results Table 1 presents the significant effects of a linearized version of equation (E) for parameter Ci ; Table 2 presents the significant effects of equation (E) for parameter c2.

Conclusion These models contribute to compare cropping systems (Figure). They can also be used to develop cropping systems for which eyespot frequency stays below a disease threshold (Table 3) and thus to choose the one adapted to a given set of technical, economic and environmental constraints: if late sowing (10/11) is possible, a high nitrogen quantity (and therefore a high yield objective) is acceptable. If however early sowing (25/10) is necessary, the nitrogen amount must be reduced and a decrease in yield of about 2500 kg ha' be expected.

Session 2.2 457

Table 1 : Model explaining cropping system influence on parameter ct associated with the primary infection cycle of eyespot (estimation of significant effects of equation E). The final model is: ln(c,) = constant + ln(EN) + In(SUxST) + a »ln(SD) + b »ln(TP) + c *ln(N) ESTIMATIONS FOR THE FACTOR 'environment' (EN) Environment Chartres A 92 Chartres B 93 Grignon 93 La Verrière 92 Le Rheu A 92 Le Rheu B 93 estimation of effect -2.90 028 L08 ]20 L67 -1.32 ESTIMATION FOR THE COMBINATION 'crop succession x soil tillage'(SUxST) PREVIOUS CROP host lucerne+ray-grass SOIL INVERSION no yes no yes

non-host no yes

PRE-PREVIOUS CROP host 2.27 0.03 lucerne+ray-grass non-host 2.54 0.78

-5.86 -0.46 0.81 -0.11

ESTIMATION OF THE PARAMETERS ASSOCIATED TO THE QUANTITATIVE VARIABLES QUANTITATIVE VARIABLE Parameter Estimation Sowing date (SD) Tillers per plant (TP) Total nitrogen amount (N)

2.53 -1.58 2.60

r2=0,73. All effects presented in this table are significant at alpha=5%.

Table 2: Model explaining cropping system influence on parameter c2 associated with the secondary infection cycle of eyespot (estimation of significant effects of equation E). The final model is: E(c2) = EN • TP" ESTIMATIONS FOR THE FACTOR 'environment' (EN) Environment Chartres A 92 estimation of effect 4.18»10~3

Chartres B 93 3.44.10"3

Grignon 93 9.29.10 4

La Verrière 92 4.32.10"3

Le Rheu A 92 Le Rheu B 93 3.60.10 3.27.10

ESTIMATION OF THE PARAMETERS ASSOCIATED TO THE QUANTTATIVE VARIABLES QUANTITATIVE VARIABLE Parameter Estimation Tillers per plant (TP) a 0.102 All values are significantly different from zero at alpha = 5% (multilateral test).

Table 3: Wheat managements permitting to keep eyespot level below 13% of diseased plants after a non-host/host succession followed by soil inversion for a site favourable to eyespot (Le Rheu 92) SOWING DATE

10/11 5/11 30/10 25/10

PLANTS PERM2

201 210 219 228

TOTAL NITROGEN

(kg/ha) 265 235 205 190

Figure: Eyespot development for various wheat managements (A=sowing on 10/10 at 350 grains/m2 and a total of 300 kg N/ha; B=on 10/10 with 240 grains/m2 and 270 kg N/ha; C=on 10/10 with 160 grains/m2 and 225 kg N/ha; D=on 11/10 with 200 grains/m2 and 225 kg N/ha) % plants with eyespot 100

• heading : on-set ."

500 1000 1500 sum of degree-days since sowing

2000

References ColbachN. and Meynard J.M. 1995. European Journal of Plant Pathology 101: 601-611.


MODELLING THE INFLUENCE OF CROPPING SYSTEM ON GENE FLOW FROM HERBICIDE RESISTANT RAPESEED. PRESENTATION OF MODEL STRUCTURE

N. Colbach1 and J.M. Meynard2

1 Station d'Agronomie, INRA, 17 rue Sully, BV 1540, 21034 Dijon Cedex, France 2 Laboratoire d'Agronomie, INRA-INAPG, Centre de Grignon, 78850 Thiverval-Grignon, France

Introduction The aim of the model is to evaluate the influence of cropping systems on transgene escape from rapeseed crops in order to determine those regions with a high dispersal risk and to propose cropping systems which limit gene flow. The model is restricted to rapeseed crops and volunteers; hybrids between rapeseed and other Brassiceae are not integrated.

Model organisation in time and space Figure 1 shows an example of spatial arrangement with: (a) fields on which various crop types succeed in time; (b) waysides and fieldedges ("borders"). Seven crop types are distinguished: herbicide resistant (transgenic) or sensitive rapeseed, winter crops, spring crops, set-aside with natural regeneration, set-aside with autumn sown cover crop or set-aside with spring sown cover crop. Before a simulation, a crop and a crop type succession are attributed to each plot.

Figure 1: Spatial organisation of the plots (E1-E4 = four corners of plot/; H | = borders; I I = fields)

•

-

' •

"

Crop successions constitute the first level of the temporal dimension. The second temporal level concerns annual rapeseed evolution, as volunteer or crop plants, on each plot, of which Figure 2 shows the general organisation. This annual evolution is however slightly modified according to crop and border types: (a) the compartment sown rape grains only exists for rape crops; (b) in spring crops and spring sown set-aside, the compartment adult plants is always nil because rape volunteers emerged after winter do not have enough time to flower before crop maturity; (c) on set-aside with natural regeneration and on borders, the pre-sowing grain stock and the post-harvest grain stock are identical as no soil tillage is done and the pre-sowing rape seedlings and dead grains compartments are empty; (d) because of cutting on set-aside plots and borders, not all the ramifications of an adult plant have time to produce flowers and grains. However, after cutting, adult plants can give rise to a second set of ramifications with flowers and grains.

post-sowing seeaimgs j

•post-sowing dead grains '• T—-~

1

sown rape grains

tr pre-sowing grain stock

pre-sowing dead grains '•. ir

: pre-sowing seedlings • * __^ \

k

Figure 2: Tempo rai organisât ion of annual rapeseec

K 1 . , . | . |

+ flowers

\"i— i V L

grains

I > post-harvest grains

l -L *:

evolution

imported pollen j

• : harvested grains •

exported grains

imported grains

Session 2.2 459

Relationship between temporal compartments For each compartment (grain stock, seedlings...) the number of individuals per m2 and the proportions of each genotype are calculated. Herbicide resistant and sensitive plants only differ in their response to the associated herbicide and in their fitness, i.e. the number of viable descendants of the resistant phenotype compared to the descendants of the sensitive phenotype. In the compartment post-harvest grain stock, grains are distinguished according to their age and their situation (superficial or deep layer). Grain mortality depends on grain age, soil layer and crop type. The grain movements between post-harvest and pre-sowing stocks depend on soil tillage as modelled by Cousens & Moss (1990). Only grains from the superficial layer give rise to seedlings. Emergence rates depend on grain age, on crop type and, for pre-sowing emergence, on stubble breaking. All pre-sowing seedlings are destroyed when the soil is tilled for sowing. The relationships between seedlings and adults, flowers and grains depend on rape density, herbicides (and therefore on rape phenotype), crop density and cutting date. On set-aside and borders, those plants having survived cutting can produce post-cutting ramifications. Genotype proportions of the new grains depend on parent genotype, fitness and the rate of allogamy. Pollen and grain dispersion are modelled by functions established by respectively Reboud et al. and Gasquez et al. (pers. comm.). Both functions depend on plot co-ordinates (xi, x2, yi, y2). Grain export by harvest tools only happens for rape crops. After the simulation of the various stages of year n, new values are attributed to the grain stock variables for year n+1.

Simulation Parameters were chosen according to literature (Leterme, 1985; Cousens & Moss, 1990; Schlink, 1994) while awaiting trial results. Several kinds of output are possible. Figure 3 shows for instance the evolution of resistant and sensitive individuals (grains, seedlings, adults etc.) on a given plot with time whereas Figure 4 presents the mean number of resistant and sensitive grains for all plots over a whole rotation.

grains/m2 grains/m2

10000 r 4000

7500

5000

A

M IM i

* 11

It In '1 n i M M M i M M M 1 MM M i MM '

I /' /' V ' VI V ' Si

R '1

M M M IM • 1 /' 1 1 V ' V

All fields Held 10

3000

2000

1000

0 5 10 year 15 20 25

Figure 3: Total ( ) and resistant (—) rape grains of the post-harvest stock on field 10 with a "regeneration set-aside/resistant rape/ winter crop/spring crop/resistant rape/winter crop/spring crop" rotation

Figure 4: Mean number of resistant ( H ) m < ^ sensitive (| |) grains over of 25 years with a "set-aside/rape/winter crop/spring crop/ rape/winter crop/

u spring crop" rotation (A=resistant rape on field 10 and sensitive rape on all other fields and natural regeneration set-aside; B=resistant rape on field 10 and sensitive rape on all other fields and spring sown set-aside; C=sensitive rape everywhere except every three times on plot 10 and natural regeneration set-aside).

References Cousens, R. and Moss, S.R., 1990. Weed Research 30: 61-70. Leterme, P., 1985. Thèse Doctorat de l'Institut National Agronomique Paris-Grignon, 112 p. Schlink, S., 1994. Dissertationes botanicae 222, Berlin, 193 p.


RESPONSES OF WINTER WHEAT AND MAIZE TO NPK NUTRIENT LEVELS IN LONG-TERM FERTILIZATION TRIALS

K. Debreczeni

Pannon University of Agricultural Sciences, P.O. Box 71. H-8361 Keszthely, HUNGARY

Introduction Long-term fertilization trials can provide reliable data for the wider understanding of crop-nutrient interrelations. There are several long-term fertilization trials in Hungary; the results presented here are from the network of National Long-term Fertilization Trials (NLFT) which have been continued at 9 experimental sites. These trials were established in 1967-69. Apart from site characteristics which show themselves in yield levels, long-term (25-27 years) effects of fertilizer treatments directs our attention to differences in crop responses. Yield results showed that winter wheat responses to phosphorus deficiencies were stronger than that of maize (Debreczeni and Debreczeni, 1994).

Methods Long-term effects of 10 fertilizer treatments on grain yields of winter wheat and maize were studied in multilocation field experiments (plot size was 50-70 m2) at 9 agro-ecological regions in four-year rotations of wheat-maize biculture. Crop rotations were initiated over a successive four year period alter 1967. Nitrogen fertilizer rates were gradually increasing by 50 kg per ha N from 50 to 150, phosphorus rates from 0 to 200 kg P205 per ha and potassium rates were 0, 100 and 200 kg K20 per hectare. Code numbers indicating the fertilizer rates are given in the order of NPK. Fertilizer treatments given in these code numbers selected for this study were as follows: 000, 101,201,301, 111,211,311, 121,221 and 321. Evaluation of long-term effects was made by calculating the main averages of grain yield results obtained for winter wheat and maize in each experimental year. Main averages of yields were plotted as zero points and average differences obtained for individual treatments as cumulated values are given in the figure indicating either positive or negative values. These averages of winter wheat and maize grain yields are given as 0 values of the x axis. The graphs are representing responses of winter wheat and maize to increasing fertilizer rates in the long-term scale i.e. after 4-8-12-16-20 years. One experimental site, Bicsérd was selected for this presentation. This experimental site is located in south-west of Hungary and has a chernozem brown forest soil, FAO category: Luvic phaeosem. Main soil characteristics of the experimental soil are as follows: Humus content 1.9 percent, pH in KCl 5.6, available phosphorus ( in AL-extract) 35 nig kg' P20?, exchangeable potassium (in AL-extract) 206 mg kg "' K20.

Results Main averages of winter wheat and maize obtained in the four year rotations in the selected experimental site, Bicsérd are represented here. The main averages of grain yield results were as follows: winter wheat 3.88 - 3.70 - 3.58 - 3.78 tons per hectare maize 7.12 - 6.97 - 7.0 - 9.55 tons per hectare, respectively. These main averages were plotted as 0 values of the x axis in the graph (Figure I). Differences obtained for the individual treatments as cumulated grain yield results (in tons per hectare) of winter wheat and maize are summarized in the Figure.

Session 2.2

Figure 1. Cumulated grain yields of winter wheat and maize (tons per hectare)

461

Ü I C S (. R Ü

winter wheat maize

t/hn

From these results it can be suggested that adequate soil phosphorus level is a determinating factor in winter wheat yield. The observed crop responses to phosphorus deficiency or nutrient imbalances could be reduced by N application, however, differences were still remarkable.

Conclusions Cumulated yield differences are effectively representing crop responses to long-term fertilizer effects. Responses of winter wheat to balanced macronutrient fertilization were much stronger than that of maize. This was especially remarkable in case of phosphorus responses which is related to the formation of grain proteins. Increasing N fertilizer rates without P application markedly reduced grain yields of winter wheat but only moderate responses to P nutrient imbalances were observed for maize yields. Differences in yield responses were even marked in the subsequent years, therefore it can be concluded that long-term effects may serve as more reliable information on crop responses for soil fertility evaluation.

References Debreczeni, B. and Debreczeni, K. (Eds.) 1994. Fertilization Research 1960-1990. Akadémiai

Kiadó, Hungary. 411 p.


THE USE OF POROUS CUPS TO ESTIMATE THE IMPACT OF CROPPING SYSTEMS ON GROUND WATER QUALITY

J-E. Delphin

INRA, Laboratoire d'Agronomie, B.P. 507, 68021 COLMAR, France

Introduction Due to the large amounts of fertilizer and agrochemicals used in intensive agriculture, it is important to estimate the quantity of pollutants lost by leaching and the consequent risks of ground water contamination. The liquid phase of soils is usually collected from drainage water, from lysimeters, from bore-holes or from vacuum extractors (porous cups). This last sampling method of the soil solution is valuable because it can be used in a large range of soil types except for coarse textured ones. However, rather large volumes of water have to be collected for pesticide determinations. The aim of this paper is to examine the possibilities and the limits of the use of porous cups for estimating nitrate and atrazine losses by leaching in the field.

Methods The experiment was carried out in the Rhine plain on a farm plot cropped with maize. N fertilizer (60 kg ha"1) and herbicide (atrazine + alachlore, 625 and 2400 g ha'1 respectively) were applied at the time of maize sowing. A second application of N (120 kg ha"1) was made one month later (25/05/95). 250 + 675 g ha"1 of the same herbicide was applied on June 1st. The total rainfall plus irrigation was 290 mm from the beginning of the experiment (06/06/95) to the end of December. The experiment was conducted on a loamy soil : 27 % clay, 68 % silt, 5 % sand, 1.8 % OM, pH 7.5. The porous cups were inserted horizontally at 3 depths (50, 80,120 cm) from a pit dug in the ground and refilled after installation. They were connected by a Teflon tube (0 2 mm) to a 21 collector placed on the ground. A 65 k Pa tension was applied for a week : the extracted volume was measured and the nitrate and atrazine concentration were determined on the water samples. The soil moisture was measured weekly by neutron scattering. Atrazine in the solution samples was detected by HPLC after extraction by C18-cartridges. Nitrate concentration was determined by a spectrophotometric method. It had been shown that no interactions occurred between atrazine and the porous cup (Perrin-Ganier et al., 1994).

-• 31.5 o > ^ 30.5 c o ^ 29.5 u I 28.5

^34 .5

*__ JW .—••""• •

1

Ä ^ — — —

•

1 h

t^000*—000~+

-50cm R2 = 0.40

1

20 4 0 J , 6 0 , ,x

extracted volume (ml) 80 100

Figure 1 Mean volume of the soil solution extracted by the porous cups

400 600 800 extracted volume (ml)

1200

Session 2.2 463

Results The volume of the soil solution collected in the porous cups varied from 0 to 1200 ml. The variation in the collected water volume between the porous cups located at the same depth was likely due to the difference of the macroporosity of the soil close to the porous ceramic and to the tightness of contact, although this contact was previously improved by putting mud on the bottom of the hole before the insertion of the porous cup. The volume of soil solution collected was related to the soil water content. The volumes at 50 cm were small (figure 1) because of the low water content throughout the experimental period of the soil layer which had a high water holding capacity (37 vol. %). At 80 and 120 cm the amounts collected averaged 600 ml because of the higher soil water content in these layers and of the lower water holding capacity of the soil (34 vol. %). The mean efficiency of the soil solution extraction was 30 %.

20.0

15.0

10.0 Figure 2. Atrazine

M iu.u I- - A ' * * content in the soil ^ n lf~l » P solution at 80cm

(each symbol represents a porous cup)

— ^ — n & . H , 1 05/06 05/07 04/08 03/09 03/10 02/11 02/12

Date The variation in the N03 content of the soil solution between the different porous cups was higher at the beginning of the experiment (CV=25 %) than at the end (CV< 10 %), probably because of the heterogeneity of the N fertilizer application to the soil. The variation in the atrazine content was higher than for nitrate (figure 2) : by reason of the minimum volume of soil solution required for the pesticide analysis, the number of duplicated measurements was not sufficient for reliable statistical analysis. Contrary to the results obtained by Hausen et al. (1975), the N03 solution content was not dependent on the extraction efficiency of the porous cup but on the time and on their position in the soil.

Conclusions The efficiency of water extraction by the porous cup was largely related to the soil water content and probably to its contact with the soil and the macroporosity of the surrounding material (presence of cracks and soil spaces). A slightly lower efficiency was obtained with the method used in this experiment (horizontally buried porous cups) in comparison to the classical method, but this technique allows all the cropping operations to be done in the field. A minimum number of 8-10 replicates is then necessary in order to estimate the pollutants in the soil solution with an acceptable precision (especially the pesticides). The porous cups must be placed at a depth where the uptake of water by the crop does not lower the soil moisture significantly below the water holding capacity. At 50 cm the water volumes collected were often insufficient for pesticide analysis. In order to estimate the amounts of pollutants lost by leaching under cropped plots, the mineral N and pesticide content of the soil solution sampled by the porous cups has to be linked with the estimation of drainage water amounts using a water balance model.

References Hausen, E.A., 1975. Soil Science Society of America Proceedings. 39 : 528-536 Perrin-Ganier, G. et al., 1994. Chemosphere 29 : 63-70.


MAIZE PRODUCTION IN A LIVING GRASS MULCH SYSTEM

S.V. Garibay, B. Feil

Institute of Plant Sciences, ETHZ, CH-8092 Zurich, Switzerland

Introduction The midlands of Switzerland are characterized by a hilly topography and a cool, humid climate (= 1000 mm annual preciptation). The traditional cropping of maize (= maize sown in the bare, autumn-ploughed soil) is often associated with soil erosion, surface runoff of agrochemicals and nutrients, and nitrate leaching into the groundwater. Further problems linked to this maize cropping system are soil compaction and the development of herbicide-resistant weed populations. Most of these problems can be solved or at least alleviated if the maize is sown into a live cover crop sod. This contibution reports results of a three year field study (1991 to 1993) on the performance of silage maize under two cropping systems in which the maize was sown into living Italian ryegrass sods.

Methods Three maize cropping systems were compared: (1) maize sown into the autumn-ploughed, bare soil (plough tillage; PT); (2) maize planted into a live Italian ryegrass stubble. The grass strips between the maize rows were killed by applying a herbicide (chemically killed grass; CKG), and (3) maize planted into a live Italian ryegrass stubble. The grass strips between the maize rows were mechanically stunted by mulching (= mechanically suppressed grass; MSG).

The Italian ryegrass (Lolium multiflorum L.) was sown in the August preceding the planting of maize. The grass was mowed and removed from the CKG and MSG plots in autumn and spring (6 to 13 d prior to planting the maize). Under PT, the grass stands were also cut in October and ploughed in autumn/winter with a mouldboard plough. The maize was sown with a one-pass minimum strip tillage seeder. The maize rows were 75 cm apart. The rototilled strips were 30 cm wide and 15 cm deep. In the CKG system, the grass strips between the maize rows were killed by a split application (2 x 30 g ha"1) of the herbicide Titus at the 1st and 2nd leaf stages of maize. In the MSG system, the grass was mulched with a mulching machine at the 1st, 3rd, and 6th leaf stages. There were two levels of nitrogen (N) supply: 110 kg N ha'1 (N110; mineral N in the soil from 0 to 90 cm depth as measured just before maize sowing plus row placed fertilizer N) and 250 kg N ha"1 (N250; as N110 plus two banded applications of 70 kg N ha"1 at the 4th and 6th leaf stages of maize). Maize samples were collected when 50% of the PT-treated plants had reached the 3rd, 6th, and 9th leaf stages and at pollen shedding and silage maturity. Leaf chlorophyll content was estimated with the SPAD 502 instrument from Minolta. Meter readings were taken on the uppermost fully expanded leaf, midway between the butt and tip and between the leaf margin and midrib.

Results and Discussion Despite large year-to-year fluctuations in the availability of water, the relative performance of the cropping systems was fairly consistent in the various years (Fig. 1). With N110, averaged across the years, the CKG system produced only 69% and the MSG system only 47% of the maize dry matter produced under PT. Sod-planted maize was markedly more responsive to an increase in the rate of N application than PT maize. Nevertheless, with N250, PT was still the most productive system: averaged across the years, maize grown in the CKG and MSG systems produced 94% and 85% of the dry matter that was produced under PT. The data

Session 2.2 465

suggest that, with NI 10, N was more yield-limiting for sod-planted maize than for PT maize, even though additional N (on average 56 kg N ha"1) was applied to the CKG and MSG systems in order to set off the low mineral N content of the soil immediately prior to maize sowing. The seasonal patterns of some indicators of the N status of plants (leaf greenness and whole-plant concentrations of nitrogen and nitrate) under N110 in one representative year (1992) demonstrate that differences in the N status of conventionally cropped and sod-planted maize are already detectable at early stages of development (Figs 2a-c).

25

20

15

10

5

N110 N250

a I

1991 1992

PT CKG MSG PT CKG MSG PT CKG MSG

Fig 1. Shoot dry matter of silage maize under three cropping systems and two levels ot'N supply. Bars indicate LSD (0.05) values within the levels of N supply (a = LSD for Nl 10; b = LSD for N250).

5.25

4.00

2.75

1.50

0.25

Nitrogen - ' l

- 'V

" i 1

concentration (%) 1 ' 1 ' 1 -

a

-

i

\ i

4-, rV_ i —

i , i , i -

0.9

0.6

0.3

0.0

Nitrate concentration (%) SPAD

J i I . L_i L

300 600 900 1200 300 600 900 1200 300 600 900 1200

Growing degree-days [ °C d ; base temperature 8 °C ]

Fig. 2. Cropping system effects on shoot nitrogen concentration (a), shoot nitrate concentration (b), and leaf greenness (c) under Nl 10. Vertical bars indicate LSD (0.05).

Conclusions The living mulch systems tested have markedly higher N requirements in order to reach maximum yield. Efforts to optimize these environmentally sound systems should focus on reducing the competition between maize and the cover crop for N. Promising approaches are the use of legumes as cover crops and an earlier suppression of the cover crop.


INTRODUCTION OF A CATCH-CROP OF SOYBEAN IN A BIENNIAL ORIENTAL TOBACCO - DURUM WHEAT ROTATION

P. Greco, G. Manzi Istituto Sperimentale per il Tabacco, via F. Calasso 3, 73100 Lecce, Italy

Introduction The cultivation of oriental tobaccos is largely praticsed in certain marginal areas of Puglia, Southern Italy. The hot, dry climate of these areas, combined with poor and shallow soils, are unfavourable conditions for other crops. Therefore, at this present time, tobacco represents the only source of income for the local population, which traditionally, has always supplied abundant manual labour. This reality has led to the consolidation of a cultivation system based, either on continuous cropping of tobacco, or on biennial rotation of tobacco-durum wheat, with negative effects on the health and fertility of the soil (Rüssel, 1982; Toderi, 1991). These observations relate to the results of 6 experimental years (1986-1991), and concern comparisons made between traditional biennial tobacco-durum wheat rotation, and the same rotation intensified with soybean catch crop. The aim of these trials was to limit the negative effects caused by tired soil, and at the same time to investigate any likely positive agronomic consequences on the two main crops, due to the effects of introducing the catch crop.

Methods The experiment was conducted in the years from 1986 to 1991 at Monteroni di Lecce (Lecce), on a sandy soil belonging to Haploxeralf family (Costantini et al, 1990). Two biennial rotations: tobacco-durum wheat and tobacco-durum wheat+soybean (T-F and T-F+Sa), were compared in interaction with two agrotechnic input treatments (MA=medium high; MB=medium low, different in fertilization, irrigation and soil management) in a split-plot design with three replications. The elementary plot was 165 square meters. The climatic environment is characterized by hot-dry summers and rainfall restricted to the fall-winter period.

Results The variable climatic conditions of the trial period exercised a notable influence on productive and commercial tobacco parameters, but in opposite ways. In fact, while the production of cured tobacco (16% moisture) diminisched in relation to the hot and dry years, to a minimum of 1,521 ha"1 reached in 1988, the percentage of leaves of the highest commercial value, (grade A+B) notably improved, with a maximum recorded in the third year, at a level of 41,8% of A+B. The above demonstrates that hot and dry years, if, on the one hand inhibit production, on the other hand favour sun-curing processing, with positive consequences on tobacco quality. Statistical analysis indicates that the interaction "rotation x input levels" (figure 1) is due principally to the positive effects which occur between inferior input and rotation intensified with soybean. Between the rotations compared, the one intensified with soybean showed significantly superior production results, (+6%) when compared with traditional rotation (1,841 ha" ) in the medium low inputs treatment. Between agrotechnical levels large differences emerged (P=0,05), in favour of the higher level (MA=1,911 ha"1; MB=1,65 t ha"1).

Session 2.2 467

J

2

MA MB agrotechnical input

Figure 1. Interaction "rotation x levels of agrotechnical input" on the production oriental tobacco (16% DM)

Concerning durum wheat, significant production differences were recorded between the two agrotechnical levels, with more favourable effects noted at lower medium level (MA=3,301 ha"1; MB=3,501 ha"1). As in the case of tobacco, the significance of the interaction "rotations x levels of agrotechnical input" is to be noted, indicating that the best combination occurs between the lower medium level and the rotation intensified with soybean.

Conclusions Greater production potential introduced into traditional tobacco-durum wheat rotation, through the addition of soybean catch crop, besides determining positive variations in both the two principle crops rotated, also contributes to the gross saleable production of the entire rotation. Tobacco benefitted from the residual nutrients left by soybean, increasing the production of cured leaves, while the lower agro-technical level improved the commercial characteristics and therefore manufacturing use. Regarding durum wheat, the presence of soybean greatly increased the effect of the inferior agrotechnical level, thus giving rise to better production results compared to the higher level. Above all, the research underlined the agronomic validity of the new rotation (T-F+Sa), which, if only within the limitations of the trial period, seems to produce better results, with reduced agronomic input, thus obtaining economic and energy resource advantages at lower level of environmental impact.

References Costantini, E.A.C. et al., 1990. Studio pedologico di alcune aree sperimentali del nord, centro e

sud Italia. Annali Istituto Sperimentale Agronomico, XXI, Suppl. 2, 255-288. Rüssel, E.W., 1982. Il terreno e la pianta. Fondamenti di agronomia. Edizione italiana a cura di P.

Paris, Edagricole, Bologna, 564 p. Toderi, G., 1991. Problemi conservativi del suolo in Italia. Da Agricoltura e Ambiente,

Edagricole, Bologna, 50-99.


THE ROLE OF MULCHING IN CROPPING SYSTEMS - SYNCHRONIZING THE RELEASE OF NUTRIENTS AND CROP REQUIREMENTS

F.C.T. Guiking and D.M. Jansen

Department of Agronomy, Wageningen Agricultural University, PO Box 341, 6700 AH Wageningen, The Netherlands

Introduction In scenarios for sustainable agriculture, mulch usually is given an important role; quantification of the effects is less clearly stated (Guiking and Stomph, 1995). The recycling or net input of nutrients through mulch is relatively easy to quantify. But a simple nutrient balance on an annual base can be misleading, even under a permanent cropping system, since release of nutrients from mulch is not synchronized with crop requirements. An example is given from the perhumid Atlantic Zone of Costa Rica, where palm heart is grown, a crop that is monthly harvested with concomitant production of leaf mulch. The cyclic fluctuation of the yield results in a cyclic, a-synchronic fluctuation of supply of recycled nitrogen, part of which is lost by leaching. The resulting situation is less favorable than predicted by a scenario where nutrient budgets are calculated on an annual base.

Methods Palm heart (Bactris gasipaes HBK) is planted at 1 m x 2.5 m (4,000 plants ha '). Several shoots are maintained per plant. Under standard production practices the field receives a mulch of leaves from the crop at monthly harvests of growing points. The following differential treatments were included to quantify the effect of mulch on crop performance: removal of mulch, standard practice (i.e. leave the pruned leaves at the spot), and double the amount (pruned leaves from zero-plots added to these plots). To moderate the effect of removal of mulch concerning export of nutrients, treatments with N-fertilizer were included, viz. standard practice (being 6 applications of 33 kg N ha"1 yr"1), half the amount, and nil. Other nutrients (P, K, Mg) were added at standard plantation rate. Plot size was 5 m x 12.5 m (5 x 5 plants). All treatments were replicated 4 times in a randomized block design (total 36 plots). Monthly yield of palm hearts was recorded for 2 years. Leaf mulch produced was recorded at some selected plots at regular time intervals, and sent for chemical analysis.

Results The average annual production per hectare is about 18,000 palm hearts of about 1.1 kg fresh weight each; with 11% dry matter this comes to a dry matter production of 2.2 t ha"1. The removal of nitrogen through the harvested product is 40 kg N ha_1 yr"1. The harvest of each palm heart is accompanied by the cutting of 0.7 kg (dry weight) leaf material, left as mulch. Since palm hearts are harvested at a given size, mulch production per harvested palm heart is fairly constant throughout the year. The return of nitrogen through this mulch amounts to 360 kg N ha"1 yr1, but monthly contributions vary from 15 to 50 kg N ha"1.

The experiment was laid out in an existing plantation which was heterogenous. After two years this still showed up in clear block effects. Variation within blocks could mask the effects of treatments; therefore the cumulative yield of the last 1.5 year was expressed as percentage of the cumulative yield of the first 4 months of the experiment. In this way a positive effect of N-fertilizer on yield was observed, in concordance with earlier experiments with this crop (Jongschaap, 1993; Roeland, 1994).

Session 2.2 469

No effect of mulch on yield was observed, although the quantities of nitrogen involved are twice as high as those supplied through inorganic fertilizer. The explanation is sought in the cyclic character of the yield (in figure 1 expressed in number of palm hearts harvested per month), resulting in a cyclic production of leaf mulch.

The uneven distribution of mulch in time, results in an uneven supply of nitrogen in time, and - with the time lag due to decomposition - not geared to the requirements of the crop. The latter will show the same cycle, but some time ahead. Under the assumption that uptake of nitrogen by the crop is one month ahead, and that release of nitrogen from the leaf mulch is one month after application of the mulch, the resulting situation can be represented schematically as in figure 2: in some months release of nitrogen from the mulch is insufficient to meet crop requirements; but where more nitrogen is supplied than needed, losses through leaching are inevitable in a perhumid climate.

< cr Q_

< X

5 < o or

CO

D 2

3000

2000

1000

0

r / /

• . /

MAR

\ \ \

'l

\ ', S

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SEP APR

/ X \

*"--*

OCT

| 60

Z 40

20

0

/ / \ \ / f --A

1/ / w r ï Ï MAR SEP APR OCT

uptake of N by crop, kg/ha

-e- release of N from mulch, kg/ha

Figure 1 - Monthly yield of palm hearts, nr ha"1

Figure 2 - Uptake of N by crop and release of N from mulch, kg ha 1

Conclusions Release of nutrients from mulch is not synchronized with crop requirements. Even for situations with a permanent crop cover, calculations of nutrient cycles at field level should not be based on annual data, but include the regular temporal variability. A consequence for practical purposes is that regular split-applications of fertilizers should be adjusted to the regular temporal variations in crop requirements and recycled nutrients.

References Guiking, F.C.T., and T.J. Stomph, 1995. The modification of soil processes by mulching in

the humid tropics. In: Cook, H.F., and H.C. Lee. Soil management in sustainable agriculture, Wye College, University of London, p.383-386.

Jongschaap, R., 1993. Palmito (Bactris gasipaes HBK) growth and management in the humid lowlands of the Atlantic Zone of Costa Rica. CATIE/AUW/MAG Phase 2, Report 60.

Roeland, R., 1994. Palmito (Bactris gasipaes HBK) cultivation in the Atlantic and Northern Zone of Costa Rica. CATIE/AUW/MAG Phase 2, Report 86.


SOYBEAN YIELD AND CANOPY WEED INFESTATION UNDER DD7FERENT CROP ROTATION SYSTEMS (INTRODUCTORY INVESTIGATIONS)

M. Jedruszczak, M. Wesotawski and K. Bujak

Department Soil and Plant Cultivation, Agricultural University, 20-950 Lublin, 13 Akademicka Str., Poland

Introduction Soybean is becoming an important alternative cultivated plant in Poland. This is mostly due to good new polish cultivars (Szyrmer, 1987; Konieczny et al., 1991) and rising new nutritional preferences of the society. Experiments on soybean growth with spécialiste crop rotations help to understand yield limiting factors and determine economic and habitat profits in Poland. Early soya was considered to yield well in monocultural system (Pendelton et al., 1973; Kahnt et al., 1985). Recently, however, higher productivity and other benefits resulting from inclusion of the plant into crop rotation have been appreciated (Johnson 1987; Clegg, 1992; Varvel et al., 1992; Lund et aio., 1993). This work was aimed at evaluation of yield and weed problems of soybean grown in four-field rotation systems.

Methods Field experiment was estabished in 1993 at Czeslawice Experimental Station (central-eastern Poland, 51° 19' N, 22° 16' E) on grey-brown podzolic soil derived from loess (1.30 % of humus, 26 mg P2O5, 28 mg K20 and 7 mg Mg per 100 g of soil, 5.4 pH) The experiment was laid out in a randomized block design. Soybean cv. Polan (000 mat. group) was grown in four-field rotations: 1-25%, 11-50%, ni-75%, rV-100% of this crop. Sequence of plants in the rotations was following: I. potato-spring wheat-soybean-winter wheat; JJ. soybean-spring wheat-soybean-winter wheat; III. soybean-soybean-soybean-winter wheat; IV. soybean monoculture. The soil was tilled conventionally. Soybean was fertilized with 34 kgN, 80 kg P205, and 100 kg K20 ha'1. Farmyard manure (30 000 kg ha"1) was applied to every first field of rotation; all fields were limed with 2500 kg ha"1 CaO in 1993. Soybean was sown in row spacing of 20 cm at the end of April and the begining of May in the amount providing 100 viable seed per 1 m2. The seeds were inoculated with Rhizobium japonicum. Linuron plus metribuzin (500 plus 350 g ha"1) were used for weed control following the sowing. Soybean growing season in 1994 was extremely unfavorable: cool and humid until the first half of June, later - hot and dry. Drought lasted 60 days and coincided with reproductive growth stages of soybean, R1-R7 (Fehr et al., 1980). Growing season of soybean in 1995 was warm with rain-free period of 40 days from when soybean was forming seeds (R5) onwards.

Results Results are presented in Tables 1-3. Table 1. Seed yield, yield structure, nodulation, and plant density just before harvesting (aver. 1994-1995) Crop rotation (soyabean %)

I. (25) II. (50) III. (75) IV. (100) LSD(p=a 0.05)acc. Tukey

Seed yield

(tha-1)

1.74 1.84 1.92 1.68 ns

Pods number per plant

13.4 14.1 15.2 13.3 ns

1000 seeds weight (g)

115 119 118 116 ns

Nodule number per plant

0.4 0.9 4.0 4.4 2.5

Plant density (m-2) 81.5 77.8 73.0 77.6 ns

Session 2.2 471

Table 2. Variability of seed yield, yield structure elements, nodulation, and plant density before harvesting in the research years, 1994 and 1995 Crop rotation

I. II. III. IV. Mean LSD(p= a 0.05)*

Seed yield (tha 1994 1.04 1.07 1.15 0.98 1.06

•1)

1995 2.43 2.62 2.68 2.37 2.52

0.22

Pods number per pi 1994 10.9 11.2 12.0 10.2 11.1

ant 1995 16.0 17.0 18.3 16.4 16.9

1.5

1000 seed weight (g) 1994 104 106 104 104 104

1995 126 132 132 127 129

5.0

Nodule number per pi 1994 0.3 0.3 1.5 1.3 0.8

ant 1995 0.6 1.5 6.5 7.4 4.0

1.3

Plant density (m-2) 1994 71.0 70.8 70.2 67.2 69.8

1995 92.0 84.8 76.0 88.0 85.2

4.2

*Acc. Tukey

Table 3.Number and air dry matter of weeds in soyabean canopy just before harvesting Crop rotation I. II. III. IV. Mean LSD(p= a 0.05)*

Weed 1994 21.7 19.8 18.0 21.4 20.2

0.

number 1995 11.3 9.4 6.5

10.2 9.4

3

m"2 mean 16.5 14.6 12.2 15.8 -ns

Air 1994 10.5 7.0 7.2

13.2 9.5

ns

dry

1995 8.1 5.6 5.9 8.6 7.0

matter (g m~2) mean 9.3 6.3 6.5

11.0 -ns

*Acc. Tukey

Conclusions Yield of soybean, grown in rotations of increasing contribution of the crop (25%, 50%, 75%» and 100%) did not differ statistically in the first two growing seasons (aver. 1994 and 1995). However, a tendency for the highest seed yield and its structure elements was observed in rotations with 50% and 75% of soybean. Significant increase of nodule number was found in rotations with 75% and 100% of soybean (Table 1). Long-lasting drought in 1994 had a substantial negative influence on all yield elements studied (Table 2) and was conducive to an increasing weed number per unit area (Table 3). Weediness of the soybean canopy was the same in all rotations (main weed species were Echinochloa crus-galli P.B. and Equisetum arvense L). Complete evaluation of the effect of the the crop rotation systems on soybean yielding needs further studies.

References Clegg, M D.,1992. Agricultural Systems 39 (1):25-31. Fehr, W.R.et al., 1980. Special Report 80. E S Iowa St. Univ., p. 11. Johnson, R.R., 1987. Soyabeans: Improvement Production and Uses.Agronomy 16: 374-378. Kahnt, G. et al,1985. Eurosoja 3:17-23. Konieczny, G. et al.,1991. Eurosoya 7/8:63-67. Lund, et al.,1993. Journal of Production Agriculture 6 (2):207-213. Pendelton, J.W.et al.,1973.Soyabeans:Improvement Production and Uses. Agronomy 16:211-237. Szyrmer, J., 1987. Bulletin of Pant Breeding and Acclimatization Inst. 164:25-35. Varvel, G.E. et al., Agronomy Journal 84 (2):215-218.


THE INFLUENCE OF THE COVER OF DIFFERENT CULTIVATED PLANTS ON THE GROUND WATER RESERVE (1981-1995)

J. Kolodziej, K. Liniewicz

Department of Agrometeorology, University of Agriculture, ul. Akaderaicka 15, 20-950 Lublin, Poland

Introduction In natural conditions and also canopies of cultivated plants there is a constant interaction between the plants cover and the microclimate in those canopies, and the microclimate in the soil. The aim of our paper was to establish the influence of the diverse plant cover and of the weather conditions on the dynamics of useful water reserve in the soil profile of 0-110 cm.

Methods The research was carried out in the years 1981-1995 in the Agrometeorological Observatory in Lublin-Felin (SE Poland <p - 54°14'N , X - 22°38'E, Hs - 215 m) on loess-like soil. The crop rotation included winter wheat, winter rye, spring barley, red clover and potatoes, and, for comparative reasons, bare fallow. The measurements of soil moisture were taken at ten-day intervals during vegatation period from May to July in the layers 0-25, 25-60 and 60-110 cm. Changes in the useful water reserve in the above-mentioned profiles were examined in connection with the mean ten-day air temperature, ten-day amount of atmospheric precipitation and ten-dey amount of real sunshine. In statistical caltulations multiple regression was used first of all (Kozminski, 1994; Samborski et al., 1993).

Results The results of the research show that in the entire soil profile the useful water reserve depended on the kind of plants, their stages of growth and the weather conditions. Under each plant and in each ten-day period the water reserve stated in mm was lower than on the bare fallow. In the first two layers of soil (0-25 and 25-60 cm) the smallest water reserve was observed under winter rye (during four ten-day periods) and under red clover (during theree ten-day periods). In the whole soil profile, i. e. in the layer 0-110 cm, the situation was a little different; the most cases (four ten-day periods) with the lowest water reserve were observated in the fields of winter wheat and winter rye. Generally speaking, water reserve decreased under all the plants from May to July with a trend towards the growth of values towards the end of the vegetation period (in July), which was caused by higher precipitation in that month and a gradual decline in the plants life activity (Kolodziej et. al., 1970, 1972; Kozminski, 1994; Samborski et. al., 1992, 1993). On the basis of statistical analysis of the examined phenomenon it was stated that in the period from the first then-day period in May till the third ten-day period in July, in the soil layer 0-25 cm, on the sigificance level of 0,05, the differences between the water reserves under the plants and on the bare fallow were not significant. In the 0-60 cm layer nine instances of significant differences were found; the majority of them in the third ten-day period of May and in the second ten-day period of July. Among the examined plants the majority of differences concerned winter wheat and winter rye. However, in the whole soil profile: from 0 to 110 cm, there were eleven instances of sigificance of differences; the majority in the second ten-day period in July. Most often the differences concerned winter wheat and winter rye.

Session 2.2 473

The multiple regression equations where water reserve (W) was the dependent feature and precipitation (p), air temperature (t) and sunshine (s) were the independent features, were used in order to establish the relation between weather conditions and useful water reserve. The following equations were obtained for the respective layers: a) 0-25 cm W = 62,15 + 0,42p - 2,66t R2 = 39,5% (1); b) 0-60 cm W = 162,27 - 6,18t R2 = 32,8% (2); c) 0-110 cm W = 293,41 - l l ,59t R2 = 40,2% (3). Explanation: p - atmospheric precipitation (mm), t - air temperature (°C). From the presented comparisons it follows that the water reserve was formed to the highest degree by air temperature, next by the sunshine and precipitation. The equation for the whole soil profile contains the most information about the examined interrelations.

Conclusions Useful water reserves on fields of cultivated plants decrease with the passage of time during the whole vegetation period. The comparison between the water reserves under different plants and on the bare fallow proves that the water reserves on the bare fallow were always higher than under the cultivated plants. The analysis of the water reserve in the whole soil profile showed that the smallest reserve was most often found under winter wheat an winter rye. Significant correlations between water reserve and meteorological elements occurred in the 0-25 cm layer: precipitation (positive), temperature (negative), and sunshine (negative). In the other layers the correlations concerned temperature and sunshine.

Figure 1. The water reserve in the 0-110cm soil layer in relation to air temperature

mm 400

350

300

250

200

150

100

50

4.3 5.9 7.5 9.1 10.7 12.3 13.9 15.5 17.1 18.7 20.3

temperature (°C)

References Kolodziej, J. et al., 1970, Annales UMCS XXV, 1: 1-20. Kolodziej, J. et al., 1972 Annales UMCS XXVII, 4: 45-62. Kozminski, C , 1994. Roczniki Akademii Rolniczej w Poznaniu CCLVII: 33-49. Samborski, A. et al., 1993. Annales UMCS XLVffl, 12: 93-96. Samborski, A. et al., 1993. Annales UMCS XLVHI, 13: 97-103.

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NITROGEN USE AND LOSSES AT (SUB) FARM LEVEL IN POLAND

J.W.A. Langeveld and G.B. Overbosch Centre for World Food Studies, De Boelelaan 1105, 1081 HV Amsterdam, the Netherlands

Introduction High to very high nutrient losses in current agricultural practices have raised questions regarding their effect on the environment. Although there is clear need for policies aiming at a reduction of these losses (90 % of ammonia emissions in the Netherlands originate from agricultural processes), there is much debate on their expected effect. Stringent measures that are necessary will influence economic and social conditions in agriculture where already major changes take place. Their effect will depend on the extent and type of losses, the place where they occur, and the assessed costs for abatement. The aim of this study is to provide information on nitrogen losses on private farms in Poland and options for their abatement.

Methods Most studies on nutrient losses in agriculture use farmgate or aggregated sectoral figures. In this study we calculate sub-farm flows to discriminate between livestock and crop sectors at farm level. Figures refer to farms in two districts in Poland (1992 data), that were selected to represent all private farms (cf Langeveld et al. (1995)). Nitrogen surplus in the livestock sector is calculated as the difference between animal feed on one side and animal products and manure on the other side. Nitrogen flows in manure were calculated as the difference between feed and animal products, corrected for losses in stables. The crop balance is defined as the difference between nitrogen imports (seed, deposition, fixation and anorganic fertilizers) and manure on one side, and crop products on the other side. It includes all losses occurring on fields. The farm balance is calculated as the difference between nitrogen imports and nitrogen in products sold (both at farm level). In order to assess the efficiency of nutrient use, Nutrient Use Efficiency (NUE) which is defined as the ratio of outgoing and incoming nutrient flows, was calculated for the animal and crop sectors as well as the farm level. Nitrogen losses are caused by volatization, leaching or run-off. Assessment of the latter two require detailed field analyses which were not available. Volatization was calculated using survey data combined with literature. Options for reduction of volatization were identified and their costs evaluated.

Table 1 Nitrogen flows at sector and farm level (kg N ha"1)

Flow

Input Output Surplus NUE (-) NUEa (-)

Livestock sector

83.4 75.0 8.4

0.91 0.23

Crop sector

201.2 43.5

157.8 0.34 0.53

Farm

144.9 22.1

122.7 0.15

-a: excluding nitrogen in manure

Results Nitrogen surpluses are low in the livestock sector, but high in the crop sector and on the farm level (Table 1). The farm surplus is higher than that in 1991 (Sapek et al., 1993). This can be explained by higher fertilizer applications in 1992, while yields in both years were comparably low (1992 yield was depressed by drought). NUE at farm level is rather low for

Session 2.2 475

both years (0.15). NUE of the livestock sector (1992) is very high as way manure is considered as an output. NUE of the crop sector is considerably lower. NUE figures for Dutch dairy farms are 0.14, 0.53 and 0.14 respectively (Aarts, pers. comm.). Exclusion of manure gives an indication of production efficiency using external inputs only. Adjusted NUE is 0.53 for the crop and 0.23 for the livestock sector. The latter figure is comparable to that for a Dutch experimental farm (Aarts, pers. comm.). Nitrogen volatization is calculated at 37 kg N ha"1 or almost 400 kg of nitrogen per farm (Table 2). This is 50 % more than in 1991 (Sapek et al., 1993). Most losses occur in the crop sector, especially during manure and chemical fertilizer application. Losses in stables and from manure storage are relatively small (20 % of the total). Aggregation to the total private agricultural sector in Poland (14.2 million ha) gives a loss of 0.52 million ton of nitrogen. This seems reasonable, although somewhat high, if compared with estimations by Klaassen (1991a) who presented a range of figures: 0.33-0.47 million ton.

Table 2 Nitrogen volatization at farm level (kg N farm"1)

Flow

Stable/storage Grazing Manure application Fertilizer application Total

Livestock sector

82.9 ---

82.9

Crop sector

-10.1

188.1 110.3 308.4

Farm

----

391.3

Abatement options include loss reduction in stables (stable adjustment, SA), manure storage (storage covering, SC) and manure application (injection or ploughing, IP). They represent considerable costs, as estimated by Klaassen (1991b). For the average farm in our survey (10.7 ha, 0.6 ha of grassland, 5 heads of cattle and 25 pigs), costs are estimated at 58,700 German Marks (once in 10 years) for SA and SC, and 525 Mark annually (IP). Expected volatization reduction rates of the measures is 50-65 % (SA), 10 % (SC) and 90 % (IP).

Conclusions Farm surpluses are rather high due to high fertilizer application levels and low yields in 1992. Ammonia volatization estimations remain in line with expectations. Most losses occur during manure and fertilizer application. Losses strictly related to animal production (excluding manure application) are rather small. Abatement costs represent major investments for private farms in Poland, especially for the livestock sector where also reduction efficiency is lowest. Loss reduction in crop sector therefore needs to be given the higher priority.

References Klaassen, G., 1991a, Emissions of ammonia in Europe as incorporated in RAINS. Paper

presented at the workshop 'Ammonia emissions in Europe: emission factors and abatement costs' at IIASA, Laxenburg, February 4-6 1991, 34 p.

Klaassen, G., 1991b, Costs of controlling ammonia emissions in Europe. Status Report 91-02, 46 p. Laxenburg, IIASA.

Langeveld, J.W.A. and G.B. Overbosch, 1995, Estimating nutrient surplus and nutrient use efficiency from farm characteristics. An application to private farms in two districts in Poland. Working Paper 95-03, 15 p. Amsterdam: Centre for World Food Studies.

Sapek, A. and B. Sapek, 1993, Water Science Technology 28, 483-488.


ENERGY BALANCE OF CROPPING SYSTEMS IN THE SUGAR BEET-GROWING REGION OF CENTRAL MORAVIA

P. Misa

Agricultural Research Institute Kromëfiz, Ltd., Havlickova 2787, CZ - 767 41 Kromëfiz, Czech Republic

Introduction A typical feature of Czech agriculture in the past was to maintain relatively stable and balanced crop rotations. This system has been basically destroyed due to market relations and farmers have begun to focus on economic effectiveness. That has caused, among others, considerable production specialization. The present state brings discussions on both productivity and sustainability and stability of plant cropping systems.

Methods This study is based on long-term stationary experiments carried out in the sugar beet-growing region in Central Moravia, location of the Agricultural Research Institute Kromëfiz, Ltd. Five cropping systems were compared: 1) eight-course crop rotation of the ecological cropping system in accordance with IFOAM instructions (clover, winter wheat, potatoes, spring barley, triticale, pea, winter barley, oats), 2) nine-course crop rotation with the conventional cropping system (alfalfa, alfalfa, winter wheat, spring barley, sugar beets, spring barley, winter wheat, silage maize, spring barley), 3) four-course Norfolk crop rotation (clover, winter wheat, sugar beets, spring barley), 4) winter wheat continuous cropping, and 5) spring barley continuous cropping. For both continuous cropping systems four variants of organic fertilization are studied (A - straw ploughed in, B - straw + green manure ploughed in, C - green manure, D - a control variant free of fertilization. The individual systems were limited by the plot (field). Inputs of the energy balance comprised only materials entering the system from outside the system, and outputs only materials that leave the system. That means the straw which remains in the field to be ploughed in was considered as material whose energy remains within the system and it is not taken as input or output. In continuous cropping systems straw remains in A and B variants; the balance does not include green fertilization in B and C variants. In the crop rotation of the ecological cropping system all the by-products remain in the field. The energy of organic fertilizers applied to the system from outside this system (farmyard manure) was expressed using their combustion heat. Energy balance was calculated for invested energy (e.g. fuel, fertilizers, pesticides, seed, machinery and labour) and total energy coming into the system (solar radiation + invested energy). In the variants, effects of cropping practices on some soil properties (pH, humus content, etc.) are also examined.

Results The results are given in Tables 1 and 2. Taking into account the energy balance the best values were obtained in the variants C and D of both continuous croppings (mainly the output energy/input energy ratio). Table 2 shows effects of these cropping systems on the soil during 25 years of the experiment.

Conclusions To calculate the energy balance of cropping systems some factors play an important role: 1) Methodological factors Definition of the system and its limits, and then the expression and inclusion of the energy from

Session 2.2 477

organic fertilizers are particularly considered. If we took into account only the energy used for the production of organic fertilizers and not their total energy content, we would obtain quite different results. 2) Problems of internal energy of the system The expression of energetic changes in the system caused by soil processes can indicate a limit of cropping system sustainability. Table 2 shows that good results of some cropping practices can be achieved but this is associated with a loss of internal energy of the system. There is, however, a question how to include changes of soil properties in the energy balance.

Table 1. Energy balance of cropping systems (MJ.ha

variant

CR in ecological S

CR in conventional S

Norfolk CR

CC of w. wheat- A

CC of w. wheat-B

CC of w. wheat-C

CC of w. wheat-D

CCofs.barley-A

CCofs.barley-B

CCofs.barley-C

CCofs.barley-D

inputs

invested energy

25 087

35 341

39 681

19 755

21010

21009

19 754

16 039

17 294

17 293

12 237

of which organic fertilization

16 363

23 800

29 750

-') outputs

76 150

25 301

146 425

94 795

106 775

208 255

201 855

93 850

109 560

166 185

133 630

O/l ratio

I = invested energy

3.04

5.81

3.69

4.8

5.08

9.91

10.22

5.85

6.34

9.61

10.92

O/I ratio

I = invested energy + SR

0.00184

0.00495

0.00353

0.00229

0.00258

0.00503

0.00487

0.00227

0.00265

0.00401

0.00323

CC = continuous cropping, CR = crop rotation, S :

SR = solar radiation = 41 400 087 MJ.ha'1 system, A, B, C, D, = variants of CC

Table 2. Effects of cropping practices on soil properties (chosen variants)

variant

1970 1995

humus content

humus content

humic acids/ fulvic

acids

pH total N content

(%)

total N content (t.ha1)

Norfolk CR

CCofs.barley-A

CCofs.barley-B

CCofs.barley-C

CCofs.barley-D

2.6

2.69

2.78

2.71

2.38

2.56

2.79

2.78

2.37

2.25

0.83

0.87

0.83

0.91

0.88

7.03

5.44

5.08

5.49

6.16

0.21

0.203

0.21

0.193

0.189

9.01

8.47

8.51

8.51

8.39

References Stout, B. A., 1992. Energy in World Agriculture, Volume 6. Elsevier Science Publishers, 367 p. Kopecky, M., 1979. Odrûdovâ agrotechnika a vyzivajarniho jecmene pro rüzné vyuziti vyssi

koncentrace obilnin. Research report, VÛO Kromëriz, 44 p. Kudrna, K., 1985. Zemëdëlské soustavy Stâtni zemëdëlské nakladatelstvi, Praha, 49-89. Preininger, M., 1987. Energy Evaluation of Production Processes in Plant Production. ISSM,

Prague, 29 p.


ECOLOGICAL AND INTEGRATED SYSTEMS IN DENMARK. INTERNAL RESOURCES IN DD7FERENT SYSTEMS AND THEIR POTENTIALS FOR USE.

Gunnar Mikkelsen.

Department of Soil Science. Research Centre Foulum, P.O. Box 23, DK-8830 Tjele.

Introduction In Denmark, ecological and integrated crop rotations have been designed and started in 1987 at three state research stations. The discipline is called Research in Cropping Systems. Different systems are designed for the different locations. The design is based on soil type, climatic possibilities and tradition for agriculture. The overall design is in correspondence with activities all over Europe, where a holistic approach is a key point for the research activities. A common feature of the research is to evolve systems not to compare systems. In integrated rotations, liquid manure is the main fertilizer. In rotations with forage crop production, liquid manure from cows is used and in rotations with production of small grain manure from pigs is used. The ammonium part of the manure is defined as 100% usable in the first growing season. The fertilization is then based on manure in amount of the crops need for potassium and phosphorus. Ammoniumnitrate is then used to adjust the nitrogen fertilizer level to 80 % of the recommended. A well designed crop rotation, including catch crops, will then be able to satisfy the crops need for nitrogen to optimal grow potential. The use of pesticides is kept at a low level by using a good crop rotation, variety mixtures, where it is possible, and keeping the nitrogen level low. A black list for chemicals based on their toxicity for humans and their persistens in soil is worked out to secure the farm manager and the environment. In the ecological rotations liquid manure is the only fertilizer. The amount is from one year cow on average per hectare. Peas and clover grass covers nearly half of the area other crops are barley, oat, fodder beet. As the rotation runs, clover grass will become the main nitrogen source for the entire rotation. The crop rotation, therefore, must take care of keeping nitrogen in the soil/plant environment instead of being leached. Weed control is mechanical by long finger harrows, hoeing machines and by hand hoeing. In grass and row cultures the main weed control is done. These fields are keeps absolutely clean in relation to weed. Pests and diseases are controlled by the crop rotation.

Methods Results from the rotation at Research Center Foulum will be presented. Foulum is situated in the middle of Jutland on a coarse sandy loam. One ecological forage crop rotation and two integrated rotations are situated here. The entire research area covers 26 hectare. Every field in all rotations is divided in two parts. A reference area and a research area. In the reference area a monitoring program for parameters as yield, fertilization, pesticide use, pests and diseases evaluates the agricultural practice in the long run. Before the project started a grid net of 40 m x 40 m was established, and in all interceptions, a so called "startcharacterization" was done. In the reference area this characterization is continued. In the integrated rotation nitrate leaching is measured. 16 ceramic cups are placed at one metres depth under the root layer. The nitrate concentration in soil water is measured every fortnight. The water movement is followed by neutron spreading technic. The leaching of nitrogen in kg per hectare is then calculated based on the amount of water percolating the soil and the nitrate concentration in the water. The evaluation of the nitrate leaching is then a function of the different treatments done in the field and the corresponding leaching. Data from 1989 up till 1995 are available.

Session 2.2 479

Results In the integrated rotations the fertilizer level is based on yield expectations for the different crop in the rotation. The levels, therefore, some time when the growing conditions are suboptimal, because of the climate, become too high. Nutrient balances for single crops and for the entire crop rotation show, that in some years, it is very difficult to make a balanced fertilization. Also because the ratio between phosphorous and potassium in manure is different from the composition in plant material. Nitrogen fertilization is a combination of the mineral nitrogen in manure and ammonium nitrate. In years with normal growing conditions, there is balance in relation to mineral nitrogen but not in relation to the total input of nitrogen. The choice of fertilizer level at 80% of the recommended, and catch crops, should secure that use of manure do not create nitrogen leaching problems. In the ecological rotation the fertilization is based on manure and clover grass. The balance for potassium is very negative because of high yields and leaching of potassium, but in ecological farming it is difficult to import potassium to the farm. In the long run, then, potassium can be the growth limiting factor instead of nitrogen. In the rotation there is plenty of nitrogen because of fixation in clover grass. The balance for nitrogen both total nitrogen and mineral nitrogen is positive. Mainly because of nitrogen fixation which is an integrated part of the balance. The balance for phosphorous is neutral with the same output as input. The results for nitrate leaching show that in years when there is an effective catch crop in the field the nitrate leaching is very low. Winter wheat as a winter green crop has very little influence on the nitrate leaching. The concentration of nitrate in ppm is, for all years, kept under the EU - level at 50 ppm nitrate per litre. Anyway, the amount of leached nitrogen per hectare still can be high on sandy soils.

Discussion The fertilizer balances for the different crops and rotations will be discussed in the lecture. Nitrate leaching as a consequence of agriculture and how to reduce it, will be discussed. The holistic approach in relation to more traditional research results will be part of the discussion, too.


WATER AND NITROGEN INTERACTION IN DIFFERENT CROPPING SYSTEMS

K. Peto Department of Rural Resource Management, Debrecen Agricultural University, PO Box: 36, H-4015, Debrecen, Hungary

Introduction The drought weather of the past years made clear that the available moisture, moisture -supply, and yield are in close correlation with each other (Debreceni, B. et al., 1983).In this paper I would like to present some results concerning to water and nitrogen interaction in different cropping systems

Methods On the Lâtokép Experimental Station of Debrecen Agricultural University a multivariate trial was conducted by Ruzsânyi at the beginning of 1980's. Debrecen is situated on the Great Hungarian Plain, in the Eastern part of the country, at 47^3 0' latitude and 21^30' longitude. The highest contour line of the region is at 118 m (Adriatic.) The soil of the experiments is calcareous chernozem. The clay content in the cultivated layer is 50 %. Physical soil type: medium heavy loam. The water holding capacity (WHCmm) of the soil is 32-34 vol. %. In these experiment we studied three different crop rotation systems: winter wheat - maize (biculture), soya - winter wheat - maize(triculture) and maize monoculture at different levels of fertilisation, irrigation and tillage. We took soil samples from the 200 cm deep soil layer separately in each 20 cm at the beginning of vegetation period and measured the soil moisture content with gravimetric method. The soil samples were taken from three different: control, medium, highest, fertilisation level (Figures 1 and 2) from each replication

Results Crop rotation and preceding crop has a most favourable effect on the modification of soil water management. The highest soil moisture content in the 0-200 cm layer may be measured both in early spring and the end of vegetation period in winter wheat - maize (biculture) production system(Figures 1 and 2). In soya - winter wheat - maize (triculture) and maize monoculture system as compared to the previous one the moisture content of the soil is less by 30-60 in early spring time and by 50-100 mm at the end of vegetation period (Figures 1 and 2). There are differences among the effect of the same preceding crops in different cropping systems too (Ruzsânyi, L. 1973). The effect of soya on soil moisture was the same as the maize which is cultivated in monoculture. It means, that according to our measurements and calculations the water consumption of soya was as high as or higher than the water consumption of corn in our experiment. On the basis of its effect on the water management of soil, soya should be considered with less favourable green crop value (Petö, K. et al., 1991). Comparing the different cropping systems we can conclude that the role of soil water balance became most important in soya -winter wheat-maize system. This refers to water deficiency relative to nutrient level (F2, F3) in this system during the vegetation period (Figure 1). In chernozem soil of good nutrient and water management the decisive agrotechnical factor is the fertilisation, more specifically, N- fertilisation (Ruzsânyi L. et al., 1993).

Session 2.2 481

The effect of fertilisation increasing the water demand is, however, differentiated. It increased most the water demand of winter wheat of all plants investigated. Depending on the previous crop(35-70 mm). Amount of fertiliser in excess to the demand of plant did not alter the water demand and did not affect the yield. Result of the investigation also prove the strict connection between the effects of fertilisation to increase the water demand and yield. Quantities of fertiliser not increasing the water demand do not increase the yield either.

Table 1.: Spring and post harvest moisture of 0-200 cm soil layer and yield of winter wheat plots per fertilisation in two different crop rotations 1990 crop rotation

Biculture Triculture

Biculture Triculture

Spring Post- harvest fertilisation levels

Fl 454.0 430.0

F2 431.9 427.0

F3 427.7 413.0

Fl 359.3 326.8

F2 336.4 299.8

F3 314.8 294.8

yield kg ha"1

2746 3479

5181 4321

5714 4160

Legende: Fl: N0+P0+K0, F2: N100+P70+K80 F3: N200+ P140+K160 Table 2. Spring and post harvest moisture of 0-200 cm soil layer and yield of maize plots per fertilisation in three different crop rotations 1990 crop rotation

Biculture Triculture Monoculture

Biculture Triculture Monoculture

Spring Post- harvest fertilisation levels

Fl 494.3 463.5 421.2

F2 479.3 428.9 412.5

F3 470.4 444.5 377.9

Fl 308.7 316.0 313.9

F2 293.3 307.2 298.0

F3 295.9 289.7 267.1

yield kg ha"1

7951 7303 3547

8584 6343 4499

8161 6412 3531

Legends:Fl: N0+P0+K0, F2: N120+P90+K90 F3: N240+ P180+K180

Conclusions Comparing the biulture and triculture, we can conclude that the effect of soil moisture on the yield is more significant in the triculture than in the biculture. It can also be concluded that the yield of winter wheat can be affected more significantly by N -fertilisation in biculture than in triculture. In corn experiment the relation between the change of soil moisture content and fertilisation is more suppressed than that in the wheat experiment.

References Campbell, C. A. et al., 1987. Can.J. Soc.Sci.Ottawa Ont. 67.3.457-472. Debreceni, B. et al., 1983. The relation between the nutrition and water supply. Budapest. Petô, K. et al., 1991. Növénytermelés. 40. (6):535-541. Ruzsânyi, L. 1973. Növénytermelés.23. (3): 249-258. Ruzsânyi L. et al., 1993. Növénytermelés.42.(l):85-94.


EFFECT OF ROTATION WITH WHEAT AND CATCH-CROPS ON PHYSICAL TRAITS OF "XANTHI" TOBACCO

F.Piro1, P. Greco2

'present address: Istituto Sperimentale per 1'Orticoltura, 1-84089 Pontecagnano (SA), Italy. 2Istituto Sperimentale per il Tabacco, 1-73100 Lecce, italy..

Introduction Tobacco monoculture is quite usual in specialised areas of production for economic reasons. Reduction of yield levels is among the shortcomings of monoculture. Short rotations with wheat, including catch-crops, have been studied through 1985-1991 as alternatives to oriental tobacco monoculture (Lanza, 1988; Greco et al., 1990; Greco et al., 1994). Effects on tobacco physical traits relevant to manufacturing are here reported.

Methods Monoculture of tobacco ("Xanthi", oriental aromatic type) (T), the same with a fennel catch crop (T+Fl), and tobacco-wheat rotations with catch-crops of soybean (T-W+Sy) or sorghum (T-W+Sm) were compared through the years 1985-1991 on a haploxeralf sandy loam in the Salento area of the Apulia Region (Costantini et al., 1990). All cropping patterns were tested at two levels of crop husbandry, differing in depth of soil plowing, levels of NPK fertilization, and seasonal irrigation volume. Field design was a split-plot, with husbandry levels in main plots and rotations in subplots, with three replications in complete blocks. Tobacco was transplanted at spacings of 0,55 m by 0,11 m. Details of field procedures have been reported previously (Greco et al., 1994). Tobacco data here reported refer to the last two years of experiment. Yield measurement and leaf grading were carried out on leaves conditioned at 16% RH. Lamina-midrib ratio was determined on samples of 20 middle leaves. Lamina specific weight was determined on samples of 50 middle leaf disks of 22 mm diameter after oven drying at 50°C for 48 h.

Results In comparison with monoculture, tobacco in rotation with wheat gave higher yields of cured tobacco, but lower leaf grades (Table 1).

Table 1. Effect of rotation and crop husbandry level on yield and grade of 'Xanthi' toDacco. I rait and year Rotation and input level Cured yield Hercent grades A+B Middle leaf weight

ton ha-1 • % g

—Two m] Twrj— 1991 rggrj T S Ï Ï I — notation Tobacco-tobacco Tobacco-tobacco+fennel Tobacco-wheat Tobacco-wheat+sorgh u m Tobacco-wheat+soybean se. Input level high low s.e.

1.17 1.05 1.58 1.65 1.63 0.07

1.43 1.40 0.05

1.47 1.53 1.76 1.77 1.55 0.02

1.81 1.41 0.01

53.0 48.9 37.1 41.6 37.9 2.50

43.2 44.3 1.6

40.6 39.5 32.9 43.1 44.4 5.8

34.9 45.2 3.7

4.5 3.9 4.8 4.2 4.9 0.1

4.5 4.4

0.04

5.6 5.4 5.6 7.0 5.9 0.6

5.7 6.1 0.4

The same trend was observed at both levels of crop husbandry in 1990, when on average a 35% yield increase was matched by a 30% decrease in grade; but in 1991 it was significant only at the high level (Table 2).

Session 2.2 483

T a b l e 2 . I n t e r a c t i o n of r o ta t i on and c rop h u s b a n d ry l e v e l in 1 9 9 1 T r a i t a n ri h n c h a n H r w s u a i i u i y i c v c i in i s 9 I . T r a i t a n d h u s b a n d r y l e v e l

R o ta t io n

C u red y ie ld t ha '

h igh low

0.1

h igh

% g r a d e s A + B

low T o b a c c o m o n o c u l t u r e 1 .5 / 1.36 4 5.3 3 5.9 T o b a c c o m o n o c u l t u r e + f e n n e l 1.63 1.43 30 .3 4 8 . 6 T o b a c c o - w h e a t 2 .07 1.46 27 .9 37 .9 T o b a c c o - w h e a t + s o r g h u m 2 .13 1.14 33 .3 52 .9 T o b a c c o - w h e a t + s o y b e a n 1.68 1.42 37 .9 50 .9

3.9

The addition of catch-crops resulted in further yield improvements, except in the case of soybean in 1991, but limited to a large extent the fall in leaf grade. Rotation with wheat reduced lamina-midrib ratio in 1990 and leaf specific weight in 1990 and 1991 (Table 3).

Table 3. Effect of rotations and crop husbandry levels on cured leaf traits or 'Xanthi' tobacco.

Rotation and input level Rotation Tobacco-tobacco Tobacco-tobacco+fennel Tobacco-wheat Tobacco-wheat+sorghum Tobacco-wheat+soybean s.e. Input level high low s.e.

Lamina-midrib 1990

4.9 4.1 4.1 3.9 3.9

0.02

4.1 4.3 0.01

ratio 1991

4.0 4.0 4.0 3.8 3.8 0.2

3.7 4.2 0.1

Lamina specific 1990

75.4 79.2 70.1 55.8 60.2 2.9

65.3 71.0 1.8

weight (g m ' ) 1991

74.0 73.8 57.8 65.9 64.6 3.6

60.2 74.2 2.3

Effects of catch-crops on leaf specific weight were incosistent over the two years. The sorghum catch-crop appeared more beneficial for tobacco yield and mean leaf weight than soybean, but only in one year. Inclusion of the fennel catch-crop to monoculture did not show noticeable or consistent effects, except a slight depression of leaf weight and grade in one year. On the whole, the high level of crop husbandry showed some potential to increase yields, but at the expense of leaf specific weight, lamina-midrib ratio and leaf grade.

Conclusions Xanthi tobacco is appreciated mainly for characteristics of aroma, which are enhanced by a dry climate like the egean and hillside, superficial soils of low fertility (Wolf, 1962). The increase of soil fertility, as through rotations and more intensive cropping of regularly fertilized cultures, risk diminishing the aromatic character of the leaf. Indeed the rotation with wheat, rising substantially the levels of nitrogen fertilization, was detrimental for leaf grade. However such negative effect could be largely offset by low levels of crop husbandry and by addition of catch-crops, which could consume some of the excess nitrogen in the soil.

References Costantini, E.A.C. et al., 1990. Annali Istituto Sperimentale Agronomico, 21, Suppl. 2, 255-288. Greco, P. et al., 1990. Annali Istituto Sperimentale Agronomico, 21, Suppl. 2, 36-37. Greco, P. et al., 1994. Agricoltura Ricerca 151/152, 35-42. Lanza, F., 1988. L'Informatore Agrario 44, 57-67. Wolf, F.A., 1962. Aromatic or oriental tobaccos. Duke University Press, Durham, NC.


INTERCROPPING SPRING TRITICALE WITH N-FIXING LEGUMES AS A COMPONENT OF SUSTAINABLE FARMING

E.K. Pisulewska, T. Zajac, R. Witkowicz

Crop Science Department, Krakow Agricultural University, al. Mickiewicza 21, Krakow, Poland

Introduction

When cereals are grown as intercrops with legume species, they generally yield similarly (Reynolds et al., 1994, Zaja_c et al., 1995) or less than they do in monoculture, and grain protein content is increased (Pisulewska, 1993 and 1995). Intercropping can also provide other benefits such as extra ground cover, and a substantial input of organic matter and N to the soil, thus becoming a sustainable approach to maintaining soil fertility. Our purpose was to compare grain yield and its quality of spring triticale grown in monoculture and intercropped with legume species

Methods

Three precise field trials were conducted in different habitats in three provinces of Southern Poland, in the growing seasons 1987 - 1995. Total rainfall was recorded in the month April to August (Fig).

BKatowice 1994 QKatowice 1995 HNowy Sacz 1987 ENowy Sacz 1988| BNowySa.cz 1989 H Krakow 1990 B Krakow 1991 BKrakówl992

Figure. Precipitation in growing season at different sites and different years.

A two-factorial, split-plot arrangement of treatments in a randomized complete block design was used, with three or four replicates. The treatments were (1) spring cereal species and (2) the planting method (monoculture vs. intercropping with a legume plant). Both grain and legume species were well adapted to their habitats: I. Katowice province - brown soils, grain species -spring triticale and oats, legume species - Serradella; II. Nowy Sacz province - brown soils (on

http://BNowySa.cz

Session 2.2 485

loam), grain species - spring triticale and barley, legume species - red clover; III. Krakow province - chernozem on loess, grain species - spring triticale and spring wheat, legume species -field peas.

Results

The results are presented in Tables 1 and 2.

Table 1. Grain and protein yield of spring cereals grown in monoculture and intercropped with legume species (average of 2 or 3 years).

Province

Katowice

Nowy Sacz

Krakow

Species

Triticale Oats Triticale Barley Triticale Wheat

Grain yield (t Monoculture

1.69 1.70 3.29 2.36 6.02 5.82

* ha1) Mixture

1.91 1.36 3.86 3.00 4.97 5.48

LSD p= 0.05

n.s.

n.s.

n.s.

Protein yield (kg * ha"1) Monoculture Mixture

216 197 379 260 826 777

220 201 484 374 759 769

LSD p= 0.05

n.s.

n.s.

n.s.

Table 2. Grain yield, grain protein content, and protein yield of spring cereals, as affected by a type of soil and growing season.

Province

Katowice

Nowy Sacz

Krakow

Year

1994 1995 1987 1988 1989 1992 1993 1994

Grain yield (t * ha')

1,98 1,35 4,61 3,97 0,80 6,51 5,51 4,70

LSD p= 0.05

0,09

0,70

0,50

Protein content (% D.M.)

14,66 12.69 14,33 13,70 12,30 14,08 13,84 14,52

LSD p= 0.05

2,22

0,91

0,81

Protein yield (kg * ha1)

256 162 570 469 84 909 764 677

LSD p= 0.05

31

111

98

Conclusions 1. In the three experimental locations, triticale yields did not differ significantly from those of the

reference cereals. In contrast, type of soil and growing season affected the yields significantly. 2. The method of planting (monoculture vs. intercropping) had no statistically significant effect on

the yields of triticale, although in Krakow province intercropping tended to decrease these yields.

3. Grain protein content and protein yields were significantly affected by growing season (total rainfall and its distribution).

References Pisulewska E., 1993, Roczniki AR w Poznaniu CCXLIII. Pisulewska E., 1995, Acta Agr. et Silv. Ser. Agr., vol. XXXIII. Reynolds M. P.et al, 1994, Journal of Agricultural Science, Cambridge, 123, 175 Zajac T. et al., 1995, Fragmenta Agronomica, nr 2 (46).

183.


MAIZE RESPONSE TO FERTILIZER NITROGEN IN MONOCULTURE AND ROTATION SYSTEMS ON VERTIC AMPHYGLEY IN UPPER SAVA VALLEY

A. Pucaric, B. Varga

Faculty of Agronomy, University of Zagreb, 10000 Zagreb, Croatia

Introduction In intensive maize production the type of crop in the rotation usually is not important as long as maize does not follow itself (Crookston et al., 1991, Raimbault et al, 1991). In such production systems heavy use of nitrogen leads to environmental problems. To solve these problems alternative practices as rotations in which legume are included and lower nitrogen fertilization are recommended. (NAS, 1989). Our objective was to determine maize response to applied N in different cropping systems on the heavy, poorly drained vertic amphygley in a humid climate.

Methods A crop rotation study was established at Oborovo near Zagreb in 1991. The cropping treatments were maize monoculture (MM) and 22 plots for seven rotations coded by the first letter of the crops: SM, S-W-M. W-M. W-RC-M. S-W-RC-M. S-W-OR-M and A-A-A-M (M=maize, S= soybean, W=w. wheat, RC= red clover, OR= oil rape, A=alfalfa). Each crop of every rotation was grown in every year. Identical split-plot experiments with five replications on maize plots were carried out from 1993 to 1995. Main plots were five nitrogen rates (40 to 240, in MM 86 to 286 kg ha_1N) and subplots two hybrids. Nitrogen was applied prior fall plowing at the rate 40 (in MM 86) kg ha'1 N to all plots. Rest of the nitrogen depending on N rates was applied before secondary tillage and side dressed twice. Ear leaf samples were taken at anthesis to evaluate N status of maize. Yield was adjusted to grain moisture of 140 g kg"1. Analyses of variance for yield showed no significant interactions betwen N rate and hybrid and year in either system. Thus, yield data are combined over three years, in A-A-A-M over two.

Results Results for maize grain yield are presented in the Figure and for leaf N in the Table. The lowest yields were observed in MM but also in S-M and A-A-A-M rotations. When low N rate of 40 (86) kg ha"1 was applied grain yield averaged only 4.2, 5.3 and 5.71 ha"1 in MM. S-M and A-A-A-M. respectively. Lower N plant status (23 g kg"1) than optimum (27 to 28 g kg"1, Dumenil, 1961., Larson et al., 1977) may be reason for low grain yields in MM and S-M. After alfalfa maize had optimum leaf N concentration indicating that some other "rotation effects" produced low yield. Maize yield response to increased N rates was most pronounced in MM

Table. Maize leaf N as affected by previous crop in different cropping systems and N rate

N rate, kg ha "'

40(86)* 120(166) 160(206) 200(246) 240(286)

MM

23 25 27 27 28

S-M

23 25 26 27 28

A-A-A-M

27 29 30 30 30

W-M Cropping system

S-W-M W-RC-M Leaf N at anthesis, g kg"1

26 27 29 29 28

26 28 27 29 29

26 27 29 30 29

S-W-RC-M

25 27 28 28 29

S-W-OR-M

27 29 29 29 30

* numbers in brackets are N rates in MM.

Session 2.2 487

WT

^ 9 -

o -c

o MM A S-M x A-A-A-M

..G....0

,...*— 'x-.4 f" ^•••••A" • ••&!••

•+•

A S-W-OR-M x W-RC-M \s OS-W-RC-M

-•5

•4- -f-"40 80 120 160 200 240 280 40 SO 120 160 200 240 40 SO 120 160 200 240

NITROGEN RATE ( kg hd1 )

Figure. Maize grain yield response to N following different previous crops in cropping systems. Equations and R2 values: for MM y = 2,262+0,0233x-0,00002 x2, 0,99; for SM y = 4,414 + 0,0236 x-0,00004x2, 0,99; for A-A-A-M y = 4,778+0,0254x-0,00006x2, 0,99; for W-M y = 6,248+0,0260x-0,00007x2, 0,96; for S-W-M y = 7,155+0,0196x-0,00005x2, 0,99; for W-RC-M y = 7,083+0,0115x-0,0002x2, 0,95; for S-W-RC-M y = 6,594+0,0132x-0,00002x2, 0,99; for S-W-OR-M y = 8,324+0,0090x-0,00002x% 0,98 yields are not significantly different.

In the dotted section of the lines measured

and then in S-M while in A-A-A-M yield significantly increased up to 160 kg N ha"1. In the rotations W-M and S-W-M where wheat was the previous crop and in W-RC-M and S-W-RC-M where red clover was the previous crop, at low N rate higher yields (7.2 to 7.8 t ha"1) were observed. Significant response to increased N rate was less pronounced, up to 120 to 160 kg N ha"1 and was stronger after wheat than after red clover. Oil rape in S-W-OR-M rotation seemed to be a very good previous crop. At low N rate of 40 kg N ha"1 leaf N was in optimum range and yield was high and averaged 8.71 ha"1. Further N rate increase gave no significant yield increase.

Conclusions On the poorly drained vertic amphygley the lowest maize grain yield and the greatest response to nitrogen fertilization was observed in monoculture and soybean-maize rotation and then after three years of growing alfalfa. After oil rape maize yield was high and response to N was poor while after wheat and one year red clover maize yield and response to N were intermediate.

References Crookston et al., 1991. Agronomy Journal 83:108-113. Dumenil, L. C, 1961. Soil Science Society of America Proceedings 25:295-298. National Academy of Science, Washington 1989. Alternative Agriculture. Larson, WE. et al., 1977. Corn Production. In Corn and Corn Improvement, ASA, Medison. Raimbault et al., 1991. Agronomy Journal 87:979-985.


MODELLING WORKABILITY OF LOAMY SOILS FOR SEED BED PREPARATION

G. Richard and H. Boizard

I.N.R.A., Unité d'Agronomie de Laon-Péronne, 02007 Laon CEDEX, France

Introduction Farm machinery and manpower often account for a large proportion of the running costs of farms in north western Europe. Hence, they must be used as effciently as possible. One of the major factor governing this efficient use is the ability to predict soil workability. Soil workability is often assessed subjectively by the farmer as good or bad, depending on the soil water (van Wijk et al., 1988). There is a need for a better definition of soil workability so that the effects of the tillage timing on crop productivity can be quantified. Soil workability mainly depends on the soil water content, which determines the fragmentation of the seed bed and the compaction of the sub-layers obtained after soil tillage (Soane et al., 1981). Modelling workability assumes that soil water content can be predicted from the soil and the climatic conditions and from there, the resulting soil structure at soil tillage as a function of soil water content and tillage characteristics. This paper presents the results of a field experiment conducted in the north of France on loamy soils (1) to test a numerical simulation model of water and heat transport into the soil in which the interactions between soil and atmosphere are simulated and (2) to establish the relationships between superficial soil water content and the aggregate size distribution of the seed bed, deeper soil water content and the volume of highly compacted zones under wheel tracks.

Methods The field experiment comparing three cropping systems was begun in 1989 in Mons en Chaussée in northern France (50°N, 3°E) in silt loam soils which contained between 160-220 g clay kg"1. Spring crops (peas, sugar beet, maize) were sown each year on different dates, consequently at various soil water profiles, with three levels of tyre inflation pressure. A soil profile was done after each crop sowing. The severely compacted zones (A zones) having a massive structure, no visible macropores and a high cohesion were delimited manually. The effects of wheeling on soil compaction was expressed as the percentage of the area of the cultivated profile immediately beneath wheel tracks that had A zones in contact with the bottom of the seed bed. Aggregate size distributions were measured by sieving air-dried seed bed samples. Soil water content, water potential and temperature, and climatic conditions were measured continuously during March and April 1994 to calibrate the heat and water transport model of Chanzy et al. (1993) used by Richard et al. (1993) to study the soil thermal regime as a function of soil structure. This is a numerical model which calculates the changes in the fluxes at the soil surface, the soil water and temperature profiles as a function of climatic conditions (solar radiation, air temperature, air moisture, wind speed), and the soil characteristics (albedo, roughness, bulk density, hydraulic and thermal conductivity, vapour diffusion, etc).

Results The soil structure resulting from seed bed preparation depends on the soil moisture and tyre inflation pressure. The percentage of fine earth (aggregate diameter <5 mm) decreased in wet conditions (Fig. 1). The percentage of A areas increased with higher tyre inflation pressure in wet conditions. Soil moisture limits for seed bed preparation quality were defined.

Session 2.2 489

60 •

20 •

n .

-•

i 1 i

• mS *

* * * : «S--

•« *

1 • 1 -

^ *

0.15 0.2 Soil moisture 0-10 cm (g g-1 )

0.3

Figure 1 : Effects of soil moisture on the percentage of aggregates with a diameter <5 mm in the seed bed

The change in soil moisture with time in spring was very different as a function of soil clay content. Water content gradients in soil with 16% clay were less pronounced than those in the soil with 22% clay during drying. The gradients into the ploughed layer were well calculated by the model after calibration of the relationships between the hydraulic conductivity and the soil water content (Fig. 2). Nevertheless, the calculated change in topsoil moisture was faster in the soil with 22% clay and slower in the soil with 16% clay than the observed changes in soil moisture. The results for other drying periods in the spring of 1994 were similar.

~ d

! / i A i w I I I ,' i u \ ' ' ' \ )

\l \ s \ I A

A A / \ / v

Figure 2 : Observed (points) and calculated (lines) changes in soil moisture with time in the ploughed layer with 22% clay content

100 102 104 106 Day of year

108 110 112

Conclusion A model simulating the change in the water profile of the ploughed layer of loamy soils over time in various climatic conditions was tested. The relationships between soil water profile and the resulting soil structure after seed bed preparation were established. It was therefore possible to quantify the effect of the time of tillage on the soil water profiles and on seed bed loosening and soil compaction. The length of time after a rainy period until the first day when seed bed loosening is maximum, or when no severe compaction occurs can be calculated as a function of soil type and climatic conditions.

References Chanzy, A. et al.; 1993. Water Ressources and Research 29: 1113-1125. Richard, G. et al., 1993. Les Colloques de l'INRA, Paris, 67: 87-101. Soane, B. D., et al., 1981. Soil and Tillage Research 1: 207-237. Van Wijk, A.L.M., et al., 1988. Impact of Water and External Forces on Soil Structure. Catena,

Cremlingen, 129-140.


OPTIMIZING N FERTILIZER SUPPLY OF WINTER RYE THROUGH QUANTITATIVE MODELING - CALIBRATION AND PRACTICAL APPLICATION

G.M. Richter, A.J. Beblik, J. Richter

Dept. of Soil Science, Institut für Geographie und Geoökologie, Technische Universität, Langer Kamp 19c, D-38106 Braunschweig, Germany

Introduction Nitrogen fertilizer application still poses a problem to growers of winter rye. Its N demand is different from winter wheat and on sandy soils nitrate leaching in spring has to be considered, especially in catchments. Field trials were conducted to calibrate and apply a soil nitrogen dynamics and plant growth model. In detail the aims were (i) to calculate soil water and N supply, (ii) to find a crop specific growth curve and N concentration function and (iii) to compare yields at different fertilization systems (zero, farmer, extension, model).

Methods The N dynamics model (Kersebaum and Richter, 1991) simulates the water balance, N turnover in the soil and plant growth of winter wheat, the latter largely based on the SU-CROS approach (van Keulen et al. 1982). For the simulation climatic data (precipitation, mean air temperature, saturation deficit and sunshine hours) were available from a nearby weather station on a daily time step. In three years, soil (0-30, 30-60, 60-90 cm) and plant samples were taken at three different sites with sandy soil (95 % sand) to determine mineral nitrogen as well as dry matter and N content, respectively, at critical growth stages (EC 25-28, 31, 61 and 87). The temperature dependence of assimilation and the sums for the critical growth stages of winter rye were changed according to the literature (van Dobben, 1979; Kuhlmann, 1987; Römer, 1988; Kavanagh, 1992). The distribution of assimilates was fitted to the data collected at one site the first year and validated in the second year at all sites. An exponential function for the N concentration in the plant material was parametrized from measured N contents versus the phenologically active temperature sums. N fertilizer demand is calculated from the expected dry matter production according to predicted weather (water availability, temperature and radiation) assuming unlimited N-uptake to meet the optimum N content also accounting for N supply from the soil and fertilizer.

Results

straw without leaves ears

E £< 40

'S 20

o-« MEASURED * - * WW_MOD • - • WR MOD

1 Apr 1 May 1 Jun 1 Jul 1 Aug 1 Apr 1 May 1 Jun 1 Jul 1 Aug

Figure 1: Measured vs. simulated dry matter with wheat (WW) and rye (WR) parameters.

Session 2.2 491

Simulated soil water and mineral N contents principally agree within one percent and ±20 kgN ha"1 of measured values, respectively. The simulation of plant growth meets all important phenological stages (EC 28, 31, 61). In agreement with long term observations (Römer, 1988) maturity of the grain (EC 89) is reached at lower temperatures than wheat. The growth curve and assimilate distribution of winter rye is significantly different from winter wheat (Figure 1), winter rye exhibiting rapid dry matter yield in April (EC 28 - 49). Dry matter yields can be predicted within 10 percent for several years at sites similar to that used for calibrating the model. At different sites, the dry matter yield may differ up to 30 percent due to local climatic conditions (frost, draught) which are not expressed in regional weather data and have to be accounted for using a site specific long-term yield potential.

E "d "cô 6

0

- JFS

ig\ 7 ^ \

1 e

EC: 31

x~^

e

49

Nopt 'or rye Ncrii for wheat

• G MOD, CON - sto E • O MOD, CON - «He D S ZERO-N - s t o D

™ 8 •--- , . .__ 61 75 91

0 500 1000 1500 Phenolog. active Temp.-E (*C days)

Figure 2: Measured N concentration (% d.m.) in the above ground dry matter in the plots of ZERO-N and those fertilized ace. to CONventional and MODeled N requirement.

Considering the rapid early growth of winter rye and the low N concentration of its grain (1.5% N) the fertilizer N has to be applied early, between EC 25 and 31. For the period of tillering (EC 25-28) the N concentration must be maintained well above N^, for winter wheat (Figure 2), especially in production systems with low sowing density. On sandy soils 100 to 120 kgN ha"1 suffice to meet the N requirement for a 6 t ha"1 yield. Compared to conventional fertilization systems modeling plant growth and N uptake reduces the amount of N fertilizer by 20 to 30 percent without significant yield reduction of winter rye.

Conclusions • for winter rye dry matter production and distribution is different from winter wheat, • the exponential function for its optimum N content emphazises early N dressing, • temporal variation (10 yrs) of simulated yield and N demand is below 10 %, and • modeling improves the N balance without yield reduction.

References Kuhlmann F., 1987. Pflichtenheft für die Datenverarbeitung in der Pflanzenproduktion,DLG. Kavanagh S.E., 1992. Diss. Abstracts Intern. B, Science and Engineering, 52, 3370B-3371B. Kersebaum K.-C. and J. Richter, 1991. Fertilizer Research 27, 273-281. Römer G., 1988. Dissertation, Berlin, Techn. Universität, FB. Internati. Agrarentwicklung. van Dobben W.H., 1979. In: Alberda, Th. (Ed), Aula-boek 250. Het Spectrum, 313-396. van Keulen H. et al., 1982. In: Penning de Vries, van Laar (eds). Simulation of plant

growth and crop production, 87-97.


LUCERNE AS A "NITRATE SCAVENGER" FOR SILTY CLAY SOIL MANURED WITH PIG SLURRY

P. Spallacci1, E. Ceotto1, R. Papini2, R. Marchetti1

1 Istituto Sperimentale Agronomico, Sezione di Modena, Viale Caduti in Guerra 134, 41100 Modena, Italy 2ISSDS, Firenze, Italy

Introduction The high concentration of pig livestock farms in some areas of the Northern Italy determines problems concerning the utilization of nitrogen (N) from manures. Crops with high N content in the harvestable biomass offer a chance to spread high amounts of animal wastes, avoiding negative environmental side effects (Daliparthy et al., 1991). The high N needs of lucerne (Medicago sativa) are usually covered by symbiotic fixation when there is lack of N in the soil, but they can be fulfilled by the substrate if it is rich enough in available mineral forms (Peterson and Russelle, 1991). Lucerne is a common crop in the part of Po Valley where dairy cattle are reared for the "Parmigiano - Reggiano" cheese production. Therefore, lucerne can be an interesting alternative to excessive applications of pig slurry to maize or other crops.

Methods A lucerne stand ("Garisenda" variety) was established in spring 1993 on a Vertic Ustochrept soil at S.Prospero, Modena, in the Low Po Valley. The second-year lucerne was treated with increasing rates of pig slurry (Psl50, Ps300, Ps450 and Ps600 kg N ha"1 year"1) and a comparison with a mineral N supply as urea (F-150 and F-300 kg N ha"1 year'1 ) was also included. The design was a randomized complete block with two replications (plot size 22.5x11.5 m). All treatments were splitted as follows: 20% late in the autumn, 30% at the end of the winter, 25% after the first forage cutting, and 25% after the second cutting. The crop was fully irrigated during the growing season with a total amount of 120 mm. Dry matter yield and N content in the forage were measured for the five cuttings. Nitrate and moisture fluctuations were monitored in the soil profile at various depths and times, since November 1993. Soil composite samples were frozen soon after collection and kept in that way until the analysis: nitrate by 2M KCl extraction and Technicon Autoanalyzer™ determination; moisture by gravimetric method.

Results Dry matter yield and N in forage of the lucerne did not show significant differences among treatments. The balance reported in Table 1 indicates that negative values decreased when N application increased. Only the supply of 658 kg N ha"1 from pig slurry determined a surplus of N in the system. However, nitrate in the soil profile at the end of the balance period did not increase, with respect to the beginning, in that case either.

Table 1. Nitrogen balance (kg N ha"1) for the second-year of lucerne stand

N actually applied N in lucerne forage Difference: applied-removed Decrease of soil nitrate (*) N fixed (-) or unaccountable (+)

Control

0 432 -432 55

-377

F-150

150 386 -236

10

-226

F-300

300 428 -128 17

-111

Treatmem

Psl50

173 381 -208 20

-188

t

Ps300

340 472 -132

3

-129

Ps450

500 539 -39 10

-29

Ps600

658 443 215 38

+253 (*) November 1994 with respect to November 1993, in 0-1 m soil profile

Session 2.2 493

The soil nitrate monitoring over the year (Figure 1) showed major increases as consequence of N applied at the end of winter and after the second forage cutting. These increases appeared proportional to the N rate applied. No significant differences resulted from the same amount of N supplied by fertilizer or pig slurry. Nitrate contents were always low and not different among the treatments at the end of the lucerne growing period (November 1994). Soil moisture monitoring (data not presented) pointed out that lucerne depleted soil water at the maximum of 1.6 m depth reached late August.

Figure

11/93 12/93 1/94 2/94 3/94 4/94 5/94 6/94 7/94 8/94 9/94 10/94 11/94

Sampling date 1. Soil nitrate (mg N kg"1) in the 0.0-0.2 m soil layer under different fertilizations

As data in Table 2 show, all treatments increased nitrate in the 0.0-0.2 and 0.2-0.4 m soil layers, but only the highest rate of pig slurry caused an increase in the 0.4-0.6 m layer. Soil nitrate at the depth from 0.6 to 1.0 m were never modified by treatments, as for the depth from 1.0 to 2.0 m (these data, not presented here, ranged from 0 to 4 mg N kg"1 as individual samples, 97 % of which were below 2 mg N kg"1).

Table 2. Content of nitrate (mg N kg"1) in soil profile under lucerne, averaged from November 1993 to November 1994

Soil layer

0.0-0.2 m 0.2-0.4 m 0.4-0.6 m 0.6-0.8 m 0.8-1.0 m

Sample number

19 19 19 19 19

Control

7.7 6.8 5.9 4.1 2.2

Treatment

F-300

11.8 9.7 6.0 3.6 1.4

Ps300

10.8 8.5 6.8 4.2 2.4

Ps600

16.1 12.1 8.6 4.4 2.0

Conclusions The dry matter yield and N removed in the forage of a second-year lucerne were not influenced by the different fertilizations. The N balance showed that N-fixation of lucerne seems to decrease when N application increase. The trends of soil nitrate during the growing season of lucerne and no accumulation of nitrate in the soil profile showed that lucerne is a powerful and efficient "nitrate scavenger". Moreover, the deep root system and the high water requirements of lucerne reduced the probability of leaching events. This behaviour of the lucerne stand seems to provide a feasible alternative in areas where the agronomic utilization of pig slurry is a constraint. These results will be compared to those obtained in the subsequent year.

Acknowledgements PANDA Project, Subproject 2, Series 2, Paper No. 43.

References Daliparthy, J. et al., 1991. Agronomy abstracts. Annual meetings ASA-CSA-SSSA. Peterson, TA. and MP. Russelle, 1991. Journal of Soil and Water Conservation, 5-6:229-235.


CULTTVAR MIXTURE STUDY ON WHEAT YIELD IN ROMANIAN CONDITIONS

V. Stefan, I. Savulescu, H.V. Halmajan

Bucharest University of Agronomical Sciences and Veterinary Medicine, Bd. Marasti nr. 59, 71331 Bucharest, Romania

Introduction Economic situation of Romania influences crop technologies and some decisions in using harvest products. The transition to the market economy in Romania is a difficult and a very complex process. The main effects of this process were the parcelling out of the land, a change in farming and animal production practices and a decrease of all productions. Even the associations were set up as a counterbalance to the parcelling of the land, it is difficult to use modern technologies due to the breaking up of the properties. All technologies inputs (fertilizers and pesticides) are very expensive. Intense utilization of the pesticides in the last period created some disturbance in agricultural ecosystems, sometimes determining the appearance of pesticide resistance forms of pests and diseases. The objective of this work was to study one aspects of sustainable agriculture in wheat (Triticum aestivum) technology (mixtures of cultivars) which could be an interesting solutions for the present period from economical and ecological point of view.

Methods The experiment were conducted under the field conditions, in the farm of the Bucharest University of Agronomical Sciences and Veterinary Medicine, on a reddish brown soil. Three Romanian cultivars (Flamura 85, Rapid and Dropia) were utilized in pure and mixture culture. Two sowing dates were used: 20 October (the end of optimum planting period in this region) and 5 November. Plant density was 550 plants m"2. Foliar and earn disease produced by Erysiphe graminis, and Septoria sp. were controlled using Sportak- 45 EC (prochloraz). The treatments were applied in the heading stage (10-2 in Feekes scale, Soltner 1990).

Results The results are presented in the Table. The best results were obtained for Rapid cultivar in all the experiments (planting dates and fungicide treatment). Plant diseases dissemination varied according to the cultivars (pure or mixture culture), sowing date and fungicide treatment. There was a positive correlation between the resistance to the pathogène fungi and the grain yield (data not shown). For that reason the grain yield was significantly higher when fungicide was used. Only two exceptions were noticed. For 20 October sowing date, the mixtures of cultivars ( Flamura 85 +Rapid and Flamura 85 + Dropia) in non treated experiment had (non significantly) higher yields compared to treated experiment. In the same case the mixtures of the cultivars produced a significant higher yield than pure cultivation did. The influence of cultivar mixtures on grain yield is stronger in non treated experiments.

Session 2.2 495

Grain yield of different wheat cultivars grown in pure and in mixture culture

Cultivars

Flamura 85

Rapid

Dropia

Flamura 85 +Rapid

Flamura 85 + Dropia

Rapid +Dropia

Flamura 85 + Rapid +Dropia

Grain yield (t ha"1)

20 October

Non treated

5.00 c

5.50 a

4.77 de

51.4 a

5.17b

4.74 e

4.87 d

Treated

5.46 b

5.59 a

5.02 b

5.36 b

5.04 c

5.68 a

5.20 c

5 November

Non treated

4.28 b

4.51 a

4.45 a

4.11 cd

4.00 d

4.54 a

4.44 a

Treated

4.74 c

5.23 a

4.99 b

4.65 c

4.77 c

4.75 c

4.57 d

Means in the same column followed by the same letter do not differ significantly P(>0.05).

Conclusions Some principles of ecological agriculture (such as the mixture of the cultivars) could be a major chance for peasants farm to obtain positive results. Even if the quality of mixture is not better than pure crop (but the yield is higher), there is another choice, because more than a half from the Romanian livestock is fed in an extensive manner on the peasant farms, where cereals are the most important feed.

References Soltner, D., 1990. Phytotechnie speciale. Colection "Sciences et Technique Agricoles", Angers.


QUANTIFICATION OF NITROGEN DYNAMICS IN ECOLOGICAL MIXED FARMING SYSTEMS

E. A. Stockdale1, A. Agarwal1, K. W. T. Goulding1 and S. C. Jarvis2

Soil Science Department, IACR-Rothamsted, Harpenden, Herts. AL5 2JQ. UK. 2 Soil Science Department, IGER-North Wyke, Okehampton, Devon. EX20 2SB. UK.

Introduction Within an ecological mixed farming system, the fertility-building grass-clover ley represents the main source of nitrogen (N) for following arable crops. However, the release of N in forms and at times when crops are able to utilize it efficiently is a key problem. We have been studying N release and dynamics as part of the Organic Farming Study (OFS) at Duchy Home Farm, Tetbury. The OFS seeks to determine the economic, agronomic and ecological aspects of sustainability and, very importantly, the interrelationships between these factors. Duchy Home Farm is a typical UK mixed farm with dairy, arable, sheep and beef enterprises; the first field received organic accreditation in 1989 while the last conventionally managed crop was harvested in 1994.

Methods The N dynamics of a five year old grass-clover ley in Red Shed field were quantified from ploughing (September 1994) to the harvest of the first winter wheat crop (August 1995). Four soil types were identified in the field (presented in the table); measurements were made at 10m intervals perpendicular to soil boundaries, to account spatial variability. Percentage clover cover {Trifolium repens) and N content of the grass-clover turf were assessed before ploughing, N leaching losses were quantified using porous cups, and crop N uptake and soil mineral N were measured through spring and summer. Indices of potential N mineralization (anaerobic incubation) and potential denitrification (denitrifying enzyme activity, DEA) were also measured in the laboratory. These data were used to compile N budgets for the soil types and the whole field. In addition, a simple N budget for the field was compiled from the available farm records.

Soil series identified in Red Shed field and some of their properties Soil series Haselor Oxpasture Waltham Oxpasture (gleyed variant)

Position along 5-55 m 65-95 m 105-155 m 165-225m

transect Topsoil texture Clay / clay loam Clay loam Sandy (clay) loam Clay loam

pH 7

5.9 5.5 5.9

Results The cover of clover varied between 15 and 75 %; such variation might be expected in a grazed field due to heterogeneous excretary returns. Under UK conditions the sward is estimated to have fixed approximately 54 kg N ha year"1 (Cowling, 1982). The grass-clover turf contained between 80 and 165 kg N ha . Between ploughing and the onset of leaching approximately 40 kg N ha"1 was mineralized in all soil types. Throughout the leaching period (October-March) concentrations of NO3 extracted from the porous cups exceeeded the EEC limit for drinking waters (data are presented in the figure); a spring emerging in the field during January 1995 contained 12.5 mg NO3 -N1" , also slightly above the EEC limit. The leaching peak was higher and earlier in the sandy soils of the Waltham series. Cumulative leaching losses were not significantly different between the soils: an average of 129 kg N ha'1 was leached. The green wheat crop had only taken up between 2 and 10 kg N ha"1 over the same period.

Session 2.2 497

Nitrate-N concentration (mg l"1) in water extracted from porous cups at 50 cm depth in 4 soil types from Red shed field

360 380 Julian day 1994-1995

440

Haselor Waltham

Oxpasture Oxpasture(g)

DEA measured on soils sampled in March 1995 was significantly different between soils, Haselor 90 kg N ha day , Oxpasture and Oxpasture (gleyed variant) 48 and 42 kg N ha day" and

-1 Waltham 25 kg N ha"l day" . These rates represent the potential for denitrification in the soil and are unlikely to have been achieved in the field due to low temperatures and a lack of C and N substrate. Potential N mineralization is also significantly lower in Waltham series soil. Total grain yields at harvest were depressed by the summer drought and were 1.2, 1.5, 1.3 and 2.11 ha" on Haselor, Oxpasture, Waltham and Oxpasture (gleyed variant) respectively.

Conclusions The data highlight the inefficient use of N fixed during grass-clover ley phase of rotation in this cropping system. As widely recorded, the main loss of N is by leaching due to the unsynchronized N release and crop uptake. Delayed ploughing and the use of spring crops to follow a ploughed ley would reduce the N loss (Phillips et al., 1995). The main features of the detailed budget were highlighted by the simple budget, but this involved much less data collection effort. Such simple budgets can be built together to give whole farm nutrient budget, to increase our understanding of nutrient flows at farming system level and to better manage N flows to minimise losses and maximise plant availability.

References Cowling, D. W.,1982. Biological nitrogen fixation and grassland production in the United Kingdom. The Nitrogen Cycle. The Royal Society, London. 95-102. Phillips, L., Stopes C. E. & Woodward L., 1995. The impact of cultivation practice on nitrate leaching from organic farming systems. Soil Management in Sustainable Agriculture, eds Cook H.F. & Lee H.C. Wye College Press. 488-496.


VALIDATION OF CROPSYST FOR WATER MANAGEMENT AT A SITE IN SOUTHWESTERN FRANCE

C. O. Stockle1, M. Cabelguenne2 and P. Debaeke2

1 Biological Systems Engineering Dept., Washington State University, Pullman, WA 99164-6120, USA 2INRA, Station d'Agronomie, BP27, 31326 Castanet Tolosan, France

Introduction Rainfall in the agricultural region around Toulouse, southwestern France, fluctuates from 400 to 800 mm annually, concentrated during the winter months. Irrigation is required to grow summer crops, and often supplementary irrigation is needed for winter crops. Due to the erratic nature of rainfall, tools for strategic or/and tactical analyses of water management, such as crop growth models, are needed. Therefore, validation of the ability of models to simulate crop response to weather, soil, and water stress is important. This report summarizes work done to validate Cropsyst (Stockle et al, 1993; Stockle et al., 1994) using data collected by INRA at Auzeville (near Toulouse), France.

Methods Long-term experiments have been conducted in this location to evaluate crop rotations at three input levels. Input level I was unirrigated and received minimum fertilization; level II received limited irrigation and moderate fertilization; and level III received full irrigation and fertilization. Three growing seasons were selected (1986,1989, and 1990), which corresponded to dry years, thus maximizing the severity of crop water stress. Three crops were simulated: maize, sorghum, and soybean. Biomass at harvest, grain yield, and seasonal ET were available for all years, crops, and irrigation levels. ET was estimated from a weekly soil water balance based on neutron probe measurements. ET data for year 1990 were found unreliable and not used. For the simulations, weather and soil data, initial soil water content, and irrigation calendars were input as observed in the experiments. Crop parameters were input as observed or as recommended in the CropSyst manual (Stockle et al, 1993). A few parameters required calibration, which was based on evolution of biomass, LAI and ET for input level III of each crop, available for year 1986.

Results Figure 1 shows a reasonable agreement between observed and predicted values, with a few noticeable outliers. Coefficients of determination are high, and regression lines are close to the 1:1 line of perfect agreement. Experimental variability and some differences in the cultivars used for different years and input levels may explain some departures. Model failure to represent some underlying processes could not be evaluated with the available data. Statistical analysis (Table 1) confirmed a reasonable model performance (Wilmott index of 1.0 implies perfect agreement).

Conclusions CropSyst was able to reproduce crop growth and yield observed in response to a wide range of water stress conditions for three crops in Southwestern France, indicating the feasibility of the use of the model for water management applications in the region.

Session 2.2 499

Table 1. Statistical comparison of observed and simulated biomass, yield, and ET for three crops and combinations of three years and three irrigation levels at Auzeville, France.

Biomass

Yield

ET

Number of data points Obs. average (kg/ha) Pred.average (kg/ha) RMSE / Obs. average Wilmott index Number of data points Obs. average (kg/ha) Pred.average (kg/ha) RMSE / Obs. average Wilmott index Number of data points Obs. average (mm) Pred.average (mm) RMSE / Obs. average Wilmott index

Sorghum 8 16684 17280 0.067 0.985 8 7601 8060 0.123 0.963 5 372 407 0.139 0.802

Soybean

....

. . . . —

9 2828 2738 0.126 0.975 6 412 440 0.097 0.960

Maize 9 19038 18370 0.143 0.971 9 8026 7494 0.231 0.958 6 416 410 0.039 0.995

RMSE = Root Mean Square Error

^ 40

S 30

J 20

â 10

1-2 = 0.91 a = 2443 b = 0.86 n = 17

• •

•

Sorghum Maize

0 10 20 30 40

Observed biomass (ton/ha)

600

500

400

300

1-2 = 0.88 a = 25.6 b = 0.98 n = 17

//

/ A

• ^

• • A

• /

'A //

Sorghum Soybean Maize

200 300 400 500 600 Observed ET (mm)

15

12

'•3 3 v u

• Sorghum r2 = 0.89 a = 947 b = 0.94 • - • n = 8 ,y7

'jf *& ~/y

/ • "

*S

&' •

r2 = 0.84 a = - 780 b = 1.03 n = 9 Maize

0 3 6 9 12 15 Observed yield (ton/ha)

d 4

o TJ 3

••3 1 0.

r2 = 0.91 a = 284 b = 0.87 n = 9

y

f/'

Soybean

0 1 2 3 4 5 Observed yield (ton/ha)

Figure 1. Graphical comparison of observed and simulated data sets in Table 1.

References Stockle, CO. et al, 1994. Agricultural Systems 46: 335-359. Stockle, CO. et al., 1993. Biological Systems Engineering Dept., Washington State University, Pullman, WA, USA.


OPTIMISING LAND PRODUCTIVITY IN CROP-LIVESTOCK SYSTEMS BY INTEGRATING LEGUMES IN THE LOWLAND MOIST SAVANNAS OF WEST AFRICA

S.A.Tarawali1, J.W.Smith1, M.Peters12, L.Muhr2, R.Schultze-Kraft2 and G.Tarawali3

'International Livestock Research Institute (ILRI), UTA, Ibadan, c/o Messrs L.W.Lambourn & Co, Carolyn House, 26 Dingwall Road, Croydon, Surrey, CR9 3EE,UK 2University of Hohenheim (380), 70593 Stuttgart-Hohenheim, Germany Consultant, c/o ILRI, UTA, Ibadan, Nigeria

Introduction The lowland moist savanna of west Africa, covering 389 million ha of sub-Saharan Africa, is typified by annual rainfall of 600 to 1400 mm with 151 to 270 growing days (Jagtap, 1995). Cereal crops, grown by land-owning crop farmers predominate during the wet season; until recently, cattle keeping has been a separate enterprise with the animals relying on grazing rangelands, and crop residues after grain harvest. Nutrition, especially in the dry season is a severe constraint limiting ruminant productivity. Rising human population is forcing expansion of agriculture, meaning that even marginal soils are being cultivated for crops, and the luxury of long fallow periods to restore fertility (in the absence of inorganic inputs) to the inherently poor soils no longer exists. This inevitably forces a closer integration of crop and livestock enterprises, which, if appropriately managed has the potential to become synergistic. Research by the International Livestock Research Institute in Nigeria has focused on introducing forage legumes into these evolving systems to optimise land output in a sustainable manner. Experiments have been conducted to test the ability of such species to provide nutritious ruminant fodder, promote soil fertility, arrest soil physical degradation and reduce weed infestation in crop fields. This presentation summarises the major findings in these areas.

Methods Initial experiments focused on identification of the most appropriate forage legume species, for fodder use and included measurements of agronomic and quality parameters. The identified species were also assessed for their direct effect on cereal production. Management options to maximize the impact of forage legumes have been investigated and these include appropriate utilisation of different species depending on their phenology and selective weeding of crops in leguminous pastures to ensure maximum forage and grain yields. A collection of Aeschynomene histrix accessions has been investigated for their ability to reduce incidence of Striga hermonthica, a parasitic weed of cereal crops.

Results Forage legumes with better quality and much higher biomass than the natural vegetation can be grown in the Nigerian Savannas (Table 1). The natural, unimproved fallow consists mainly of grasses which for most of the year, cannot meet ruminant requirements. When maize is grown on land following forage legumes, substantial increases in grain yield are recorded (Table 2). Increases greater than 400 % reflect areas where the soil was so poor that grain yield from natural fallow plots was negligable. Smaller changes arose where soil was less degraded and fallow period was short or the legume areas were unweeded and grazed prior to the cropping. Crop management practices, such as selective weeding have been shown to ensure good forage quantity and quality following maize cropping (Tarawali et al., 1995). From a collection of 64 accessions of Aeschynomene histrix, 9 accessions were

Session 2.2 501

identified with potential to give good forage and act as a trap crop for Striga hermonthica (Merkel, unpublished).

Table 1. Maximum forage quantities and qualities of promising forage legumes, and natural fallow in the Nigerian moist savanna.

Species Accession number

Dry forage % crude % in sacco References tha-' protein digestibility

Aeschynomene histrix Centrosema brasilianum

ILCA 12463 ILCA 155

Centrosema macrocarpumClAT 5713 Centrosema pascuorum Centrosema pubescens

ILCA 9857 ILCA 152

Chamaecrista rotundifolia ILCA 10918 Stylosanthes guianensis Stylosanthes guianensis Stylosanthes hamata Stylosanthes hamata Natural fallow

ILCA 164 ILCA 15557 ILCA 75 ILCA 15876

12.5 4.5 3.9 4.8 4.0 7.0 13.6 3.3 6.2 4.8 6.5

13 15 18 13 20 11 11 11 11 12 4

52 48 51 51 50 47 52 59 49 48 30

Tarawali, 1994; Peters, unpub. Tarawali, 1991; Peters, unpub. Muhr, unpub.; Peters, unpub. Tarawali, 1991; Peters, unpub. Muhr, unpub.; Peters, unpub. Peters et al., 1994; unpub. Tarawali, 1994; Peters, unpub. Tarawali, 1994; Peters, unpub. Peters et al., 1994; unpub. Tarawali, 1995; Peters, unpub. Peters et al., 1994; Muhr.unpub.

Table 2. Increases in maize grain yield (with no added N fertilizer) following forage legumes as compared to natural fallow. (History refers to the age of the forage legume prior to cropping the maize (year); ungrazed = weeded experimental plots; grazed = unweeded, grazed pastures)

Species

Aeschynomene histrix

Accession number

ILCA 12463 Centrosema macrocarpum CIAT 5713 Centrosema pascuorum Centrosema pascuorum Centrosema pubescens

ILCA 9857 ILCA 9857 ILCA 152

Chamaecrista rotundifolia ILCA 10918 Stylosanthes guianensis Stylosanthes guianensis Stylosanthes hamata Stylosanthes hamata Stylosanthes hamata

ILCA 164 ILCA 15557 ILCA 75 ILCA 75 ILCA 15876

History year/type

3/ungrazed 1/ungrazed 3/grazed 3/ungrazed 1/ungrazed 3/grazed 3/ungrazed 3/ungrazed 3/grazed 3/ungrazed 3/ungrazed

% increase in maize grain yield over natural fallow

733 27 50 600 69 251 811 1166 94 466 750

References

Tarawali, 1994 Muhr, unpub. Tarawali et al., Tarawali, 1994 Muhr, unpub Tarawali et al., Tarawali, 1994 Tarawali, 1994 Tarawali et al., Tarawali, 1994 Tarawali, 1995

1996

1996

1996

Conclusions By integrating forage legumes into farming systems in the moist savannas of west Africa, both ruminant and crop yields can be maintained, without detriment to the environment.

References Jagtap, S.S., 1995. Moist Savannas of Africa. Potentials and Constraints for Crop

Production. Ed. B.T.Kang et al UTA, Ibadan, Nigeria, p. 9-30. Peters, M. et al., 1994. Tropical Grasslands 28: 65-73 Tarawali, S.A., 1991. Tropical Agriculture (Trinidad) 68: 88-94 Tarawali, S.A., 1994. Journal of Agricultural Sciencel23: 55-60 Tarawali, S.A., 1995. Australian Journal of Experimental Agriculture 35: 375-379 Tarawali, G. et al., 1995. Soil Management in Sustainable Agriculture. Ed. H.F. Cook et

al Wye College, UK. p. 435-443. Tarawali, S.A. et al, 1996. Journal of Agricultural Science, in press.


GROWTH AND NITROGEN ACCUMULATION OF WINTER RYE AS A CATCH CROP: MODEL AND EXPERIMENT

A.M. van Dam1, J. Vos2, J. Wolfen1, E.A. Lantinga1 and P.A. Leffelaar1

Wageningen Agricultural University,l Dept. of Theoretical Production Ecology. 2 Dept. of Agronomy. P.O.Box 430, 6700 AK Wageningen, The Netherlands.

Introduction Cultivation of catch crops after the harvest of the main crop, in the otherwise fallow autumn and winter period, can reduce N leaching. Field experiments show a large variation in catch crop N uptake for different sowing dates, crop species and locations. The aim of our study is to explain this variation and to assess how much N can be taken up by catch crops under various conditions. To this aim, an explanatory simulation model is developed to calculate catch crop growth and N accumulation. It is coupled to a soil water and nitrogen model to estimate the effect on N leaching. This paper presents the model for potential growth of winter rye (Secale cereale L.) as a catch crop. It is tested with results of a field experiment.

Methods The crop growth model is based on SUCROS (Spitters et al., 1989), as used for simulation of growth of winter wheat by Groot et al. (1991). The following adaptations were made. The rye crop is modelled in the vegetative phase; the shoots consist of leaves only. The N concentration in the shoot decreases exponentially with the temperature sum after crop emergence, approaching a level of 2.47 % above 1400 °C day (base temperature is 0 °C). The N concentration in the root is a fixed fraction (0.46) of the concentration in the shoot. N is assumed not to limit growth: N uptake is determined by the crop demand. Leaf area index is a linear function of the amount of organic N in the shoot. Temperature and radiation levels during leaf development determine the light saturated assimilation rate (Sheehy et al., 1980). Assimilation is independent of the N concentration in the shoot. A constant fraction (0.124) of assimilates is allocated to the roots. The rate of N uptake rises with temperature to a maximum value at optimal temperatures. Leaves live during a fixed lifespan: 443 °C days. Crop growth was parameterised with results from a field experiment. Crop growth and N uptake were simulated using weather data from Wageningen, the Netherlands. Simulation results are compared with an independent data set from a field experiment in Wageningen, in which winter rye (cv. Halo) was sown in a sandy soil on 21 August 1992. It was fertilised by 50 kg ha-1 N, supplied as calcium ammonium nitrate, at sowing, and by 25 kg ha-1 N at 14, 28, 42 and 63 days after sowing. Plant shoots and roots were sampled regularly to determine weights, N concentrations and leaf area.

Results The trends in root and shoot biomass (Figure la), crop N content (Figure lb) and leaf area index (Figure lc) are well simulated. The biomass, amount of N in the crop and leaf area increase until the end of October. After that, there is a net decrease in shoot biomass, N and leaf area index, because shoot growth rate is lower than shoot death rate under winter conditions. The lower growth rate is explained by a decrease in the light saturated assimilation rate in the second half of October (Figure Id), and lower radiation and temperature levels (data not shown). Levels of shoot and root biomass are somewhat overestimated, whereas the amount of crop N is underestimated. This implies that the N concentration that was imposed in the model, is too low for this crop, grown at a very high fertilisation rate. The light saturated assimilation rate fluctuates in time, reflecting fluctuations in temperature and radiation intensity during growth of the leaves.

Session 2.2 503

Conclusions The model simulates trends in growth of root and shoot biomass, and N accumulation well, but predictions of the exact amounts can still be improved. The model will be further validated. To explain the nitrogen accumulation by catch crops in agricultural practice, the model will be adapted to simulate the N limited growth of rye and other catch crops. Models for soil N dynamics under autumn and winter conditions and for water transport are developed to assess the effect of catch crop cultivation on N leaching.

4500 Figure 1. Time courses of simulated (lines) and measured (symbols) variables during the catch crop growing season. a. Biomass (dry weight) of shoots (thin line and closed symbol) and roots (thick line and open symbol) b. Amount of N in the crop c. Leaf area index d. Light saturated assimilation rate (AmaxX modelled according to Sheehy et al. (1980), calibrated with data from Van Dam (1994).

References Groot, J.J.R. et al., 1991.

Fertilizer Research 27: 261-272. Sheehy, J.E. et al., 1980. Annals

of Botany 46: 343-365. Spitters, C.J.T. et al., 1989. In:

Rabbinge, R. et al. Simulation and systems management in crop protection: 147-181. PUDOC, Wageningen.

Van Dam, A.M., 1994. Proceedings 3rd ESA Congress, Abano-Padova: 264-265.

date


CROPSYST-WITH-OBJECTS 3.0: GEARED FOR COMPARISON OF COMPONENT MODELS

F.K. van Evert1 and J.M. Baker2

'Department of Soil, Water and Climate, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108, USA 2USDA-ARS, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108, USA

Introduction One of the design goals of CropSyst was to determine how the performance of a cropping systems simulation model would be influenced by different models of a component of the system (Van Evert et al., 1994; Van Evert, 1992). A CropSyst simulation model therefore consists of component models which interact through a narrow and well-defined interface (McCown et al., 1996; Van Evert et al., 1994; Van Evert, 1992; Crosby et al., 1990). This is one of the tenets of object-orientation and, in principle, it opens the road for combining and comparing component models that were developed by different groups. In practice, the fact that not all groups use the same programming language has made this less than straightforward. In this paper, we examine the usefulness of dynamic link libraries to ease, in conjunction with object-orientation, the integration of component models written in different programming languages. Model performance is judged via a comparison with observations made in experiments. Some of the descriptive data of an experiment are required by the model as input. A simulation model then generates a large amount of output which relates to the same experimental units that observations were made on. The logical connection between observations, model input and model output makes it desirable to manage them together. In the second part of this paper, we consider the use of a database for this purpose.

Methods In CropSyst, all modeled real-world processes are represented in one of the component models. Component models are controlled through the procedures Initialize (), CalcRatesQ and Update State (). Component models communicate with each other via messages through the central message handling mechanism. Each component model implements a procedure RequestQ to request an item and a procedure RespondQ to supply an item in response to a request (Fig. 1). Thus, a component model needs to implement only five procedures to integrate with CropSyst. Component models written in different languages can communicate as long as there is a standard interface for these procedures. Dynamic link libraries (DLLs) provide such an interface because they contain executable code that (when compiled with the STDCALL directive) is largely independent of the source code language. CropSyst is written in Delphi 2.0 (Borland, 1996) for Windows 95. We used Powerstation 4.0 (Microsoft, 1995; other compilers provide similar capability) to compile several existing models written in Fortran and use them in CropSyst.

Figure 1. Components communicate via messages through the messaging mechanism. When the crop component requests information (1), the messaging mechanism queries each of the other component models in turn (2,3). In the Figure, the soil component is able to supply the requested information (4) which is range-checked by the messaging mechanism before it is passed to the crop (5).

Messaging mechanism

| Weather ] [ Crop | ( Soil |

Session 2.2 505

Each component model requires inputs at the beginning of the simulation run. Some of these inputs, such as the planting date of a crop and the amounts of irrigation water applied, form part of the descriptive data of the experiment being simulated. We designed and implemented a general, stand-alone experiment database from which component models can extract these kinds of information. The database consists of a set of Paradox tables (Borland, 1994) which are accessed efficiently from a Delphi application through the Borland Database Engine (Borland, 1995). Access routines could also be compiled into DLLs for use from programs written in other languages. The experiment database stores all observations relative to experimental units such as treatments, plots, and sampling locations. The database design permits an unlimited number of links between these units, so that a treatment may be allocated to any number of plots; plots may be nested within other plots to any depth; and a wide variety of designs (e.g. unbalanced; Latin-square) can be accomodated. Because simulation output relates to the same experimental units that the experimenter collected data on, it can be stored conveniently in the same database.

Results Calling DLLs compiled with PowerStation from a Delphi application gave no problems. Some modification of existing models is required before they answer to the CropSyst interface. For a well-structured model, this modification does not require much work. One restriction is that interaction between component models is limited to the one-day time step that CropSyst uses. The use of a database, even though its design is still relatively immature, has proven useful. For example, having both experimental data and simulation results available in the same format made it easy to develop a simple graphing application that automates the process of comparing the two.

Conclusions Monteith (1994) has exhorted modelers to remove from crop models 'components that contribute noise rather than numerical precision to the final output'. Applied to cropping systems models, this could be translated to using those component models that most improve the precision/noise ratio of the systems model in which they are used. While the previous version of CropSyst could already be used to compare component models, this capability has now been extended to include models written in different programming languages. Such a comparison is made even easier by CropSyst's integration with an experiment database to allow for rapid setup of input data and joining of measured and simulated performance.

References Borland International, Inc., 1994. Paradox 5.0. Scotts Valley, CA, USA. Borland International, Inc., 1995. Borland Database Engine. Scotts Valley, CA, USA. Borland International, Inc., 1996. Delphi 2.0. Scotts Valley, CA, USA. Crosby, C.J., et al., 1990. A simulation modeling tool for nitrogen dynamics using object-oriented programming. AI Applications in natural resource management 4:94-100. McCown et al., 1996. APSIM - A novel software system for model development, model testing and simulation in agricultural systems research. Agricultural Systems 50:255-271. Microsoft Corporation, 1995. Powerstation 4.0. Redmond, WA, USA. Monteith, J.L., 1994. The quest for balance in crop modelling. p25 in ASA Abstracts 1994. Van Evert, F.K., 1992. Pullman, WA, USA, PhD Thesis, University of Washington, 83 p. Van Evert, F.K. et al., 1994. CropSyst: a collection of object-oriented simulation models of agricultural systems. Agronomy Journal 86:325-331.


WATER USE EFFICIENCY OF NINE CROPPING SYSTEMS IN A WATER LIMITED ENVIRONMENT

D. Ventrella, M. Rinaldi, V. Rizzo and F. Fornaro

Istituto Sperimentale Agronomico, Via C. Ulpiani 5, 70125 Bari, Italy

Introduction In Mediterranean areas, where amount and distibution of water supply are major determinants of crop yield, the choice of a crop to insert in a rotation must be considered taking into account the ability in water suction, lenght of crop cycle, productivity, effects on following crop and, mainly, water use efficiency in saleable yield production.

Methods Nine cropping systems (Table) were compared in a long-term trial (1986/87 - 1993/94) carried out at Foggia, Southern Italy (lat. 41° 27" N, long. 3° 04" E). The soil is a vertisoil (Typic Chromoxerert) with a good fertility; typical values of volumetric water content at field capacity and permanent wilting point were 42% and 21%, respectively. Fertilizer amount was, except for soybean, 150 kg N ha"1, 200 kg P205 ha"1 and 50 kg K20 ha'1; irrigation water was delivered at Dw (winter sowing) only if severe water stress occours, while about 200-400 mm per year was applied, depending on soil moisture, to the other crops. At harvest, saleable yield (roots for sugar beet) and aboveground dry matter were measured for each crop and then yearly added up for each rotation.

Soil water content at 0-60 cm depth was Table 1 - Rotations in experiment. measured at 7-day intervals with gravimetric methods. Seasonal water use (WU) was calculated for each crop and then for each rotation using a hydrological balance in which runoff and deep percolation were neglected. Water use efficiency for aboveground dry matter (WUEb) and for grain yield (WUEy) were calculated as the ratio of dry matter and grain yield to seasonal WU. Further information on experimental design and crop management are reported by Rizzo et al. (1993).

Results The rainfall in the period investigated was lower than the long term average (430 vs 585 mm year"1) especially in 1991 and 1993. At the same time water resources were reduced because of lowering of the water table, since the amount of irrigation water supplied decreased through years. The WU decreased during the 8 years of trial, particularly between the 1990 and the 1992 showing a large variability in the 1-year and 2-year rotations with summer catch crops that grow during a period characterized by very high evapotranspirative demand and water requirement (Fig. 1). Besides the "W" rotation with 332 mm year"1, also the "W-G" and the "W-F" rotations with seasonal WU of about 415 mm, represent reduced cropping systems with a low water consumption. In the figure 2 we can note the variability of "W" for WUEy parameter because of the influence of drought during reproductive phase on harvest index of durum wheat (Passioura, 1977). The rotations with sugar beet had a high mean WUEy (thanks to a high harvest index) the same was

Crops Durum wheat Dw + sorghum Dw + soybean Dw - sugar beet Dw - sunflower Dw - sorghum Dw + soybean -Dw + soybean -Dw + soybean -

sugar beet sunflower sorghum

Abv. W W+G W+Y W-B W-F W-G W+Y-B W+Y-F W+Y-G

Figl a d d b b b c c c

Session 2.2 507

true for grain sorghum which is also a result of a positive effect of sorghum on following durum wheat (Di Bari et al 1993; Rinaldi et al 1994). Experimental data of WUEb varied less among years than WUEy. The rotations with grain sorghum, either as main or catch crop, were the most efficient in water use (C4 crop) with a mean value of 31.2 kg ha'1 mm'1. The addition of soybean in 1 -year and 2-year rotations generally reduced the WUEb values because of the low productivity of biomass in a soybean catch crop.

1000

800

§ 600

400

200

} • • • • • *

/ \ \ / \ ••

Y \ \

\ V \ \ I A \ \

.- / / / /

/ Y"--f-"""

/

- •••' d " 1

h^-j h* y

\ / *

87 88 89 90 91 92 93 94 Year

Figure 1 - Seasonal water use of different crop rotations (see tab. 1)

2

1.5

0.5 I

- - - _ • - -

I

—I—

Ï

Ï

ï

—-_- -

WUEy

ï

WUEb

_ _ . _ _ J . _ _ _ _

_

ï

ï

ï

ï

ï

ï

ï

I 2

§ 1.5

M 1

0.5

W W + G W + Y W - B W - F W - G W + Y - B W + Y - F W + Y - G Rotation

Figure 2 - Water use efficiency index: for WUEy 9.2 Kg ha"1 mm"1 = 100; for WUEb 26.2 Kg ha"1 mm"1 = 100.

Conclusions In the trial environment, with hot-drought summer, the incomplete availability of water supply, the use of catch crops, especially soybean, reduced the WUEb of whole cropping systems. The rotations with grain sorghum, showed a high water use efficiency or had positive effects on next durum wheat crop.

References DiBari, V. et al., 1993. Agricoltura Ricerca, 151/152, 15-22. Passiuora, J. B., 1977. J. Australian Institute Agriculture Science, 43, 117-120. Rinaldi, M., et al., 1994. Proceedings 3rd ESA Congress, 740-741. Rizzo, V. et al., 1993. Agricoltura Ricerca, 151/152, 57-68.

http://__.__J.____


IMPORTANCE OF UNDERPLANT CROP AND FARMYARD AS MANURES IN MONOCULTURE OF WINTER TRITICALE

A. Wozniak

Department Soil and Plant Cultivation, Agricultural University, 20-950 Lublin, 13 Akademicka Str., Poland

Introduction Monocuhural growing of winter triticale leads to a decrease in grain yield and elements of yield structure (Pawlowski and Wozniak, 1994; Wozniak, 1993). In these conditions increasing weediness and susceptibility to culm base diseases are also observed (Kus, 1993; Wozniak, 1995). It has been suggested in the literature (Laskowski, 1972; Roszak et aL, 1982) that growing of green-manure crops and plants preventing occurrence of diseases and pests is an effective method of limiting the grain yield decline of cereal crops grown in monoculture. In this work the influence of plowing under of green-manure intercrops and farmyard manure on grain yield and some elements of yield structure of winter triticale was evaluated. The effectiveness of fungicides used was also estimated.

Methods Field experiment was established in 1988 at Uhrusk Experimental Station of Lublin Agricultural University. Presented results were collected in 1991-1994. The experiment was established in a randomized block design with 37.5 m2 plots in 4 replications. The soil used was rendzina of light loam texture. The subjects of the experiment were: I. Regeneration of soil by the use of: (A) farmyard manure (FYM) - 301 ha"1 plowed under every 4 years ; (B) FYM -151 ha"1 plowed under every year; (C) undersown green-manure Serradella (Ornithopus sativus L.) plowed under yearly; (D) undersown green-manure Italian ryegrass {Lolium multiflorum v. westervoldicum Wittm.) plowed under every year. H Plant protection: (a) without fungicides (control) ; (b) with the application of fungicides. Green-manure crops Le. Serradella and Italian ryegrass were undersown to triticale in the amount of 40 kg ha"1 between 15th and 30th April depending on the year of study. FYM was used every year or every four years on the stubble and plowed under by skimming and then by presowing plough. Winter triticale cv. Bolero was sown in the amount of 400 germinating seeds between 20th and 25th September. This abstract includes only mean values of grain yield and elements of yield structure, obtained in the years 1991-1994.

Results Plowing under of 15 or 301 ha"1 of FYM proved to be the most effective method of soil regeneration with monoculture of winter triticale. The grain yield of triticale obtained on these plots was 20% higher than that obtained on plots where green-manure Italian ryegrass as aftercrop was plowed under (Table 1). Fungicides used for plant protection showed to rise the grain yield by 7-8%, but only on plots where FYM (301 ha"1) and Serradella as aftercrop were plowed under. Yield structure elements (number of ears per 1 m2, weight 1000 grains, number of grains per ear) were highest on the farmyard plowed under plots. However, application of fungicides showed no substantial effect on the values of these yield elements.

Conclusions The decline of grain yield of winter triticale monoculture can be partly counteracted by applying farmyard manure. Plowing under of green-manure Serradella as aftercrop produced worse results and that of Italian ryegrass showed to be the least effective method. This was due to small yield of green mass (6 -101 ha"1) produced by these aftercrops and increased susceptibility to culm base diseases.

Session 2.2 509

Fungicides used in these conditions showed no essential effect on the grain yield and crop yield elements studied.

Table 1. Grain yield of winter triticale and some crop yield elements (mean of 4 years)

Soil regeneration method A-FYM

301 ha1

B-FYM

15tha_1

C - under-sown serradella D - under -sown Italian ryegrass LSD (p=0,05)

Plant protection

no fungicides fungicides mean no fungicides fungicides mean no fungicides fungicides mean no fungicides fungicides mean

Grain yield tha"1

3.8 4.1 4.0 4.1 4.1 4.1 3.4 3.7 3.5 3.3 3.2 3.3

0.2

Ear number per m2

461 453 457 462 451 457 423 418 420 416 412 414

15

1000 grains weight (g)

38.9 39.1 39.0 38.0 38.8 38.4 37.5 37.8 37.6 37.8 38.4 38.0

1.2

Grain number per ear

41.8 41.8 41.8 40.4 41.3 40.8 40.5 41.5 41.0 38.9 38.1 38.5

1.9

References Kus, I , 1993. Wyd. IUNG, Pulawy. Laskowski, St.,1972. Zeszyty Problemowe Postepów Nauk Rolniczych, 137 : 121-128. Pawlowski, F., Wozniak, A.,1994. Fragmenta Agronomica, 3 : 40-45. Roszak, W., et al., 1982. Roczniki Nauk Rolniczych, ser.A, 105, 2 : 97-105. Wozniak, A., 1993. Fragmenta Agronomica., 4 : 45-46. Wozniak, A,1995. Annales Univ. Mariae Curie-Sklodowska, sec.E, vol.L,3: 13-20.


DEVELOPMENT OF A SUSTAINABLE BED-PLANTING-TECHNOLOGY TO ALLOW REDUCED-TILLAGE AND CROP RESIDUE MANAGEMENT IN FURROW-ntRIGATED WHEAT PRODUCTION SYSTEMS

K. D. Sayre

CIMMYT, Apdo. Postal 6-641, 06600, Mexico D.F., Mexico

Introduction Irrigated wheat (flood or furrow irrigated) accounts for nearly 35 % of wheat area and about 45% of total production in developing countries. In south Asia alone (India, Nepal, Pakistan, Bangladesh and Nepal), nearly 25 million ha of irrigated wheat are grown and an additional 13 million ha are sown in China. Sizable areas are also grown in other developing countries including Turkey, Afganistan, Iran, Egypt, Sudan, Nigeria, Mexico and Chile. A substantial part of this irrigated wheat is grown in rotation with other upland crops such as cotton, soybean, maize and sorghum using surface irrigation. Such production systems have been largely by-passed by technologies that allow reductions in conventional tillage practices and/or opportunities to manage crop residues without resorting to costly incorporation, removal or, most commonly, burning. Wheat agronomists at CIMMYT have initiated research to develop a furrow-irrigated reduced-till bed-planting system (FIRBS) to overcome these limitations based on the conventional-tilled wheat planting system on beds currently used by farmers in northwest Mexico.

Methods Several trials have been initiated over the past four years comparing furrow-irrigated wheat-maize systems planted on 75 cm beds with either conventional tillage with beds reformed for each crop or with superficial reshaping of the beds at the time of crop establishment without tillage. Variable crop residue management practices are being tested including incorporation, burning, partial removal and complete retention. Nitrogen management is also being evaluated for each tillage and crop residue management strategy and N-uptake patterns are being assessed. Disease and weed interactions with these treatment effects are also being monitored. Adaptations to available seeding and bed-shaping equipment have made it possible to plant two or three rows of wheat on each bed with reduced tillage in the presence of sizable quantities of crop residues (6-8 t/ha).

Results The trials have shown that wheat can be successfully planted on beds occupied by the previous summer crop (either maize or soybean) with the only tillage before wheat planting being a minor reshaping of the summer crop's beds with full retention of crop residues. Proper management of the crop residues can reduce their interference with irrigation in the furrows between the beds. Maize and soybean planted similarly after wheat have been satisfactorily established with an apparent advantage to both crops yields when the previous wheat crop's residues are left in place, perhaps due to better moisture retention during the hot summer. The bed system also offers advantages for N placement and timing that enhance nutrient use efficiency especially in the presence of crop residues.

Conclusions The strategy of using a bed-planting system as a basis to reduce tillage and manage crop residues for surface-irrigated production systems that include wheat offers many new and useful approaches to develop potentially more sustainable crop management practices. The opportunity to use this technology is relevant to farmers in both developed as well as developing countries.

Session 2.3

Resource use at crop level.


THE EFFICIENT USE OF WATER AND NITROGEN IN ARABLE FARMING IN EUROPE: IS THERE SCOPE FOR IMPROVEMENT ?

A.J. Haverkort and M.I. Minguez

DLO-Research Institute for Agrobiology and Soil Fertility (AB-DLO) P.O. Box 14 6700 AA Wageningen, The Netherlands

2 Depto Produccion Vegetal: Fitotecnia. E.T.S. Ingenieros Agronomos. Universidad Politecnica de Madrid, Ciudad Universitaria 28040 Madrid, Spain

Introduction Consumers, producers and scientists are aware that agricultural products should be produced such as to optimize the use of natural resources and minimize emissions to the environment. To obtain potential yields in an environment, resources, notably nitrogen and nutrients should be applied at rates which are both economically and environmentally unacceptably high. Current attainable yield by farmers, although economically feasible, may be unsustainable at the long term as for the food and export requirements for Europe on the whole, ground water is threatened because of contamination with nitrogen and because of depletion of this resource at the expense of natural ecosystems. A growing proportion of food, following consumer demands is produced without chemical fertilizers and biocides but the attainable organic yields are lower than current yields and their resource-use efficiency is amenable to debate. This paper evaluates the various yield levels in arable farming in terms of their resource use and resource-use efficiency with emphasis on the use of water and nitrogen and in relation to solar radiation that varies from northern summer and southern summer and winter growing seasons.

Resource-use efficiency Potential (P), attainable (A) and organic (O) yields can be expressed in terms of resource availability (water (W), solar radiation (R) and nitrogen (N) and resource-use efficiency E (Ep, EA and Eo), i.e. grams of dry matter produced per unit resource used by the crop, e.g. per litre water (WUEP, WUEA and WUEo), per megajoule intercepted solar radiation (RUEp, RUEA and RUEo) or per g of nitrogen taken up by the crop (NUEp, NUEA and NUEo).. Fresh crop yield (Y) is then expressed as

Y=W(RorN)x WUE (RUE or NUE) x HI/DMC where HI is the harvest index and DMC is the dry matter content of the harvested produce. The greater the availability of a resource, the lower its efficiency. De Wit (1992) referring to the optimum law of Liebscher (1895) argued that, as a production factor which is in minimum supply contributes more to production the closer other production factors are close to their optimum, strategic research should be into the minimum of each production factor needed to allow maximum utilization of all other resources.

Growth influencing factors Temperature, solar radiation and crop species or cultivar are the main growth defining factors determining the lengths of the available growing season and actual growth cycle and hence the potential yields. In Europe, solar radiation is further from but water supply is nearer to its optimum in the North than in the South, hence the RUEP

is greater in northern Europe than in Mediterranean solar conditions and, following

Session 2.3 513

Liebscher's Law also the WUEP and NUEP. Actual yields are mainly limited by the availability of water and nutrients, especially nitrogen. Although actual yields may be higher in the South than in the North because of higher radiation levels, the lower RUEA, combined with lower availability of water reduce the efficient use of water and nitrogen unless their supply is strategically timed. In organic farming, yields are often lower than in current systems because of a reduced availability of mineral nitrogen and because of yield reducing factors such as pests, diseases and weeds further reducing yields, hence WUEo and NUEo are lower.

Increased efficiency through physiology and management To meet the currrent European domestic and export demand for agricultural production options are formulated such as realizing it by optimizing all resources within limited space (de Wit, 1992, WRR, 1992). Spreading production over Europe to make best use of available precipitation and ground water and to reduce local emission of nitrogen or by producing in organic farming systems without input of chemicals is discussed. Using the concept of optimizing W,N,and R and WUE, NUE and RUE we now can calculate how changes of crop physiology, management and environment (climate change) influence the use of the resources, depletion and emission.

Advances have been made in maximizing the use of available resources and increasing the resource use efficiencies in selection of crop species (C4/C3-plants) and breeding for adaptation to adverse conditions such as drought, high temperatures and climate change.Crop management practices, however, matching crop cycles with periods of low evaporative demand (Loomis, 1983), response farming (Steward, 1988), concentration of limiting resources such as strategic irrigation and application of fallow (Loomis and Connor, 1992) and organic farming techniques may have far greater immediate impact. The most efficient use of water and nitrogen is supplying them such that yields are close to potential, solar radiation defined yields, provided that the financial rate of return of each unit of water and nitrogen added is still positive. Environmental (water conservation and contamination) constraints and market demands (for products from organic farming), however, often require supplies below the economic rate. The quantitative approach implying resource availability and use efficiency offers scope for optimizing yields given the ecological and economic constraints. This approach also provides the quantitative information needed to prescribe irrigation as well as fertilization.

References De Wit, C. T, 1992. Agricultural Systems: 40:125-151. Liebscher, G., 1895. Journal fur Landwirtschaft 43:49. Loomis, 1983. In:H.M. Taylor, W.J. Jordan and T.S. Sinclair (Eds) Limitations to

efficient water use in crop production. Am. Soc. of Agr. Madison WL346-373 Loomis, R.S. and D.J. Connor, 1992. Crop Ecology: productivity and management in

agricultural systems. Cambridge university press, Cambridge, 538 pp. Steward, J.I., 1988. In: F.R. Bidinger & C. Johansen (Eds) Drought research priorities

for the dryland tropics. ICRISAT, Patancheru, India: pp 131-150. WRR, 1992. Ground for choices. Reports to Gouvernment. SDU the Hague, 147 pp.


EFFECT OF SOIL NITRATE AND N FERTILIZATION ON BREAD AND DURUM WHEAT YffiLD AND QUALITY AND ON RESIDUAL N-N03 CONCENTRATIONS UNDER IRRIGATION IN EBRO VALLEY (SPAIN).

A. Abad, J. Lloveras, A. Michelena

Universität de Lleida-IRTA. Alcalde Rovira Roure 177,25198 Lleida. Spain

Introduction Nitrogen is normally a key factor in achieving optimum cereal grain yields and wheat baking and pasta quality (Hadjichristtodoulou, 1979; Beaux and Martin, 1984). However applying too much is not only uneconomic, but also significantly increases the amount of mineral N which could be subsequently lost to the environment (Chaney, 1990; Alcoz et al. 1993).

Methods Nitrogen fertilization trials were conducted in Lleida (Torregrossa, 1993-95 and Bell.lloc 1994-95) Spain, on Typic Xerofluvent soils with different initial soil N-N03 contents, to study the effect of N fertilization on bread and durum wheat yield and quality, and on soil residual N-N03 after harvest. The experimental design was split-split-plot with 8 treatments of N fertilization; in 5 of them différents rates of N (0, 50, 100, 150 and 200 kg ha~l) were applied in two complementary stages: at sowing (50 kg ha~l, except in the rate 0) and at shooting. In the other 3 treatments the total rate (150 and 200 kg ha~l) was splitted in 3 applications: at sowing (50 kg ha'1), at shooting (50 and 100 kg ha"l), and at flag leaf stage as a foliar spray (urea, 50 Kg ha~l) or to the soil surface (50 kg ha"l). Two varieties of bread wheat and two of durum wheat were used in 4 replicates. N treatments were main factors and varieties split factors. Plots were of 8.4 m^ with eight rows spaced 12 cm apart. The harvested grain was measured for yield, protein content, test weight and sedimentation test (SDS). Baking quality (W, P and L, evaluated with the Chopin alveograph) was measured in bread wheat, and yellow pigments and grain vitreousneuss in durum wheat. Soil cores were collected at seeding, at shooting and after grain harvest from each plot at 2 depths (0 to 30 and 30 to 60 cm) to evaluate soil N-N03 content.

Results The agronomic and qualitative results (means of the two cultivars of each wheat type, bread and durum) are summarized in Figures 1 and 2. Grain yield differences among localities were most obvious at the highest soil N level. In Bell.lloc (high initial soil nitrate content), grain yield did not increase by N fertilization, but in Torregrossa (with low soil nitrate content) grain yield clearly raised with N fetilization. Late application of N did not increase grain yield. Grain protein content significantly increased with N fertilization in all years and localities. In general, in any locations late foliar application of N in the 200 kg ha~l treatment did not increase grain protein content compared with the same rates of N applied at soil at shooting; however, late application of N at the 150 kg ha'1 treatment increased grain protein compared with the same rate of N applied at soil at shooting. Test weight decreased with N application in all years and localities. Quality parameters, W and L alveograph, increased by N fertilization in all locations and years, but mainly in the fields with low initial nitrate content (Torregrossa, 1995). P alveograph was not affected either by year, location or N rates. Durum wheat quality, measured as yellow pigments and vitreousneuss, increased with N fertilization, except vitreousneuss in Bell.lloc that had high vitreousneuss at all the rates of N; possibly due to the high soil nitrate content and low grain yields. No effect in durum wheat quality was found by late application of N. In both types of wheat SDS increased with N fertilization in all years and localities but SDS was not affected by late N applications. Soil nitrate content after harvest increased in all locations and years by aplication of nitrogen fertilization.

Session 2.3 515

Protein content (%) L(mm) Vltreousmeus« (%)

-•—•-

:if^ y 100 150 200

kg N/ha

100 150 150

«50 «50 «50 50 100 150 200

kg W h «

100 150 150

«50 «50 «50

Torreqrossa-94 Torregrossa-95 Bell.lloc-95 Figure 1. Effect of nitrogen application on grain yield, protein content (means of bread wheat and durum wheat), alveograph W and L (in bread wheat), yellow pigments and vitreousneuss (in durum wheat) in two locations of Ebro Valley: Torregrossa (1994-1995) and Bell.lloc (1995). Five nitrogen rates were applied (0, 50, 100, 150 and 200 Kg ha -1; splitted in 50 at seeding and the rest at shooting, except for the rate 0) plus three other N treatments (of either 150 or 200 kg ha"') in which 50 kg N ha"' was applied at flag leaf stage as a foliar spray (100+50u and 15O+50u) or to the soil surface (150+50s).

Figure 2. A) Soil N-N03 content at shooting (mean of all treatments) in Torregrossa (1994 and 1995) and in Bell.lloc (1995) in 0 to 60 cm of depth. B) Effect of nitrogen application on soil N-N03 content after harvest in Torregrossa (1993-195) and in Bell.lloc (1995). Five nitrogen rates were applied (0, 50, 100, 150 and 200 Kg ha"1, splitted in 50 at seeding and the rest at shooting, except for the rate 0) plus three other N treatments (of

either 150 or 200 kg ha*1) in which 50 kg N ha"1 was applied at flag leaf stage as a foliar spray (100+SOu and 150+50u) or to the soil surface (150+50s).

Conclusions N fertilization increased yield and quality of durum and bread wheat but also increased soil N-N03 content after harvest. Yield reached a plateau before wheat quality parameters. In the climatic conditions of the Ebro Valley with a low summer and winter rainfall, soil with high N-N03 content can supply most of the nitrogen needed by the crop and consequently lower response to N fertilization can be expected

References Alcoz, M.M. et al, 1993. Agronomy Journal 85: 1198-1203. Beaux, Y. and Martin, G., 1984. I.T.C.F. Journées techniques. Chaney, K., 1990. Journal of Agricultural Science 114: 171-176. Hadjichristtodoulou, A., 1979. Eyphytica 28: 711-716.


CHANGES IN PHOTOSYNTHETIC CAPACITY ASSOCIATED WITH SOIL WATER DEPLETION IN MAIZE GROWN UNDER CONVENTIONAL AND MINIMUM TILLAGE

L. G. Angelini, M. Mazzoncini, L. Ceccarini

Department of Agronomy, University of Pisa, Via S. Michèle degli Scalzi 2, 56100 Italy.

Introduction In recent years the feasibility of replacing conventional tillage systems with minimum tillage and no-till techniques in different agricultural areas of Italy have been considered (Caliandro et al., 1992; Bonari et al., 1992; Bonari et al., 1994; Bonari et al., 1995; Angelini et al., 1995). The main goal of research on this subject included an evaluation of the effects of alternative tillage techniques on factors such as soil fertility, soil erosion and crop yield. Little efforts have been made on the implications of continuous superficial tillage on the photosynthetic responses and water-use efficiency of plants grown in rainfed systems of Mediterranean areas, where water is the main limiting factor to crop yield. Therefore we monitored leaf gas exchanges of maize under a period of increasing water stress in crops grown with conventional (CT) and minimum-tillage (MT).

Methods Leaf gas exchanges of maize were studied over two seasons in a long-term tillage trial on loam soil, on which tillage treatments comparing minimum tillage (10-15 cm deep disk harrowing -MT) with a conventional tillage (ploughing to a depth of 50 cm - CT) had been established more than 10 years before. Rainfed maize crops (cv. Aida, FAO 500) were studied in field experiments carried out in Central Italy (43 °40'N; 10°23' E; 3 m above sea level). The crops were sown on 30 May 1991 and 28 April 1992. Plant density was 80,000 plants ha"1. Before planting, phosphate and potassium fertilizers were applied at a rate of 150 kg P2O5 ha-1

(superphosphate) and 150 kg ha-1 (potassium sulphate). The plots received 200 kg ha-1 of nitrogen (29-0-0 as liquid N) split in two doses of 100 kg ha-1 each, applied ten days and one month after emergence. The main management practices were in accordance with the ordinary agronomic practices used in Central Italy for maize crops. Leaf gas exchange measurements were taken over a period of increasing soil water deficit naturally experienced during the dry season of 1991 and 1992 when plants were in the vegetative (from 2 to 4 stages of growth, corresponding to collar of 8th and 16th leaf visible respectively, according to Hanway, 1963) and in the reproductive (from 4 to 6, the last corresponding to 12 days after 75% silked) growth phase respectively. Gas exchanges characteristics were measured for youngest fully expanded leaves using a portable open differential system (ADC LCA, Hoddesdon, UK). All measurements were conducted in the mid-part of the day when irradiance was saturating (>1800 pi mol mV1) and air temperature ranged from 30-37°C. Changes in gravimetric soil water content (from 0 to 50 cm in 10 cm increments) were examined.

Results Changes in the soil water content throughout the entire profile were not significant different between the two tillage systems (Figures 1 and 2). In each year no significant differences were found between the two tillage techniques in CO2 assimilation, transpiration rate and stomatal conductance (gs) as soil was getting dried (Table 1). During the vegetative growth (1991) phase an increase in leaf temperature, a decrease in transpiration rate and a strong depression of net photosynthesis were observed as the soil was getting dried. Stomatal conductance was reduced by >20% by soil dried and water use efficiency by 50%. During reproductive growth (1992), photosynthesis values remained more stable as water stress increased due to higher leaf

Session 2.3 517

conductance values. Transpiration rates increased and the water vapour gradient between the leaf and air was substantially lower than before.

Conclusions The photosynthetic response and the water-use efficiency of maize leaves were not affected by tillage tecniques. For the two years changes in the gas exchange parameters associated with soil water depletion were observed. According to Henson et al. (1983) stomata of maize appear to respond to changes in soil water content in a different way during plant development Water is conserved by midday stomatal closure during the vegetative phases of development, but after flowering, assimilation is maximized at the expense of increased water consumption, due to stomata remaining at least partly open.

0 '

10'

? » • ^ 3 0 -

ü 4 0

•= 50-

60-

Wilting point

-B-107/91 -*- 17*7/91

••••307/91

f i *\ k '

' s \

'r*

•

1991-CT

— 50-O

Wilting point Fig. 1 - 1991 Soil water content in the 0-60 cm layer in CT and MT and during a period of increasing water deficit

Soil water content (m 100 m "') 10 M 30 « Soil water content (m 100 m' )

10'

? » -S 30-

c l 4 0 ' "° 50-

O 60-

•-,

Wfflmg point;

-a-2775/92 i

- • - 107 /92 < •••• 28/7/92 •

1992-CT

\ \ ' )

•• \ \

'• V

*

10 .

20 .

30 .

40 .

50.

6 0 .

70 -

Wjlting point

—•-27/5/92

—*- 10/7/92

•-«--287/92

, , , ,

i* t

; k V

ß

i

m

1992- MT

J

{ \ \ \ \1

Fig. 2 - 1992 Soil water content in the 0-60 cm layer in CT and MT and during a period of increasing water deficit.

Soil water content (m 100m" 3 ) 10 20 30 J « Soil water content (m 100 m )

Table 1 - Mean values of net photosynthesis, transpiration, water use efficiency, stomatal conductance'(gs) and leaf to air temperature ratio (Tleaf/Tair) affected by conventional (CT) and minimum tillage (MT).

1991 stage3

2 3 4 1992 stage0

4 5 6 " Han way.

Net photosynthesis (^mol n vV 1 )

CT MT 35.10 32.76 17.54 17.09 15.53 15.79

35.80 33^92 34.83 33.07 29.19 31.49

1963

Transpiration (mmol n r V 1 )

CT 9.71 7.62 8.68

7.79 9.26 11.17

MT 9.21 7.72 8.72

7.53 9.02 10.92

Water use efficiency (mmol/mol n v V )

cr 3.58 2.28 1.79

4.59 3.76 2.61

MT 3.51 2.22 1.81

4.07 3.66 2.87

VPD (KPa)

cr 2.48 2.08 2.93

2.47 2.25 1.95

MT 2.54 2.33 3.07

2.63 2.64 1.76

( m o l n r V )

CT MT 0.415 0.396 0.381 0.371 0.353 0.310

0.339 0.307 0.460 0.373 0.653 0.630

Tleaf/Tair

CT MT 0.97 0.97 0.98 1.00 0.99 0.99

1.00 1.01 0.98 0.99 0.95 0.94

References Angelini, L.G., et al., 1995. Proceedings Xth International Photosynthesis Congress,

Montpellier, France, pp 46-50. Bonari, E., et al., 1992. Informatore Agrario 1: 11-25. Bonari, E., et al., 1994. Proceedings 3rd ESA Congress, Abano-Padova, Italy, pp. 636-644. Bonari, E., et al., 1995. Soil Tillage Research 33: 91-108. Caliandro, A., et al., 1992. Rivista di Agronomia, 26, 3: 215-222. Hanway, J.J., 1963. Agronomy Journal, 55:487-491. Henson, I.E., et al., 1983. Annals of Botany, 54:641-648. Toderi, G., et al., 1986. Rivista di Agronomia 2-3:6-13.


RESPONSE OF COTTON TO NITROGEN AND WATER IN A SUBTROPICAL ENVIRONMENT

M. Aydin

Department of Soil Science, Faculty of Agriculture, Mustafa Kemal University, 31040-Antakya, Turkey

Introduction Cotton is one of the most responsive crops to irrigation as well as to nitrogen applications. Therefore, the most appropriate combination of nitrogen rates and irrigation schedules should be experimentally determined and practiced (Ali et al., 1974; Vories et al., 1991). For this purpose, a multifactorial experiment was carried out in three different locations of a subtropical region.

Methods The field experiments were established at Adana, Haciali and Tarsus which are located in the Çukurova Region - Southern Turkey. The experiments were conducted during 1983-1986. The soils at the experimental sites are Vertic Luvisols and / or Chromic Vertisols (Aydin et al., 1993; Dinç et al.,1991). The sites have a Mediterranean climate with mild rainy winters and hot dry summers. Cotton (Gossypium hirsutum L. cv. "Carolina Queen 201/971-1518") was planted at the end of April and harvested between mid-September and mid-October. Soils were fertilized with 80 kg P205 ha"1 (Yesüsoy et al., 1989). The plant population density was about 70,000 plants per hectare with a distance of 80 cm between rows. Combinations of five different levels of nitrogen applications (N0, Ni, N2, N3, N4, which correspond to 0, 120, 160, 200, 240 kg N ha'1) and three different levels of soil water content (Ii, I2,13, which represent the irrigations, when the available water in 0-120 cm of the soil profile was depleted to 20%, 40%, 60% of the maximum available) were used as the treatments, which were applied to the fields as randomized complete block designs with three replications (Güzel et al., 1983). Cotton plots were equipped with tensiometers, gypsum blocks, access tubes for neutron probe, soil water samplers and piezometers. The whole of the nitrogen fertilizer was applied at one time after emergence. The irrigation water was applied by furrows (Aydin et al., 1989). The water consumption of cotton was determined by observing changes in soil water content. In the presence of a water table, the contribution ofthat to the water consumption was calculated with the aid of known hydraulic functions (Aydin, 1994). The total yields of seedcotton were based on the sum of all harvests for each year. The qualitative analyses of cotton fibres were accomplished.

Results Results are summarized in the Table. The effects of nitrogen rates and nitrogen-water combinations on the yield of seedcotton were significant. The yield response curves or production functions of cotton to nitrogen were obtained for each of four years. Then the four years of data were pooled and a composite function was fitted to the pooled data, because there was not a significant between-year variation by treatments. The regression equations of the seedcotton yields (Y=kg ha"1) on nitrogen rates (X=kg N ha"1) are presented below: Y = 2460.6+17.31 X-0.055 X2

R2= O.995" (^significant at P< 0.01) for Adana 3133.5+14.01 X-0.050 X2

R2= 0.979" for Haciali •2 Y = 2706.7 + 8.02 X - 0.029 X

R2= 0.887" for Tarsus

3820 4093 at N2I2 at N1I1

Non-significant 90 150 5-6 3-4 730 678

-

-70 kPa -65 kPa at 30 cm at 60 cm

3250 atNjI,

110 2-3 955 600

-65kPa at 60 cm

Session 2.3 519

Table. Effects of nitrogen and water treatments on cotton production at three locations

Results and/or suggestions Locations (Four - year means) Adana Haciali Tarsus

(Bajada) (Bottom lands)

-Nitrogen rates with highest yields (kg N ha"1) N2=160 Nj=120 Ni=120 -The available water level, in the soil profile, at which irrigation was favourable I2=40% Ii=20% Ii=20% -Seedcotton yield (kg ha"1) at the most appropriate combination of treatments (three-replication means)

-Effects of nitrogen rates and irrigation regimes on the quality of fibres -The amount of water applied per irrigation (mm) -Number of irrigations per season -Seasonal water consumption (mm) at the suitable treatment -The contribution of water table (mm) to the water consumption - Recommendable soil water potential (kPa) for determining time of irrigation, and installation depths of tensiometers (cm)

(-50 kPa for first irrigation) -The lowest and highest concentrations of nitrate-N in the soil water (mg N L"1) extracted from 120 cm depth of soils 8-19 28-35 24-37

Conclusions The cotton crop responded well to application of 120 kg N ha'1 at all locations and continued to show increases in yield at application of 160 kg N ha"1 on Adana soils. When the available water in 0-120 cm of the soil profile was depleted to 40%, irrigation appeared to be the suitable treatment at the most appropriate nitrogen rate (160 kg N ha'1) for the Adana soils. In Haciali and Tarsus, irrigation was favourable when the available soil water was reduced to 20%, and application of 120 kg N ha"1 was optimum. When soil water potential at 30 cm soil depth decreases to -70 kPa during the irrigation season, 90 mm irrigation water should be applied on Adana soils. If soil water potential at 60 cm depth decreases to -65 kPa, 150 and 110 mm water should be applied on Haciali and Tarsus soils, respectively. The seedcotton yields were lower at Tarsus than at the other two experimental sites, partly due to the presence of a water table, close to the rooting zone. In general, nitrate concentrations in soil water extracted from different depths of soil profiles did not differ significantly between treatments. However, concentrations of nitrate-N at 120 cm depth of soils may indicate possible environmental and economical problems to be encountered in the future.

References Ali, A. et al., 1974. Indian Journal of Agricultural Research 8: 83-88. Aydin, M., 1994. Irrigation Science 15:17-23. Aydin, M. et al., 1989. Proceedings of 10th Congress of Soil Science Society of Turkey 5:28/1-10 Aydin, M. et al., 1993. Zeitschrift fur Pflanzenernaehrung und Bodenkunde 156:441-446. Dinc, U. et al., 1991. Catena 18: 185-196. Güzel, N. et al., 1983. Turkish Journal of Agriculture and Forestry 7: 185-191. Vories, ED. et al., 1991. Irrigation Science 12: 199-203. Yesjlsoy, M.S. et al., 1989. Proceedings of 10th Congress of Soil Science Society of Turkey

5:35/1-10.


EFFECT OF TILLAGE SYSTEMS ON WEED PRESENCE AND DIVERSITY IN A CONTINUOUS MAIZE CROPPING SYSTEM

P. Barberi1, M. Ginanni2, S. Menini2, N. Silvestri2, M. Mazzoncini2

'Centra Interdipartimentale di Ricerche Agro-Ambientali "E. Avanzi", University of Pisa, Italy 2Dipartimento di Agronomia e Gestione dell'Agro-Ecosistema, University of Pisa, Via S. Michèle degli Scalzi 2, 56124 Pisa, Italy

Introduction Intensive production systems for field crops have raised public concern because of increasing costs and environmental hazards (Sharpley et al., 1994; Clements et al., 1995). Less intensive cultural practices, such as the adoption of tillage systems alternative to deep ploughing, should therefore be fostered. A shallower tillage depth is likely to modify the weed flora spectrum of crops. Limited soil disturbance may result in increasing weed number and in higher percentage of perennial weeds within weed communities (Froud-Williams, 1988). Moreover, the effect of tillage systems on the density and composition of the weed flora depends upon crop sequence and length of rotation (Ziliotto et al., 1992). A field trial was carried out in Central Italy to investigate on the effects of different tillage systems on weed density and structure of a continuous maize cropping system.

Methods Seven tillage systems for a continuous maize cropping system were compared since 1990 on an alluvial loamy soil (Typic Xerofluvent). Tillage systems were: 50 cm deep ploughing (P50), 25 cm ploughing (P25), 25 cm ploughing + subsoiling (P25 +S), 50 cm chisel ploughing (C50), minimum tillage (MT), 50 cm ploughing following minimum tillage (P50/MT), and minimum tillage following 50 cm ploughing (MT/P50). The effect of tillage systems on maize weed flora was evaluated after a four-year period during which all plots received the same herbicide treatment (post-emergence spraying of dicamba 1 1 ha'1). Weeds were counted by species at maize fourth leaf stage (23 May 1994) just before herbicide application. The structure of weed communities was outlined by means of the Shannon-Wiener H' diversity index (Mahn et al., 1979), computed as:

s with hi=pi • In (1/pj), where ft is the Relative Abundance Index of each of the S H' = £ h; weed species present. The Relative Abundance Index was computed as: relative

i=l density + relative frequency/2 (Derksen et al., 1993). For each tillage system, the cumulative h; values were plotted versus the number of species sorted in decreasing order of importance. Before analysis of variance, total weed densities and Relative Abundance Indices were transformed as (x+1) and arcsiny(x) respectively, to increase homogeneity of variance.

Results The lack of soil inversion (MT) resulted in higher total weed density (Table 1) and in higher presence of Cynodon dactylon (L.) Pers. (Table 2). In MT and C50 this species was highly dominant, thus reducing the diversity index of the weed flora, as shown in the Figure. Deep ploughing was characterized by a high density oîXanthium strumarium L. (Table 2).

Conclusions Although the decrease in tillage depth caused higher weed presence, its effect on the weed structure seemed limited. The establishment of few and aggressive weed species observed in all tillage systems after four years of trial is likely to be a result of continuous cropping. The low diversity of weed communities might lead to severe weed control problems in the oncoming years.

Session 2.3 521

Table 1. Total weed density recorded at maize fourth leaf stage in 1994 for each tillage system.

Tillage system Weed density (plants m"2)

P50 P25 P25 + S C50 MT P50/MT MT/P50

9.2 c 25.0 b 7.7 c

21.0b 45.3 a 16.5 be 41.5 a

Values labelled with the same letter are not significantly different at Ps 0.05 (DMR Test)

Table 2. Relative Abundance Indices of the weed species found in the tillage systems.

Tillage system Relative Abundance Index (%)

Convolvulus Cynodon Equisetum Xanthium Others* arvensis dactylon arvense strumarium

P50 P25 P25 + S C50 MT P50/MT MT/P50

37.6 ab 47.2 a 37.3 ab 4.5 c

14.1 be 31.1 ab 30.6 ab

18.5 c 40.5 b 20.9 c 72.2 a 72.9 a 59.7 ab 63.5 ab

0.0 b 10.3 b 32.6 a 8.3 b 2.5 b 0.0 b 4.7 b

43.9 a 1.9 b 9.2 b 8.6 b 7.2 b 7.4 b 1.2b

0.0 n.s. 0.0 n.s. 0.0 n.s. 1.6 n.s. 0.8 n.s. 0.4 n.s. 0.0 n.s.

*Chenopodium album, Phalaris canariensis, Rumex crispus, and Solanum nigrum. Within each column, values labelled with the same letter are not significantly different at P< 0.05 (DMR Test), n.s. = not significant.

x •a 0 c

Ï5 0 >

-a a> 0

Diversity indices of maize weed flora. P50 = 50 cm ploughing, P25 = 25 cm ploughing, P25+S = 25 cm ploughing+ subsoiling, C50 = 50 cm chisel ploughing, MT = minimum tillage, P50/MT:

50 cm ploughing following minimum tillage, MT/P50 = minimum tillage following 50 cm ploughing.

2 3 4 5 6 7 Number of species

-»P50 • MT

-B-P25 -©• P50/MT -

P25+S ^ C 5 0 - MT/P50

References Clements, D.R. et al., 1995. Agriculture, Ecosystems and Environment 52: 119-128. Derksen, D.A. et al., 1993. Weed Science 41: 409-417. Froud-Williams, R.J., 1988. In: Weed management in agroecosystems: ecological approaches.

CRC Press, Boca Raton, 213-236. Mahn, E.G. et al., 1979. Agro-Ecosystems 5: 159-179. Sharpley, A.N. et al., 1994. Soil and Tillage Research 30: 33-48. Ziliotto, U. et al., 1992. Rivista di Agronomia 26: 241-252.


EXPLAINING THE YIELD RESPONSE OF WINTER WHEAT DUE TO FUNGICIDES BY THE EFFECTS ON GREEN LEAF AREA DURATION AND RADIATION INTERCEPTION.

R. J. Bryson1, W. S. Clark2 and N. D. Paveley3.

!. ADAS Anstey Hall, Maris Lane, Trumpington. Cambridge. CB2 2LF. 2. ADAS Cambridge, Brooklands Ave., Cambridge. CB2 2BL. 3. ADAS High Mowthorpe, Duggleby, Malton, North Yorks. Y017 8BP.

Introduction. Crop yield is predominantly determined by the ability of the crop to intercept light energy and utilise it for growth (Hay & Walker, 1979). Potential yield can be related to both the crops green area index (GAI) and incident solar radiation through an equation derived from Beers Law (Monteith & Unsworth, 1990). The Beers Law analogy implies that there is an optimal canopy size for growth at which the cost of protecting a further increment in canopy size will prove uneconomic (Sylvester-Bradley et al., 1995). The aim of this poster is to show that the protection of yield by foliar fungicides can be better explained by monitoring the loss of light intercepting green leaf area than by assessments of percentage disease alone.

Materials and Method. Experimental plots (1.8m x 24m) of the yellow rust susceptible cultivar, Slejpner, were arranged in a fully randomised factorial design in two blocks at ADAS Terrington, Norfolk. Sixty one spray treatments were applied as a 1, 2 or 3 spray programme applied at any of four timings at four dose rates. Disease assessments were carried out weekly on 10 randomly selected main shoots. Disease was assessed as a percentage of the total leaf area expressing symptoms (Anon, 1976). Leaves were assessed in a similar way for the percentage of green leaf area present. Actual green leaf areas were determined in the field using measurements of leaf length and width in conjunction with a form factor (0.83) as described by Gaunt & Bryson (1995). Shoot number per m2 were determined by shoot counts on five randomly selected 1.0m rows per plot at GS75. Total incident radiation (MJm2) was measured using a dome solarimeter supplied by Delta-T (Cambs.).

Results. Crop yield (t ha"1) was found to relate poorly to both the percentage of yellow rust symptoms on leaf 2 at GS75 (Fig. 1) and the area under disease progress curve (AUDPC) (Teng, 1983) on leaf 2 (Fig. 2). Healthy area duration (HAD) (Waggoner & Berger, 1987) of leaves 1-3 from GS39 was found to relate to crop yield by a curvi-linear relationship (R2 = 0.83) (Fig. 3). This relationship, by analogy to Beers Law, takes account of the amount of green area available for light interception but not the amount of intercepted radiation. The healthy area absorption (HAA) (Waggoner & Berger, 1987) of leaves 1-3 from GS39 in the treated and control canopies related linearly to crop yield (R2 = 0.83) when the canopy extinction coefficient, k, was assumed to be 0.5 (Monteith, 1976).

Conclusion. In this trial the measurement of the duration of green leaf area from GS39, and hence an estimation of accumulated radiation intercepted by green tissue, related well with final yield (R2

= 0.83). The potential yield of a crop is directly related to solar radiation and agronomic

Session 2.3 523

conditions, such as fertiliser applications. Whilst percentage disease assessments may be useful in fungicide efficacy trials they take no account of the physiology of the growing crop. They are therefore are of limited use in fungicide experiments where an understanding of yield loss is required. This preliminary study demonstrates that a more detailed understanding of the growing crop is essential for the analysis and interpretation of the effects of fungicide treatments for the protection of crop yield. It is believed that further analysis of data from similar multi-site experiments carried out in 1994 and 1995 will support the findings presented in this poster.

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« 1 0 £ S" 6 f * 4 -i-x 2

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0 200 400 600 800 1000

AUDPC

0 10 20 30 40 50

% yellow rust

Fig. 1. Mean % yellow rust v's yield (t/ha) Fig. 2. Mean AUDPC v's yield (t/ha)

100 150 200

HAD (GS39)

Fig. 3 Mean HAD v's yield (t/ha)

250 — H

550

Fig. 4.Mean HAA v's yield (t/ha).

References. Anonymous, 1976. Manual of Plant Growth Stage and Disease Assessment Keys. MAFF. UK Gaunt, R. E. et al. 1995. Aspects of Applied Biology 42:1-7 Hay, R. K. M. et al. 1989. An Introduction to the Physiology of Crop Yield. Wiley & Sons. NY pp292. Monteith, J. L 1976. Vegetation and the Atmosphere. Vol. 2. Academic Press, London Monteith, J. L etal. 1990. Principles of Environmental Physics. Edward Arnold. London. Sylvester-Bradley. R. etal. 1995. A Vital Role for Fungicides in Cereal Production. SCI p43-56 Teng. P. S. 1983 Phytopathology 73:1587-1590 Waggoner. P. E. etal. 1987 Phytopathology 77(3):393-398.


VARIATION OF THE SOIL HUMIDITY IN AN ECOLOGICAL CULTURE OF ASPARAGUS (ASPARAGUS OFFICINALIS L.) IN GALICIA (N.W. SPAIN)

A. M. Castelao1, M. J. Sâinz1, M. Bujân2

iDepartamento de Ingenierîa Agroforestal y Production Vegetal, Facultad de Veterinaria, Universidad de Santiago de Compostela, E-27002 Lugo, Spain 2Departamento de Biologia Vegetal, Universidad de Santiago de Compostela

Introduction In Spain, 25397 ha of land were cultivated with asparagus in 1992 (M.A.P.A., 1994), mainly under irrigated conditions. In Galicia (NW Spain), this crop is almost unknown, only 2 ha being devoted to the culture under irrigation that year. However, asparagus could be an interesting plant to diversify the agricultural productions in the process that the galician rural economy must follow to fit the requirements of the Agricultural Politics of the European Community. In this work, we studied the variation of soil volumetric humidity (Hv) in a field ecologically cultivated with asparagus without irrigation.

Methods The study was carried out in Galicia (NW Spain) in 500 m2 of an ecological cultivation of asparagus (Asparagus officinalis L.) cv. Cito in the third year of production. The region has a humid climate and the culture had never received irrigation. The cultivated soil was a humic cambisol with the following characteristics: sandy loam texture, pH(H20) 5.26, organic matter 4.68%, soil field capacity 17.8% and soil wilting point 7.5%. Cattle manure applied in autumn 1994 was the only fertilization treatment received by the plants. No herbicide was applied and the culture was strongly invaded by weeds (Bujân et al., 1995). In February 1995, the ridges were formed and the asparagus harvest carried out from late March to late May. After harvesting, sixteen equal plots of 21m2 were established in the cultivated surface. Humidity measurements were made weekly, from June to November in 1995, with a Trase System using the Time Domain Reflectometry (TDR) technique (Topp et al., 1982). Waveguides of 15, 30,45 and 60 cm length were buried in each plot to evaluate the water content and to determine irrigation needs of the asparagus culture.

Results Means + s.e.m. of the % volumetric humidity are presented in the figure (f.c.= soil field capacity, w.p.= soil wilting point). Data showed two cycles of water deficit, one lasting from July to August with a strong drought (the volumetric humidity reaching values under the wilting point of the soil) and a second one, not that strong, in October, which was particularly observed up to 15 cm depth (the volumetric humidity showing values near the wilting point of the soil). The second cycle followed a period of soil rewetting due to the rainfall beginning on the 6th of September. A nearby metereological station (situated 3 km far from the asparagus field) registered 149 mm of precipitation in September. The sandy loam texture of the cultivated soil favoured a quick drainage after the rainfall.

Session 2.3 525

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From November on, together with the lowering of temperature, rainfall again started, the soil finally reaching water saturation conditions. In November, 230 mm of total precipitation were measured.

Conclusions Although the asparagus cultivation was carried out in a humid region of Spain, our results let advise the establishment of an irrigation system to increase asparagus yields and help the plant to withstand the strong drought during July and August. The agronomic situation is in a way similar to that found in the more productive areas of asparagus in Spain, where irrigation is a common practice during summers characterized by high temperatures and a strong drought. In future work, we intend to study the effects of irrigation on asparagus yields under ecological cultivation.

References Bujân, M. et al., 1995. Actas del Congreso 1995 de la Sociedad Espanola de Malherbologia,

Huesca (Spain), 83-86. M.A.P.A., 1994. Anuario de Estadistica Agraria 1992. Ministerio de Agricultura, Pesca y

Alimentación (M.A.P.A.), Madrid, 679 p. Topp, G.C. et al., 1982. Soil Science Society of America Journal 46: 678-684.


CORRECTION OF ZINC AND COPPER DEFICIENCIES ON MAIZE CROPS

P. Castillon, A. Bouthier

ITCF - 31450 Baziège - France

Introduction Maize is well known for its sensitivity mainly to zinc deficiency but also to copper and manganese deficiencies (Loué, 1993). So some growers systematicaly supply their maize crops with zinc or several blended micronutrients. However micronutrients deficiencies are not very frequent and often transitory. In many trials carried out in the south-west of France, zinc supply did not increase the maize yields despite obvious zinc deficiency symptoms on the young crops. Therefore supplying systematically the maize crops with micronutrients is not always profitable. On the contrary when the supply is not justified one might fear the competition between zinc and copper absorptions. This antagonism has been demonstrated in laboratory conditions with excised barley roots (Schmid et al., 1965), on cotton leaves (Bowen et al., 1969) and with isolated cuticles (Charnel et al., 1982). But in field conditions it has been observed that zinc applied on a grassland increased copper bio availability in the soil and improved Cu and Zn nutrition of the Ray-Grass (Dejou et al., 1985). Reciprocally applying copper increased Zinc bio availabililty and Cu and Zn nutrition. Therefore we wondered whether this interaction could occur on maize in field conditions. In order to investigate this problem, field trials on maize crops were carried out in the south-west of France from 1985 to 1995.

Methods Five trials were carried out in silty clayey or silty sandy soils whose main characteristics are shown in Table 1.

Table 1. Main characteristics of the soils Trial

1 2 3 4 5

Year

1985 1986 1986 1987 1995

Clay % 24 25 28 22 10

Silt % 53 45 46 52 37

Sand % 23 30 26 26 53

O.M. % 2.0 2.1 2.5 2.0 4.8

pH water

7.3 6.6 8.0 7.3 5.7

Cu EDTA mg.kg"1

0.1 0.1 1.1 2.9 2.3

Zn EDTA mg.kg"1

0.7 0.9 0.6 2.5 2.0

Except soil number 3 which is weakly calcareous, all the others are originally acid but in soil 1, 2 and 4 liming has araised soil pH above 6.2. This is considered a worsening factor for the Zn bio availability especialy for the soils with low extractable Zn (Dartigues et al., 1967). Furthermore it has been found that copper deficiency can occur on wheat when Cu EDTA/OM < 0.5 (Laurent et al., 1989), which is the case for soils 1, 2, 3 and 5. Four treatments were compared in randomized blocks (3 or 4) designs : control, Zn, Cu and Zn + Cu. In soils 1, 2, 3 and 4, 5-7.5 kg ha"1 rate of Zn and Cu from sulphates were supplied at sowing. In trial 5, 0.70 kg Zn ha" and 0.75 kg Cu ha" from sulphates were sprayed at the 9 leaves stage. In the Zn + Cu treatment of all the trials, Zn and Cu were applied separately but the same day.

Session 2.3 527

Results Grain yields for trials 1, 2, 3 and 4 and dry matter yield for trial 5 are presented in Table 2.

Table 2. Effect of Cu and Zn supplies on the yield of maize (t ha" dry weight) Soils Control Differences between treatments and the control

Cu Zn Cu + Zn 1 2 3 4 5

10.36 9.96

10.15 9.35

12.31

0.55 (S) 0.83 (S)

-0.12 (NS) -0.10 (NS)

1.09 (S)

0.91 (S) -0.85 (S) 0.01 (NS) 0.34 (NS) 1.46 (S)

-0.31 (NS) -0.65 (S) -0.23 (NS) 0.26 (NS) 0.65 (NS)

(S) : significant at P < 0.10, (NS) : non significant

Except for the trials 3 and 5 for Zn treatment the results were in good agreement with the soils' characteristics since Cu and Zn supplies increased the maize yield only on the soils where Cu and Zn bio availability were considered low. Where there were no responses to Cu and Zn, Cu + Zn had no effect on the yields. Where Cu and/or Zn increased the yield, Cu + Zn had no effect or significantly decreased the yield. Besides in trial 2 where only copper was deficient Zn and Cu + Zn decreased the maize yield.

Conclusions These trials confirm the existence of copper and zinc antagonism that can occur in field conditions when these elements are supplied to the soil or sprayed on the leaves. Therefore the diagnosis from soil analysis is imperative before supplying a maize crop with Cu or Zn because a wrong choice of the element can worsen the actual deficiency as shown in trial 2. Furthermore Copper and Zinc should never be associated in the same application. In the case of double deficiency Cu and Zn, the supply of this two elements should be dissociated. For example, Zn could be supplied to the soil before sowing (5 kg ha" Zn) and copper sprayed at the 8 to 10 leaves stage (0.5 kg ha' Cu).

References Bowen, J.E. et al. 1969. Plant physiology 44 : 255-261. Charnel, A. et al. 1982. Journal of Plant Nutrition 5 : 153-171. Dartigues, A. et al 1967. Annales Agronomiques 18 (3) : 285-299. Dejou, J. et al. 1985. Agronomie 5 (9) : 841-850. Laurent, F. et al. 1989. Les oligoéléments et le sol. Ed. Frontières, Fr. : 97-107. Loue, A. 1993. Oligoéléments en agriculture. Ed. Nathan, Paris : 283-308. Schmid, W.E. et al. 1965. Physiologia Planturum, 18 : 860-869.


BLACK-GRASS (Alopecurus myosuroides Huds.) DEVELOPMENT AND SEED PRODUCTION IN WHEAT

B. Chauvel ', C. Angonin 2, N. Colbach '

1 Station d'Agronomie, INRA, 17 rue Sully, BV 1540, 21034 Dijon Cedex, France 2 Laboratoire de Malherbologie, INRA, 17 rue Sully, BV 1540, 21034 Dijon Cedex, France

Introduction Alopecurus myosuroides is a frequent and harmful annual weed of winter crop rotations in France. To understand and to prevent the spread of this weed, its biology must be better known. The aim of this work was to study its growth and development as influenced by interspecific competition and nitrogen nutrition.

Material and methods All techniques besides the experimental factors (Table 1) were identical. The "competition" factor compared A. myosuroides potential growth and development to that in competition with wheat (cv. Soissons sown at 280 grains m~2). The "nitrogen" factor compared the impact of early-starting (NO) and late-starting nitrogen deficiencies (Nl) with a non-deficient situation (N3). Plots were sown on 29 September 1993. Vegetative (plant m"2, tillering, shoot dry matter) and reproductive variables (ears plant"1, ear length, grain viability, ear dry matter) were measured on the A. myosuroides plants of a 1.5 x 0.36 m"2 area for each plot. The number of spikelets was counted on 60 randomly chosen ears per plot and a relationship with ear length was estimated to predict spikelet number on all plants.

Factor Competition X Nitrogen fertiliser (kg ha') * T a b l e 1 • Factors combined stage 24* stage 25 stage 31 in a 4-block-design in

Levels A A. myosuroides NO 0 0 0 Dijon ( ' 36 kg ha 'of AW A. myosuroides Nl 60 0 0 mineral soil nitrogen. *

+ winter wheat * N3 60 40 60 according to Zadoks et al. (1974). * at 280 grains m2

Results The number of spikelets per unit of ear length was constant between treatments; there was a mean of 20 spikelets per cm of ear length which is consistent with Naylor ( 1972). Emergence of A. myosuroides was not influenced by experimental treatments (Table 2). Tillering was affected by early nitrogen deficiency (less tillering for NO than for Nl and N3) in combination with competition with wheat. This nitrogen effect was stronger if there was competition. Plant height was only reduced by early nitrogen deficiency. Even after the tiller number per plant was fixed, dry matter accumulation was still influenced by competition and slightly by nitrogen deficiency (as shoot dry matter is positively correlated to the tiller number), both by early and late deficiencies. Similarly, even for a given tiller number, the total number of ears per plant was affected more strongly by competition than by nitrogen deficiency (Table 3). If there was no competition, the number of ears was reduced only by late nitrogen deficiency (less ears for NO and Nl than for N3); in case of competition, early deficiency also reduced the ear number. Less ears ripened in case of competition. Despite its strong correlation with the number of ears, the number of spikelets per plant was still affected by competition and both early and late nitrogen deficiency. However, total ear dry matter depended almost entirely on the number of ears. Grain viability depended both on competition and nitrogen; it was increased by competition and reduced both by early and late deficiencies.

Session 2.3 529

Conclusions Competition always had a stronger effect than nitrogen deficiency; the impact of the latter was often increased if there was interspecific competition. Competition had an impact whatever the period during which the A. myosuroides components were determined. Early nitrogen deficiency mostly reduced early growth and development components such as tillering; late deficiencies affected late characteristics such the total number of ears for a given number of tillers. Nitrogen deficiencies had no impact on ripening of ears.

References Naylor, R.E.L., 1972, Journal of Applied Ecology 9: 127-139. Zadoks, J.C. et al., 1974. Weed Research 14: 415-421.

Table 2. A. myosuroides vegetative growth and development. A. Means per treatment.

FACTORS Competition Nitrogen Plants m'

A. myosuroides CHARACTERISTICS Tillers plant"1 Plant height (cm) Shoot dry matter per plant (g plant"')

A. myosuroides

A. myosuroides + winter wheat

NO Nl N3 NO Nl N3

28 35 36 38 27 30

53 52 64 8

52 64

97 101 108 88 103 114

24 26 24 2 3 5

B. Level of significance of factors and covariables. Factors and covariables

Plants m" Tillers plant" Plant height (cm)

Shoot dry matter per plant (g plant')

V Competition Nitrogen Plants m"~ Tillers plant"1

0 ns ns

0.92 **** ** **(n (negative correlation)

0.58 ns ** ns ns

0.93 *** * ns **(t (positive correlation)

ns = effect not significant at a= 5% * ** *** **** = significant atcc=5%, 1%, 0.1%, 0.01%. * for significant factors and covariables.

Table 3. A. myosuroides reproductive growth and development. A. Means per treatment.

FACTORS Competition Nitrogen

A. myosuroides CHARACTERISTICS Number of Number of ripe Spikelets ear ' Grain Ear dry matter per

ears per plant ears per plant viability (%) plant (g plant"1) A. myosuroides

A. myosuroides + winter wheat

NO Nl N3 NO Nl N3

44 44 49 8 11 13

32 27 25 5 6 6

5811 4391 4092 604 878 994

0.31 0.31 0.41 0.35 0.48 0.57

4.17 3.58 2.89 0.30 0.19 0.36

B. Level of significance of factors and covariables. Factors and covariables

Total number of ears per plant

Number of ripe ears per plant

Grains ear" Grain viability

Ear dry matter per plant (g plant" )

r2* Competition Nitrogen Tillers plant Total ears plant"' Ripe ears plant"1

0.93 0.91 0.93 *** **** **** * ns * *** (positive corr.)

** (positive corr.) *** (positive corr.

ns = effect not significant at a= 5%. *, **, ***, **** = significant at a= 5%, 1%,

0.40 * *

• )

0.1%, 0.01%.

0.88 ns ns

**** (positive corr.)

* for significant factors and covariables.


SOIL ANALYSES AND FERTILIZER RECOMMENDATIONS.

SOFTWARE FOR SOIL TEST LABORATORIES AND EXTENSION SERVICES.

B. Colomb1, G. Fayet2, C. Villette3, M. Gigout2, P. Dubrulle4, D. Baudet1

1INRA, Laboratoire d'Agronomie, BP 27, 31326 Castanet Tolosan Cedex, France 2 EMRA, Laboratoire de Génie logiciel Nancy, France 3 SAA, Laboratoire d'analyse des sols Laon, France 4 INRA, Laboratoire d'Agronomie Laon, France Introduction DEMETER is a software package designed to improve and facilitate, from regular fertility control based on soil analysis, fertilizer decision-making at the field level, for farm managers using a conventional cropping system in temperate or Mediterranean areas. All nutrients of agronomic relevance other than N and S are considered : P, K, Mg, Ca, B, Zn, Cu, Mn. We concentrate this presentation on the three major macro or secondary elements.

Methods Agronomic principles: The following main parameters are considered: 1/ Crop responsiveness: crops are classified as demanding crops (e. g. sugar beet, potato, forage maize...) or non-demanding crops (wheat, grain maize...), according to their responsiveness (significant yield changes) to nutrient inputs as mineral fertilizer. 2/ Soil nutrient levels: extractable nutrient levels are rated in three classes (low, medium, high). The lower threshold value refers to non-demanding crops, the upper one to demanding crops. Calibration follows a method described by Morel et al. (1992). There is no constraint concerning the analytical procedures which are under the control of the laboratory and chosen from among State or EU recommended lists (AFNOR, ISO ...). 3/ Soil ability to transform added nutrients into non- or poorly plant-available chemical compounds or to affect physico-chemical status is rated in three main classes (moderate, medium to high, very high to extremely high), whatever the analytical method (e.g. kinetic isotope exchange for P, Van der Marel for K...). If analytical data are not available, soil survey results may be used. Threshold values for nutrient levels and fixation capacity for elements are specified and associated with any homogenous agronomic area defined by the user of the system. Then, depending on the values of these criteria, field by field and year by year, recommended amounts of nutrients to be applied would be 0, fc, fe, or max(fc, fe) where fc is the amount of nutrient to be added to ensure production of the intended crop, and fe is the amount to compensate for annual nutrient losses. Amounts (fe) of nutrients lost every year are calculated by adding up leaching and crop removals and multiplying results by coefficients related to fixing capacities of the soil towards the elements. The function which enables fc to be calculated for P and K is : fc = a + u Prb (1 - Cs) / Cu where Pr represents the maximum nutrient uptake during the growing period and required for the expected yield; Cs describes the fraction of crop nutrient demand which is supplied by the soil (when fertilizer is added); Cu refers to fertilizer efficiency. The other parameters a, u and b are required to calibrate the function against reference data from field studies of crop responses to fertilizer input conducted in representative agronomic situations. A sensitivity analysis has shown that Cs and Cu parameters are the most important factors influencing fc. So, any information or new knowledge concerning both criteria should be adequately incorporated in the system thanks to empirical rules, taking into account soil and crop characteristics.

Session 2.3 531

Software description: DEMETER consists of five independent parts: 1/ A database designed to handle soils, crop characteristics, composition of animal manures or urban wastes, identification of analytical procedures, threshold values for extractable elements and various criteria used for diagnosis or evaluation of nutrient requirements. 2/ A core program to perform all calculations required for nutrient ratings and prescriptive information processing. 3/ A Graphical User Interface to update the database and to tune agronomic parameters. 4/ A rule interpreter allowing the evaluation of input data (other than the analytical data) from the environmental conditions, field characteristics and cropping system features. For example it enables statements such as ' 'if soil texture is loamy-sand and if one crop out of two is irrigated, then P-Olsen threshold values are 12 and 20 mg P kg-' soil". 5/ A collector of the flow of output information allowing production of any kind of reports and connection with a linear equation system solver to optimize fertilizer use at farm level. The software was developed using the Object Oriented Analysis - Recursive Design method (Shlaer and Mellor, 1988), a C++ compiler and some C++ libraries. Particular attention was paid to quality criteria, portability and extensibility to new algorithms. The different parts of the application may evolve - as regards their technical aspects - independently from one another.

Results The information allows the farmer to answer the primary question that emerges when a crop has been chosen for a field, taking into account its responsiveness and the field fertility features : is it necessary to add nutrients ? If the answer is yes, further questions follow: why ?(to meet crop demand and/or to restore the fertility level to its basic value), how much ? (amounts expressed in entirely soluble chemical form), in what ways ? (preferred or highly recommended chemical forms of nutrients, timing and incorporation requirements). When there is sufficient certainty that there will be no loss of yield and no fall of nutrient availability below a minimum level, the system clearly indicates for how long nutrients may be withheld, which ranges from 1 to 3 years depending on nutrient availability level, fixing capacity of soil, and crop responsiveness. Furthermore, from intended applications of farmyard manure, industrial or urban wastes to be used by the farmer during the next four years of the crop succession, DEMETER computes actual amounts of P, K and Mg (used in making assessment of the potential for nutrient loss in agricultural runoff), maximum amounts of nutrient available for any crop 1, 2 or 3 years after soil incorporation (to be deduced from nutrient requirement to forecast mineral fertilizer amounts) and annual average nutrient input (contribution to long term nutrient balances).

Conclusions DEMETER delivers relevant information in the form of a set of rules and indicators to be used for fertilizer decisions by farmers for four successive years whatever the crops. It is usable for extensive or intensive crop management, depending on the ways it will be adapted and tuned by the users. The system was primarily designed for soil testing laboratories and extension services which intend to process numerous soil analyses originating from large and variable cropping areas. From the user's point of view, DEMETER shows a high level of flexibility, allowing accurate customizing for any agronomic area. On the long term this new system is expected, if adequately fed with accurate references and widely used, to enhance the economic return and reduce detrimental effects on the environment of nutrient inputs.

References Morel C. et al., 1992. Agronomie 12: 565-579. Shlaer S. and Mellor S., 1988. Object-Oriented Systems Analysis. Prentice Hall. 251 p.


THE REACTION OF CULTIVARS SPRING BARLEY TO FERTILISERS AND SOWING RATES OF THE SEED UNDER CONDITION OF WESTERN REGION OF UKRAINE

Z.M. Copchyk and AY. Maruhnyak

Institute of Agriculture and Animal Husbandry of West Region of Ukraine. Obroshyn L'viv region 292084 Ukraine.

Introduction The spring barley at the Ukraine takes the the second place after winter wheat and on average (1991-1994 ) the sown area amounts 3.4 million hectares and grain yields 2.83 t ha"1 . The most powerful growing area of grain spring barey is the western part, where sowing area made up 0.5-0.6 million hectares. Here soils-climatic conditions allow to obtain the best grain brewing quality. Important meaning in the technology growing of the spring barley is the application of mineral fertilisers (Copchyk et al. 1979, 1985, 1989). Besides, apply new more productive cultivars and sowing rates spare the large attention (Copchyk et al., 1978).

Methods The investigations of the institute (vil. Stavchany, near L'viv) by field trials were conducted in 1994-1995 on dark grey sandy-loam soil. Predecessor were row crops (potatoes and fodder beets). Two cultivars - Roland and Nadiya (Nadiya created by institute and is presently under state strain testing in Ukraine), four rates (0, N30 P30 K30, N60 P60 K60, N90 P90 K90) and three sowing rates (4, 5, 6, million viable seeds per hectare) were studied in four replications. The mineral fertilisers (as nitroammofosca) respectively scheme of field trial were applied. The density of seedling was calculated and the plants for definition of the sctructure yield were chosen. The grain yield (14%) was estimated, 100-seed mass, protein and starch content were measured.

Results The mineral fertilisers influence positively on grain yield. They gave increase grain yield for cv. Roland 0.51-1.18 and cv. Nadiya 0.56-1.411 ha"1. The cultivars responded different to mineral nutrition. Highest grain yield both cultivars was obtained under mineral nutrition N90 P90 K90 on all sowing rates. The cultivars responded different to mineral nutrition. If for formation grain yield in range 3.2-3.5 t ha"1 cv. Nadiya fertiliser rate sufficient was N30 P30 K30 for cv, Roland it is N90 P90 K90. Better fertiliser rate forv cv. Nadiya was N30-60 P60 K60, for cv. Roland N60-90 P90 K90. Those fertiliser rates were most economical advisable because they provided highest increase of grain on 1 kg NPK.

The yield andquality of grain the cultivars depending on fertilisers and sowing rates, 1994-1995. Control N30-P30-K30 N60-P60-K60 N90-P90-K90

Sowing rate (mln ha"1) 4 6 4 6 4 6 4 6 Cultivar Roland

Grain yield (t ha"1) 2.16 2.29 2.67 Protein contant (%) 11.1 10.5 11.1 Starch content (%) 58.5 60.6 57.1

Cultivar Nadiya Grain yield (t ha"1) 2.62 2.90 3.18 Protein contant (%) 10.4 10.0 10.6 Starch content (%) 60.8 62.0 59.1

3.00 10.8 58.0

3.50 10.4 61.2

3.03 11.7 56.0

3.70 11.3 59.1

3.26 11.5 58.0

3.99 11.0 59.5

3.28 12.3 56.4

4.03 11.5 57.8

3.47 11.8 58.0

4.20 11.2 59.3

LSD 0.05. For cultivars 0.22; for fertliser 0.2; for sowing rates 0.15.

Session 2.3 533

Increasing sowing rates from 4 to 6 million viable seeds ha"1 increased grain yield both cultivars on all variants of mineral nutrition. However, more advisable sowing rates were 4-5 million seeds ha"1. Data structure grain yield show on the positive effect of mineral fertiliser on mass and number of grains per ear, number of ears per square meter, 1000-grain mass, number of grain per ear, mass of grain per ear and increased number of ears per square meter. The protein content in the grain barley increased with increasing the level of fertiliser nutrition and decreased with increasing density plants, starch content on the contrary. The grain barley cv. Nadiya characterised smaller protein content and higher starch content in comparison to cv. Roland, that is pointed on its better brewing quality.

Conclusions As to grain yield at western part of the Ukraine cv. Nadiya prevailed from cv. Roland from 0.45 to 0.811 ha"1. This cultivar also better responded to application of the mineral fertilisers. Better of fertilisers rate for cv. Nadiya was N30-60 P60 K60, for cv. Roland - N60-90 P90 K90 under optimal sowing rates 4-5 million viable seeds per ha. The cultivar of the spring barley Nadiya characterised better brewing quality of grain in comparison to cv. Roland.

References Copchyk, Z.M. et al., 1979. production of small grains in the region normal and axcesseable of

moisture Kyiv "Urozhai": 94-119. Copchyk, Z.M. et al., 1985. Journal of the news of agricultural science 2: 45-47. Copchyk, Z.M. et al., 1979. Variety's agrotechics of small grain Kyiv "Urozhai":; 228-242. Copchyk, Z.M. et al., 1979. Proceedings Institute of Agriculture and Animal Husbandry of

Western Region of the Ukraine 23: 22-24.


POTATO CROP GROWTH AND NUTRIENT CONCENTRATION AS INFLUENCED BY SOIL-PH AND POTATO CYST NEMATODES

F.J. de Ruijter & A.J. Haverkort

DLO Research Institute for Agrobiology and Soil Fertility (AB-DLO), P.O.Box 14, 6700 AA Wageningen, the Netherlands

Introduction Infection by potato cyst nematodes {Globodera pallida) is associated in general with reduced concentrations of nitrogen, phosphorus and potassium in the foliage. Trudgill (1987) found that NPK-fertilisation increased yield stronger at high than at low nematode densities, indicating that nematodes induce nutrient deficiency. As phosphorus is one of the elements most likely to limit the growth of nematode infested plants (Trudgill, 1980), we studied the effect of potato cyst nematodes in combination with phosphate fertilisation and soil-pH. Here we focus on the first part of the growing season.

Methods The experiment was carried out in 1995 on a sandy soil with cultivar Mentor. Previously, different levels of soil-pH were established by liming and current soil-pH-KCl was 4.8 and 6.1. Different levels of nematode density were established by soil fumigation and plots were split into two levels of P-fertilisation, 0 and 225 kg P per hectare. All plots received 230 kg N and 125 kg K per hectare. Effects of the different treatments on phosphorus availability index Pw and on nematode population density are shown in Table 1. Tubers were planted on April 21 and the crop was harvested on June 21.

Table 1. Effects of phosphate application on Pw-value and of soil fumigation on the number of living juveniles per gram soil at two pH-levels. LSD for comparison of all means.

treatment pH-KCl LSD

phosphorus index (Pw)

population density

non-fertilised fertilised

fumigated non-fumigated

4.8 62 84 5 47

6.1 47 62 6 25

7

9

Results The treatments led to differences in total dry matter production and affected concentrations of N, P and K in the leaves (Table 2). On fumigated soil, the reduced yield at pH 6.1 without P-fertilisation appeared to be caused by phophorus limitation as leaf-P concentration was near the deficiency level of 3.0 (Walworth and Muniz, 1993) and P-fertilisation increased leaf-P concentration and yield. Leaf concentrations of N and K hardly differed between the soil-pH or P-fertilisation treatments on fumigated soil. Nematodes significantly reduced total dry matter production and leaf nutrient concentrations (Table 2). The effect of nematodes could largely be attributed to P-limitation, as leaf-P concentrations similar to that of the limiting concentration of 'pH 6.1 without P-fertilisation on fumigated soil' gave similar yields. Lower leaf-P concentrations showed a further yield decrease.

Session 2.3 535

However, not all damage by nematodes could be attributed to P-limitation. At pH 4.8 with P-fertilisation, leaf-P concentration was near sufficiency levels (Walworth and Muniz, 1993) but dry matter production of non-fumigated treatments was reduced. Leaf-N concentrations were reduced by high levels of nematodes but the reduced dry matter production could not be attributed to nitrogen limitation, as variation in P-fertilisation and soil-pH resulted in large differences in dry matter production at equal leaf-N concentrations. High levels of nematodes decreased leaf-K concentrations but the highest dry matter production levels had the lowest leaf-K concentrations, indicating that dilution of K took place. The lowest leaf-K concentrations were close to the deficiency level and may explain the reduced dry matter production on non-fumigated soil at pH 4.8 without P-fertilisation.

Table 2. Effects of soil-pH, phosphate fertilisation and soil fumigation on total dry matter production (g m"2) and leaf nutrient concentrations (g kg"1), 61 days after planting. LSD = least significant difference (P=0.05), value in parentheses is for comparison within the same level of fumigation.

total dry matter (g m"2)

leaf N-concentration (g kg"1)

leaf P-concentration (g kg"1)

leaf K-concentration (g kg"1)

fumigated non-fumigated LSD




pH4.8 P- P+ 288 293 198 222

39 (32)

59.2 58.2 49.6 53.4

2.9(3.1)

5.68 6.30 3.90 5.17

0.50(0.57)

47.8 51.6 40.2 40.5

7.4 (8.8)

pH6.1 P- P+ 182 253 111 164

58 (52)

54.6 56.4 49.8 50.2

2.9(3.1)

3.77 4.64 3.13 3.99

0.49 (0.43)

51.8 55.0 46.5 44.3

4.6 (4.2)

Conclusions We conclude that potato cyst nematodes affect nutrient uptake, leading to reduced concentrations of N, P and K in the foliage that may cause nutrient deficiency. Which element becomes deficient depends on the availability in the soil. As we found most effects of phosphorus at relatively high Pw-values in the soil, we expect phosphorus, in general, to limit early crop growth when infected by potato cyst nematodes.

References Trudgill, D. L., 1980. Nematologica 26: 243-254. Trudgill, D. L., 1987. Plant and Soil 104: 235-243. Walworth, J. L. & Muniz, J. E., 1993. American Potato Journal 70: 579-597.


INFLUENCES OF BIO-DYNAMIC AND ORGANIC TREATMENTS ON YIELD AND QUALITY OF WHEAT AND POTATOES: THE WAY TO APPLIED ALLELOPATHY?

G. Deffune', A.M. Scofield, H.C. Lee, J.M. Lopez-Real and P. Simünek2

Sustainable Agriculture Research Group and Biological Sciences Department. Wye College, University of London, Wye, Ashford, Kent TN25 5AH, Fax: (01233) 813320, U.K. 'E-mail: [email protected]

Introduction Many organic substances have allelopathic effects in agroecosystems (Rice, 1984). The so-called biodynamic (BD) preparations were the first set of plant extracts and solutions widely used in what can be regarded as applied allelopathy in farming systems (Deffune, 1990). This method has been succesfully used by Brazilian farmers (Pio et al, 1984) and holds a great potential regarding biodiversity, for the discovery of new sources of active principles or ingredients (Almeida, 1988). A PhD research project to investigate these effects and techniques is using spring wheat (T. aestivum, var. Canon) and potatoes (S. tuberosum, vars. Cara and Pentland Crown) in field trials, supplemented by glasshouse and axenic experiments. Crop yield and health, nutritional and keeping qualities of produce as well as soil changes are the parameters evaluated.

Methods Randomized complete block blind experiments, with secret codes for both compost, soil and spray treatments: A=control, A+= chemical fertilizer and foliar spray, B&C=blind BD & Organic, using 60 T ha"1 of standardized compost treated with preparation sets and sprays blind-labelled B&C. Double-blind re-coding of wheat samples was used for quality assessment of grain and flour. Successive cropping seasons (1993-95) are used to check for cumulative effects, with crops cultivated in spring/summer of 1993-95 and rotation with rye/vetch mixture for green manure and weed control (1994). The biomass was left as mulch in B&C plots and removed from the control plots. The treatments were Bio-dynamic preparations applied as follows (Koepf HH et al., 1976): 1. Field sprays - used in sequence and additional to compost treatments: • P500 soil spray (17 ml m"2), fermented cow manure, stir-diluted 3.3 g l"1. • P501 plant spray (138 ml m"2), silica dynamized 83 mg l_1(5g per 60 1). • Nettle water 2% Urtica dioica (planta tota) 138 ml m"2; 1st month • Equisetum arvense decoction 1% stir-diluted, 138 ml m"2. • Kieselguhr (diatomaceous earth) 0.5% stir-diluted, 138 ml m"2. 2. Compost additives P502 to P507 (200mg m"3): Achilea millefolium - flowers, Matricaria recutita - flowers, Urtica dioica- planta tota, Quercus robur - bark, Taraxacum officinale -flowers and Valeriana officinalis - flowers' liquid extract. 3. Mixed spray (blind coded) for tilled soil manured with untreated standard compost in 1993 (1st

year) trials: P500 (200g per 60 1) + P502-P506 (4g per 60 1 = 66.7 mg l"1) + P507 (4ml per 601). 4. In the second year (1994), while the first year plots were under green manure rotation, two additional field trials of wheat & potatoes were set in split-plot designs between the same soil treatments and five sprays: 10% solutions of Urtica dioica, composts B and C; a mimic concentration Murashige & Skoog salts nutrient solution and a water control. 5. In the third year the successive cropping plots were re-planted with wheat & potatoes under split-plot designs between the four soil treatments and two blind-sprays, with and without P501 silica.

Results Contrasts of interest (Pearce, 1992) show statistically significant differences as follows:

mailto:[email protected]

Session 2.3 537

1 Wheat - A vs B&C and A+ vs B&C in both grain and biomass yields and quality in terms of Thousand Grain Weight (TGW ) and baking properties (HFN*- Hagberg Falling No.). A+ had higher yield but lower quality than the others. The BD treatment showed optimal HFN*(249.83) with a lower phosphorus** content than the Organic (the highest in P), while other element levels like Ca, K, Na, N03 and Ash did not vary significantly. 2. Potatoes - A+ vs B&C; yields did not differ in dry weight and A+ potatoes had the lowest dry matter content " after a 6 month storage period. B&C have also shown better conservation* (less "spraing" i.e. tissue darkening). B vs C; B had a higher amount of "chats"* (tubers smaller than 40mm) than C. There were overall differences between treatment systems* and varieties***.

HFN scores: below 150 = sticky bread; between 200 & 300 = acceptable; 300 plus = dry bread.

| Ideal: 250

Contrasts: A+vsO, BD

(FProb-0,0308); O vs BD

(FProb= 0,0105)

Control (A) Agrochemical (A+) Organic (O) Biodynamic(BD)

Figure: Baking quality of spring wheat "Canon", using Hagberg Falling Number (inverse of alpha-amylase activity), comparing four treatment systems in double-blind RCB field trials (1993).

Conclusions Significant quality differences between Bio-dynamic and Organic treatments indicate the presence of allelopathic stimulation by the BD preparations, showing the way to detect these subtle effects (Smith, 1993). Much higher soil nitrate levels in the positive control "A+" plots did not increase proportionally the yields, but significantly relate to lower quality in both wheat and potatoes. Results show the possibility to improve crop yield and quality of produce, through simple and environmentally adequate techniques, directly available to farmers (Reganold et al, 1993).

References Almeida, F.S. (1988). A alelopatia e as plantas. Circular n°53, IAPAR, Parana, Brazil, 60 p. Deffune, G. 1990. MSc Dissertation, Wye College, 1-28. Koepf, H.H. et al, 1976. Bio-dynamic Agriculture: an introduction, 4: 206-224. Pearce, SC 1992. Experimental Agriculture 28: 245-253. Pio, D.M. et al., 1984. Lebendige Erde 6: 269-274. Reganold, J.P. et al, 1993. Science 260: 344-349. Rice, EL. 1984. Allelopathy, Academic Press, Orlando, 10: 266-291 Smith, R.L. 1993. Journal of Applied Nutrition, 45(1): 35-39.

PhD Student sponsored by CNPQ - the Brazilian National Research Council. PhD Student - Department of Food Technology, Mendel University, Brno, Czech Republic.


EFFECTS OF NITROGEN DEFICIENCIES ON GRAIN SET IN WHEAT

S. Demotes-Mainard, M.H. Jeuffroy

Institut National de la Recherche Agronomique, Laboratoire d'Agronomie, 78850 Thiverval-Grignon, France

Introduction Much variation in grain yield of wheat crops is closely associated with variation in kernel number per unit land area (Midmore et al, 1984). It is thus important to study the effects of the different factors affecting kernel number. The effects of plant nitrogen nutrition on grain set are still not well known. The aim of this experiment was therefore to study in wheat the relationships between the N supply to the plant, and particularly to the ear, and kernel number per ear in situations of nitrogen deficiencies.

Methods Winter wheat cv. Soissons was grown in the field near Paris for one season. N fertilizer was brought at different dates and rates in order to achieve 8 experimental treatments: one control treatment (N non limiting), and seven treatments with nitrogen deficiencies (Fig. 1). The beginning of periods of N deficiency was dated by weekly measurements of the concentration of nitrates in the base of the stems of main shoots (Justes, 1993). Accumulation of dry matter and nitrogen in ears of main shoots was measured twice a week until anthesis. Kernel number was counted at harvest.

degree -days from sowing (b: 850 900 950

dates 18/3 Treatment c. Nl

26/3

ase 0*C) 1000 1050

8/4 1100 1150 1200

28/4 1250 1300

1/5 1350

6/5 1400

N2 N3 N4 N5 N6 N7

Fig. 1. Experimental treatments. Bold lines represent periods of nitrogen deficiency, dotted lines periods of non limiting nitrogen nutrition. N deficiencies of treatments Nl, N2, N3 and N4 lasted until harvest. Beginning of stem elongation: 950 degree-days, anthesis: 1644 degree-days.

Results and discussion The treatments induced different kinetics of accumulation of biomass and N in the ear and affected kernel number per ear. There was a significant linear relation between the number of kernels per ear and ear dry weight at anthesis (Fig. 2, dotted line, r2=0.96, df=6), showing that N deficiencies affected kernel number per ear largely through their effect on carbon assimilates supply to the ear. However, for all treatments that had been subjected to N deficiencies kernel number per ear was lower than expected according to the curvilinear regression (Fig. 2, bold line) between kernel number and ear dry weight established by Gate and Grimaud (1989) on a wide range of varieties and growing conditions in non limiting N nutrition. The fact that the number of

Session 2.3 539

kernels was lower under N deficiencies than expected in non limiting N nutrition (curvilinear relation) is consistent with the results of Abbate et al. (1995). The difference between the observed number of kernels per ear and the value expected according to the regression of Gate and Grimaud can be interpreted as a direct effect of N deficiency on kernel number. This difference is linearly correlated (r^O.64, df=6) to the concentration of N in the ear at the beginning of the period of linear accumulation of N in the ear (1380 degree-days after sowing) (Fig. 3), suggesting that this direct effect of N shortage was determined rather early, before the rapid growth of the ear.

§«

r £ 2

150 200 250 300 350

Ear dry weight at anthesis (mg ear-1)

400

Fig. 2. Relationship between ear dry weight at anthesis and kernel number per ear. Bars represent ± standard deviation. Dotted line: linear regression on the experimental data. Bold line: regression established by Gate and Grimaud (1989) on crops grown without N deficiency.

2.7 2.9 3.1 3.3 3.5

N concentration of the ear (%)

3.7

Fig. 3. Difference between the kernel number per ear predicted by the regression of Gate and Grimaud (1989) and the observed kernel number, plotted against N concentration of the ear at the beginning of the period of linear accumulation of N in the ear

References Abbate, P.E. et al, 1995. Journal of Agricultural Science, Cambridge 124: 351-360. Gate, P. et ai, 1989. Perspectives Agricoles 132:18-30. Justes, E., 1993. Thèse de doctorat, ESTA P-G, 227p. Midmore, P.M., et al, 1984. Field Crops Research 8:207-227.


OILSEED RAPE OIL YIELD AND QUALITY IN RELATION TO FUNGAL DISEASE

K. J. Doughty', C. J. Lewis1, H. A. McCartney1, G. Norton2, E. J. Booth3, K. C. Walker3

'Department of Crop and Disease Management, IACR-Rothamsted, Harpenden AL5 2JQ, UK. department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE 12 5RD, UK. Scottish Agricultural College, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA, UK.

Introduction Oil produced from rapeseed in Europe is currently used mainly for food, but it can also be used for an increasing number of industrial applications. The fatty acid composition of the oil is a major determinant of quality for both end-uses, hence the importance of an agronomic approach that maintains the yield of the desired component(s). Fungal pathogens of rape can reduce dry matter yield substantially, but little is known of their effect on seed oil content and quality. Economic and environmental constraints preclude the prophylactic application of fungicides to rape, so they should be used only when likely to improve yield and quality. To investigate the stability of quality under 'low-input' conditions (at least with regard to crop protection), we measured the oil content and fatty acid composition of seed from a range of conventional cultivars grown with and without fungicides.

Methods Seed samples of double-low winter rape were obtained from three experiments done at two sites in the UK during 1994-5. At IACR-Rothamsted (IACR), two cultivars were grown in replicated plots that were either inoculated at the beginning of the season (by applying contaminated rape straw), or treated with fungicides in autumn, spring and summer to control disease. At SAC-Aberdeen (SAC), eighteen cultivars were grown without replication in plots that were either treated with fungicides (following a similar programme) or left untreated. Analyses were made of disease incidence at both sites, and of the effects of disease on plant growth and canopy structure at IACR. In addition, individual plants infected with Sclerotinia sclerotiorum (stem rot) were collected from plots at IACR shortly before harvest. Seed samples from all sources were dried, cleaned and analysed for thousand seed weight, oil content and fatty acid composition at the University of Nottingham. IACR samples were also graded for seed diameter, and the different grades were then re-analysed for oil content.

Results Fungicide-treated plots were characterised by later-developing and less severe epidemics of most diseases. Compared with fungicide-treatment, inoculation typically led to reduced plant populations, delayed flowering and, eventually, patchy maturation on the more highly-branched surviving plants. Inoculated plots produced dry matter yields up to 1 t ha ' (approx. 25%) lower than those from corresponding fungicide-treated plots. Of the diseases recorded, light leaf and pod spot (Pyrenopeziza brassicae) and dark leaf and pod spot (Alternaria brassicae & A.brassicicola) were those most closely associated with these effects. Seed from inoculated or untreated plots usually had a lower oil content than that from corresponding fungicide-treated plots. In the SAC experiment, seed oil content at harvest was associated with the severity of earlier light leaf spot infection, irrespective of whether plots had been treated with fungicides (Figure 1). The oil- and protein-contents of seed dry matter were generally inversely related, seed from heavily-diseased plants having a higher protein content. The lower oil content of samples from inoculated plots was associated with smaller

Session 2.3 541

seeds, and oil analysis of graded samples showed that seed from inoculated plots contained slightly less oil than seed of similar diameter from fungicide-treated plots (Figure 2).

r = -0.498, PO.01

- - i + t-10 15 20

Light leaf spot severity (%) 25 30

Figure 1. Relationship between disease severity (April) and oil content (harvest) in fungicide-treated and -untreated plots of eighteen cultivars (SAC). Oil analysis after Soxhlet extraction.

I Fungicide-treated •Untreated

C

C O

> 2.4 mm 2.0 - 2.4 mm 1.7 - 2.0 mm

Seed diameter grade

Figure 2. Association between seed size and oil content of cv. Capricorn, as affected by disease (IACR). Oil analysis by NMR.

Disease also caused marked changes in the fatty acid composition of the oil. Seed from heavily-diseased plots generally contained less oleic acid [18:1], but more polyunsaturated fatty acids (linoleic acid [18:2] and a-linolenic acid [18:3]). Oil from plants that were girdled by stem rot had the same composition as that from uninfected plants with respect to the major fatty acid components [16:0, 18:1, 18:2 & 18:3] but it contained more eicosenoic acid [20:1]. Erucic acid [22:1] and hexadecatrienoic acid [16:3] were only present in the oil of the infected plants.

Conclusions The results confirm that, as well as reducing the dry matter yield of oilseed rape, severe disease can further affect oil yield by reducing seed oil content, mainly through an effect on seed size. They also indicate that particular diseases can affect oil quality via specific changes in fatty acid composition. A combination of cultivar disease resistance and the directed, economic use of fungicides appears to be essential if processors are to be supplied consistently with a product of the appropriate quality, and will be a precondition for the success of future industrial rape crops.

Acknowledgement This work is being funded by the United Kingdom Home-Grown Cereals Authority


RELATIONSHIP BETWEEN WEED LEVEL AND LEAF AREA IN INBRED MAIZE LINES

M. Burkic, M. Knezevic, I. Juric

Faculty of Agriculture, P.O. Box 117, 31000 Osijek, Croatia

Introduction The modern maize production prefers an integrated crop protecting system of weed control by means of reduced herbicide application (Prasad et al., 1990; Blair et al., 1993; Pimentel et al., 1993; Ford et al., 1994). Development and use of an integrated system of weed control requires detailed information on crop- weed interactions, including the impact of the relative competitive ability of the crop during different phases of development on weed growth, (Tollenaar et al., 1994). The aim of this research was to determine the effects of the mechanical and chemical weed control with reduced herbicide use on leaf area index and seed yield of the maize line on different types of soil in Eastern Croatia.

Methods Field trials were conducted on eutric cambisol (EC), luvisol pseudogleyic (LP), and luvisol (L) soil types on two inbred maize lines: male "OS 1-44" and female "OS 36-16" from 1993 tol995. Five mechanical and chemical weed control systems were as follows: 1. one interrow cultivation; 2. one interrow cultivation + two hoeings; 3. mixture of metolachlor + atrazine (1800 + 1200 g ha"1) pre-em. broadcast; 4. mixture of metolachlor + atrazine (900 + 600 g ha"1) applied in bands; 5. rimsulfuron (60 g ha"1) post-em. The trial was set up as a split-split plot design in four replications. The inbred lines were sown from the third decade of April to the first decade of May every year. The surface of each plot was 44.8 m2. Weed number and weed biomass of each species were estimated by counting and weighing the plants per m2, 60 to 65 days after sowing. Leaf area index values for female and male lines were estimated on the basis of the total leaf number of five plants from each variant randomly selected shortly after silking. Crops were harvested at the end of September. The seed yield values of the female line, having 14% of moisture, are given in t ha"1.

Results Weed control and seed yield are presented in the table and LAI values are shown in the figure.

Table. Number of weeds (m2) and seed yield (t ha"1) in 1993-1994

Treatment

1 2 3 4 5

Mean

Eutric cambisol No. of weeds 185.3 30.6 75.8 96.7 70.1 91.7

Seed yield 1.22 3.14 2.31 1.57 2.02 2.05

Luvisol pseudogleyic No. of Seed weeds yield 33.8 2.94 12.6 3.62 5.3 4.16

12.4 3.51 7.5 3.47

14.3 3.54

Luvisol No. of weeds 57.9 27.1 16.2 20.4 30.3 30.4

Seed yield 2.23 3.32 3.38 3.15 3.11 3.04

Mean No. of weeds 92.3 23.4 32.4 43.2 36.0 45.5

Seed yield 2.13 3.36 3.28 2.74 2.87 2.88

Session 2.3 543

Figure. Influence of mechanical and chemical weed control on leaf area index in male (•) and female (D) maize lines. EC, LP and L: soil types; 1-5 mechanical and chemical weed control treatments.

1993

1994

3.6 i|l|]ffl[|J]|M

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<"*st*». ^ H w *-** x ^ r \ is L*> ^ i ; - 3 *

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L»aiiÉi8lBgB 3^••fctoftS4t^sT*1^**J,^Ä'*-r BHmBjiZS&Ml^^^B^ """"-•J 3-* • ^ ^ M ^ ^ H ^ ^ B * - ^ ! ! ^ 3.2 H^^H^^BH^p^iÄ^fi teC^"'^^ 2.8 ^ ~ : ä E h r ^ * Z — f f Z 4

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V - ^ ^ 1 ^ ^ 9 ^ H H ^ H | H V fsÊJËÊËm*™? L 6

S JmMBF -.rigm --"dSI B - ••M^^^Mi L 2

D É ^ H Baal J R ^ f c a d ^ ^ as ^^H^^V^ ^^^^H^^^r^?^*^ ? ;5?l^^^Eti^^^B^^^ , , -e^ 4 ^ ^ ^ ^ ^ H ^ ^ ^ ^ * * ^ 3

^ ^ ^ S ^ * " ^ 2 BC; i

Conclusions Leaf area index, weed number and seed yield depend on the soil characteristics, climatic conditions in the growth seasons and weed control treatments. Leaf area index was in negative correlation with weed level on all types of soil. The lowest LAI and seed yield values were determined in the variant with the highest weed number, i. e. with one interrow cultivation (1). Variants with one interrow cultivation + two hoeings (2) and mixture of metolachlor + atrazine (1800 + 1200 g ha"1) pre-em., applied broadcast (3) gave a significantly lower weed number, higher LAI and higher yield (P<0.01). The highest yield (3.541 ha"1) and highest LAI values (2.21) were determined on luvisol pseudogleyic soil.

References Blair, A.M. et al., 1993. Brighton Crop Protection Conference, 985-990. Ford, G.T. et al., 1994. Weed Technology, 8: 124-128. Pimentel, D. et al., 1993. Agjculture Ecosystems and Environment, 46: 273-278. Prasad, T.V.R. et al., 1990. Mysore Journal of Agricultural Sciences, 24: 39-44. Tollenaar, M. et al., 1994. Agronomy Journal, 86: 591-595.


REDUCING FERTILIZATION IN MAIZE IN SOUTH-WEST SPAIN

J.E. Fernandez, J.M. Murillo, F. Moreno, F. Cabrera, E. Fernândez-Boy

Instituto de Recursos Naturales y Agrobiologia (IRNAS, CSIC) Apartado 1052, 41080-Sevilla (Spain)

Introduction In many areas of South-West Spain where maize is intensively cropped, the worrying increase of nitrates in groundwaters detected in the last years has led to a marked interest in the possibilities of reducing fertilization. This paper shows the crop response of maize cropped consecutively for five years under Mediterranean management practices, using two different fertilization rates: that widely used by the farmers (500 kg N ha"1 yr"1); the other one third of it (just to cover the N crop requirements).

Methods The experiments were conducted in SW Spain (37.2° N, 6.1° W). Maize (cv. Prisma) was cropped in a 0.1 ha experimental plot from 1991 to 1995 (March to August, 75,000 plants ha"1, 50 mm weekly furrow irrigation). The plot was divided into two 450 m2 subplots, to establish two N fertilization treatments. Subplot A had 510 kg N ha"1 yr"1, a rate widely used in the area. Subplot B, had 170 kg ha"1 yr"1 (28% of the N applied some 10 days before planting, and the rest on two occasions, at about 45 and 75 days after planting). Drainage and nitrate leaching in each subplot were monitored throughout the experimental period (Fernandez et al., 1994). Crop height, leaf area index and phenological state were monitored every 7-10 days. Yield parameters and nutrient concentrations in Kernel were also measured (Murillo et al., 1992).

Results Results are presented in Tables 1 and 2, and in the Figure.

Conclusions It can be concluded that the reduction in fertilization caused no reduction in final crop development and production. The only difference was that N concentrations in the kernels were found to be higher for the higher fertilization rate. The reduction of crop performance throughout the experimental years may be due to the negative effects of monocropping (Bhowmik et al. 1982). The high fertilization rate in subplot A gave high N03-N contents below the root zone, the excess not being taken up by the crop but temporarily incorporated into the soil organic matter, as observed by Fernândez-Boy (1994). Therefore, not only can crop performance be maintained with lower fertilization rates, but a significant reduction of N03-N pollution of groundwaters is achieved.

References Bhowmik P.C. et al., 1982. Agronomy Journal 74: 601-606. Fernandez, J.E. et al., 1994. International Conference on Land and Water Resources

Management in the Mediterranean Region. 4-8 September, Valenzano, Italy. Vol. I Water Resources management, pp 327-340.

Femändez-Boy, E., 1994. PhD Thesis, University of Seville, 251 p. Jones, J.B. et al., 1990. In: Soil Testing and Plant Analysis, ed Westerman R.L. Soil Science

Society of America Inc, 521-547 pp.

Session 2.3 545

Murillo, J.M. et al., 1992. Communications in Soil Science and Plant Analysis, 23: 1767-1779.

Table 1. Mean values of plant height (cm), leaf area index (LAI), ear weight (g), 1000 kernel weight (g) and total grain yield (Mg ha'1) (at 10% moisture). N rate in kg N ha"1 yr'.

Year

1991

1995

N rate

510 170

510 170

Plant height

291 a 294 a

154 b 167 a

LAI

5.45 a 5.37 a

3.24 a 3.36 a

Ear weight

209 a 214 a

129 b 156 a

1000 kernel weight

314 b 334 a

281 a 288 a

Yield

13.0 13.2

8.3 9.9

Table 2. Concentrations of N, P, K (g kg"1) and Fe and Zn (mg kg"1) in kernels (mean values on a dry matter basis). N rate in kg N ha"1 yr"1.

Year N rate

1991 510 170

1995 510 170

(*)

N

13.1a 12.3 b

12.1a 10.3 b

10.0-25.0

P

2.80 a 2.60 b

2.30 a 2.50 a

2.0-6.0

K

3.38 a 3.24 b

4.50 a 4.50 a

2.0-4.0

Fe

26 a 32 a

15 a 20 a

30-50

Zn

21 a 19 a

15 a 16 a

—

(*) = Normal ranges for corn kernels (Jones et al., 1990)

is

60

40

20

_T" 0

BO

I CO

O

dry crop period nerïód Ta^n7 period

K 0 <b° NoO N«f> ,jCP T*P -#P •$&

Day after planting

Figure. Water and NO,,—N contents of the soil at 0.8 - 1 m depth (below the root zone) in subplots A (•) and B (o), from March 1993. The arrows represent deep fertilization (day -13) and two top dressing fer t i lizations (days 43 and 77) (day 0 = planting date, 24 March).


AMMONIUM THIOSULPHATE (ATS) AS AN ENVIRONMENTALLY FRIENDLY TOOL

FOR N AND S NUTRITION OF RAPESEED {Brassica napus L )

J. Fismes, P C Vong, A. Guckert

Laboratoire Agronomie et Environnement ENSAIA-INRA, 2, avenue de la Forêt de Haye, BP 172, 54 505 Vandoeuvre lès Nancy, France

Introduction For its inhibitory action on nitrificatin and urease activity, the ammonium thiosulphate (ATS) is commonly used in combination with liquid urea ammonium nitrate (Janzen et al, 1984; Goos, 1985). Moreover, because the ATS contains a double source of N and S, its utilization in conjunction with other fertilizers would contribute to a better uptake of these two elements by the plants. Our aim was to examine the influence of ATS-amended fertilizers on fate of N and S in the plant-soil system and on the quality of oilseed rape (due to S-uptake and N-regulatory effect). This plant was chosen because of its high demand of S.

Methods A double O spring rape was used in a pot experiment in growth chamber. A calcareous soil (rendzina) was selected; this soil was collected from the Ap horizon (0-20 cm), air-dried, sieved (2 mm) and fertilized at a rate of 200 kg N ha-1 applied as ammonium nitrate (AN),urea and cattle slurry, and 75 kg S ha-1 as ATS (283 kg ATS ha1). The experiment consisted of 7 treatments (AN+ATS, urea+ATS, slurry+ATS, AN, urea, slurry and control) with 5 replicates per treatment. The growth conditions were : 14 h day at 16°C and 10 h night at 12°C from sowing to flowering, 16 h day at 21°C and 8 h night at 16°C from flowering to maturity, 250 |0,mol nr2 s_1

light intensity and 70% air humidity. The pots were sampled at "rosette" stage (one month after cultivation), at flowering and at seed maturity. The plants were separated from the soil. For soil samples, the inorganic N (NH4

+, N 0 3 ) was determined with 1 M KCl extraction by distillation, and the inorganic S (S04

2-) with 0,01 M CaCl2 by turbidimetric method. The plants were separated into leaves, stems, roots, pods and seed; after determination of the fresh and the dry matter, the different plant parts were ground and analysed by auto-analyser NA 1500 for total N and S content.

Results The ATS reduced significantly the amount of nitrate in soil by 50% one month after application (Table 1); these results confirmed the significant effect of ATS as an inhibitor of nitrification. Similarly, we observed a decrease of total inorganic N content (Table 1) in the soil treated with AN+ATS, urea+ATS and slurry+ATS (-4.9, -8.2 and -8.3 mg N kg"1 soil respectively); this indicates that ATS had also a high efficiency with slurry, and that N would be immobilized in the soil after ATS application.

Table 1 - NQ3-N, NH4-N and total inorganic N in soil (mg N kg'1 soil) at "rosette" stage Treatments N03-N NH4-N Total inorganic N

AN+ATS 3.77 b 4.03 b

7.80 c

AN 8.51 a 4.23 b

12.74 ab

Urea+ATS 4.09 b 3.89 b

7.98 be

Urea 9.04 a

7.15 ab

16.19 a

Control 7.68 ab 9.83 a

17.51 a

Slurrv+ATS 39.00 b 8.95 b

47.95 b

Slurry 47,28 ab 14,81 a

62,09 ab

Control SI 56,31 a 13,74 a

70,05 a The results are given as means. Different letters within the same row (horizontal) indicate that values are significantly different at p=().05 according lo Tukcy test

Session 2.3 547

An excessive N/S ratio enhanced vegetative growth and suppressed pods and seed production due probably to an excessive N assimilation and an accumulation of toxic N metabolites (Janzen et al, 1984) : no seed was obtained with AN and urea treatments. The total N exported by the plants at maturity increased significantly when ATS was applied (Figure 1); the higher effect with urea than with AN could be probably due to a double action of ATS on urease activity and on nitrification. The total N content in aerial parts at different stages of growth showed a transfer of N from vegetative parts to seed at maturity (data not shown). Used as a source of S, the ATS contributed, via a rapid oxidation to sulphates in the soil, to increase significantly the total S exported by the plants (Figure 1). With slurry the S content was higher than with other fertilizers.

Figure 1 - Total N and S exported by the plants at maturity (mg N plant"1 and mg S plant"1) a

b „ 80-

I 60 40

20

0

o,

Control UAN AN AN+ATS U U+ATS

Control SI SI Sl+ATS

1st experiment 2nd experiment. 1st experiment 2nd experiment Different letters within an experiment indicate that values are significantly different at p=0,05 according to Tukey test

The results show an improvement of seed yield when ATS was added to fertilizers (Table 2), and the seed yield is maximum with slurry, corresponding to maximum N and S exported by the plant. In accordance to Zhao et al (1993), N and S addition increased seed yield and oil content with AN and urea, increased seed yield but also glucosinolates (GLS) content with slurry, and decreased oil content with slurry; this resulted from the important elevation of alkenyl GLS found with slurry+ATS (data not shown). The alkenyl GLS is derived from methionine and S present in pods contributes significantly to seed metabolites synthesis (Fieldsen et al, 1994).

Table 2 - Seed yield, oil and glucosinolates (umol g"1 of dry seed) contents Treatments AN+ATS Urea+ATS Control Slurry+ATS Slurry Control SI

Seed yield (g pof') 1.01 a 1,29 a 0.67 b Oil content (% of DM) 45.95 47.40 43.00

1,37 a 1,16 a 0,80 b 40.70 42,30 42.90

GLS content 8.2 8.5 7.9 13,5 8.9 8.9

Conclusions ATS reduced significantly the amount of nitrate in soil, but this retarding effect was observed only within a short period of about one month during which nitrogen seems to be predominantly immobilized in the soil. The application of N and S in a balanced proportion is important for plants development and seed production : the level of GLS is mostly conditioned by the S metabolized within the period of pods development. Further investigations of soil organic N, and determination of the optimum ATS rate and the optimum N/S ratio are needed to confirm ATS efficiency on oilseed rape.

References Fieldsen, J. et al., 1994. Annals of Applied Biology 124 : 531-542 Goos, R.J., 1985. Journal of Fertilizer Issues, Vol. 2, Number 2 : 38-41 Janzen, H.H. et al., 1984. Soil Sciences Society American Journal 48 : 100-112 Zhao, F. et al., 1993. Journal Science Food Agriculture 63 : 29-37

5 4 8 Book of Abstracts 4th ESA-congress

WATER AND NITROGEN BUDGET OF SPRING BARLEY FIELD

E. Fotyma, M. Fotyma

Institute of Soil Science and Plant Cultivation, Osada Palacowa IUNG, 24-100 Pulawy, Poland

Introduction Spring barley is the third, after winter wheat and rye, most widespread cereal crop in Poland. The barley yields are much lower though due to often occuring spring droughts and poorer ability to transform nitrogen into grain biomass. As in paralel work concerning winter wheat ( Fotyma M. et al, 1996) the aim of this one was to estimate the productive water consumption and the nitrogen uptake by spring barley grown on typical soil in Poland and fertilized with different doses of nitrogen.

Methods Spring barley was grown in the years 1993 - 1995 in four course crop rotation rape - winter wheat- sugar beet ( on FYM ) - spring barley fertilized with nitrogen in the doses 0, 20, 40, 60, 80 and 100 kg N ha"1. Soil characteristic , the extent of field measurements and the methods of date processing were presented in the paper concerning winter wheat ( Fotyma M. et al., 1996).

Results The most favourable water conditions were recorded in 1993 ( Figure 1 ).

13S US 1«2 1H 1*9 171 1 » 117 194 202 2 » l i t

Jul ian day*

1 » 144 1(2 1 » 1W 172 190 IS« 192 200 207 214

Julian day*

l E T p -water depletion

- water depletion

14« ISS 1S4 171 17«

Julian day*

191 191 209 213 Figure 1. Depletion of available water by spring barley from the layer 0 - 60 cm

Session 2.3 549

In 1993 the soil water depletion exceeded the depletion limit in Mid July only. The lowest yield of barley grain (Table ) was recorded in 1995 which can be explained by water deficit occuring already in Mid June. The daily actual évapotranspiration rate of spring barley was 3.8 mm/day in May, 5.0 mm/day in June and 3.3 mm/day in July independently on the nitrogen doses. Actual évapotranspiration was higher from the potential one by 10 - 40 % in May and June and lower by 15 - 35 % in July. The productive water consumption depends strongly on nitrogen doses (Table ) and generally exceeded the values found for winter wheat. The relation between spring barley grain yield, nitrogen uptake and fertilizers doses is presented on Figure 2 as a three quadrant diagram. The diagram contains all most important parameters of nitrogen efficiency and utilization including the unit uptake of this element per 100 kg of barley grain ( right, lower quadrant ). This

unit uptake is shown in Table as well for the sake of good confrontation with the date for winter wheat ( Fotyma M. et al., 1996 ). The unit uptake of nitrogen increased with increasing doses of fertilizers but was generally lower than the uptake by winter wheat.

grain yield

N rate kg/ha

100 80 60 40 20 0

rat«

40 -20 90 -40 60 -90

1»*«.

•ffidtncv

aoronom, 41.4 32 3 22.7 13.1 3.5

chvslotoo, 60.4 44.1 35.B 24.5

7,«.,

utiJJzalion

93.1 73.2 »3.4 53.4 44.3

N uptake kg/ba

120 140

N r kg/bi

Figure 2. The three quadrant diagram of nitrogen efficiency for spring barely.

Table. Water and nitrogen efficiency in spring barley cultivation Characteristic dose of nitrogen fertilizers kg N ha'1

0 20 40 60 80 100 grain yield t/ha 3.62 field water consumption May -July mm/100 kg of grain 8.79 uptake of nitrogen kg N/100 kg of grain ( + straw) 1.95

4.46

7.08

1.96

5.10

6.09

2.00

5.56

5.72

2.06

5.82

5.46

2.16

5.89

5.27

2.28

Conclusions Spring barley shows higher water demands in vegetation season and lower nitrogen utilization capacity than winter wheat. The highest yield is in the range of 0.75 of winter wheat yield. For achieving this yield the water supply of about 300 mm in May - July and nitrogen supply of 130 kg N ha"1 from the soil and fertilizers is a must.

References Fotyma M. et al., 1996. Book of Abstracts 4th ESA Congress Veldhaven the Netherlands


WATER AND NITROGEN BUDGET OF WINTER WHEAT FIELD

M. Fotyma, E. Fotyma

Institute of Soil Science and Plant Cultivation, Osada Palacowa IUNG, 24-100 Pulawy, Poland

Introduction The productivity of winter wheat depends mainly on water supply from soil reserves and from rainfall in vegetation period as well as on nitrogen supply from soil and fertilizers. The relation of actual to potential yield is proportional to the relation of actual to potential évapotranspiration (Sarnacka,1983) and to the nitrogen nutrition status of crop. There is a close correlation between water and nitrogen supply because the efficiency of these factors depends very much on each other. The aim of the work was to estimate the productive water consumption and the nitrogen uptake by winter wheat grown on typical soil in Poland and fertilized with different doses of nitrogen.

Methods The water and nitrogen budget was calculated for the winter wheat grown in 1993 - 1995 in field experiment on sandy loam underlined from 50 cm by loam . In the upper layers field water capacity was 23.8 %v and wilting point 6.4 %v. The figures for deeper layer were 33.0 and 13.3 %v. respectively. In a factorial experiment nitrogen fertilizers were applied in the doses 0, 25, 50, 75, 100 and 125 kg N/ha. From the beginning of May until the harvest the content of water was measured in the soil profile 0 -100 cm in weekly intervals by means of neutron probe provided with date processor. Potential évapotranspiration was calculated according to Górski's ( 1995) equation. The results were presented in form of isopleths and the water depletion diagrams. The depletion of soil available water was compared to so called water depletion limit eg. the value which does not influence negatively the crop yield. The relation between winter wheat grain yield, nitrogen uptake and fertilizer doses was presented in form of four quadrants diagram ( Fotyma E. et al, 1995 ). From this diagram the uptake of nitrogen per 100 kg of grain with corresponding yield of straw was calculated.

Results The course of the isopleths showed that the depletion of soil moisture by winter wheat was limited to the soil layer 0 - 60 cm . Consequently by constructing the moisture exhaustion diagrams this soil layer was recognized only ( Figure ). The daily actual évapotranspiration rate of winter wheat canopy was independent on the doses of nitrogen fertilizers and the mean values for the years 1993 - 1995 equaled to 4.0 mm/day in May, 4.5 mm/day in June and 3.0 mm/day in July. This independency on nitrogen doses can be explained by hypothesis that the sum of evaporation and transpiration is constant no matter how dense the crop canopy is. In May and June actual évapotranspiration rate was in the range 0.9 -1.3 of potential one calculated according to Górski. In July the ratio of actual and potential evapotranspiratio was 0.7 only. The productive water consumption per 100 kg of winter wheat grain depends significantly on the nitrogen doses (Table). In the treatment with maximal nitrogen dose ( 125 kg N /ha ) winter wheat consumed 60 % of the water used for production of 100 kg grain in the control treatment. In all fertilizer treatments in comparison to the treatment with 125 kg N/ha winter wheat was undernourished in respect to nitrogen. In the control treatment nitrogen nutrition index (Lemaire et al., 1989 ) was only 0.6 which means that the actual nitrogen concentration was 40 % less then the critical one. The uptake of nitrogen increased with increasing doses of mineral fertilizers. Newertheless even in the treatment with the highest dose of nitrogen the unit uptake of this element was only 2.4 kg N/100 kg of grain.

Session 2.3 551

124 131 138 145 151 1 » 1 M 171 112 1S7 1 M 202 201

Julian days

• ETp -water depletion

- water depletion limit

US 138 144 i e : 1 » 1M 1TZ 177 HC 102 200 207

Julian days

-water depletion

-water depletion limit

• ETp -water depletion

- water depletion limit

Figure. Depletion of available water by winter wheat from the layer 0 - 60 cm

Table. Water and nitrogen efficiency in winter wheat cultivation Characteristic

grain yield t ha"1

field water consumption May-July mm/100 kg of gram uptake of nitrogen kg N/100kgofgrain( + straw )

0

4.49

6.81

1.9

dose of nitrogen

25 5.45

5.58

2.0

50 6.27

4.72

2.1

fertilizers 75

6.95

4.59

2.2

H Nha"1

100 7.49

4.17

2.3

125 7.88

4.04

2.4

Conclusions In May and June the actual évapotranspiration rate of winter wheat canopy is somewhat higher than the potential évapotranspiration ( according to Górski) and the depletion of available soil water beyond the limit is often a restrictive factor of crop yield. The actual évapotranspiration is independent on nitrogen doses applied to winter wheat while the water consumption per 100 kg of grain decreased with increasing nitrogen doses. The uptake of nitrogen per 100 kg of grain increases proportionally with fertilizer doses but even in the treatment with 125 kg N/ha does not reach the luxury limit. The prerequisites for high yield is water supply in May-July over 300 mm and the nitrogen supply of about 200 kg N ha"1.

References Fotyma, E. et al., 1995. Fertilizer Research: 1-4 Górski,T. et al, 1995. Roczniki AR Poznan 140:227-243 Leinaire, G., et aL 1992.Proc. 2end ESA Congress:98-99 Sarnacka, S., 1983. Zeszyty Problemowe Post. Nauk Rolniczych 277:219-226


HIGH-YIELD VARIETIES OF WINTER VETCH AND USE OF VARIETY-STRAIN TECHNOLOGY FOR THEIR GROWING

M. Galan, N.Lisova

Research Institute of Agriculture and Cattle-Breeding of West Region UAAS, Lviv-Obroshyn 292084, Ukraine

Introduction The winter hairy vetch (Vicia villosa Roth) is the important source of protein and used for feeding of the animals. In the combined sowing of vetch with winter wheat, rye, barley, ryegrass, triticale for green feed has ensured the production of green mass up to 35.0-45.0 t ha '. The inoculation of vetch with the Rhizobium strains in field conditions increased significantly yield of the vetch - gramineous mixture ,the total and digestible protein content. However, highest potential for increase of the vetch yields has the breeding of varieties and adaptive, complementative Rhizobium strains.

Methods The field experiments were conducted in 1991-1995 with winter hairy vetch on dark-grey soil at Experimental Station near Lviv. The mineral fertilizers were: N20P60K60. The varieties of vetch, Shyrocolysta, Vusata, Fascialform, Tetraploidform, were created by the inducted (chemical) mutagenesis method from the winter hairy vetch variety Stavchanca (Galan, 1988). The seeds of vetch were inoculated with Rhizobium leguminosarum bv. vicae strains that were isolated from root nodules of the vetch varieties and forms (Kurchak et al., 1990). Fresh weight of the vetch-wheat mixture was measured at the blooming period. The experimental date have been statistically processed by dispersion analysis.

Results Results are presented in the Table and Figure.

Yield of green mass of the hairy vetch varieties

Variety

Stavchanca Shyrocolysta Vusata Fascialform Tetraploidform

Number field experi ments

6 8 5 5 4

Green mass, t ha"1

vetch-wheat mixture

33.9 44.4 35.2 35.5 43.7

vetch pure

17.8 21.3 168 17.3 22.9

Dry vetch mass, tha-1

2.7 3.3 2.6 2.8 3.5

We have selected four mutant forms (varieties) of hairy vetch with altered stem and leaf phenotypes as well as tetraploid form. The plants of Vusata variety are characterised by total reduction of leaves to the tendrils during the flowering. This variety has a good productivity of green mass and seeds. Mutant plants with fascialitied and thickened stem

Session 2.3 553

have an axial type of floscule position. They have also partial growth determination of the main stem and second order shoots. Such plants have very good productivity of the green mass. The tetraploid mutant is characterised by increased sizes of all organs and it has high potential of the fooder productivity. Plants of the variety Shyrocolysta have an enlarged leaf surface.

Green mass 10

610 622 1-11 1-32 1-42 4-31 R.leguminosarum strains

| Vusata Q Tetraploidform Fascialform Shyrocolysta Stavchanca

Figure. The Rhizobium strain specification of symbioses with winter hairy vetch varieties ( green mass addition to non-inoculated plants, t ha"1 ).

Conclusions The multi-year investigations showed high potential of the yield capacity of novel winter hairy vetch varieties in soil-climatic conditions of West Ukraine. The efficiency of vetch - Rhizobium symbioses was determined to a marked degree by the variety and strain genotypes complementation. The inoculation of the vetch varieties with adaptive and complementative Rhizobium strains increased the yield of the vetch-wheat green mass mixture with 2.3 to 8.8t ha1.

References Galan, M., 1988. Selektia i Semenovodstvo 6: '32-35. Kurchak, O.et al., 1990. Bull. VNIISCHM 53: 18-21.


EFFECT OF NITROGEN FERTILISATION ON LEAF PHOTOSYNTHESIS AND LIGHT ABSORPTION IN TOBACCO

M. Guiducci, P. Benincasa, M. Migni

Istitute of Agronomy, University of Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy

Introduction Crop biomass production can be considered as a direct function of the product of the amount of photosynthetically active radiation absorbed (PARa) by a crop and the canopy radiation use efficiency (RUE = mol C02 mol1 PARa) (Monteith, 1977). Nitrogen (N) fertilisation can affect both PARa and RUE, mainly as a consequence of its effects on canopy size and structure and on leaf photosynthetic activity (net C02 assimilation rate of leaf area unit) (Giménez et al, 1994; Sinclair and Horie, 1989). This is of particular interest in tobacco, where crop productivity has to be joined to the quality of the commercial product, which depends, inter alia, on leaf content of N-compounds. A field experiment was carried out in 1995 in central Italy in order to investigate in tobacco the effect of N fertilisation on leaf N content and photosynthesis and on canopy light environment.

Methods In a completely randomized block design with 4 replicates, 2 treatments were compared: NO (no N fertilization) and N90 (90 kg N ha1 at transplanting). Tobacco (Virginia, cv K394) was transplanted on 23 May, at a density of 2 plants nr2. All of the components of crop light balance were determined continuously throughout the day by using several quantum sensors, according to Guiducci and Marroni (1992). Leaf area index (LAI) was determined destructively by harvesting all leaves from 4 plants per plot and measuring their area with a leaf area meter. Leaf net assimilation vs photosynthetically photon flux density relationship (A vs PFD) was determined at around noon in several leaves from lower (L), medium (M) and upper (U) layers of the canopy, by using a portable gas exchange device (ADC-LCA3). The N content of the above mentioned leaves was then determined destructively by a Kjeldhal method. Measurements were performed during 4 consecutive days (from 31 July to 3 August) just before topping.

Results Daily PAR absorption (Table 1; Fig. 1) was higher in N90 than in NO (+19%), mainly as a consequence of higher LAI values of the former (+46%). On the other hand, NO showed a higher portion of LAI directly lit by sunbeam (LAIs/LAI) and, therefore, a more uniform distribution of light inside the canopy, which generally involves positive effects on crop photosynthesis (Hay and Walker, 1989; Guiducci and Benincasa, 1995). Specific leaf N content (SLN, g N nr2 of leaf) was affected by N fertilisation and leaf position. SLN of L, M and U leaves was (± s.e.) in order 1.22 (± 0.11), 1.41 (± 0.03) and 1.53 (± 0.20) g nr2 in NO, and 1.93 (+ 0.10), 2.12 (± 0.12) and 2.40 (± 0.09) g m-2 in N90.

2000

1500 -

1000

Table 1. PAR absorption (PARa, % of incident PAR), total (LAI, m2nr2) and sunlit (LAIs/LAI) leaf area index in NO and N90. s.e. = standard error

PARa LAI LAIs/LAI NO N90 s.e.

75.3 89.7 2.62

2.74 4.00 0.09

0.493 0.334 0.034

~ 500

Fig.1. Incident (—) and absorbed PAR in NO (O) and N90 (•) on 2 August.

Session 2.3 555

N fertilisation and leaf position also affected the A vs PFD response curve (Fig. 2), especially in terms of assimilation at saturating irradiance levels (Amax). Within each leaf position, Amax values were always higher in N90 than in NO. In both treatments, L leaves showed the lowest values of Amax in comparison to M and U leaves. A smaller effect was observed on apparent quantum efficiency (O) and dark respiration rate (R) (data not shown). Only in NO a remarkably higher <ï> value of U leaves (0.031 ± 0.0039) was recorded with respect to M and L leaves (0.020 ± 0.0059 on average). Amax was clearly linked to SLN. The asymptotic relationship between leaf Amax and SLN (plotted over all treatments and leaf positions) showed a good fit in a logistic model, similar to that indicated for other C3 crops (Fig. 3) (Sinclair and Horie, 1989; Connor et al., 1993). On the contrary, no relationship was observed between <E> and SLN and between R and SLN, although possible linkages could have been partly masked by the acclimation of U, M and L leaves to different levels of PAR.

1000 2000 0 1000 incident PFD (pmol Photons m V )

2000

Fig. 2. A vs PFD relationships in leaves of the upper (•) medium (O) and lower (•) canopy layer of treatments NO (left) and N90 (right).

25

20

15

10

5

-

-

-

- Q

0

A 0

°7 / °

/ 0 y = 25-Y.-^fr-"D-1

1 1 1

1.0 1.5 2.0 SLN (g m')

2.5

Conclusions N fertilisation increased both crop PAR absorption and photosynthesis of sunlit leaves, but involved a decrease of the LAIs/LAI ratio. Leaf Amax was strictly related to SLN, which increased with N fertilisation and leaf position. Further experiments are needed, after this preliminary result, to accurately investigate the effects of N fertilisation on the conditions affecting leaf and crop photosynthesis of tobacco, in order to model crop yield performance.

Fig. 3. Logistic relationship between leaf Amax and SLN plotted over all treatments and leaf positions. Equation in figure (R^O.866).

References Connor, D.J., et al, 1993. Australian Journal of Plant Physiology 20: 251-263. Hay, K.M. and Walker, AJ., 1989. Introduction to the physiology of crop yield. Longman, UK, pp. 292. Giménez, C , et al, 1994. Field Crops Research, 38: 15-27. Guiducci, M., and Benincasa, P., 1995. In: P. Mathis (ed.). Photosynthesis, from light to biosphere. Kluwer Academic, The Netherlands, Vol. IV, 613-616. Guiducci, M., and Marroni, M.G., 1992. Rivista di Agronomia, 26,4 suppl, 616-622. Monteith, J.L., 1977. Philosophical Transactions of the Royal Soc. of London B281: 277-294. Sinclair, T.R., and Horie, T., 1989. Crop Science, 29: 90-98.


VARIETY SPECIFIC WEED TOLERANCE - A KEY TO NON CHEMICAL WEED CONTROL

M. Jolânkai1, Z. Szentpétery^, T. Szalai^

1 Hungarian Academy of Sciences, Nâdor utca 7., 1051 Budapest, Hungary 2 Gödöllö University of Agricultural Sciences

Introduction Varieties of field crops belonging to different genotypes show different responses to weed populations (Cox and Jackson, 1949). Apart of extremities concerning weed canopy, there is a dynamic, naturally balanced coenosys including weeds and the crop produced in all fields. Weeds reduce crop yields since they compete with crops for essential sources of life (Jolânkai, 1995). There are three major factors influencing the competition between field crops and weed populations: water utilization, nutrient uptake and the vegetative growth dynamics. The latter can be considered as a main characteristic of a coenosys, since any component ofthat which may have a different chance for growth will dominate and so obstruct both physically and physiologically its neighbouring plants (Sprague, 1959, Maas, 1970). Apart of these there is a wide range of other factors wich may influence alterations of a coenosys (eg. diseases, epdemics and gradations etc), however these are more occasional. Within field crop species there are significant varietal differences in weed tolerance (Ubrizsy, 1962, Jolânkai et al., 1992, 1995). In our research winter wheat varieties were examined under various agronomic conditions to determine weed tolerance characteristics.

Methods In a three year herbicide provocation field trial at Nagygombos, Hungary (1993-1995), six wheat varieties representing different genotypes were tested under exposed and protected conditions on small plots with four replicates. Three types of herbicide treatments (fluroxipir, bromoxinyl and dicamba ai.) were applied in comparison with untreated "weedy" and hand picked "weed proof' controls. Weed populations were sorted into two major groups according to the level of their occurence. The most frequent weed species are listed in the table.

Table 1. Major weed species observed on experimental plots

High occurence weed species Low occurence weed species

Bilderdykia convolvulus Fumaria officinalis Capsella bursa-pastoris Viola arvensis Stachys annua Chenopodium album Matricaria inodora Adonis aestivalis Conium maculatum Sinapis alba Lathyrus tuberosus Lamium amplexicaule Stellaria media Sonchus arvensis Thlaspi arvense Lactuca spp. Galium aparine Cannabis sativa

Papaver rhoeas Convolvulus arvensis

Plant growth, yield components and grain yield of each experimental treatment were evaluated and weed tolerance of varieties was determined.

Session 2.3 557

Results and conclusions The magnitude of weed populations has shown significant differences. All weed control treatments including chemical and mechanical applications had an influence in weed development. Herbicide treatments had about fifty per cent, while mechanical applications had a nearly hundred per cent effect concerning weed reduction. The latter can be considered as a level of total weed extinction. High weed canopies were observed in the case of untreated controls only (Table 2).

Table 2. Effect of treatments on the number of weeds per plot

before treatment

after treatment

untreated control weedproof control herbicide applications

6.8 6.5 6.7

6.0 0.1 3.3

Yield figures were affected by the experimental treatments. Yield reduction of wheat varieties in high weed canopies was calculated relative to yield figures of handpicked weedproof controls. Wheat cultivars have shown a variety specific yield response. Figure 1. shows the magnitude of yield losses induced by high weed canopies.

Mv18 Mv19 Mv21 Mv22 Mv23 Fatima

Figure 1. Yield reduction of wheat varieties in high weed canopies

The results obtained suggest varietal differences concerning weed tolerance. The extent of yield losses between varieties had a range from one to four fold which is similar to the results of Maas (1970). According to the study Martonvasari 19 and Martonvasari 21 wheat varieties were proved to have the best weed tolerance abilities.

References Cox, J.F.and Jackson, L.E. 1949. Crop management and soil conservation.John Wiley & Sons,

New York. Jolânkai, M.and Lövei, I. 1992. Büzafajtak herbicidérzékenysége. Növényvédelmi Forum,

Keszthely, 20 p. Jolânkai, M. et al., 1995. Sustainability in agricultural development, 41 s t EAAE Seminar,Gödöllö,

Proc. 27-30 pp. Jolânkai, M. 1995. Crop production. Printorg Publishers, 70-75 pp. Maas, G. 1970. Über die Einfluß von Herbiziden auf die Standfestigkeit von Getreide. Zeitschrift

für Pflanzenkrankheit. Sonderdruck 5. Sprague, H.B. 1959. Grasslands. American Association for the Advancement of Science,

Washington D.C. Ubrizsy, G. 1962. Vegyszeres gyomirtâs. Mezögazdasagi Kiadó, Budapest.


SOIL TILLAGE AS AN IMPORTANT MEASURE IN WEED CONTROL FOR WINTER WHEAT ( TRITICVM AESTWUML. )

M. Knezevic, I. Zugec, I. Juric, M. Burkic

Faculty of Agriculture, P.O. Box 117, 31000 Osijek, Croatia

Introduction Weed control is the main reason for soil tillage. Reduced tillage or no-tillage brings about major changes in weed communities by influencing species composition, relative importance of individual species, and rates of population growth (Weston, 1990; Coffinan et al., 1992). Weed communities that evolve as results of adaption of such practices need not to be more difficult to control than those with conventional tillage (Swanton et al., 1991). In addition to herbicides, some tillage degrees are required for weed control in wheat (Miller et al., 1985; Hume et al., 1991). The objective of this work was to identify tillage systems as a cultural method, which could provide opportunities to reduce herbicide usage on winter wheat.

Methods Field trials were conducted on humogley soil type in Eastern Croatia during two winter wheat seasons, 1993-94 and 1994-95. Wheat was planted after soybean in both years. Five soil tillage systems were tested: 1. conventional tillage (ploughing, disk-harrowing)-CT; 2. disk-harrowing -DH; 3. tillage by a multitiller with chisel - MT; 4. no ploughing, seedbed preparation + sowing by a rotosem -R, and 5. ploughing, seedbed preparation + sowing by a rotosem - PK Floristical observations of each plot were made in April, May and June on 1440 m2 (240 m x 6 m). The plots had neither been treated by herbicides, nor fertilized. Weed plants and air dry weed biomass were counted and measured from 0.25 m2 plots in 20 replications, respectively. Grain yields of wheat were determined by hand harvesting samples (0.25 m2, 20 samples per tillage treatment) that were collected shortly before the final harvest. All data were subjected to analysis of variance. Rainfall and air temperatures during the growing seasons (October-July) were 638 mm and 9.6°C in 1993-94, and 656 mm and 11.4°C in 1994-95. Both growth seasons were extremely unfavourable for wheat production. The season of 1993-94 was characterized by a long, cold and wet autumn, whereas the period from the heading to the maturity stage, May and June, was extremely dry and warm. On the other hand, the whole season of 1994-95 was rather wet and cold.

Results Weed number and weed biomass were significantly (P<0.01) influenced by season (Table). Mean weed biomass was 712 kg ha"1 and 106 kg ha"1 in 1994 and 1995, respectively. The main species were annual broad-leaved weeds in both years: Anagallis arvensis (scarlet pimpernel), Ambrosia artemisiifolia (common ragweed), Chenopodium album (lamb's quarters goosfoot), Fallopia convolvulus (dull-seed cornbind), Galium aparine (catchweed), Papaver rhoeas (common poppy), Polygonum persicaria (spotted lady's thumb), Thlaspi alliaceum ( garlic pennycress) and Viola arvensis (field violet). Weed biomass under DH tillage was significantly higher (P<0.01) in both years, compared to other systems with the exception of MT in 1995. The MT treatment produced higher weed biomass than R ( P<0.01) as well as CT and PR ( P<0.05) treatments in 1995. The lowest weed number was under R tillage system with significant differences (P<0.01) compared to other treatments in both years. On the other hand, values of weed biomass in R treatment were significantly lower (P<0.01) only in relation to DH tillage in both years, as well

Session 2.3 559

as with respect to MT tillage in 1995. The described differences between other tillage treatments were not significant. Under DH tillage a large number of Galium aparine, Anagallis arvensis and Viola arvensis was stimulated to emerge. Ambrosia artemisiifolia and Polygonum persicaria populations showed a tendency to increase under PR tillage treatment, which was indicated by their higher plant densities, compared to the other treatments. Weed biomass data indicate that a relatively high number of mentioned species was not competitive with the wheat crop.

Table. Weed number, weed biomass and wheat grain yield

Tillage treatment

Weed number m"2

1994 1995

Weed biomass kg ha '

1994 1995

Grain yield kg ha '

1994 1995

CT DH MT R PR

46.8 70.6 61.4 11.4 48.0

9.6 9.8 7.4 4.0

11.6

664 980 684 575 652

64 176 141 29 80

3.990 3.480 3.420 4.110 4.190

5.000 4.310 4.300 3.750 4.780

SEM LSD (0.05) LSD (0.01)

3.5 9.8

13.0

1.2 2.9 4.2

8.1 168 211

23.2 54.4 81.7

248 580 770

19 240 350

Conclusions Preliminary results showed that differences in the composition of weed community exist induced by various tillage systems. On the basis of weed levels, the five tillage systems could be ranked in a decreasing order as DH, MT, PR, CT and R, although the differences were not always significant. Weed infestation levels were generally low, having no great influence on wheat yields, which were much more influenced by weather conditions.

References Coffman, C. B. et al., 1992. Agronomy Journal, 87: 17-21. Hume, L. et al., 1991. Canadian Journal of Plant Science, 71: 783-789. Miller, S. D. et al., 1985. North Dakota Farm Research Publication 43: 11-141,

Experimental Station, Fargo, ND Swanton, C. I. et al., 1991. Weed Technology, 5: 657-663. Weston, L. A., 1990. Weed Science, 38: 166-171.


POSSIBILITIES OF USING MODULAR GROWTH AND PLANT HIERARCHICAL STRUCTURE TO EVALUATE RESOURCE USE IN CEREAL GROWING

JanKfen

Agricultural Research Institute Kromëfiz, Ltd., Havlickova 2787, CZ-767 41 Kromëfiz, Czech Republic

Introduction White (1979, 1984) and Porter (1983a, b) demonstrate that plants can be studied as developing modular systems and their growth described analogically to processes of the population type. Thus, an individual plant may be considered as comprising cohorts of meristems of different age and growth intensity. The other important feature that must be considered in morphological studies is the hierarchical structure with branching at various levels (Arber, 1941). The cohorts of modules are designated as metapopulations (White, 1979). To consider the plants as systems hierarchical in design and built up in a modular way simplifies the description of plant form. Using this approach the knowledge of plant morphology, physiology and ecology can be synthesized: 1) Dynamics of formation and reduction of cereal yield components (shoots and grains) per unit area of the stand which is analogical to growth processes of natural populations (Miyagawa, 1983; Kfen, 1985, 1987). 2) Higher determination of growth and development of modular units in comparison with entire plants. The growth and development of the entire plant consist of a series of growth and development stages of modules some of which overlap each other (Malet, 1979). 3) Hierarchical structure of plants and intraplant competitive relationships affecting a level of modular differentiation in plant responses to environmental resources. Plants can be understood as cohorts of autonomous mutually competitive units (White, 1984). 4) A large number of random effects which influence plant and module growth in the stand (Knight, 1983). Weight distribution of productive stems or grains in maturity is, therefore, close to normal distribution (Kfen, 1985; Kfen et al., 1992). In cereals, tillers (shoots) and grains can be considered as the modules which correspond to the plant nature and practical purposes. The final size of stems is influenced by one hierarchical level. The final size of the grain is influenced by 2 to 5 hierarchical levels depending on the inflorescence morphological structure.

Methods Single productive stems and grains in extensive samples were weighed (the number of measured units in samples ranged from 100 to 3,000). They were taken among chosen variants of field experiments with winter wheat and oats covering differences in sowing date, seeding rate, nitrogen rate, and agrobiological properties (adaptation) of varieties (Kfen, 1987; Kfen et al., 1992). For these sets of values standard characteristics of variability were calculated (mean, maximum and minimum values, range, variance, standard deviation, coefficient of variation, skewness and standard error of skewness). Separation of the variability in shoot and grain weight caused by intraplant competition from their entire variability in the stand was performed by testing significance of skewness.

Results There are interplant relationships in the population. The distribution of seed or seedling weight is usually symmetric (skewness 013 = 0 ) and close to the normal distribution (see figure). At the end of the growth, the plant weight distribution is characterized by an L-shape corresponding to a

Session 2.3 561

a possitive value of the skewness (a3 > 0) as the result of an exponential character of the growth (Koyama et al, 1956). In the metapopulation, the distribution of module weight is asymmetric (log-normal or exponential) at the beginning of their growth which is given by time sequences of modules (tiller or grain) formation. At the end of the growth, the distribution of productive stems and grains is close to the normal one. The weight of modules is influenced by both inter- and intraplant competition. The intraplant competition among modules, which resulted from crop reactions to the environment, modify the variability and the skewness of their weight distribution. A positive value of skewness (I) indicates unfavourable conditions. A zero value of skewness (II) indicates prevailing random relationships in the metapopulation, i.e. the intraplant competition does not occur, the variety is adapted to the conditions. A negative value of skewness (III) indicates favourable conditions when also the later formed modules reach the similar weight (or size) as the early formed ones.

Population of plants dying out surviving a, > 0

weight (size) Metapopulation of modules (shoots or grains)

, a , > 0 dying out ^^ surviving a 3 > 0 a 3 = 0 a 3 < 0

I A II X m '

weight (size) Growth beginning • Time Differentiation period • Time Growth end

Conclusions The analysis of variability in metapopulations of modules in cereal stands and separation of variability components caused by intraplant competition enable to evaluate: - resource use (i.e. production factors of the location and inputs supplied by management

practices), as well as the influence of growth limiting factors, - utilization of variety biological potential.

References Arber, A., 1941. Biological Reviews 16: 81-103. Kira, T., 1953. Journal of the Institute of Polytechnics, Osaka City University, D4: 1-16. Knight, R., 1983. Australian Journal of Agricultural Research 34 (3): 219-228. Koyama, H. et al., 1956. J. of the Institute of Polytechnics, Osaka City University, D7: 76-94. Kren, J., 1985. Rostlinnâ Vyroba 31 (10): 1045-1054. Kren, J., 1987. University of Agriculture Brno, The Czech Republic, PhD Thesis, 134 p. Kren, J. et al., 1992. Grain growth in oats: experimentation and modelling, CABO-DLO report

165, 132 p. Malet, Ph., 1979. Annals of Agronomy 30 (5): 415-430. Miyagawa, S., 1983. Bulletin of National Institute of Agricultural Sciences, Ser. A, Yabete

Ibaraki, Japan, 30: 1-30. Porter, J.R, 1983a. New Phytologist 94: 183-190. Porter, J.R., 1983b. New Phytologist 94: 191-200. White, J., 1979. Annual Review of Ecology and Systematics 10: 109-145. White, J., 1984. Perspective on plant population ecology, ed. Dirzo, R. and Sarukhân, J., Sinauer

Associates INC., Massachusetts, USA, 15-47.


COMPARISON OF ECOLOGICAL AND CONVENTIONAL CROPPING PRACTICES OF CEREALS UNDER FERTILE CONDITIONS IN CENTRAL MORAVIA

JanKren

Agricultural Research Institute Kromënz, Ltd. Havlickova 2787, CZ-767 41 Kromènz, Czech Republic

Introduction The aim of the research was to compare the conventional and ecological variants of cereal management practices in field experiments which were carried out in the fertile sugar beet growing area. The management practices were compared for: yield level, yield structure, variable costs, profit per hectare and per ton of production, balance of energy.

Methods The analysed data have been obtained from the field experiments of the Agricultural Research Institute Kromènz, Ltd. in the years 1992-1995, except of rye and triticale which were grown in 1994 and 1995 only. The inputs in conventional variants were equal to those used in practical cereal growing in the sugar beet growing area. The inputs in ecological management practices corresponded to the IFOAM rules. The actual prices of the labour and the inputs were used for the economic analyses of cereal management practices. To compare the conventional and the ecological crop management practices the variants (1-5 for each crop) were used which had the same forecrop, variety, sowing date, sowing rate and the way of stand establishment. The size of harvesting plots was 8 m2 in four replications. The seed for sowing of the ecological variants was not dressed with any protectant. Economic evaluation of results was made on the basis of variable costs which corresponded to the inputs in crop management practices conducted in the field experiments. Since other variable costs (i.e. which were not measured) and especially fixed costs were not included in the calculation, the comparison of profit and profitability in conventional and ecological management practices was expressed in relative values (%). The energy consumption in the crop management practices was calculated according to the method and equivalents of energy inputs in crop production used in the Czech Republic (Preininger, 1987).

Results Table 1. The comparison of grain yields achieved in conventional and ecological cereal crop management practices

Cereal crop

Winter wheat Rye (1994-95 only) Triticale (1994-95 only) Winter barley Spring barley Oats

Conventional management practices

grain yield (t.ha1) 8.74 6.58 7.84 6.46 7.80 6.69

Ecological management practices - % of conventional variants

grain yield range 79.1 55.6-105.4 76.4 63.4- 91.7 68.8 61.0-77.7 89.0 66.5 - 106.2 66.2 51.5-88.5 72.9 28.2- 116.0

The ecological crop management practices resulted in the lower number of productive stems and grains per stand unit area and in lower grain yields. The lower stand density in ecological growing was connected with higher 1000-grain weight. On the contrary, in the denser conventional variants the lower values of 1000-grain weight were observed. This phenomenon

Session 2.3 563

can be explained as a result of larger branching on all levels of plant morphological structure in conventional variants (higher number of tillers per plant and grains per spike).

Table 2. The inputs of ecological management practices (conventional variants =100 %) Cereal crop

Winter wheat Rye Triticale Winter barley Spring barley Oats

Variable costs per hectare 76.1 58.7 56.6 76.6 91.0 90.0

Table 3. The economic characteristics variants = 100%) Cereal crop Winter wheat Rye Triticale Winter barley Spring barley Oats

ton of grain 96.3 76.8 82.3 86.1 137.6 123.4

Energy consumption per hectare

34.4 31.5 33.8 32.1 56.4 54.3

ton of grain 42.3 41.2 49.1 36.1 85.3 74.5

of ecological management practices (conventional

Profit per hectare Profit 80.7 94.5 81.2 112.0 54.9 44.3

per ton of grain 102.1 123.6 118.1 125.8 82.9 60.7

Profitability 106.1 161.2 142.9 146.3 60.5 48.3

Conclusions a) In ecological crop management practices the input variable costs were reduced by 9 - 43 % and the inputs of energy by 46 - 69 % (Table 2). These values of energy inputs reduction resulted from restrictions in using chemical fertilizers and pesticides in ecological growing. Similar results were also presented by Alföldi et al. (1994) and Abdulhamid (1994). b) The cereal crops differ in sensitivity to reduced inputs in cropping practices (Table 1). The lowest response was observed in winter barley due to its lowest grain yield in conventional growing. By contrast, spring barley and oats demonstrated the highest sensitivity. Generally, in ecological growing winter cereals achieved better results than spring cereals. c) In winter cereals the ecological crop management practices resulted in the higher profitability of input variable costs and in the lower costs per ton of produced grain (Table 2 and 3). On the contrary, the higher profit per hectare was reached in conventional cropping practices (except winter barley). d) The energy output/input ratio in ecological variants was almost two times higher in winter cereals and 1-1.5 time higher in spring cereals than in conventional growing. e) There are some possibilities of economically effective cereal growing in the Czech Republic using ecological crop management practices in small farms. Using the low-input practices in marginal areas, winter cereals can be grown for production of bioethanol or for above-ground biomass combustion.

References Abdulhamid, T. S. S., 1994. Proceedings of the 3rd Congress of the European Society for

Agronomy, Padova University, 18.-22. September 1994, 648-649. Alfbldi, Th.et al., 1994. Proceedings of the 3rd Congress of the European Society for

Agronomy, Padova University, 18.-22. September 1994, 650-651. Jones, MR., 1989. Agricultural Systems 29: 339-355. Preininger, M., 1987. Energy evaluation of production processes in plant production, ISSM

Praque, 29 p.


EVALUATION OF ALTERNATIVE GRAIN CROPS IN SOUTH-WEST GERMANY: NITROGEN ECONOMY

M. Kruse and W. Aufhammer

Institute for Crop Production and Grassland Research, Hohenheim University, Fruwirthstraße 23, D - 70599 Stuttgart, Germany

Introduction Amaranth (Amaranthus spp.), quinoa {Chenopodium quinod) and buckwheat (Fagopyrum esculentum) are crops producing grains with high nutritional value. These crops are supposed to make lower demands on environmental factors than most of the well known crops (Espig, 1989). According to their specific demands on climatic conditions they differ in sowing dates and vegetation periods (Aufhammer et al., 1995) and subsequently in growing conditions and nitrogen (N) supply. Very little is known about N-uptake and use of accumulated N of these crops. Thus, the aim of the present study was to compare the N-uptake and the N-utilization of these three species grown for grain production. The well known cereal crop oat which needs a similar vegetation period and which produces grains of comparable nutritional value was included in the experiment as a standard of comparison.

Methods Field experiments were conducted in 1994 and 1995 at the experimental station Ihinger Hof (near Stuttgart in southwest Germany; mean temperature: 8°C; precipitation: 700 mm). They comprised the species amaranth, quinoa, buckwheat and oat. Two genotypes of each crop were cultivated on two levels of crop density and three levels of nitrogen fertilization. During crop development N^-content of the soil in 0 - 0.9 m (kg N03-N ha1) and nitrogen uptake in above-ground parts of the plants (kg N ha ') were recorded at five dates. Hand harvested and threshed grain yield (t ha1) and its nitrogen concentration (%) were measured at harvest. Furthermore the following parameters were calculated:

N-Harvestindex (NHI) = 100 x grain N~uPtak^ above ground N-uptake

physiological N-efficiency (pNE) = 9ram yield

above-ground N-uptake

N-fertilization-efficiency (NFS) = additional N-uptake caused by N-fertilization N-fertilization

N-yield-efficiency (NYE) = additional 9rain Vield caused by N-fertilization N-ferilization

Results Dates of field emergence and N^-values at these dates are given in the table. Field emergence problems of amaranth prevented the realization of the high crop density level of amaranth, cultivar K 343, in 1995. So results of amaranth are only presented for a low crop density level. From emergence to 4-6-leaf-stage N,,^-values under amaranth and quinoa crops raised to above 100 kg N ha ' because of their very slow initial development combined with a low N-uptake during this period. This was not true for buckwheat and oat. Under these crops N^-levels decreased after emergence. Without N-fertilization amaranth exceeded the other

Session 2.3 565

Table: Species mean values of parameters of nitrogen economy (means across of nitrogen-fertilization levels and crop density levels ).

Species

Date of field emergence

Nmin in soil at field emergence (kg N ha"1)

Hand-harvested grain yield (t ha1)

N-uptake (kg N ha ')

physiological N-efficiency (kg grain kg N"1)

N-Harvestindex (%)

N-fertilization-efficiency (%)

N-grain yield-efficiency (kg grain kg N"1)

Oat

22.4.1994 8.4.1995

1994: 38 1995: 58

3.58

134.1

27.00

59.8

54.7

7.50

Amaranth

26.5.1994 8.6.1995

1994: 55 1995: 84

2.41

141.6

13.8

35.5

62.00

3.88

Quinoa

4.5.1994 23.5.1995

1994: 54 1995: 70

2.73

115.1

22.5

48.4

59.2

9.55

Buckwheat

30.5.1994 18.5.1995

1994: 70 1995: 76

1.45

90.1

16.7

36.2

61.4

4.18

crops in N-uptake until harvest (amaranth: 150; oat: 100; quinoa: 80; buckwheat: 70 kg N ha"1). The ranking of the species in N-uptake was not influenced by N-fertilization. During vegetation period significant differences between levels of N-fertilization in soil-N^ were obtained with all species except amaranth. They occured with quinoa only until heading, with buckwheat and oat almost during the whole vegetation period. The use of N accumulated by the plants, described by pNE and NHI, was best with oat and worst with amaranth and buckwheat. N-fertilization significantly affected NFE of amarant only. With this crop it raised to 92.2% when an additional late dressing was given but was 34,7% with early dressing. The NFE of the other species tendentially decreased slightly with increasing N-fertilization. Quinoa had the highest value of NYE, amarant and buckwheat the lowest.

Conclusions Amaranth seems to have a higher capability to take up soil N and late dressed fertilizer N than oat. But its low values of pNE, NHI and NYE show a low utilization of the N taken up. The N-utilization was also low for buckwheat, but in contrast to amaranth the N-uptake of this crop seems to be quite limited. The N-uptake of quinoa was similar to oat, its translocation was between oat and the other crops. Breeding genotypes with a better transfer of dry matter and N to the grain can ressolve this disadvantage, and perhaps increase the relatively low grain yields. The use of N-fertilizer to increase grain yield of quinoa was more efficient than that of oat, showing that this crop may be more interesting for high-input than for low-input cropping systems. Problems of amaranth and quinoa with very high Nmin-values in June can perhaps be resolved by later fertilizer dressing and more uniform crops.

References Aufhammer, W. et al, 1995. Die Bodenkultur 46(2): 125-140 Espig, G., 1989. Entwicklung und ländl. Raum 6:6-9


PRODUCTIVITY OF HORSE BEAN IN RELATION TO THE NITROGEN FERTILIZATION

B.Kulig, W.Ziolek

Department of Crop Production, Agricultural University, Al Mickiewicza 21, 31-120 Krakow, Poland

Introduction Nitrogen belongs to the components having the largest influence on plant yield. In leguminous crops the effectiveness of its usage depends on many factors, among them: N-mineral content in soil, chemical form of fertilizers, rate, term and way of usage, cultivars and the Rhizobium strain (Eaglesham et al., 1983; Koch et al., 1984; Mytton et al., 1977). The urea foliar spray limited activity of nitrogenase to the lower degree (Kocoh, 1993) and causes the increase of seed yield (Day et al, 1979; Kocoh, 1993). The research purpose was an investigation of the response to N-fertilization of cultivars differing in morphology.

Methods In field experiments made on degraded chernozem soil at the Agricultural Experimental Station near Krakow (south Poland) the authors tested in the years 1993-1995 the response of two horse bean cultivars: Nadwislahski and Tibo to nitrogen fertilization: O, 20, 40 kg N ha"1 - applied pre-sowing and 40* kg N ha"1 (20 kg pre-sowing + 10 kg by foliar spray before plants start flowering + 10 kg by foliar spray to the seed filling). The phosphorus and potassium fertilization in the rates 100 kg P20, and 140 kg K20 ha"1 was applied before horse bean sowing. The agricultural measures were carried on according to the horse bean requirement. An estimation of the effect of the investigated factors was made on the base of seed yield and of the separate components of yield structure (the number of plants bearing seeds per unit of area, the number of seeds per plant, the mass of 1000 seeds).

Results

^

Figure 1. Horse bean yield in dependence of the investigated factors

Session 2.3 567

The average seed yield in the conducted research was 3.61 t ha"1 . Examined factors did not actually influence the seed yield however the Nadwislanski cultivar with undetermined growth rhythm had a 21% higher yield than the Tibo cultivar (self-determinate). The climatic conditions in different years had high influence on horse bean seed yield (Figure 1). It resulted in interaction between years and cultivars as well as N-fertilization. Nitrogen fertilization caused a yield increase in 1995 only, whereas in the remaining years its negative influence on seed yield could be observed. In the conducted experiment the Nadwislanski cultivar was characterized (in comparison to Tibo cultivar) by 4% increase in the 1000 seed mass, the number of pods was 15% higher and the number of plants per m2 was by 15%> lower (Table 1).

Table l.The effect of the investigated factors on the yield structure components

Features

Mass of 1000 seeds (g)

No. pods per plant

No. seeds per pod

No. plants m"2

Cultivars

Nadwislanski

446

7.38

3.04

51.4

Tibo

429

6.31

2.64

60.7

N treatment (k

Control 0 20

441

7.51

2.81

55.8

446

6.73

2.91

55.5

;gN ha"

40

428

6.82

2.81

57.6

' )

40*

435

6.98

2.82

55.3

Means

438

7.01

2.84

56.1

Conclusions In the conducted research the Nadwislanski cultivar showed a higher yield as a result of the higher mass of 1000 seeds, number of pods and number of seeds in the pod. The seed yield depended on the climatic conditions in the particular year of research. The interaction between years and cultivars was wident,the same was true for years and N-fertilization. Nitrogen application on good soils before sowing as well as partially before sowing, partially as foliar spray, is insufficiently effective and can even cause yield reduction.

References Day J.M. et al, 1979. Journal of Agricultural Science, Cambridge 93: 629-633. Eaglesham A.R.J.et al, 1983. Agronomy Journal 75: 61-66. Koch K. et al., 1984. Kali-Briefe 17(l):53-58. Kocoh A.,1993. Fragmenta Agronomica 4: 169-171. Mytton L.R.et al., 1977. Euphytica 26: 785-791.


EFFECT OF SULPHUR NUTRITION ON THE ACTIVITY OF NITROGENASE AND ENZYMES OF THE C- AND N-METABOLISM OF VICIA FABA MINOR AND PISUM SATIVUM

A. Lange and H.W. Scherer

Institute of Agricultural Chemistry, University of Bonn, 53115 Bonn, Germany

Introduction Studies with different legumes have shown that the depression of the biological N2

fixation (BNF) under conditions of insufficient S supply is often correlated with a decrease in the formation of nodules as well as with lower N contents in the above grown plant parts. For this reason it may be assumed that N2 fixation is directly influenced by S deficiency. Therefore the objective of our experiments was to study the influence of S nutrition on the nitrogenase activity and the activity of different enzymes, involved in the C- and N-metabolism of nodules.

Methods In a pot experiment with the mixture of quartz sand and the top soil of a luvisol derived from loess (2:1; 11 kg pot"1) two S rates (0 and 200 mg S as S04 ' pot"1) were applied to Vicia f aba minor and Pisum sativum. At two and three times, respectively, (for more information see figures) the nitrogenase activity was determined using the acetylene reduction (AR) method after separating the tops of the plants from the roots with the nodules and rinsing the roots with tapwater. The assay to determine the activity of different enzymes in the cytoplasm of the nodules (malate-dehydrogenase [MDH], PEP-carboxylase [PEP-C], glutamate-synthase [GOGAT]) was performed after extraction of the isolated nodules spectrophotometrically, monitoring the oxidation of NADH at 365 nm. Conditions for enzyme assays were described previously (Duke et al., 1975; 1976; Groat et al., 1984).

Results With both legumes the reduction of acetylene pot"1 was significantly reduced under S deficiency conditions (Fig. 1). With Vicia f aba minor this decrease may be explained with the decrease of the specific nitrogenase activity (AR g'1 dry matter of nodules). With Pisum sativum the decrease was further caused by a reduced nodule formation. The results also demonstrate that with both legumes the activities of key enzymes of the C- and N-metabolism, based on g fresh weight of nodules, significantly decreased under S deficiency conditions (Fig. 2). However the influence of S nutrition on the activity of MDH and PEP-C was more pronounced as compared with GOGAT.

Conclusions Finally it is stated that with both grain legumes the activity of enzymes, concerning N2

fixation, is reduced in early stages of S deficiency, that means before S deficiency symptoms or yield reduction appears.

References Duke, S.H. et al., 1975. Physiologia Plantarum 34: 8-13. Duke, S.H. et al., 1976. Plant and Cell Physiology 17: 1037-1044 Groat, R.G. et a l , 1984. Crop Science 24: 895-898

Session 2.3

• t h y l a n a I n m g / p o t — n - - i

569

z

1 . s

-1

o . s

o

Vicia faba Pisum sativum

o t h y l s n o I n mç//a d r y w t . n o d u l e s * n - 1

Figure 1. Influence of S supply on nitrogenase activity of Vicia faba minor and Pisum sativum (means with the same letters are not significantly different)

U/g fresh wt. nodules

1 0 0

10

0,1

V i c i a f à b à

rvtDH

PEP-C

1 5 20 25 30 35 40 45 50 55 60 65 70

days after planting

ooo

1 0 0

1 0

1

U/g fresh wt. nodules

: Pisùpi sativum : • * * * *

' " * ^ < ^ ; MDH

; : I4-: : ; ; (: : ;**: : ; : : : ; :

r . . . : - ^ ~ - ^ . PEP-C

** : : ' - - - • ' - — - Ï - ^ : GOGAT

— 0 mg S -1- 200 mg S

15 20 25 30 35 40 45 50 55 60 65

days after planting

Figure 2. Influence of S supply on the activity of enzymes of the C- and N-metabolism (* LSD 5 %; " LSD 1 %; * " LSD 0,1 %)


OPTIMAL USE OF RESISTANCE FOR AN INTEGRATED MANAGEMENT PROGRAM OF CEREAL NEMATODE POPULATIONS

F. Lasserre"3', B. Jouan1, R. Rivoal2

1INRA, Service de Recherches Intégrées en Productions Végétales,2 Laboratoire de Zoologie, BP 29 35650 Le Rheu, France 3 Present address: INRA, Laboratoire d'Agronomie-Environnement, ENSAIA, BP 172 54505 Vandoeuvre-les-Nancy, France

Introduction The aim of this study was to develop proposals for an integrated management programme to control nematode populations in a cereal agro-ecosystem. Previous research has been carried out to develop control means against the cyst cereal nematode, Heterodera avenae, as rotations, resistant varieties, weak hosts and nematicides (Rivoal & Cook, 1993). No work had been ever made on integrated control of the cereal nematode community.

Methods The study was done in a long term experiment (1982-1993) located at Argentan (Orne, France) on soil infested by H. avenae, Hal 1 pathotype. Rotations were designed to establish H. avenae densities above (rotation A) or below (rotation B) the damage threshold (5 larvae / g of soil), by cropping respectively H. avenae susceptible cv. Peniarth (A) or resistant cv. Panema (B) oats at high frequency (70%) in a pair of 360 m2 (6x60m) strips for 12 consecutive years. First, we studied population dynamics of//, avenae and Pratylenchus neglectus, a secondary nematode species. H. avenae post-culture densities were assessed through samples often soil cores which were taken from each of four equidistant 10 m2 (2x5m) areas, along the middle of each strip in October of each year after ploughing. Both nematode root densities were estimated at 2-node stage from two parallel 0.50 m rows (0.20 m2) at five points 10 m apart along the middle of each strip. Nematode extraction from roots and soil is described by Rivoal et al (1995). Secondly, fifty cysts of//, avenae were collected in each rotation in October 1990 and 1992 for fungal parasitism assessment with Crump's method (Crump, 1987). Finally, possible selection of a resistance-breaking pathotype was checked in rotations A and B. For this, soil samples were taken from 4 m2 (2x2m) areas, the center of these areas being 5 m equidistant and the areas beginning 7.5 m from the end of each strip. Each of these 10 samples were divided in three PVC tubes sown with a pregerminated seed of resistant Panema. Activity of the nematode was monitored by its development on 3 cv. Peniarth controls. Numbers of white females were assessed at the 1-2 node stage of plant growth after washing the roots.

Results Nematode population dynamics are presented in the table and the figure.

Heterodera avenae and Pratylenchus neglectus population densities (nematodes per g of root) in wheat Arminda at 2-node stage grown after susceptible (rotation A) or resistant (rotation B) oats.

rotation 1991 1992 Pratylenchus neglectus

Heterodera avenae

A B A B

129.6(38) a 407.0 (69.2) b 62.5(19.7) a 0.3 (0.7) b

565.3 (280.9) a 1594.2(601.2) b

90.2(30.5) a 53.8(19.5) b

Means per column (standard deviation) of replicates followed by the same letter are not significantly different at P<0.05 by the Newman-Keuls test.

Session 2.3 571

Year Rotation A Crop' Rotation B

1982 S oat R

83 S wheat S

84 S oat R

85 R maize R

86 S oat R

87

: S oat R

88 S wheat S

89 S oat R

90 S oat R

91 S wheat S

92 S wheat S

93 S oat S

Heterodera avenae population dynamics in rotations differing in the frequency of resistant (R) and susceptible (S) cereal crops. Each point represents the mean of 4-5 replicates. Vertical bars show standard error of the mean.

Fungal parasitism of cysts, especially by Verticillium chlamydosporium, was much more prevalent in rotation A (32.3 % in 1990, 25.5% in 1992) than in rotation B (9.5% in 1990, 4.1% in 1992). In pots of soil sampled from rotation B for selection pressure study, a consequent number ofH. avenae white females developed on resistant cv. Panema (mean of 6.3 females per plant) whereas quite no female was found in rotation A (mean of 0.2 per plant). The number of females in rotation B varied with the position along the strip: maximal numbers were found at 22.5 and 27.5 m (respectively means of 20.0 and 10.3 females per plant) from the end of the strip.

Conclusions There were important consequences of long term cropping with the H. avenae resistant oat variety cv. Panema. Decrease of densities of//, avenae was associated with a proliferation of P. neglectus which could reach damaging levels. Extremely rapid re-establishments of//, avenae populations was observed on susceptible wheat grown for two years after the resistant oat. The incidence of endoparasitic fungi as V. chlamydosporium was also reduced, which played a main role in permitting rapid re-infestation. Long term use of the resistance also led to the selection of a resistance-breaking pathotype of the cyst nematode on Panema, localized specially in one part of the strip. All these phenomena showed that the long term use of highly effective resistance could provoke deep modification of nematode populations. This should be taken into account when devising a strategy for optimal use of resistance, with combinations of partial resistances, rotations of genes and mixtures of isogenic lines and this contributed to a basis of integrated management programs of nematode populations.

References Crump, D.H., 1987. Nematologica 33: 232-243. Rivoal, R. and Cook R., 1993. Nematode pests of cereals. In. Evans K., Trugdill D.L. & Webster J.M. (eds), Plant parasitic nematodes in temperate agriculture, CAB International, Wallingford, 259-303.

Rivoal, R, et al., 1995. Nematologica, 41: 516-529.


USE OF ASSOCIATIVE DIAZOTROPHS FOR NITROGEN NUTRITION OF GRAMINEOUS CROPS

Lisova N ' , Galan M.1, Patyka V.2, Bezdushny M.1, Pogorecky A.'

'Institute of Agriculture and Cattle-Breeding UAAS, 292084 Lviv - Obroshyn, Ukraine 2Departament of Soil Mikrobiology, Institute of Agriculture UAAS, 334080 Gvardejsky, Crimea, Ukraine

Introduction Nitrogen fixation associated with the roots of gramineous plants has been reported previously by Day and Doberejner (1976). Extensive investigation during the last years has shown that inoculation of cereal crops with different diazotrophs improved the plant growth and productivity in many cases ( Okon, 1985; Pacowsky, 1988; Belimov et al', 1994; Lisova et al, 1995). The positive benefits from inoculation with diazotrophs have been attributed to several mechanisms such as biological nitrogen fixation and increased root uptake capacity because of enhanced root development and root hair formation in responce to production by bacteria of plant growth hormones (Harari et al., 1988; Zimmer and Bothe, 1988; Strzelczyket al.,1994).

Methods The sensibility of cereal crops (winter wheat, rye, maize and oat) to inoculation with associative N2-fixing bacteria belonging to Azospirillum, Flavobacterium, Agrobacterium, Enterobacter was studied in field experiments. All associative diazotrophs were positive in an acetylene reduction test (nitrogen fixation activity). The trials were conducted at the Stavchany Experimental Station near Lviv on dark-grey, podsolic soils. Fertilization levels were: P^K^, but for maize- P^K^.The levels of N2-fixation in root zone of plants were measured by acetylene method. The yield of the green biomass was analysed: maize- in milk-wax ripeness period; oat - in flowering period.

Results Results are presented in Tables 1,2,3. For rye (variety Belta) the highest grain yield was obtained with Azospirillum sp. inoculation ( 5,3 t ha1; without inoculation - 4,3 t ha1).

Table 1. Grain yield and yield components of winter wheat variety Kyjanka with diazotrophs inoculation

Inoculation treatment

1 without inoculation 2. Agrobacterium 3 Enterobacter A Azospirillum 5.mixture 2+3+4

LSD005

shoots number per plant

3.8 3.9 4.1 4.2 4.6 0.4

gram number per plant

117.5 110.2 116.8 112.7 113.0 5.2

grain mass, g plant

6.1 6.9 7.9 7.2 7.7 0.97

1000 grain mass, g

47.6 48.6 49.0 48.6 49.0 1.0

grain yield, t ha-1

4.3 4.5 4.8 4.8 4.8 0.44

Session 2.3 573

Table 2. The influence of inoculation with' associative diazotrophs on biomass (dry matter) yield of maize (hybrid Juvilejny 70), in tons ha1.

Nitrogen rate(with P90K90 )

without fertilizers 0 N 3 0

N 6 0

NM

LSD„„5

without inoculation

1994 8.7 8.8 8.9 9.5 10.3

0.41

1995 7.9 7.8 8.9 9.7 9.8

0.51

Agrobacterium sp.

1994 8.7 8.7 9.2 9.7 10.3

0.22

1995 8.6 9.3 9.6 10.4 10.8

0.37

Flavobacterium sp.

1994 8.7 9.5 9.6 10.3 11.0

0.22

1995 9.0 9.5 9.5 10.3 11.0

0.37

Table 3. The effect of inoculation with Enterobacter sp. on grain yield of different oat varieties, 1992-1994.

Inoculation Grain, t ha1, rate, cell ml1

Lvivsky early Bug Ô 4~8 5~Ö 2-109 5.1 5.4 4-109 5.3 5.2 6-109 5_1 5_2 LSD005 0.29 0.29

Conclusions Under field conditions it was shown that the inoculation with associative diazotrophs of the cereal plants increased the green mass yield and grain yield. In winter wheat inoculation with Enterobacter and Azospihllutn has the highest influence on grain yield. Our results show on important role of the associative diazotrophs in nitrogen nutrition of cereal crops growing in West Ukraine. Nearly 30% of the nitrogen may be taken in place of mineral nitrogen in nutriment of the maize because of inoculation with associative diazotrophs. The highest nitrogen fixation at roots zone of maize plants was found in the variant with inoculation Flavobacterium sp. (5-6 times as large as control). On the basis of the obtained results in trials with oat it can be concluded that it is the cultivar sensibility to inoculation with Enterobacter, the variety Lvivsky early was more sensibility to inoculation.

References Belimov, A.et al.,1994.Mikrobiology 63:900-908. Day, I.M.,Doberejner, J,1976. Soil Biological Biochemistry. 8:45-50. Harari, A. et al., 1988. Plant and Soil 110:275-282. Lisova, N. et al., 1995.Fragmenta Agronomica 2(46):116-117. Okon, Y.,1985.Trends in Biotechnology 3:223-228. Pacovsky, RS,1988. Plant and Soil 110:283-287. Strzelczyk, E.et al.,1994. Microbiological Research. 149:55-60. Zimmer W.,Bothe H. 1988. Plant and Soil 110:239-2477.


ESTIMATED RADIATION USE EFFICIENCY IN ALTERNATIVE CROPS UNDER TYPICAL MEDITERRANEAN CONDITIONS

N. Losavio, N. Lamascese, F. Serio, A.V. Vonella

Istituto Sperimentale Agronomico, Via C. Ulpiani 5, 70125 Bari, Italy

Introduction Crop biomass accumulation can be described as a function of the quantity of Photosynthetically Active Radiation (PAR) intercepted by the canopy, that is, the efficiency with which the radiant energy is transformed into biomass (Gallagher et al., 1978). Some functional models use this approach to simulate crop biomass accumulation (Charles-Edwards et al., 1986). This paper examines the growth of four alternative crops (part of the "PRisCA" Project, of the Italian Ministry of Agricultural, Alimentary and Forest Resources) in terms of radiation interception and the efficiency of utilization of intercepted light (radiation use efficiency, RUE) in dry matter production.

Methods Field studies were conducted at Metaponto in Southern Italy (Lat 40° 24' N, Long 16° 48' E) during the 1993 season. Crops of kenaf {Hibiscus cannabinus L) , sweet sorghum {Sorghum bicolor L. Moench), grain sorghum {Sorghum vulgare L.) and Jerusalem artichoke {Helianthus tuberosus L.) were grown on a clay loam soil (Typic Epiaquerts according to the Soil Taxonomy) on plots adequately irrigated (re-establishing the calculated évapotranspiration on the basis of agrometeorological data) and with large amounts of fertilization. The total aerial dry matter and leaf area index evolution were measured once every 10 days (from 10 days after emergence) on a sample of 5 plants for each block. Total solar radiation, rainfall, Class-A pan evaporation and other standard weather conditions were continuously recorded in a meteorological station near to the experimental site. Using the terminology proposed by Charles-Edwards (1982), the simplest form of model for crop dry matter production is DM = G PARi =€F0.48Rs, where DM is dry matter production per unit ground area; F, the fraction of light intercepted, PARi, the daily intercepted PAR and Rs, total solar radiation, and G is the efficiency with which the crop transforms light energy into dry matter. F (1 - e<KIAI)) depends on Leaf Area Index (LAI) and light extinction coefficient (K). Daily values of PARi were calculated from values of total solar radiation measured, assuming that 48% of the total solar radiation was PARo (incident photosynthetically active radiation). RUE was calculated from the slope of the regression line for dry matter as a function of PARi.

Results LAI, measured during the biological cycle for the four crops examined, is shown in Figure 1. The highest value of LAI in absolute (7.8) was measured in the grain sorghum 53 days after emergence. The accumulation of dry matter (Figure 2), always increased during the biological cycle of the four crops until reaching the maximum value at the harvest.The highest quantity of dry matter was obtained in sweet sorghum (3430 g m"2) while the kenaf produced the lowest quantity (1502 gm"2). The RUE was estimated from a linear regression between cumulated PARi and dry matter (Figure 3). Our results show that sweet and grain sorghum have the highest values of RUE (3.1 and 3.0 g ML1, respectively); the Jerusalem artichoke, on the contrary, for its long biological cycle, has the lowest value.

Session 2.3 575

b

6

3"

2

0

j /

[/ i Figure 1. Leaf area index for sweet sorghum

(1), grain sorghum (2), kenaf (3) and Jerusalem articoke (4)

40 60 80 100 120 140 160

DAYS AFTEH EMERGENCE

4000

3000

E

S 2000

3: a

1000

0 ig

Â 4 j/s

Figure 2. Dry matter time trend of aerial part for sweet sorghum (1), grain sorghum (2), kenaf (3) and Jerusalem articoke (4)

20 40 60 80 100 120 140 160

DAYS AFTER EMERGENCE

3600

3000

_ 2400

'E

S 1800

° 1200

600

0 Â

.1

Figure 3. Relationship between accumulated aerial dry matter and intercepted photosyntetically active radiation for sweet sorghum (1), grain sorghum (2), kenaf (3) and Jerusalem articoke (4)

200 400 600 800 1000 1200 1400

PARI (Mj ni!)

Conclusions This study has shown that, in a Mediterranean environment, among the four alternative crops under comparison, each grown under non-limiting water and nutrient conditions, the RUE in sweet sorghum and grain sorghum, is higher than that reported in literature for crops classified as C4 plants.

References Charles-Edwards, DA., 1982. Academic Press, North Ryde, N.S.W., 161 p. Charles-Edwards, DA. et al., 1986. Academic Press, Sydney, 235 p. Gallagher, H.N. et al., 1978. Journ. Agriculture Ski., Camb. 91: 47-60


CROP RESIDUES AND SOIL TILLAGE MANAGEMENT: EFFECTS ON SOIL STRENGTH

M. Maiorana, R. Colucci, D. Ventrella

Istituto Sperimentale Agronomico, Via C. Ulpiani, 5 , 70125 Bari, Italy

Introduction In Southern Italy, durum wheat is a widespread crop, both in rotation with industrial crops (sunflower, sugar beet, etc.) and in continuous cropping. The wheat residues are normally burned. Since the use of manure is by now very scanty and the progressive worsening of soil fertility cannot be counterbalanced applying ever higher levels of mineral fertilizers for economic and ecological reasons, the ploughing in of straw and stubble seems to be the most suitable agronomic technique, also because of the positive effects that it can have on some chemical, physical and hydrological characteristics of soil. With the aim of making a contribution to these issues, this Institute undertook a long-term research on the ploughing in of crop residues, in comparison with their burning (Maiorana et al., 1992). This paper evaluates the effects of these treatments on soil strength, soil moisture and on water infiltration rate at the fifth year of trial.

Methods The research is carried out since 1990 in Foggia, a typical wheat-growing area of Southern Italy, on a silty-clay soil (Typic chromoxerert, fine, Mesic) of alluvial origin. The climate is classified as "accentuated thermomediterranean", by Unesco-FAO, with scanty rains (440 mm per year, mean of the last ten years), concentrated mainly in the winter months. On plots of 200m2 each, laid out in a split-plot design with 3 blocks, 2 soil tillage depths (Dl= 40-45 cm, by traditional moulboard ploughing; D2 = 20-25 cm, by surface disc-harrowing) and 2 ways of straw disposal (B = burning; I = incorporation) are compared in a continuous dryland cropping of durum wheat. The soil tillage is the main factor, the straw disposal the split factor. The soil strength was evaluated, in January, February, March and April, 1995, in about 0-50 cm layer, using a Bush recording penetrometer (Findlay, UK). The readings were taken at 3.5 cm depth increments up to the total lenght of 52.5 cm. Ten measurements were made for each block. Since the penetrometer resistance may be affected by soil moisture (Vyn and Raimbault, 1993), the soil water content at 3 depth layers (0-20, 21-40 and 41-60 cm) was determined gravimetrically, at the same time of penetrometer measurements. Besides, the water infiltration rate was determined by a double cylinder method. The values of soil moisture and soil strength were submitted to analysis of variance (AOV); the first step of reading of penetrometer was not considered, because it was completely unreliable (the penetrometer did not allow for complete support of the probe on the soil).

Results To better evaluate the effects of the treatments on soil strength, even the cone resistance values obtained in the first year, at the beginning of the research, were submitted to AOV; as only very small differences were found among them, and then the whole trial field was characterized by fairly homogenous soil strength, they are not reported in this paper. Figure 1 shows the trend of penetrometer resistance values for the different treatments. The most marked effects were determined by soil tillage (Fig. 1 A). In fact, a lesser soil compaction was observed with the deeper tillage (Dl), especially starting from a depth of about 35 cm. The influence of different ways of straw treatment, on the other hand, was negligible (Fig. IB). Ploughing in showed soil strength values slightly lower than those achieved with burning. The

Session 2.3 577

superiority of Dl treatment is confirmed by the "soil tillage x crop residues treatments" interaction (Fig. 1C): in fact, the significantly best responses are those of ID1 and BDI treatments.

0 500

10.5

17.5

24.5

31.5

37.5

44.5

51.5 0

Cone resistance (kPa) 1000 1500 2000 2500 3000 3500 4000

Dl O

\ M—°~

V \— ***

\ \^ ***

Ö n***

Cone resistance (kPa)

0 500 1000 1500 2000 2500 3000 3500 4000

Cone resistance (kPa)

0 500 1000 1500 2000 2500 3000 3500 4000

Figure 1 - Soil strength profile according to soil tillage (A), crop residue treatments (B) and "soil tillage x crop residue" interaction (C) (*,**,*** significant difference at the 0.05,0.01, and 0.001 probability levels, respectively).

On the contrary, the effects of the treatments on soil moisture were very scanty and not significant to the AOV. The influence that soil moisture can have on soil compaction has been then studied; the analysis of the data showed a relationship of the inverse linear type between these two

parameters, but only considering the straw treatments (Fig. 2). Particularly, this relationship was more evident with the crop residues burning (R2= 0.871) than with their incorporation (R2= 0.372). Instead, no relationship resulted for the different tillage systems. Referring to the water infiltration rate, the highest values were observed in the plots submitted to crop residues incorporation (7.1 cm h"1 vs. 5.5 of burning) and in those with deeper soil tillage (6.8 vs. 5.8 cm h"' for shallow tillage).

Soil moisture (g g-1 )

Figure 2 - Influence of soil moisture on soil strength in the 0-60 cm layer.

Conclusions Although the effects of crop residues ploughing in on some physical-hydrological parameters of soil can appear after many years, the results obtained with this research have shown that tillage at 40-45 cm, especially with the straw incorporation, determined a lesser soil strength and a higher water infiltration rate. With these treatments, therefore, even in presence of a silty-clay soil, it seems possible to obtain a greater permeability and a better soil structure.

References Maiorana, M. et al., 1992. Proc. 2nd ESA Congress, Warwick Univ.: 100-101. Vyn, T.J. and Raimbault, B.A., 1993. Agronomy Journal 85: 1074-1079.


STUDY ON THE EFFECT OF N FERTILIZERS ON TOTAL NITROGEN AND NITRATE CONTENT OF GREEN PEA AND GARLIC

E.Nâdasy

Department of Agrochemistry, Pannon University of Agricultural Sciences, 57 Deék St. 8360 Keszthely, Hungary

H-

Introduction One of the main consequences of intensive N fertilization is the nitrate accumulation often causing health problems. The quantity and form of N fertilizers are very important factors of nitrate accumulation. This problem is very important at vegetables, because they are generally consumed immatuiately and uncooked besides they are usually manured to the highest degree. The aim of our experiments was to study the changes of the nitrogen and nitrate content of green pea and garlic using different N fertilizer forms at increasing rates.

Methods The experiments were set up in 5-kilo pots on brow» forest soil ( N:2.4 mg kg"', pH(KQv6.82, humus: 1.8%) under greenhouse conditions in four replicates. Petit Provencal green pea variety and garlic were used with five increasing doses (40, 80, 160, 320, 640 mg N kg"' soil) of tliree N fertilizers: NH4N03(32% N), (NH4)2SO4(20.5% N) and Ca(N03)2 (7.6% N). Treatments were also given 120 mg P2O5 and 200 mg K 2 0 kg" ' soil. Water was dosed by weight using irrigation as far as 60% of water capacity.The pea experiment was carried out during eight weeks. Samples were collected at three growth stages (4. 6. 8. weeks) from the leaves and in the eight-week age from the seeds. Garlic was grown up to seven weeks then we collected samples from the leaves and bulbs. The nitrogen content of samples was determined with sodium-hypo-bromite titration with dead-stop indication, the water soluble nitrate content of dry matter from the 1:800 rate water extract with photometric method using N-( l-naphtyl)-ethylene-diamine and sulphanilamide as reagents.

Results Results are presented in Figures 1-4.

8week -Ca(N03)2 8 week (NH4)2S04

8 week N H 4 N 0 3 _ 4 week Ca(N03)2 / 4 w e e k (NH4)2S04

4 week N H 4 N 0 3

V

O 40 80 160320340 N doses (mg kg soil)

180

160

140

20

OO

80

60

40

20

0

Leaf-Ca(N03)2 L e a H N H 4 ) 2 S 0 4

Lea f -NH4N03 Bulb-Ca(N03)2

Bulb (NH4)2S04 Bulb N H 4 N 0 3

N doses (mg kg soil)

Figure 1. Effect of N fertiliters on nitrate content of green pea

Figure 2. Effect of N fertilizers 011 nitrate content of garlic

Session 2.3 579

10i

Figure 3. The N content of green pea

40 80 160 320 H doses (mg kg" soll)

E

-o

Leal 4th week

Leaf 6th week

ss Leaf 8th week

Seed

Figure 4. The N content of garlic

160 N doses (mg kg soil)

Conclusions It was established that the nitrogen content in the leaves of green pea increased with the higher N doses, but it was decreased when the plant became mature. N concentration in the seed was high in all treatments (3.42-5.60%) and rised continuously applying greater N rates. The nitrate content of green pea leaf-samples was low and it decreased during vegetation period. The seed had no measurable nitrate content at all. The results indicate that the nitrate accumulation of Petit Provencal green pea variety is low ( 200 mg kg-1 dry matter). Comparing the effect of the applied N fertilizers on the realization of the nitrogen and nitrate content of the plant it was established that the different N fertilizers did not changed nitrogen content of pea samples significantly. Nitrate content of the four-week leaves was significantly increased after using NFI4NO3 compared to the other two fertilizers.

The nitrogen content in the leaves of garlic was higher than in the bulb and it also was increased by the maximum N doses. The nitrate content of garlic rised with the increasing fertilizer doses, but its rate WAS low both in leaves und bulbs. The young garlic did not Accumulate nitrate in great quantities. We bad no significant differences between effect of applied N fertilizers both on the nitrogen and the nitrate content of the plant.

References Duvvalda J.G. et al. I987. Scientia Horticulturae 3-4, 161-173 p. Fiileky, Gy. 1970. Agrochemistry and Soil Science Hungary 3. 339-345 p. Smukalski, M. et al. 1991. Archives of Agronomy and Soil Science 6. 459-467 p. Terbe I. et a l , 1986. I.Lippay Jânos Conference Budapest Proceedings 125-131 p. Thammné, f 1987-1988. Agrochemistry and Soil Science Hungary 36-37. 323-337 p.


THE EFFECTS OF IRRIGATION, FERTILIZATION, TILLAGE AND PLANT DENSITY ON CORN (Zea Mays L.) YD3LD

J. Nagy ', L. Huzsvai \ J. Tamâs ', G.J. Kovâcs2,1. Mészâros3

'Agricultural University, Debrecen, Hungary 2Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences, Budapest, Hungary, 3L. Kossuth University, Debrecen

Introduction The yield of a plant culture depends not only on ecological, genetic and technological factors, but on their interactions as well. In research, the evaluation of both the individual effects of the factors and their joint effects are necessary. The joint effects of different plant cultivation factors were estimated by Györffy (1976), who found that the largest yield increase is achieved when the most significant plant cultivation factors are at their optimal levels. The crucial effect of fertilization on the yield of corn hybrids was shown by Berzsenyi (1993). Those interactions which involved environmental effects proved to be the most significant.

Methods At the Arable Land Experimental Farm of the Department of Crop Production and Land Use we examined the effect of plant cultivation factors on the yield of corn. Our multifactorial experiments allow for the evaluation of the effects of fertilization, plant density and irrigation (all with two variants). In our experiments we had adjacent irrigated and non-irrigated blocks (5376 m ). The former were provided water in the following amounts, enough to satisfy the plant's demand for water: 1990,100 mm; 1991, 60 mm; 1992, 170 mm; 1993, 120 mm; 1994, 110 mm. These major blocks were then subdivided for each hybrid; in turn, these were divided to allow for different fertilizer/plant density treatments. In all, there were four random repetitions of each combination of treatments, each on a 448 m plot. Our experiment was supported by the National Science Fund (T 017047). The statistical model used was a improved adaptation of Box-Wilson (1951) methods. The data were evaluated using analysis of variance methods (Svab, 1981; John, 1971). The method was used to stabilize the variance of the cells. Maximum likelihood methods were used to disaggregate the variance components. A mixed fixed-random effects model was used to estimate the effects, as suggested by Huzsvai (1994). The joint effects of irrigation, plant density and fertilization were quantified using ANOVA methods.

Results When evaluating the data only effects and interactions not related to weather and interactions valid every year were examined. Symmetric effects of the treatments were estimated in relation to the major average of the experiment. The model design can be seen in Table 1, which includes all treatments and the interactions between irrigation and fertilization and plant density and fertilization. These two interactions were not related to weather and the direction of their effect was the same each year. The congruency of the direction of the effects does not mean a congruency of their degree. For the evaluation of the significance of the effects a two-sided symmetrical test was used. The statistical significace of the test can be found in the last column of Table 1. During the 5 year period the major average of the experiment was 8.21 ha'1, a value which serves as a comparison point for the treatment averages. The yield increase due to irrigation was 869 kg/ha, and without irrigation the yield decreased by the same amount. The effect of irrigation was significant at p=0.001. The effect of plant density was 185 kg ha"1 Changing the treatments in the same direction increases their effect on yield. Our research results correspond with those of Györffy(1986) and

Session 2.3 581

Berzsenyi(1993): varying the use of one factor in plant production will not achieve the most favourable result. Interventions in production are not independent of each other; varying one factor should be accompanied by variation of others so as to produce most efficiently. During the 5 years lower plant density (60,000 ha"1) was more favourable for the achievement of high yields; a plant density of 80,000 ha'1 density resulted in a fall in yield due to the drought years analyzed. High density planting involves great risks. The effect of plant density was significant at p=0.05. By examining the effect of fertilization we have come to the conclusion that no fertilization results in a considerable yield loss (1541 kg ha'1) while applying a fertilizer dosage of 120 kg N + 90 kg P2O5 + 105 kg K2O increases yield by a similar amount. Fertilization had the biggest effect on yield every year. This effect was significant at p=0.001.

Table 1. Results of the analysis of variance components (Debrecen, 1990-1994) Treatments Fix Tillage Irrigation Plant density Fertilization Irrigation x Fertilization Plant density x Replicates Test parameter

fertilization

= -2 • Log X --

Estimated 8.159 0.560

-0.869 0.183

-1.541 0.448 0.151

* 0.000 = 2557,5

Dispersion 0.093 0.093 0.093 0.093 0.093 0.093 0.093

* 0.000

Significant at p 0.000 0.000 0.000 0.048 0.000 0.000 0.100

Conclusions After an evaluation of crop production factors (tillage, irrigation, plant density and fertilization), the individual effects of each factor and the interaction between irrigation and fertilization and that between plant density and fertilization proved to be significant. On the basis of our experiments we have established that these two interactions are positive, independent of the weather conditions, and that the direction of their effect is the same each year, but the degree of their effect varies. The results indicate that the plant cultivation factors are related to each other. The irrigation - fertilization and plant density - fertilization interactions are positive, and accordingly all three factors have to be adjusted simultaneously when production levels are changed. When disaggregating the variance components, the major averages showed a mid-tech level of production. When considering a shift to low-input production it should be considered that a decrease in the use of one production factor reduces the effects of the others; relatively high amounts invested in the other factors will not be effective. No matter what production level is targeted the most favourable interactions of water, nutrient supply and plant density have to be simultaneously assured.

References Berzsenyi, Z., 1993. Plant analysis in maize production research. Doctoral dissertation,

Martonvâsâr. 1-150. Box, G.E.P. and Wilson, K.B., 1951. On the Experimental Attainment of Optimum Conditions.

Journal of the Royal Statistical Society. Series B. 13.1. Györffy, B., 1976. Evaluation of crop production factors affecting the yield of maize.

Agrârtudomânyi Közlemények 35, pp. 239-266. Huzsvai, L., 1994. Comparison of biométrie methods of experiments in crop production and tillage.

Ph.D. Thesis, Debrecen. 1-145. John, P.W.M., 1971. Statistical Design and Analysis of Experiments. New York, McGraw-Hill. Svâb, J. 1981., Biometrie methods in research. Mezögazdasägi Kiadó, Budapest. 1-55.


ENERGETIC ANALYSIS OF EUROPEAN WINTER WHEAT MANAGEMENT PRACTICES COMPARED AT THE DLG-FELDTAGE IN GERMANY

LubomirNeudert1, Jan Kren1,2

1 Departmnet of General Plant Production, Mendel University of Agriculture and Forestry Brno, Zemëdëlskâ 1, CZ-613 00 Brno, Czech Republic 2 Agricultural Research Institute Kromëfiz, Ltd., Havlickova 2787, CZ-767 41 Kromëfiz, Czech Republic

Introduction Comparison of European winter wheat management practices is a traditional part of the international agricultural exhibition DLG-Feldtage which is held by the German Agricultural Society (DLG - Deutsche Landwirtschaft Geselschaft) always in a different federal country of Germany bi-yearly. The aim of the demonstration experiments is to show cropping practices of winter wheat in federal countries of Germany and advanced European countries, to evaluate the economic aspects of management practices based on input variable costs, grain yield and its quality. Since 1992, the Agricultural Research Institute Kromëfiz, Ltd. has also participated in this undertaking. The paper is focused on the evaluation of energy balance of tested management practices and comparison of results with the economic evaluation published previously (DLG, 1994; Roßberg et al., 1995). The evaluation of the energy use is one of the important objective criteria of agricultural production efficiencies. Energy balance covers a stable utility value of agricultural products, it is less subjected to various market fluctuations and enables to compare both different production kinds and considerably different production practices. The analysis of energy balance may be, therefore, complementary to economic analyses (Jones, 1989).

Methods DLG-Feldtage'94 were held on the farm Oberbigelhof in Bad Rappenau neer Heilbronn. Twenty-two management practices of winter wheat were tested on small-plots (10 m with isolation strips 0.5 m wide) field experiments in four replications. During the growing season, the stand was treated based on recommendations of representatives of the participating organizations. Costs for all treatments were recorded and after the harvest, the profit per lha was calculated for the economic evaluation by the accounting system used in Germany (Roßberg et al., 1995). The direct and indirect energy consumption was determined for each management practice using the standard methodology (Preininger, 1987; Stout, 1992). Both the energy for the production of the crop in the field and the energy needed to produce machinery, inorganic fertilizers and pesticides were included.The influence of a forecrop and effects of organic fertilization were not included in calculations.

Results The average grain yield was 7.65 t ha "' and its variability evaluated by the coefficient of variation (c.v.)was 7.73%. The average level of inputs (variable costs) was 1,083.90 DM ha"1 (c.v. = 12.05 %). The average energetic equivalent of inputs was 22.15 GJ ha"1 (c.v.= 11.92 %). The variable costs per ton of grain was 139 DM (c.v. = 13.59 %). The consumption of energy per ton of grain was 2.84 GJ ( c.v = 13.56 %). According to the proportion of the total energy the individual inputs ranked as follows (Figure 1): 1. fertilizers (68%), 2. machines (20 %), 3. seeds (10 %), 4. pesticides (1.2 %), 5. labour (0.8 %). The order of input items differs according to the costs (Figure 1): 1. machines (38 %), 2. fertilizers (17%), 3. pesticides (16.5 %), 4. seeds (15 %), 5. labour (13.5 %). The order of the input items according to the costs per 1 G J of energy was as follows: 1. labour

Session 2.3 583

(901DM), 2. pesticides (718 DM), 3. machines (92 DM), 4. seeds (76 DM), 5. fertilizers (12 DM). Different approaches used by the representatives of the participating organizations resulted in the variability of input items in the set of 22 evaluated crop management practices. The individual input items (seeds, fertilizers, pesticides, machines, labour) expressed in both GJ and DM differ in the value of the coefficient of variation (Figure 2). It may be supposed that the low value of coefficient of variation indicates the low possibility of input item modification (i.e. small chance of input reduction). On the contrary, the higher value of coefficient of variation indicates the possibility a large range of input item modification (i.e. the input item may be reduced by the optimization of management practices). From this point of view, the inputs in winter wheat crop management practices may be reduced by reasonable application of pesticides and fertilizers.

Figure 1. Percentage of input items proportion

100%

Figure 2. The coefficients of variation of input items in the set of 22 winter wheat management practices

60 .

50

% 30

M •• =•

• seeds

•ferti l izers

D pesticides

D machines

• labour

GJ DM

Conclusions The international comparison of winter wheat management practices has showed: 1) The management practice should be considered as a complex of optimized cropping treatments „tailored " for certain regional agroecological conditions. 2) To improve the economic effects of winter wheat growing the highest possibilities are in reasonable pesticide and fertilizer using. The rational application of pesticides has only small effects on input energy reduction. The balance of energy may be mostly influenced by optimization of nitrogen fertilization. 3) Further increasing the effectiveness of winter wheat management practices will need to develop diagnostic methods, signalization and quality advisory services which facilitate fast responses (using cropping treatments) to varieties with different agrobiological properties and to weather conditions in individual years. The materialized inputs (seed, fertilizers, pesticides, and growth regulators) may be saved during the growing season in this way.

References DLG, 1994. Vergleich europäischer Winterweizen-Anbauvervahren, Feldtagebücher, 24 p. Jones, M. R., 1989. Agricultural Systems 29: 339-355. Roßberg, R. et al., 1995. DLG-Mitteilungen 110: 18-23. Preininger, M., 1987. Energy evaluation of production processes in plant production, ISSM

Prague, 29 p. Stout, B. A., 1992. Energy in world agriculture, Vol. 6, Elsevier Science Publishers, 367 p.


INTEGRATING WEED-CROP COMPETITION INTO A PROCESS-ORIENTED CROP GROWTH MODEL: EVALUATION OF COCKLEBUR COMPETITION WITH SOYBEAN

1 2

D. J. Pantone , J. R. Kiniry

Blackland Research Center, Texas A&M University, Temple, Texas 76502, USA Grassland, Soil & Water Research Laboratory,

Research Service, Temple, Texas 76502, USA Grassland, Soil & Water Research Laboratory, US Department of Agriculture, Agricultural

Introduction Models that predict the performance of a crop based on crop and weed densities are particularly valuable in agronomy where crop yield losses can be estimated and weed management practices can be developed. Process-oriented models of plant competition have the potential to change the way crops are grown and weeds are managed. Recently, a general, process-oriented model, ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria), which simulates competing plant species, has been produced by USDA-ARS scientists at Temple, Texas (Kiniry et al., 1992) using technology derived from the EPIC (Erosion/Productivity Impact Calculator) model (Williams et al., 1989). ALMANAC simulates weed and crop growth and development, including competition for light, nutrients and water. Plant growth simulation models are important both as basic research devices and as applied decision-making tools. As research devices, plant growth models allow researchers to easily simulate many different scenarios that would be difficult, if not impossible, to construct in the field. In addition, plant growth models allow researchers to identify basic research areas that need further investigation for developing an in-depth understanding of growth processes. Previously, most models of plant competition were based on empirically derived density-yield relationships (Pantone et al., 1991). Models that predict crop yield based on empirical density-yield relationships are of limited utility due to varying edaphic and climatic conditions. In contrast, process-oriented models can simulate crop growth with different soils, rainfall, fertilization, temperatures, and radiation. The primary object of this project was to evaluate a process-oriented simulation model of weed-crop competition (ALMANAC) using cocklebur (Xanthium strumarium L.) as the weed and soybean [Glycine max (L.) Merr.] as the crop.

Methods ALMANAC is a process-oriented model that simulates water balance, nitrogen and phosphorus use, and crop growth based on light interception. The model uses Beer's law (Monsi et al., 1953) and the leaf area index (LAI) of the total canopy to simulate light interception by the leaf canopies. Using the system of Spitters et al (1983), the model divides the intercepted light between the competing plant species. Yield production is predicted on the basis of a modified harvest-index approach. Climatic input parameters consist of solar radiation, maximum and minimum temperatures, and rainfall. All inputs are on a daily time step. Soil parameters contain soil water characteristics and nutrient levels. During 1993, 1994, and 1995 field studies were used to evaluate the impact of a weed, cocklebur, on soybean yields on the Blackland Prairie of Texas. The soil was a Houston Black clay (fine, montmorillonitic, thermic Udic Pellustert). The experimental design was a partial additive arrangement (Rejmanek, 1989) with weed densities of 0, 0.5, 1, 2, 3, and 4 cocklebur plants m" . Soybean was planted in rows spaced 69 cm at a constant crop density of 30 plants m"2. The ALMANAC model was used to predict crop yields

Session 2.3 585

for each year. Crop monocultures were used as controls to evaluate the effect of weed-crop competition on crop yield. The main model prediction of interest was crop yield under weed-free and weedy conditions. The focus was on comparing model simulations of the effects of cocklebur to actual field measurements. Cocklebur was selected because it is one of the primary weed species of economic importance in the United States (Jordan, 1992).

Results Results of model simulations and field experiments are presented in the Table.

Simulated and measured soybean yield (t ha" ) for each of six weed densities (plants m"2) during 1993, 1994, and 1995

Weed Density

0 0.5 1 2 3 4

1993

Simulated

1.96 1.86 1.58 0.97 0.81 0.78

Measured

2.14 1.43 1.25 1.01 0.85 0.70

1994

Simulated

1.97 1.68 1.16 0.65 0.54 0.48

Measured

2.45 1.50 1.14 0.96 0.71 0.72

1995

Simulated

1.96 1.71 1.26 0.72 0.56 0.53

Measured

2.33 1.67 1.42 1.30 0.94 0.73

Conclusions Results of model simulations correspond relatively close to measured field data. The model tended to underestimate the yield of the crop in monoculture. During 1994 and 1995, the simulated yields at the highest weed densities (3 and 4 plants m" ) were lower than that observed in the field. However the model did not consistently underestimate the yields, and field measurements of many intermediate weed densities were fairly accurate. The results presented are not an independent validation of ALMANAC, but rather a demonstration of model performance under similar environmental conditions over a range of years. In conclusion, ALMANAC is a versatile model which can reasonably simulate cocklebur-soybean competition over a range of weed densities. The input parameters are easily derived and do not necessitate further details on leaf angles that individual leaf simulation would require. The model provides the user with an efficient tool for assessing the impact of weeds on crop yields and for management optimization related to weed control.

References Jordan, N. 1992. Weed Science 40: 614-620. Kiniry, J.R. et al., 1992. Transactions of the American Society of Agricultural Engineers 35:

801-809. Monsi, M. et al, 1953. Japanese Journal of Botany 14: 22-52. Pantone, D.J. et al., 1991. Crop Science 31: 1105-1110. Rejmanek, M. et al., 1989. Weed Science 37: 276-284. Spitters, C.J.T. et al, 1983. Aspects of Applied Biology 4: 467-483. Williams, J.R. et al., 1989. Transactions of the American Society of Agricultural Engineers

32:497-511.


NITROGEN NUTRITION MANAGEMENT IN WINTER WHEAT IN ORGANIC FARMING

F. Promayon, C David

ISARA, 31 place Bellecour, 69288 Lyon Cedex 02, France

Introduction Nitrogen nutrition in organic farming depends essentially on soil contribution. The N management affects wheat yield, baking quality and occasionally the environment by ground water pollution. The aim of this research is to evaluate soil nitrogen fertility as affected by crop rotation and fertilisation practices

Methods Nitrogen management was estimated by three interrelated networks (farm network, field network and trials) on organic and conversion stockless farming systems. Farmers' practices were identified on 17 farms by survey (Promayon, 1995). Each year, an on-farm agronomic monitoring was established on 15 fields selected on two criteria: the cropping system and the type of soil. On some fields, several improved nitrogen management were tested in comparison with farmers' practices The crop yield build up was assessed using a crop diagnosis (Meynard and Sebillotte,1993). Yield components (tills, spike, grain m"2, 4 times), N-content (%, 4 times) and grain protein level (%) were measured. The « grain number index » (GNI) and « nitrogen nutrition index » (NNI) (Greenwood et al., 1991) were used. The GNI relates the ratio between the observed number of grain m2 to the upmost potential per cultivar The NNI relates the ratio between the observed N uptake to optimal N uptake which quantifies the nitrogen deficiency (4 times: Feekes 2-3; 4; 6; 8). The nitrate test was tested to detect N-deficiency (concentration of the « stem base extract » Justes, 1993)

Results Two types of farmers' practices are identified to improve nitrogen nutrition: fertilisation practices on wheat and fertility building by legumes or green manures in crop rotation. In our network, four groups have been identified (Table 1):

Table 1. Nitrogen management practices

fertilisation in spring < 30 kg N ha"1

total fertilisation < 60 kg N ha "'*

fertilisation in spring > 50kg N ha ' total fertilisation > 60kg N ha "'

multiannual legumes > 35% no green manure regular N fertilisation in autumn possible N fertilisation in spring

Type I

Typen

annual legumes < 50% possible green manure possible N fertilisation in autumn systematic N fertilisation in spring

Typem

Type IV

* efficient kg N ha" (assessment with Ziegler and Masson efficiency coefficient, 1990)

Session 2.3 587

There is a statistical relation between the NNI (measured at Feekes 8) and the NGI (r =0,69) (Figure 1) Nevertheless, it is impossible to define a threshold (under this level, nitrogen deficiency has automatically an influence on wheat yield , Justes, 1993).

Figure 1 :Re la t ionsh ip b e t w e e n NNI and N G I s tem e longa t ion ( F e e k e s 8 )

0,90

0,80

0 , 70 - -

0 , 60 - -

GNI 0,50

0,40

0,30

0,20

• Type I

• Type II

AType III

O Type IV

0,20 0,30 0,40 0,50 0,60 0,70

NNI

Conclusions The NNI levels were under 0,85 and decreased during the stem elongation. Fields with an important soil N-content in Febuary (> 70 kg N ha"1) and a favourable soil structure had good N nutrition and the best results during tillering (tillers per plant> 1,5 , NNI > 0,8). Other explanation factors are lucerne as the preceding crop (type I and II) and an earlier N fertilisation The nitrogen deficiency was thoroughly observed from the beginning of stem elongation. Nitrogen input by annual legumes or green manure (type III and IV) was insufficient to ensure satisfactorily nitrogen nutrition. Manure spread in autumn or at the beginning of spring facilitated yield build up. However, there is no statistical relationship between N-fertiliser quantity and the NNI. The efficiency of manure application depends on the type of source and the quality of spreading. The mineralisation rate, the absorption and the efficiency were dependent on the soil structure, water resources and weeds competition. Despite the low N-content level, the number of the grain m"2 was over 60% of the upmost potential obtained in non-organic agriculture which can be explained by an important N-efficiency. This occurred when the N-application improved the NNI during the stem elongation. Water and nitrogen deficiency during grain filling and pathogenic infestation at early stage influenced the accumulation of the different classes of proteins by a decrease and a modification of the protein pool Baking quality and grain protein level were insufficient. The nitrate test cannot be used to control the N-fertilisation because crops are already N deficient and this indicator of N crop status does not allow to quantify the level of N deficiency. Further research will provide information on the possibility to use the NNI for N-fertilisation monitoring.

References Greenwood, D. J. et al., 1991. Annals of Botany, 67: 181-190. Justes, E., 1993. Paris, FR, Thesis, Institut National Agronomique Paris-Grignon, 227 p. Meynard, J M and Sebillotte, M, 1993. Le point sur l'élaboration du rendement, Eds INRA, Versailles Promayon, F , 1995. Paris, FR, Ing Dipl, Institut National Agronomique Paris-Grignon, 59 p. Ziegler, D and Masson, E ., 1990 Perspectives agricoles 145: 79-86.


NITROGEN FERTILIZATION NEEDS OF RAPESEED IN AUTUMN

R. Reaul, C. Colnenne^, D. Wagner^

1 Centre Technique Interprofessionnel des Oléagineux Métropolitains, 174 ave Victor Hugo, 75116 Paris, France 2ISA, Lille, France

Introduction In Europe, winter rapeseed is one of the rare field crops receiving a nitrogen (N) fertilization before winter. For many farmers, N fertilizer supply is good when oilseed rape growth results are higher. Although, these N supplies are not generalized, they raise problems for they are applied just before a period of too much water, when risks of nitrate losses and pollution are high. To study the interest of N fertilization before winter, we analysed yield response to different spring fertilization rates versus autumn fertilization.

Methods 12 multilocal experiments were carried out in different French regions for two years. Each experiment was laid out in a split plot design with two factors and four replications. The first factor was the seedbed N fertilization rate, with 2 levels: 0 and 50 (or 80) kg N ha-1. The second factor was top dressing spring fertilization rate, with 5 levels: 0, X-50, X, X+50, X+100 kg N ha~l ; X being calculated for the whole experiment with a balance method adapted for oilseed rape (Reau et al, 1994, 1995). Autumn nitrogen utilization was estimated with the Coefficient of Apparent Utilization (CAU) calculated from the difference between N content at the end of winter with and without N autumn fertilizer, divided by autumn N fertilization rate (de Wit, 1953). The yield was measured harvesting 50-100 m2 in each plot. Statistical analysis was realized with SAS and the means were compared with the Newmann and Keuls test (ct=0.05).

Results The results showed that generally N fertilization before winter has no consequence on the yield potential, on condition that spring fertilization is suficient (Figure la, b): there was no significant difference between the maximum yields for plots with and without seedbed N fertilizer in 11 out of 12 trials, as presented in the table. These results confirmed that temporary nitrogen deficiencies in autumn have no effect on oilseed rape yield. We noted one exception to this rule: in the north of France, when the photosynthetic active radiation was limited before flowering, nil seedbed N supply reduced biomass obtained in winter and then, spring growth was insuficient to reach the yield potential despite a non limiting N fertilization in spring (Figure 1 c). When N spring rate was too low to reach potential yield, spring fertilizer was a limiting factor for the yield. The effect of N fertilizer before winter depended on N utilization in autumn. When N utilization was low, yield response to low total N rate was higher without N fertilizer before winter because of a better utilization of N fertilizer in spring (Figure la). When N utilization was as high as in the spring, there was no difference of yield (Figure lb).

Session 2.3 589

Table. Rapeseed yields after different N-treatments in 12 trials.

Seedbe

Trial

1 2 3 4 5 6 7 8 9 10 11 12

1 N fertilizer

CAU

0 0.3 0.3 0.4 0.7 0.8 1 1.1 1.2 1.2 1.4 0.5

Maximum yield (t ha"l)

no

4.16 3.77 3.07 3.36 4.77 4.69 3.84 3.17 4.64 3.99 4.77 4.68

yes

4.34 3.81 3.04 3.39 4.93 4.87 4.06 2.89 4.21 3.93 4.80 5.01

Stat, test

NS NS NS NS NS NS NS NS NS NS NS S

Yield at

no

2.52 0.96 2.27 2.03 2.31 1.50 2.39 1.65 2.31 2.99 2.30 2.61

nil sprir

yes

3.02 1.21 2.61 2.11 2.56 2.27 1.98 2.03 2.74 3.34 3.09 2.81

g rate (tha"')

Stat, test

S NS NS NS S S

s s NS

s s NS

0

ab , a ,

nil seedbed N

seedbed N

0 i 0

yield (t / ha )

• e

C

ab _ 4 c Jm^Hl

K ni] seedbed N

4 * 50 seedbed N

0 80 160 240 260 290 310 340 390 0 50 165 215 265 315 365 0 50 120 170 220 270 320

total N fertilizer total N fertilizer total N fertilizer Figure 1. Yield response of rapeseed to N treatments in trials 2, 6 and 12.

Conclusions Generally, in the main production area of oilseed rape in France, N fertilizer utilization is rather low in autumn (Merrien et al, 1996; Reau et al, 1996), so that splitting total N fertilizer between autumn and spring is not efficient. Nowadays N fertilization before winter is not recommended in France. However, under certain circumstances, when the yield potential may be affected by the state of rapeseed growth in winter, the interest of N supply during autumn could be justified. For this, we have to understand better, and explain the possible effect of rapeseed state in winter on setting-up of rapeseed yield.

References de Wit CT., 1953. Versl. Land-bouwk. Onderz. Agricultural Research Report, 59(4), 71 p. Merrien, A. et al, 1996. Paris, France, Oléoscope spécial 20: 7-15. Reau, R. et al, 1994. Paris, France, Oléoscope 19: 22-23. Reau, R. et al, 1995. Cambridge, UK, 9th international rapeseed congress 1: 317-319. Reau, R. et al. 1996. Paris, France, Oléoscope spécial 20: 16-27.


EFFICIENCY OF DIFFERENT TECHNOLOGIES FOR THE APPLICATION OF FERTILIZERS TO CEREALS

R. Richter, Z. Poulîk, J. Rikanovâ

Mendel University of Agriculture and Forestry, Brno, Czech Republic

Introduction With regard to a decrease of nutrient consumption in fertilizers it is more and more important to take any measures which could improve the utilization of individual nutrients. As one of such measures it is possible to mention a local application of fertilizers, the aim of which is to accumulate fertilizer particles into a certain depth of soil in such a way that the nutrients could be absorbed by plants in the most efficient manner. It is not always required to increase yields of the corresponding crop but to reach the same or even better efficiency of nutrients supplied in a lower dose of fertilizer. Recently, this problem was studied e.g. by Leikam et al. (1983), Malhi and Nyborg (1985), Randall and Hoeft (1986), Matzel and Suntheim (1988), Mulla et al. (1992) and others. The aim of this study was to test the effect of a pelleted multi-component fertilizer Synferta P 16 containing N:P205:K20 (16:12:12) when using different methods of application on the major yield parameters of spring wheat as well as on chemical composition of kernels and straw.

Methods Experiments were carried out in pots containing medium heavy soil with pH/KCl 6.2 and with the following contents of available nutrients (Mehlich II): P - 89 mg.kg"1, K - 175 mg.kg', Ca - 1514 mg.kg1 and Mg 223 mg.kg"1. In this experiment, partly the different doses of fertilizers (i.e. 5 variants: Variant 1 - no fertilizers; Variant 2 - 0.2 g N, 0.15 g P205 and 0.15 g K20 per pot; Variant 3 - 0 . 4gN,0 .30g P205 and 0.30 g K20 per pot; Variant 4 - 0.6 g N, 0.45 g P205 and 0.45 g K20 per pot; Variant 5 - 0.8 g N, 0.60 g P205 and 0.60 g K20 per pot) and partly various methods of fertilizer application (i.e. 3 variants: Variant 1 - application into the depth of 2 - 3 cm; Variant 2 - application into the depth of 5 - 6 cm and Variant 3 - application within the whole soil profile in the pot) were tested. The obtained results were statistically analyzed using the method of variance analysis.

Results The obtained results are presented in Figures 1 and 2. The application into the depth of 5 - 6 cm showed to be the most suitable because the nutrients were accumulated near to the active surface of the fully developed root system of plants. The worst results were obtained after mixing the soil with the fertilizer because the nutrients were too dispersed and their accumulation in the active root zone was insufficient. As far as the other yield parameters were concerned (i.e. number of fertile tillers, number of kernels per pot and yield of straw), they were affected more than the yield of grain by the increasing doses of nutrients; however, the differences were statistically significant in some cases only. Changes in the number of fertile tillers were manifested more in the yield of straw than that of grain. The content of N and, partly also, of Ca in kernels increased with the increasing doses of nutrients while those of P, K and Mg did not show any marked changes. A local application

Session 2.3 591

of the fertilizer increased the accumulation of K and Ca in kernels, decreased the content of P and did not change the levels of N and Mg.

d e p t h 2 - 3 c m d e p t h 5 — 6 t=m u h o l e p r o f i l e ?

y i e l d o f s t r a u L^II e l cd o f g r . a i n

Figure 1. Yields of grain and straw in spring wheat (g per pot)

3 . 5 r ;

d e p t h 2 — 3 d m d e p t h 5 — «Scrm u h o l e p r o f -

H t i g

Figure 2. Contents of macronutrients in grain (%)

Conclusions Both yield parameters and content of the major part of principal nutrients in grain of spring wheat were favourably affected by a local application of a multi-component fertilizer Synferta P 16, especially after its application at the depth of 5 - 6 cm. The obtained results demonstrated that after the application of fertilizers at a certain depth it is possible to reach the same production efficiency even with a lower dose of nutrients.

References Leikam, D.F. et al., 1983. Soil Science Society of America Journal, 47: 530-535. Malhi, S.S. and Nyborg, M., 1985. Agronomy Journal, 77: 27-32. Matzel, W. and Suntheim, L., 1988. Charakterisierung pflanzenverfugbarer Nährstoffe

im Boden. Berlin, AdL der DDR: 255-260. Mulla, DJ . et al., 1992. Agriculture, Ecosystems and Environment, 38: 301-311. Randall, G.V. and Hoeft, R.G., 1986. Crops Soils Magazine, 38: 17-22.


YIELDING OF WINTER TRITICALE var. PRESTO UNDER LOW-INPUT AND INTENSIVE METHODS OF CROP MANAGEMENT

1 2 1 1 J.Rozbicki , W.Madry , M.Kalinowska-Zdun , Z.Wyszynski

Department of Plant Production, Warsaw Agriculture University - SGGW, 02-528 Warsaw, Rakowiecka 26/30, Poland

SGGW, Warsaw, Poland

Introduction Sustainable agriculture needs reduced fertiliser and pesticide use in cropping systems. Triticale may be an attractive alternative to wheat, barley or rye for feed grain as a low-input crop because of its greater disease resistance (Naylor et al., 1993; Wolski, 1989). The goal of this study was to evaluate winter triticale yielding and grain quality as influenced by a reduction of nitrogen fertilizer use and omission of pesticides (excluding herbicides) in intensive crop management as in the work of Easson (1995) with winter wheat.

Methods o

The date used come from the multifactorial experiment 2 conducted at Chylice Experimental Station (52,5° N) in 1992-1994.The experiment tested the effects of the following eight factors, each at two levels : sowing date (20 September, 10 October), nitrogen (N) level (150, 90 kg N ha'),pattern of N application (split 40 + 60%, 100%), timing of N (BV-beginning of vegetative growth, growth stage 25-27 according to Zadoks et al., (1974)), growth regulator (Chloromequat - 3 1 ha , 0), foliar fertilizer (Insol - 1 1 ha"1, 0), summer fungicide (Folicur BT - 1 1 ha~',0) and insecticide (Decis - 0,25 1 ha"1, 0). Winter triticale was sown on a very good rye complex after spring wheat, grown as a second cereal.

Grain yield per plot, grain protein content, disease infestation and post-harvest residual soil nitrogen content were observed. Analysis of variance for all data was carried out.

Results Grain yield was significantly reduced (7.9-10.5% ) at the lower N rate (Table),due to a

reduction in ear number and grain number per ear (data not shown).There was also a significant reduction in protein content at the lower rate of applied N. Post-harvest residual soil N was higher at the higher rate of applied N (Rozbicki et al., 1995). Non-application of the growth regulator caused the significant decrease in the grain yield but a small but still significant increase in protein content. With the exception of timing of N, where yield was higher and protein lower with the earlier application, the other factors did not lead to significant changes in grain yield except for a small positive effect (6.1%) of the fungicide in 1992 only. Leaf spot of winter triticale (in DC 85) in 700% James Scale on the untreated plots was on average 5.9% on the flag leaf, 16.2% on the next eldest and 22.8% on the next leaf (Rozbicki et al., 1996).

Session 2.3 593

Table. Means of grain yield (t ha ) and protein content( %) in grain, estimated at two levels for each factor in the experiment

Factors and treatments Dose of nitrogen 150 kg N ha '

90 kg N ha"1

Division of nitrogen 60 +40 % 100%

Timing of nitrogen BV DC 25-27

Growth regul.- Chloromeqwat 3 1 ha none

Foliar fertilization - Insol 1 1 ha ' none

Summer fungicide -Folicur BT 1 1 ha none

Insecticide - Decis 0.25 1 ha ' none

LSD 0.05 +

grain yield ( t ha

1992 7.10* 6.38 6.69 6.78 6.84* 6.63 6.93* 6.55 6.77 6.69 6.94* 6.54 6.78 6.70 0.22

1993 8.09* 7.45 7.78 7.76 7.92* 7.62 7.86* 7.68 7.83 7.71 7.83 7.71 7.86 7.68 0.18

')

1994 6.85* 6.13 6.43 6.55 6.54 6.43 6.65* 6.33 6.38 6.60 6.53 6.45 6.51 6.47 0.20

protein (%)

1992 11.3* 9.8

10.8* 10.4 10.2* 10.9 10.4* 10.7 10.6 10.5 10.5 10.6 10.5 10.6 0.23

i content of grain

1993 12.2* 10.7 11.6* 11.3 11.0* 11.9 11.3* 11.6 11.5 11.4 11.5 11.4 11.5 11.4 0.27

1994 10.4* 9.2

10.1* 9.5 9.2*

10.4 9.9 9.7 9.9 9.7 9.7 9.9 9.9 9.7 0.30

LSD is calculated to test the differences of the means at both levels of every factor * the difference of means for both levels of a given factor is significant at the level 0.05

Conclusions The observed reduction in grain yield caused by the lower nitrogen fertilizer application rate was relatively large (about 10%) on average over the three years, but omitting pesticides only coused a slight decrease in this trait. Low-input management of winter triticale may be effective in reducing the environmental impact. In the light of our investigation, winter triticale seems to be a crop that may be grown under low-input management without problem of greatly decreased grain yield and quality. This species could therefore be recommended for growing more widely in sustainable farming systems.

References Easson D.L., 1995. Journal of Agricultural Science Cambridge 124: 343-350 Naylor R.E.L. et al., 1993. Journal of Agricultural Science Cambridge 120: 159-169 Rozbicki J. et al., 1995. Annals of Warsaw Agricultural University, Agriculture 29: 51-58 Rozbicki J. et al., 1996. Roczniki Nauk Rolniczych Séria A (in press) Wolski T., 1989. Lublin, Poland, Proceeding of Triticale Conference 9-21 Zadoks et al., 1974. Weed Research 14: 415-421


LOWER YIELD LOSS DUE TO DISEASES IN NEW WHEAT V ARIETEES

K.D. Sayre' and C. van der Wilk2

1 CIMMYT, Mexico D.F., Mexico 2 Department of Agronomy, WAU, PO Box 341, 6700 AH Wageningen, The Netherlands

Introduction The Centro Internacional de Mejoramiente de Maiz y Trigo (CIMMYT) gives high emphasis to genetic resistance to prevalent, important diseases (Sayre et al, 1991, unpublished report) and the yield potential of bread wheat (Triticum aestivum L.). Periodic evaluation of this genetic improvement is carried out, to identify traits that may require increased efforts by breeders (Cox et al., 1988).

Methods A historical set of ten bread wheat varieties developed from germplasm from CIMMYT and released between 1962 and 1989 in Mexico and other developing countries as well as 10 advanced CIMMYT lines were grown under optimum management conditions on the CIMMYT experiment station at El Batan both with and without disease control. Leaf rust was scored regularly. The chlorophyll content of the flag leaf was determined with the Chlorophyll Meter SPAD-502. The SPAD values of this meter correspond to the amount of chlorophyll present in the leaf calculated on the basis of light transmitted by the leaf (Spectrum Technologies INC. 1989).

Results Results are presented in the following figure and tables.

-4.8 • 10000 + 26.87 • year

2 OÜ

a 3 > 2

<

8000 -

6000 -

4000 -

2000 - 1.5 • 100000 + 78.93 • year

1960 1965 1970 1975 1980 1985

YEAR OF VARIETY RELEASE

1990 1995

O actual yield - control

O actual yield - no control

- predicted yield - control

-predicted yield - no control

Figure. Yield trend with and without disease control

Table 1. The correlation between grain yield and yield components.

grain yield (kg ha"1) yield components

spikes m'2 grains m-2 grains spike'1 kernel weight

with control without control

0.433* 0.454**

0.582*** 0.673***

0.330 0.539**

0.180 0.843*

Session 2.3 595

Table 2. The correlation between kernel weight and chlorophyll content of the flag leaf during grain filling, with and without disease control.

kernel weight (g)

01/08/95

chlorophyll content

11/08/95 21/08/95 31/08/95

with control without control

-0.096 0.491**

0.242 0.680***

0.339 0.628***

0.014 0.580***

Table 3. Grain yield and percentage yield loss.

genotypes grain yield (kg ha'1) yield loss (%)

Pitic 62 Lerma Rojo 64 Jupateco 73 Pavon 76 Seri 82 Opata 85 Super KAUZ 88 Galvez 87 Temporalera 89 Culiacan 89 BOW/GEN//DERN

with control

4698 4532 5553 5702 6012 5982 6305 5332 5367 5673 5048

without control

1387 1981 1501 3994 3096 2826 4092 3658 2708 3903 4500

70.48 56.29 72.97 29.95 48.51 52.76 35.09 31.40 49.55 31.19 10.85

Conclusions Difference for rust resistance between genotypes was significant (p<l%). Genetic gain in yield per year with and without disease control was 0.57 % (r2=0.33*) and 3.33 % (r2= 0.68***) respectively (figure). BOW/GEN//DERN was chosen for 1995, because it yields best under for small farmers most realistic conditions. This increase in yield over the years was strongly and positively associated with an increase in number of grains per m2 with and without disease control. (Table 1). Kernel weight was markedly affected by the prevalent diseases and was highly positively correlated with the chlorophyll content of the flag leaves (p < 5%) during grain-filling when no disease control was applied (Table 2). More research on the chlorophyll content as a possible feature for selecting for yield potential in an early stage could be interesting. The yield loss caused by diseases was lower in the newer genotypes than in the older ones (r2= 0.62), with the advanced line BOW/GEN//DERN performing best (Table 3). Although this line gave the highest yield when diseases are present, it did have a lower yield than the best released varieties under disease controlled conditions. That is why the search for a combination of a high yield potential and good disease resistance is still going on.

References Cox, T.S. et al., 1988. Crop Science 28 :756-760. Spectrum Technologies INC, 1989. Chlorophyll Meter SPAD-520.

Minolta Camera Co., Ltd. Plainfield, USA. 23 p.


INPUT, OUTPUT AND RESIDUE OF NUTRIENTS

Schouls, J." and G.O. Nijland 2)

" Department of Agronomy, and 2) Department of Ecological Agriculture, WAU, Haarweg 333, 6709 RZ Wageningen, The Netherlands.

When studying the issue whether in crop production intensification or extensification is advisable, the relations between input, output and residue of nutrients are of great relevance, as are markets and prices. In recent studies, a S-course of the output curve has been demonstrated when various nutrients are increased proportionally (e.g. De Wit, 1992). In that case, rather high levels of nutrients are advisable thus minimizing residues. These results appear to follow from accepting the Mitscherlich model for the relation between amount of output and amount of nutrient.

However, we found a Michaelis-Menten curve of response of both uptake to input and yield to uptake, both single and in proportional combination, on theoretical and empirical basis as more appropriate (Nijland et al., 1996). As Figure 1 demonstrates, it is clear and easy to distinguish - if represented reciprocally - the different patterns of the different lines representing the relations between input and output according to Mitscherlich, Liebscher (to be approached with a Michaelis-Menten relation) and Liebig. The highest productivity of a nutrient is in case of a Michaelis Menten relation established at zero input of external nutrients. With increasing input, marginal productivities always decrease.

The lowest residues may be expected when just producing with the internally available nutrients both from biological fixation and deposition. Assuming a Michaelis-Menten relation, residues per kg product will increase strongly at higher levels of (proportionally) applied nutrients. At low input level a nearly constant residue per kg product is found in many cases (data of Chaney, 1992), if yields and residues are almost proportional. In exceptional cases we observed decreasing residue per kg product at increasing nutrient input in the lower range of input, where apparently the greater size and activity of the root system, induced by applying more nutrients, utilized the available nutrients better. Besides, losses from large soil stocks will be relatively bigger than from small ones. Even in case of a linear relation between input and output, increasing absolute and relative residues are found when producing a certain amount of product with more nutrients of one kind per unit area.

From an economic viewpoint, one prefers the input level, at which the difference between output revenue and variable costs is maximal. This Gross Margin and the ecological productivity (output per kg internal + external input) do not have their maximum at the same level of input, neither in the Mitscherlich nor in the Michaelis-Menten model. Comparing both models, the discrepancy between ecological and economic optimum appears largest in the Michaelis-Menten model. Because of the low prices of nutrients in Western countries the highest economic productivity occurs at very high nutrient levels. Ecologically a low level is advisable. Thus a political consideration of this issue is necessary.

Relations between input, output and residue are different on different soils. In case of a surplus of area, the issue whether to produce intensively on a small area or extensively on a large area has yet wider dimensions (such as labour, food and nature). Our studies indicate that higher levels of nutrients are ecologically more feasible on the better soils than on the less fertile soils. Taking soils out of production will be rarely expedient, when aiming at the highest ecological productivity, since soils in Western Europe generally have a relative high internal availability of nutrients. However, other aspects as minimal total emission and maximal economic yield will generally be considered as important. Actually, all inputs as well as all outputs and secondary effects should be considered simultaneously.

Session 2.3 597

MITSCHERLICH INVERSE

YIELD in ton ha

10

J/ton per ha 10

0 kg N ha-' 100 0

MICHAELIS-MENTEN

l / kg N per ha 1

INVERSE

100 0.0

LIEBIG INVERSE

100 0.00 0.05

Figure 1. The theoretical relation between output and input of nitrogen (left) at 4 levels of phosphor, according to Mitscherlich, Liebscher and Liebig, with (hypothetical) initial response coefficients (nitrogen: 200 kg/kg N; phosphor: 2000 kg/kg P); the relation between the inverses of the same variables (right). The numbers in the first graph refer to the amounts of Phosphor in kg per ha applied.

References Chaney, K., 1990. Journal of Agricultural Science, Cambridge. 114: 171-178. Nijland, CO . , et al., 1996. The relation between nutrient application, nutrient uptake, production and nutrient residues. Wageningen Agricultural University Press (submitted) Wit, CT . de, 1992. Agricultural Systems 40: 125-151.


FACTORS INFLUENCING CROP WATER USE EFFICIENCY

L.P. Simmonds, C.C. Daamen, C.J.Pilbeam

Department of Soil Science, The University of Reading, PO Box 233, Whiteknights, Reading, UK

Introduction In many areas of the world, the loss of water through direct evaporation from the soil surface (Es) is a major component of the water balance of cropped fields, and is often an important factor contributing to low water use efficiency (defined as crop productivity per unit of water lost through évapotranspiration). Intensification of crop production (for example, using fertilisers, denser planting and improved varieties) in such environments has often resulted in increases in yield, with a reduction in Es often being presumed to be the factor responsible for the increased water availability to plants.

There has been much recent progress in understanding the factors controlling evaporation from sparse vegetation (embodied in comprehensive Soil-Vegetation-Atmosphere Transfer models which incorporate soil water and heat dynamics, plant hydraulics and aerodynamic transfer processes within plant canopies). The objective of this paper is to apply such understanding to identify the mechanisms by which improved crop management might reduce Es, and to evaluate the magnitude of the potential for reducing Es in a given environment. The analysis presented here is based on the use of the 'SWEAT' SVAT model (Daamen and Simmonds, 1996).

Methods and Results Examples based on field measurements of Es using microlysimetry (following the criteria set out by Daamen et al, 1993) in Kenya, Niger, Syria and the UK are presented to illustrate how in different environments, the presence of a crop can reduce Es via the following mechanisms: • shading by foliage reducing the radiation penetrating to the soil surface • foliage influencing the aerodynamic transfer of vapour away from the soil surface • root water uptake drying the near-surface, thereby reducing the water supply for Es

In particular, it is shown that in environments with a large evaporative demand, infrequent rainfall, and soils of low unsaturated hydraulic conductivity (e.g. sandy soils in Niger) there is a remarkably small reduction in Es (c. 10%) in intensively cropped soils in comparison with bare soils. This reduction is attributable primarily to water uptake by roots rather than by the direct effect of the canopy on evaporation from the soil surface. At the other extreme (e.g. winter rainfall, Mediterranean climates) are environments with frequent rain and low evaporative demand during the rainy season. In such environments, especially with conductive soils, shading by foliage can cause a substantial reduction in Es.

A simple soil evaporation model is presented which can be used with readily-available daily synoptic meteorological data to assess, for a given environment, the extent to which changing the characteristics of a crop (leaf area index, canopy height and root distribution) influences Es. The model is in the form of a Modified Two-Stage Evaporation Model (MOTSEM), based on that described by Daamen, Simmonds and Sivakumar (1995). During the 'demand-limited' phase when the surface is wet, Es occurs at a potential rate that is derived from the Penman equation, where the radiation and aerodynamic terms of the Penman equation are influenced independently by the crop canopy. During the 'supply-limited' phase, Es is calculated from knowledge of the soil desorptivity (which can be estimated from measurements of Es from bare soil, or else

Session 2.3 599

estimated from soil texture), with account taken of the extent to which the surface layers are dried by root water uptake. Examples are given of typical ranges of values for the three crop coefficients that are required as model inputs.

An analysis of the measurements from Kenya, Niger and the UK using MOTSEM shows that Es

can contribute between 30% and 90% of the total evaporative loss from a cropped field through a growing season. There is evidence of considerable variation between environments in the extent to which crop water use efficiency can be improved through reduction of Es by improved crop management. There was a good correlation between the seasonal rainfall and the proportion of total evaporation that is transpiration. The relatively large contribution from Es in low rainfall environments is attributed mainly to the shallower depth of wetting. In environments with similar rainfall, those with frequent, small rain events lose substantially more water through Es than when rain arrives in infrequent, large events.

Finally, SWEAT is used to examine the question of whether reduction in direct evaporation from the soil surface is offset, in part, by enhanced transpiration as a consequence of localised advection processes driven by the soil surface becoming hotter. Examples (supported by measurements of sap flow) demonstrate that this enhancement of transpiration occurs (as much as 25% enhancement in the case of a tall millet crop in Niger with leaf area index of 0.5). However, the magnitude of the enhanced water loss through transpiration on a unit land area basis is generally very much smaller than the reduction in Es.

Conclusions It is shown that environments differ widely in the extent to which direct evaporation from the soil surface can be reduced by the presence of vegetation, and that the mechanisms responsible for the reduction in Es also vary. A model is proposed that could form the basis of a simple classification scheme that takes account of the amount and distribution of rainfall, evaporative demand and soil type in order to identify environments where there is greatest scope for reducing direct evaporation from the soil surface though improved crop management practices.

References Daamen, C.C. et al., 1993. Agricultural and Forest Meteorology 65:159-173. Daamen, C.C. et al., 1995. Agricultural Water Management 27:225-242. Daamen, C.C. et al., 1996. Water Resources Research. In Press (accepted 19/1/96).


MODELING CROP N REQUIREMENTS: A CRITICAL ANALYSIS

C. O. Stockle1 and P. Debaeke2

'Biological Systems Engineering Dept., Washington State University, Pullman, WA 99164-6120, USA 2INRA Station d'Agronomie, BP27, 31326 Castanet Tolosan, France

Introduction Simulation models are increasingly used for prediction of crop production and environmental impact in response to water availability and N fertilization. The prediction of crop N requirements, both in terms of total requirement as well as its distribution throughout the growing season is important.

A review of approaches utilized to estimate crop N requirements in several crop models was done. We selected four that were representative: AFRCWheat2 (Porter, 1993), Daisy (Hansen et al., 1991), EPIC (Sharpley and Williams, 1990), and CropSyst (Stockle and Nelson, 1996). The most complete approaches include the definition of three characteristic plant N concentration curves: a maximum (Nmax), a critical (Ncrit), and a minimum (Nmin) concentration. Plant growth is not limited if plant concentrations are at or above Ncrit, while Nmax establishes the maximum crop N demand. Below Ncrit, plant growth is reduced, stopping completely when N concentration reaches Nmin. Some models (e.g., EPIC and AFRCWheat2) do not include Nmax, limiting maximum N demand to Ncrit. This is unlikely to result in proper simulations considering that a substantial amount of N can be stored above Ncrit.

Plant N concentration is not constant but decreases with time, and so do the three concentration curves. To describe this process, some models decrease the curves as a function of crop growth stage (AFRCWheat2), the fraction of the cycle (EPIC), or as a function of thermal time (Daisy). Research has shown that Ncrit decreases with increasing plant mass according to an allometric equation (Salette and Lemaire, 1981, Greenwood et al., 1990), usually referred to as the growth dilution law. This approach has been tested with field data and shown able to discriminate between well-supplied and N-deficient crops (e.g., Justes et al., 1994, Plénet, 1995). Furthermore, single allometric equations for C3 and C4 crops, respectively have been proposed (Greenwood et al., 1990). Similar equation forms may be used for Nmax and Nmin. A generic implementation based on this concept has been recently introduced to the CropSyst model (Stockle and Nelson, 1996).

Methods Experimental data collected for wheat at the INRA station in Auzeville, France was used to compare the four modeling approaches. This included plant N concentration, biomass, thermal time, and growth stages throughout the growing season, and final biomass, N content, and yield at harvest of wheat plots grown with different levels of available N. Data were analyzed to separate N-limited and non-limited plots.

Results Figure 1 compares the performance of the four models. The method in AFRCWheat2 tends to discriminate well (Ncrit curve properly separating N-limited from non-limited data points), with problems between growth stages 30 and 40% and towards the end of the cycle. Performance of the EPIC model is less acceptable. Both models share the same problem of the

Session 2.3 601

lack of Nmax definition. The Daisy model includes the three characteristic curves, but its performance is the worst of all methods tested. The method based on biomass increase (CropSyst) was able to better represent crop N requirements. This method is only valid until flowering, requiring specification of ending values for the three curves at maturity, which are approached linearly after flowering.

Conclusion The use of the growth dilution concept provides a solid base to determine characteristic plant N concentration curves throughout the growth cycle, which are fundamental for proper simulation of crop N demand and crop response to limited nitrogen.

20 40 60 80 100

Growth stages (%) 500 1000 1500

Degree Days

0.2 0.4 0.6 0.8 Fraction of the cycle

£ <»

0

CropSyst

1 il D *

• " • ^ . f i a ? .

0 3 6 9 Aboveground biomass (Mg/ha)

Figure 1.- Comparison of four models to estimate characteristic plant N concentration curves with wheat data from N-limited and non-limited plots at Auzeville, France (Symbols: open = N limited, close = N non limited; Lines: dashed = Nmax, solid = Ncrit, dotted = Nmin).

References Greenwood, D.J. et al., 1990. Annals of Botany 66: 425-436. Hansen, S. et al., 1991. Fertilizer Research 27: 245-259. Justes, E. et al., 1994. Annals of Botany 74: 397-407. Plénet, D., 1995. Doctoral Thesis, Académie de Nancy-Metz, Porter, J.R., 1993. European Journal of Agronomy 2: 69-82. Salette, J. and G. Lemaire, 1981. CR Acad. Sei. Paris 292, 267-281, Institut National Polytechnique de Lorraine, France. Sharpley, A.N. and J.R. Williams, 1990. USDA Tech. Bull. No. 1768. Stockle, CO. and R. Nelson, 1996. Biological Systems. Engineering Dept., Washington State University, Pullman, WA.


RELATIONSHIP BETWEEN N-CONCENTRATION AND GROWTH IN SWEET PEPPER

F. Tei, A. Onofri, M Guiducci

Institute of Agronomy - University of Perugia, Borgo XX giugno 74, 06121 Perugia, Italy

Introduction Crop growth rate is reduced when nitrogen concentration within plant drops below a certain threshold level, that is defined as the critical nitrogen concentration. This concentration decreases as plant biomass increases, following a similar relationship for several C3 crops (Greenwood et al., 1990). Considering N-deficient plants (i.e. with nitrogen concentrations lower than the critical levels), relative growth rates have been found to be linearly related to N concentration within plant (Âgren, 1985; Lemaire et al., 1990). The above mentioned relationships have been studied for several crops, but not yet for sweet pepper, that presents some particular characteristics, such as low plant density, wide row spacing, low leaf area, early development and high sink strength of fruits. The aim of this paper was to study the relationship between %N and growth in field grown sweet pepper.

Methods Field experiments on sweet pepper, cv Heldor, were carried out in 1991 and 1992 at Perugia (Italy, 43° N, 165 m a.s.1.). In each experiment a range of N fertiliser levels (0 to 300 kg ha-1) was applied and plant dry weight (leaves, stems and fruits, excluding fibrous roots) was weekly recorded during the growth cycle, until the first commercial fruit harvest. The nitrogen content (%N in plant dry matter) was determined by a Kjeldahl method. As proposed by Greenwood et al. (1991), data were used to calculate the growth rate coefficient KX(F) and, afterwards, the relative growth rate, as: RGR(F,t) = KX(F) I [x+W(F,t)] where RGR(Fj) is the relative growth rate, dependent on fertiliser level (F) and time (t, hereby expressed in terms of accumulated degree days, with T|,ase = 12°C), KX(F) is the growth rate coefficient (constant for a substantial period of growth at each level of N fertiliser), x is a constant (set at 1, by preliminary analysis) and W(F,t) is plant dry weight in t ha"1. The minimum level of N fertiliser maximizing the growth rate coefficient was identified; the nitrogen contents recorded for this fertiliser level at the different harvesting times were regarded as the critical nitrogen contents for sweet pepper. Conversely, plants grown at fertiliser levels lower than the above mentioned were assumed as N-deficient plants. For these plants, the relationship between plant growth and %N was studied by regression analysis.

Results In both years, the critical %N was found to be at a fertilisation level of 150 kg N ha"1 (data not reported); therefore, fertilisation levels up to 75 kg N ha-1 were considered insufficient to meet crop demand (N-deficient crop). In this case, the relationship between %N and relative growth rates (Fig.1) was linear in both years (R2 = 0.963 in 1991 and 0.883 in 1992) with curves showing similar slopes (0.00333 ± 0.00017 in 1991 and 0.00305 ± 0.00035 in 1991) but different intercepts (about 1.5 %N in 1991 and about 2.0 %N in 1992). It has to be mentioned that the intercept represents the minimum %N at which growth just takes place; the values obtained for sweet pepper seemed to be higher than those observed for other crops (Greenwood et al., 1991). Due to the different intercepts, for a given %N in the whole plant, RGR values were higher in the first than in the second year. This can be explained by differences in transplanting dates (16 June 1991 and 25 May 1992) and, subsequently, in environmental conditions that promoted a higher dry matter and nitrogen allocation in the leaves in 1991, with respect to 1992, as shown in Figure 2. As a result, in 1991,

Session 2.3 603

at the last sampling cite the axp shewed hi^ier IÄE (2.4 vs 1.3, cna«3ge), Hgt. i rtsaaçtiai (70% vs 48% of inxmirg ladiarim en auaage), radiatim use eÊEkdsxy (1.9 vs 1.5 g dw MJ"1) and, as a consequence, higher dry matter yield (5.9 vs 2.61 ha"1). When N allocation was taken into account and RGRs were plotted against the Nieaves/Nwhole plant ratio, the relationship proved to follow the same linear pattern in both years (Fig. 3), accounting for a great part of data variability (R2 = 0.928). This seems to indicate that when storage organs (such as fruits) compete with leaves for N allocation, %N cannot adequately explain variations in RGRs.

a: Ü PS

0.012

0.010

0.008

0.006

0.004

0.002

0.000

• o

1991 1992

2

, i

3 4

%N

— "3 J3 1 t. Z

1.0

0.8

0.6

0.4

0.2

0.0

Figure 1. Linear relationship between %N (whole plant) and RGR in N-deficient sweet pepper in 1991 and 1992.

%N Figure 2. Linear relationship between %N (whole plant) and the ratio Nieaves /Nwhole plant in N-deficient sweet pepper in 1991 and 1992.

0.0 0.2 0.4 0.6 0.8

Nieaves / Nwhole Figure 3. Linear relationship between the ratio Nieaves / Nwhole plant and RGR in N-deficient sweet pepper.

The relationships between critical %N and plant dry weight for 1991 and 1992 are presented in Figure 4. In 1991 the relationship proved to follow rather closely the one proposed by

Greenwood et al. (1990) for other C3 crops. Otherwise, in 1992 the observed critical %N levels were sensibly lower than those calculated by the above mentioned authors, due to the lower N allocation on leaves.

£

1 7 8 0 1 2 3 4 5 6

Dry weight ( t h a ' ) Figure 4. Relationship between plant dry weight and critical %N observed for sweet pepper in 1991 and 1992, in comparison with that proposed by Greenwood et al. (1990).

Conclusions Also in sweet pepper, the relationship between %N and RGRs proved to be linear in N-deficient plants. However, factors related to environmental conditions or cropping technique can promote changes on allocation pattern of N, that may in turn alter the relationship between %N and RGR. For this reason, the general relationship between critical %N and plant biomass proposed by Greenwood et al (1990) for other C3 crops may not always hold for sweet pepper. Furthermore, the minimum %N for growth seemed to be rather high in sweet pepper, with respect to other C3 crops and tended to increase as the N allocated to leaves decreased.

References Âgren, G.I., 1985. Physiologia Plantarum 64: 17-28. Greenwood, D.J. et al., 1990. Annals of Botany 66: 425-431. Greenwood, D.J. et al., 1991. Annals of Botany 67: 181-190. Lemaire, G. et al., 1990. First Congress ESA, Paris, 1 O 05.


EFFECT OF MYCORRHIZAL INFECTION ON PHOTOSYNTHETIC METABOLISM

A. J. Valentine, B. A. Osborne, D. T. Mitchell

Department of Botany, University College Dublin, Belfield, Dublin 4, Ireland.

Introduction Although the effects of mycorrhizal infection on nutrient acquisition by roots are well-documented (Marschner, 1995), less is understood about their consequences for photosynthesis by shoot tissues. Previous studies have indicated that mycorrhizal stimulation of photosynthesis can either be dependent or independent of any improvement in the nutrient status of shoot tissues (Wright et al., 1995; Fay et al., 1996). In order to examine this question in more detail we have investigated the effect of arbuscular mycorrhizal infection on photosynthesis of cucumber grown at a range of irradiances.

Methods Plants of cucumber (Cucumis sativus L. var. Telegraph Improved) were grown in sterilised sand at a phosphorus supply (0.13 mol m~3) shown in earlier experiments to be associated with a stimulation of the maximum rate of photosynthesis under ambient irradiances. The material was inoculated with live (+AM) or autoclaved (-AM) Glomus mosseae (strain YV, Microbio Ltd., UK) and grown at irradiances of 10,45, 75 and 100% of the ambient light level. Measurements of the response of photosynthesis to instantaneous variations in irradiance or intercellular CO2 concentration were made at a temperature of 25°C and a vapour pressure deficit of ~1.5kPa on intact leaves using a CIRAS infra-red gas analyser (PP Systems, Hoddeston, UK) and a thermostatted leaf chamber. Leaf N was determined using a modified microkjeldahl technique and P was analysed on sulphuric acid digests by the method of Murphy and Riley (1962). The extent of mycorrhizal infection and the proportion of different mycorrhizal components (vesicles, arbuscules and hyphae) per unit root length was estimated using a modified line intersect technique (Brundrett, et al, 1994).

45%

OOO r D O

100% n p o

1 1.5 Irradiance (mmol m~2 s~l)

Figure 1: The photosynthetic response to irradiance (X=400-700nm) by cucumber (Cucumis sativus L. var. Telegraph Improved) plants grown at 0.13 mol m~3 phosphorus and varying percentages (10%, 45%, 75%, 100%) of ambient light. At each light level, the plants were inoculated with either live ( •) or dead (O) arbsucular mycorrhizal inoculum.

Session 2.3 605

N

1 O O

e

e c C O

a. e o

60-

40-

20-

0 -

g vesicles

• arbuscules

H hyphae

• 1 u • 1 y • i u

D L D L D L D 10 45

Treatment

75 100

Figure 2: Percentage of mycorrhizal components present in the root tissue of cucumber plants. The host cucumbers were grown at 0.13 mol m~3 phosphorus and varying degrees (10%, 45%, 75% 100%) of ambient light. At each light level, the plants were inoculated with either live (L) or dead (D) arbsucular mycorrhizal inoculum.

Mycorrhizal enhancement of the maximum rate of photosynthesis (Pm) w a s dependent on irradiance with a greater enhancement at the higher growth light levels, although this was not dependent on leaf N or P levels (Fig. 1). Examination of the underlying factors responsible for the stimulation of P m indicated that this was a consequence of both an increase in electron transport activity and carboxylation capacity. Whilst consistently higher (30-60%) levels of infection were found in +AM plants this was not directly related to the extent of enhancement of Pm . +AM plants grown at 10, 45 and 75% of ambient irradiance had similar total levels of infection (Fig. 2), but different values for Pm (Fig. 1). Of the mycorrhizal components examined, the proportion of arbuscules, correlated best with the degree of enhancement of Pm (Fig. 2, y=0.353x + 3.801 ; r^= 0.906, P< 0.05).

Conclusions This work confirms that mycorrhizal infection can have a significant stimulatory effect on Pm . As the enhancement of Pm was independent of leaf N or P or the total level of infection, but dependent on irradiance, suggests that this is due to a 'sink' effect, which is related specifically to the arbuscular mycorrhizal component. At a mechanistic level the enhancement of Pm caused by the removal of end-product limitations to photosynthesis appears to operate via adjustments in both electron transport and carboxylation reactions.

References Fay, P. et al., 1996. New Phytologist (in press). Brundrett, et al., 1994. Practical methods in mycorrhizal research. Mycologue Publication,

Guelph, Ontario. Marschner, H. 1995. Mineral nutrition of higher plants. Academic Press, London, 889 pp. Murphy, J. and Riley, J. P., 1962. Analytico Chimica Acta 27: 31-36. Wright, D. P. et al., 1995. Aspects of Applied Biology 42: 109-115.


EFFECTS OF DEFOLIATION ON GROWTH OF CAULIFLOWER

R. Van den Boogaard, K. Thorup-Kristensen

Department of Fruit and Vegetables, Danish Institute of Plant and Soil Science, Kristinebjerg-vej 6, DK 5792 Ârslev, Denmark

Introduction To develop cropping systems where vegetables are grown with a reduced amount of chemicals, we need knowledge on their growth under sub-optimal conditions. Models can help to integrate the different aspects of crop growth in such systems, and can help to improve crop protection strategies. Present plant growth models generally describe growth under optimal conditions. However, models are needed that can appropriately describe plant growth under sub-optimal conditions. Pests and diseases will affect a plant's leaf area and by that its growth. Therefore, we have studied the effect on growth, yield and development of leaf removal at different times, and of removal of old (source) or young (sink) leaves in cauliflower.

Methods Plants were grown on a sandy loam at Ârslev Research Centre in Denmark (55°18TST,10°27'E). Row and plant spacing were 0.5 m and 0.6 m, respectively. Pest and disease control, fertilisation and irrigation were according to guidelines of normal production. Leaf area was measured using a Delta-T area meter. Weights were determined before and after oven-drying at 80°C for 24 hours. Total-N, nitrate-N, sugar and starch concentrations were measured on the dry material.

Results The table shows an example of the effect of defoliation on growth and yield. When leaf area was reduced with up to ca. 70 %, final curd weight of the defoliated plants was only reduced by up to ca. 30%. Defoliation during the curd induction phase generally affected curd yield less than defoliation during the curd growth phase. By weekly samplings after defoliation, it was found that after the leaf damage the loss of leaf area was compensated by increased leaf growth, but that this was at the cost of reduced stem growth. The dry matter percentage of the plant, and the sugar and starch concentrations in midribs and stems of damaged plants were reduced, showing that probably remobilisation of stored assimilates from midribs and stems to leaves took place. Although leaf area per unit plant weight was much reduced in the damaged plants, the relative growth rate of damaged plants was similar to that of control plants. This showed that the net assimilation rate of the remaining leaf area was increased. The results also showed that curd growth was delayed after defoliation, and thus a longer growing period diminished curd yield losses in defoliated plants.

Session 2.3 607

Table 1. Growth of cauliflower cultivar Plana in a field experiment in 1995. Plants were partially defoliated at four different times during growth. The length of the growing period was 69 days. Planting date was 5 July and final harvest was at 12 September.

Defoliation Time Leaf

Type (days)

Control 20 6 Oldest 36 10 Oldest 47 10 Oldest 55 11 Oldest

Growth

Stage

Curd Induction Curd growth Curd growth Curd growth

Leaf Area Before After Reduction (m2) (m*)

0.18 -» 0.05 0.96 -* 0.36 1.57 -» 0.65 2.17 -> 1.06

(%)

72% 63% 58% 51%

Harvest Leaf Area (m2)

1.88 2.00 1.61 1.41 1.20

Plant DW

(g)

272 248 209 220 198

Curd DW

(g)

84 68 63 74 59

Reduction

(%)

19% 25% 12% 30%

Conclusions An increased rate of leaf growth and a reduction in stem growth after defoliation, associated with remobilisation of assimilates stored in stems and midribs, compensate the loss of leaf area in cauliflower. Due to this compensation and the increased length of the curd growth phase, only small reductions in yield compared to the level of leaf damage were found. Effects of defoliation may be different under other climatic conditions. Development of cauliflower mainly depends on temperature. High temperatures during curd induction will lead to a long curd induction phase and a large number of leaves formed (Grevsen and Olesen 1994). Due to high temperatures during the '94 and '95 seasons, plants developed large leaf areas. Therefore, leaf area may not have been limiting growth, despite removal of more than half of the leaf area. In '96 we will conduct experiments from early spring onwards, to investigate the effects of damage at a lower temperature and lower leaf area. The results of the present and further studies, showing the sensitivity of yield to defoliation at different times during crop development and the underlying physiological processes, will be used in a model describing cauliflower growth and development, which will be linked with pest and disease models. This model can form the basis of decision support systems for integrated pest management in vegetables. The model will take account of the changed physiology and development of damaged plants, such as an increase in the duration of the growing period and remobilisation of stored assimilates.

References K. Grevsen and JE. Olesen 1994 Journal of Horticultural Science 69, 755-766.


EFFECT OF NITROGEN SUPPLY ON LEAF GROWTH AND PHOTOSYNTHETIC CAPACITY IN POTATO

P.E.L. van der Putten1, G. Posca1'2, J. Vos

Department of Agronomy, WAU, Haarweg 333, 6709 RZ Wageningen, The Netherlands Università della Basilicata, Potenza, Italy

Introduction Nitrogen supply primarily affects the rate of leaf expansion and the total number of leaves in potato (Solanum tuberosum L.). The photosynthetic capacity, Pmax, measured at saturating irradiance, often shows a direct relation with the concentration of nitrogen in leaf dry matter (Marshall and Vos, 1991). However, at low levels of irradiance, there is no association between the rate of photosynthesis on the nitrogen concentration. It is not efficient for a plant to keep nitrogen in weakly illuminated leaves. Hirose and Werger (1987) found that (re)allocation of nitrogen in the plant canopy is such that the distribution is often close to the one optimal for maximal production. Mutual shading is more severe in nitrogen-rich crops than in nitrogen-deficient crops. The hypothesis is that this influences life spans of leaves and nitrogen (re)allocation. Often, life spans in N-rich crops are shorter than in N-deficient crops. We examine in experiments the effect of the level of irradiance (or actually: shade) on (i) the change with time in Pmax and nitrogen concentration of individual leaves, and (ii) the allocation of carbon and nitrogen in the plant. Nitrogen supply itself was included as an experimental factor. In two experiments (to be reported elsewhere) we observed that Pmax of leaves was lower in the treatment with non-limiting nitrogen supply than for a moderate rate of N supply. Yet, the high-N plants had larger leaves and grew faster than the low-N plants (spaced plants). The objective of the experiment reported here was to analyze leaf growth and Pmax for a wide range of N supply. The particular interest was to understand under which conditions decline in Pmax can occur for increase in N supply.

Methods Seed potatoes were planted on June 8, 1995 in sand in 20 litre pots. The greenhouse was kept at 18/12 °C day/night (12/12 h). Plants were spaced and put in six randomized blocks. Treatments were five levels of nitrogen supply (Nl - N5). Nutrients were supplied every 10 days, starting at one week after emergence. Treatments Nl - N5 received 1, 2, 4, 6 and 8 g nitrogen per pot, respectively. Changes in leaf length and maximum width were recorded in situ for main stem leaf numbers 4, 6, 8 and 10 (numbers counted acropetally). Leaf areas (A; cm ) were calculated from recordings of leaf length (L; cm) (from the stem till tip of terminal leaflet) and width (W; cm) using: A = 0.45 LW (r2 = 0.99; SE = 0.006). Leaf area growth was fitted to the logistic equation:

A = c/ (1 + exp("b (x • m))) (Eqn 1), where x is leaf age since appearance (days), c is the maximum leaf area (asymptote; cm2), and b and m parameters. Fits generally showed r values of 0.99. Effects of N supply were evaluated by ANOVA on the values of c and mr. (mr=b.c/4 = maximum expansion rate). Photosynthesis rates were measured using ADC portable equipment. Recordings were made for main stem leaves 8 and 10 on 31, 38, and 45 days after emergence (DAE). Irradiance in the cuvette at the level of the leaf was 1200 uE m"2 s"1 (PAR).

Results Maximum leaf expansion rate and full-grown leaf size (Table 1) increased with nitrogen

Session 2.3 609

supply, although the differences between N3 - N5 were not significant for each leaf layer. Nitrogen effects increased with leaf number. More than 90 per cent of the variation in maximum leaf sizes (c) was accounted for by variation in mr, implying that the expansion rate rather than the duration of expansion determined leaf size (cf. Vos and Biemond, 1992).

Table 1. Effects of nitrogen supply on maximum, mature leaf area (cm ) obtained by fitting Eqn 1 to data on leaf expansion. Means (within leaf numbers) followed by different letters are significantly different (P < 0.05).

Pmax declined with leaf age from ca 0.95 to 0.55 mg C02 m'2 s"1. Examining the data from both leaf numbers, no consistent, statistically significant effects were apparent of nitrogen treatment on Pmax and its change with time (Fig. 1). On 50 DAE, N content increased from 0.93 g plant"' in Nl to 4.35 g plant"1 in N5. Plant dry weight increased from 52 g in Nl to an average value of 110 g plant" for N3, N4 and N5.

-1 „ ,___ „ ™ __-2_--U -a- N1

Leaf number

4 6 8 10

Nitrogen Nl

156a 154a 166a 146a

treatment N2

181ab 226b 262b 229b

N3

235bc 282c 284bc 277bc

N4

246c 350d 33 led 352d

N5

232bc 375d 380d 310cd

-1

Pmax

N2

- ° - N3

N4

N5

35 10 15 20 25 30 35

Time after leaf appearance (d) Time after leaf appearance (d)

Figure 1. Pmax versus leaf age, (a) leaf number 8, (b) leaf number 10.

Conclusions 1. Up to a maximum in response, leaf sizes were larger for higher rates of nitrogen supply,

primarily through increased leaf expansion rate with more nitrogen. 2. There were no systematic effects of nitrogen supply on Pmax. 3. The experiment offered no explanation for earlier observations of lower Pmax in leaves

of plants with ample supply in nitrogen than for moderate levels of nitrogen supply.

References Hirose, T. and Werger, M.J.A., 1987. Oecologia 72:520-526. Marshall, B., and Vos, J., 1991. Annals of Botany 68: 33-39. Vos, J. and Biemond, H., 1992. Annals of Botany 70: 27-35.


GROUND COVER IN VINEYARDS WITH GRASS AND LEGUME SPECIES IN PURE AND MIXED STANDS

M. Volterrani1, M. Gaetani1, N. Grossi' , G. Pardini1, S. Miele1, G. Scalabrelli2.

'Dipartimento di Agronomia e Gestione dell'Agro-Ecosistema, University of Pisa, Italy. 2Dipartimento di Coltivazione e Difesa delle Specie Legnose, University of Pisa Italy.

Introduction Grass covers in vineyards are gradually becoming more widespread in Central-Northern Italy. This management scheme reduces soil erosion and leads to an increase in soil organic matter, total nitrogen, water holding capacity and structure stability as well as a decrease in bulk density (Morlat et al., 1993). On the other hand, grass-vine competition causes a reduction in vine vegetative growth and production (Haynes, 1980; Lombard et al., 1988). By seeding particular crops growers could achieve more targeted results than using the spontaneous weed covers. The purpose of this research was to compare different vineyard soil management techniques.

Methods Trial was carried out in Rispescia, near Grosseto (Italy). 24 different soil management schemes were compared: - 3 without seeding: straw mulching, tillage, spontaneous weed covers; - 7 pure grass stands - 7 pure legume stands Agrostis stolonifera L. "Carmen"(As) Lotus corniculatus L. Bromus catharticus Vahl "Cabro" (Be) Medicago lupolina L. Dactylis glomerata L. "Dora" (Dg) Trifolium fragiferum L. Festuca arundinacea Schreb. "Apache"(Fa) Trifolium repens L. Festuca ovina L. "Bornita"(Fo) Trifolium subterraneum L. Festuca rubra L. "Artist" (Fr) Trifolium subterraneum L. Lolium perenne L. "Ovation"(Lp) Trifolium subterraneum L - 1 mixed grass stand : Lp "Bianca"(25%); Poapratensis "Mosa"(40%); Fr "Commodore"(35%) - 2 mixed legume stands :Tr+Tsj; Ml +Tsj; - 4 mixed grasses and legume stands: Fa+Tsj; Fo+Tr; Fa+Lp+Tr+Tsj; Fa+Lp+Fo+Tr+Tsj+Ml. Seeding was carried out on 20th November 1994. A randomized block design with 4 replications was adopted. The plots were mown three times to a height of 7 cm. In each plot, area covered by the crops and weeds was rated subjectively at five different times during the year. In April 1995, height and fresh biomass production were measured. In April and October 1995, in mixed stands the percent of each species was determined. At harvest, vines were evaluated for cane length and berry yield.

Results Due to the particularly dry June-August period, the herbaceous covers dried up even if Fo, Fa, Dg, Tr and Lc achieved green ground cover over an area ranging between 1% and 7%. During the other months of the year spontaneous weed covers showed a mean ground cover value of 73% (Tab.1). Among the seeded species, the most successfully grass stands were Be, Fa, Dg and Lp, together with the legume species Tr and above all Ts. In the mixed grass stand Lp was found to be predominant (Tab.2). The mixed stand Tr+Tsi was composed almost exclusively of TST in spring, but in the fall a better balance was achieved. Ml, Fo or Fa where absent or present in a minimal proportion in the mixed stands. The mixed stands of grasses and legume species showed a marked predominance of the latter, while Lp was found to be the most competitive grass. Fresh biomass was particularly elevated in TST, the 4 and 6 crop mixed stands and TSTT, with values ranging between 11.7 and 18.6 kg m"2. Weed cover fresh biomass also exceeded 10 kg m~2.

"S. Gabriele"

"Palestinese" "Tamar" "Clare"

(Lc) (Ml) (Tf) (Tr) (TST)

"Mount Barker"(Tsn) "Dalkeith" (TSUI)

Session 2.3 611

Greatest height was recorded in the TST, Be and weed cover treatments, with values close to 25 cm. Among the well-established species, the lowest values were found in Fa (8 cm), Lp (9 cm) and in the mixed grass stand (8 cm). Soil management techniques exerted a significant effect on vine vegetative growth and production. Overall competition with ground cover caused a reduction in cane growth and yield. This was particularly evident in Be, Tr and Fa, where cane length was 26, 23 and 21 % lower respectively, as compared to tillage. The percent decrease in yield ranged between 20 (Be) and 29% (Fa). In contrast, straw mulching stimulated cane growth (+70%) and berry yield (+59%).

Tab. 2 Mixed stands composition (%) Tab. 1 - Mean Crop (C) and Weed (W) ground cover, Fresh Weight (FW), Height (H).

(C) (W) (FW) (H) kg m"z < •cm

Straw mulching Tillage Weed cover As Be Fa Fr Fo Dg Lp Tf Ml Tsi Ts n TsIII Tr Lc Lp+Pp+Fr Tr+TsT Ml+Tsj Fa+Ts! Fo+Tr Fa+Lp+Tr+TsT Fa+Lp+Fo+Tr+Ts

0 0 73 11 78 61 21 18 71 79 36 20 83 87 62 61 37 71 79 76 80 55 78

r+M178

12 23 0 53 10 22 54 48 14 12 33 47 9 8 24 17 34 16 10 11 12 18 11 12

--10.2 1.0 5.6 2.6 2.7 0.6 1.8 3.5 1.3 2.4 18.6 13.1 5.1 6.8 2.1 5.3 7.7 8.6 15.9 4.5 15.0 11.7

--25 2 25 8 7 4 14 9 11 4 24 21 21 14 7 8 25 26 25 14 20 19

in April and October

April 1995

75 Lp OPp 25 Fr 4Tr 96 Ts! 0M1 100 TST 5 Fa 95 TST 6Fo 94 Tr 2 Fa 12 Lp lFa 15 Lp

7Tr 79 TST 3Fo 4Tr 77TsT0Ml

October 1995

88 Lp 34 Tr

OPp 66 Ts!

0M1 100 TST 2 Fa 4Fo lFa lFa

98Tsj 96 Tr 10 Lp 15 Lp

12 Fr

27 Tr 62Tsj 0 Fo 28 Tr 56 TsT 0M1

LSD (PO.05) 15 11 4.8

Conclusions During the first trial year the most successfully established species were Ts, Tr, Lp, Be, Dg and Fa. Mixed stands did not lead to greater ground cover as compared to pure stands. The grasses species showed lower height and lower biomass production. Vines in competition with ground cover crops showed decreased yield (as much as 29% lower as compared to tillage), whereas mulching was found to enhance vegetative growth and yield.

References Haynes, R.J., 1980. Agro-Ecosystems, 6:3-32. Lombard, P. et al., 1988. Proc. 2nd International Cool Climate Viticulture and Oenology

Symposium, Auckland, New Zealand : 152-155. Morlat, R. et al., 1993. Progrès Agricole et Viticole ,110, 19: 406-410.


YIELD OF SUGAR BEET USING ALTERNATIVES FOR FARM YARD MANURE

M. Wesotowski, M. Jedruszczak

Department Soil and Plant Cultivation, Agricultural University, 20-250 Lublin, Akademicka 13, Poland

Introduction Biological properties of root crops ( roots is the yield which was taken away from the soil ) and technology of their cultivation impoverish the reserves of soil organic matter (Fotyma, 1988). This implies the need to supplement it in the from of manures. Since Farm Yard Manure (FYM) production is limited, substitutes which could replace FYM in field management are in demand. So far, experiments have proved that properly prepared cereal straw or green manure from other plants, especially of leguminous crops, can replace FYM without detrimental effects to the humus management of soil and its physical and chemical properties (Ceglarek et al., 1985; Fotyma, 1988; Gruczek, 1994; Pawlowski et al,1988; Pawlowski et al., 1991) The response of sugar beet -traditionally planted with FYM in Poland- to the manuring by using cereal straw and stubble catch crops, as the substitutes of FYM was investigated.

Methods The field experiment was conducted in Czeslawice Experimental Station (middle-east Poland) according to a randomized complete blocks design method in four replications in 1992-1993. The manuring methods were the treatments of the experiment. They were: A. NPK (in kg ha~l, N = 140, P2O5=90, K.2O=180); B. Farmyard manure (30 t ha"1) + NPK; C. Cereal straw (9 t ha"1) + NPK; D. Cereal straw (9 t ha"1) + 1% of N by straw weight + NPK; E. Catch crop I, field bean + field pea (2.11 ha"l on dry basis); F. Catch crop II, white mustard (2.2 Mg ha~l on dry basis).The mineral fertilizers were applied in spring, half of the N rateduring seedbed preparation and another one after thinning of sugar beet. The dose of the fertilizers was the same in all treatments. Sugar beet was grown after cereal crops. The experiment was performed on Orthic Luvisol derived from loess. The soil has neutral reaction and is relatively rich in P, K, Mg and humus (more than 2%) and is free of sugar beet-root eelworms. Mean yearly precipitations and air temperature were 530 mm and 7.3°C, respectively. The corresponding values for the growing season (IV-X) are 404mm and 13.2°C.

Results Results are presented in Table 1 and 2.

Table 1 Yield of roots and leaves and saccharinity of sugar beet Kind of manure

A.Without manure * B. Farmyard manure C. Straw D. Straw + 1%N E. Catch crop I F. Catch crop II

Yield roots

79.8 85.2 77.6 80.6 80.5 84.2

in t per leaves

44.3 52.4 45.0 48.4 48.9 48.0

ha conversional

sugar

15.9 16.3 15.0 15.6 15.8 16.5

Saccharinity (%)

19.9 19.1 19.4 19.4 19.6 19.6

*NPK only

Session 2.3 613

Although the differences in sugar beet parameters among the experimental treatments were not statistically significant (acc.Tukey) there were some clear tendences. The highest yield of sugar beet roots being 85.2 t ha'1 was obtained from the plots with application of FYM (B) (Tablel). Only slightly lower yield was found in treatment with ploughing under white mustard (F) where sugar beet yield was reduced only by 1.5% relative to plots with FYM. The yields from plots with other manures were much lower. The substitution of FYM by cereal straw (C,winter barley -1992 and winter wheat -1993) gave the worst result. The highest yield of sugar beet leaves equalled 52.3 t ha"l was obtained, as with roots, from the plots with FYM. This yield was reduced by 14 to 15% in treatments without any manure (A) and with only straw (C) ( Tablel). The saccharinity of sugar beets, that is noteworthy, was almost inversely correlated with joint yield of roots and leaves. Finally, the lowest sugar content was recorded in treatment with FYM (B) and the highest one in that without any manure (A). However, the conversional biological yield of sugar was the highest on FYM (B) and mustard (F) treatments.

Table 2 Fresh weigt of single root and number of normal and forked roots of sugar beet Kind of manure

A. Without manure * B. Farmyard manure C. Straw D. Straw + 1% E. Catch crop I F. Catch crop II

Mass of root

(g)

1300 1367 1195 1191 1272 1315

Number of roots normal

56 56 59 63 57 57

per 10 sq. m forked

6 7 6 6 7 7

* NPK only

The mass of single root was the highest in treatments with FYM (B) and white mustard as the stubble catch crop (F), with equal numbers of forked roots, unfortunately over 12%. The lowest values of the yield parameters were on the plots with application of straw (C) and straw + 1% N (D), Table 2. Thus this indicates the productivity of sugar beet was principally dependent on the weight of the individual roots, since the total number of roots per 10 m~2 was similar in all treatments.

Conclusions Two year studies revealed that sugar beet yield was not statistical significantly affected by manuring methods. However, the green mass of white mustard (as a stubble catch crop) can be the best alternative manure to the FYM in growing of sugar beet on loess soil in the midde-east Poland, free from sugar beet-root eelworms. Productivity of sugar beet on the soil enriched with this green manure was similar to that in treatment with FYM, which was relatively high. Sugar beet was least productive on the plots with ploughing under straw without addition of N. In this case the yield was even lower than that from plots with mineral fertilization without any manure.

References Ceglarek, F. et al. 1985. Zeszyty Naukowe WSRP w Siedlcach, seria Rolnictwo 5:23-33. Fotyma, M. 1988. Zeszyty Problemowe Postçpow Nauk Rolniczych 311: 205-215. Gruczek, T. 1994. Fragmenta Agronomica 2:72-82. Pawtowski, F. et al. 1998. Zeszyty Problemowe Postçpow Nauk Rolniczych 331: 217-226. Pawlowski F. et al. 1991. Materialy V seminarium ptodozmianowego. Cz. II. ART 01sztyn:116-119.


EFFECTS OF FOLIAR FERTILIZATION WITH NITROGEN AND MICROELEMENTS ON SEED YIELD OF PEAS

W.Zioiek, B.Kulig

Department of Crop Production, Agricultural University, Al. Mickiewicza 21, 31-120 Krakow, Poland

Introduction The issue of using increased rates of nitrogen in leguminous crops is quite controversial. It is thought that they limit fixation of the atmospheric nitrogen (Glazewski, 1975; Jasiiîska et al., 1983) but newer research indicates there is usefulness in applying higher nitrogen rates for the new, high yielding cultivars (Wojcieska et al., 1993). Nitrogen can be used for foliar spray in a composition with microelements before plants start flowering (Pode, 1983; Rhoden, 1983) The research confirmed the positive influence of such treatment on the seed yield, protein content, and on the yield structure elements of peas (Ziólek et al., 1996).

Methods In the years 1992-1994 field experiments made on degraded chernozem soils were carried out at the Agricultural Experimental Station near Krakow. The investigation included: two peas cultivars - Ramir and Rubin differentiated as to morphology and biology, three multicomponent microelement fertilizers (Agrosol-S, Insol-6, and Mikrovit-1), applied before plants start flowering, and nitrogen fertilization (O, 20, 40 kg N ha"1). The phosphorus and potassium fertilization in the rates 100 kg P205 and 140 kg K20 ha"1 was applied before sowing of the peas An estimation of the effect of the investigated factors was made on the base of seed yield and of the separate components of yield structure (the number of plants bearing seeds per unit of area, the number of seeds per plant, the mass of 1000 seeds) as well as the content and yield of crude protein.

Results

Ramir Rubin Cultivars

Aoroao(-S InaoW MikroviM

Figure 1. The effect of investigated factors on the yield of seeds and crude protein of peas

Session 2.3 615

The seed yield and protein analysis indicates that Rubin with the ordinary foliage was the better yielding cultivar (Figure 1). There was interaction between the research years and the cultivars, dozes of nitrogen and microelements fertilizers. That gave evidence of the strong influence of climatic conditions on the peas yield. Increased level of nitrogen fertilization up to 40 kg N ha"1, with application of a half dose as foliar spray jointly with the microelement fertilizers contributed to higher seed yield and to a much higher degree - to protein yield. Among the compared microfertilizers Mikrovit and Agrosol were the most beneficial for the seed and protein yield of peas. There was interaction between the nitrogen dozes and the yield structure components (number of plants per m2, the mass of 1000 seeds and the number seeds per plant) in the investigated cultivars (Table 1). Increased seed yield of Rubin cultivar was associated with an increased number of plants m"2 and the mass of 1000 seeds. The above features were strong effected with the fertilizer dose of 20 kg N ha"1 and 20+20 kg N ha"1 and the microfertilizers Mikrovit and Insol. The number of seeds from a plant was increased by the higher dose of nitrogen used a half as foliar spray plus Mikrovit.

Table 1. Yield structure elements in relation to the investigated factors

Features

Cultivars kg N ha"1 Microelements fertilizers

Ramir Rubin Control 20 20+20 Control Agrosol- Insol-6 Mikrovit-S 1

Mea-

Mass of 1000 seeds 199 227 209 216 213 216 210 212 213 213

No. plant m"2

56.1 61.2 58.3 59.7 57.9 58.6 58.7 58 59.3 58.6

No. seeds per plant 28.8 25.1 26.3 26.3 28.1 26.4 27.2 26.1 28.0 26.9

Conclusions The results of the three year field research on peas entitle to draw the following conclusions: 1. The climatic conditions have crucial influence on pea yields. 2. The pea cultivar of ordinary foliage ensured the highest yield of seeds and protein. 3. From all the yield structure elements - the number of plants bearing seeds and the mass of 1000

seeds - are the major factors modifying pea yield.

References Glazewski, S., 1975. Pamietnik Pulawski 64: 167-189. Jasihska, Z , 1983. Zeszyty Naukowe AR we Wroclawiu: 141, 125-133. Pode, W.D., 1983. Agronomy Journal 75: 195-200. Rhoden, E.G., 1983. Agronomy Journal 66: 173-178. Wojcieska, U. et al., 1993. Fragmenta Agronomica 4: 175-176. Ziólek W. et al., 1996. Acta Agraria et Silvestria, series agraria XXXIV,60-72.

Agroforestry Session


ALTERNATIVE AGRICULTURAL LAND USE WITH FAST GROWING TREES : SCIENTIFIC BASES AND MODEL FOR EUROPEAN AGROFORESTRY

Daniel Auclair INRA - CIRAD, Unité de modélisation des plantes, BP. 5035, 34032 Montpellier cedex 1, France

Introduction A research project oriented towards the development of extensive land-use systems, adapted to environment and market requirements, was initiated in 1993 by 18 research and development institutes from six European countries, with the financial help of the European Commission. It aims at diversifying the intensive uses of agricultural land with fast growing trees. They are planted at wide spacings in order to produce high quality timber and to allow agricultural activities. The specific objective of the research project is to develop an integrated agroforestry modelling system devoted to simulation and decision-making for farmers, land-owners, and land managers. It includes technical aspects and integrates biological and economic data.

Methods Research is being developed on two main aspects (Figure 1): 1. A study of the technical and scientific bases of agroforestry systems management, conducted through a European network of field experiments: • site characteristics of available agricultural land and tree growth potential, • choice of tree genotype, tree establishment and management techniques, • impact of agroforestry techniques on tree growth, form, and wood quality, • agricultural techniques and rearing systems adapted to agroforestry, • interaction processes between tree—microclimate—crop or pasture—soil—animal. 2. The integration of these data in an agroforestry modelling system, aimed at predicting mean-term and long-term consequences of the adoption of agroforestry systems, at micro- and macro-economic levels. Biophysical models have been developed for tree and agricultural components and their interactions, and linked to a biologically-based economic modelling system. Social and environmental aspects are also being investigated.

Practical results A great number of scientific results (Auclair, 1996a) have been obtained through the individual tasks of the project (arrows pointing outwards in figure 1). They have been summarized by Auclair (1996b). The main practical results are the following: • Tree damage and mortality, due to livestock or wind, result from inappropriate rearing systems (overstocking), misadapted tree-shelters, or increased sensitivity of trees to wind due to growth modifications within tree-shelters. • New tree-shelters have been designed, which improve tree growth and form. • The impact of weeding is extremely important in the first years, and interacts with water and nutrient cycling.

Figure 1. General description of the project: individual tasks provide results (outwards) and data for the modelling tasks (inwards), which form the main core of the project.


• Growth of a given species within the tree-shelters is homogeneous on each study site, but at later stages the site/genotype interaction predominates and inter-tree variability becomes very high. Diameter growth increases and H/D ratio decreases during the years after emerging. • In most experimental plots, there is no evidence of total annual pasture production being reduced by the presence of trees of up to eight years old at densities of up to 400 stems ha" . • Wide tree diameter growth increments produced on agroforestry plots have a negative effect on the quantity of heart wood, thus on timber quality (of Prunus avium). • Greater pasture growth was observed below trees than in the open during dry weather. • Sheep grazing behaviour is modified among trees at wide spacing. Animals are attracted to the trees, resulting in greater foot pressure in the area immediately around them. This could explain differences in soil compaction and tree survival. • Important parameters for the bio-economic model are the duration of the intercrop or the width between tree plantation lines. Intensified agricultural management may significantly improve economic return, however important questions concerning competition between trees and crop remain insufficiently answered.

Modelling A field-based bio-physical model describing a silvopastoral system—ALWAYS—has been developed (Bergez and Msika, 1996, see figure 2). It has been linked to the BEAM economic module (Thomas et al., 1994), and is now undergoing the calibration and validation processes with the data obtained by other R&D institutes in other regions.

BIOPHYSICAL SYSTEM MANAGEMENT SYSTEMS

Figure 2. Summary of the bio-economic modelling system. Five compartments— two physical and three biological—are in interaction in the biophysical model. Management modifies the biophysical inputs and economic outputs.

Conclusions The technical results stress the imperative necessity to use high quality plant material, adapted to the site, to control the herbaceous layer during tree establishment, and to practise pruning operations early. The modelling system developed here has up to now been used primarily as a research and education tool to help understand processes driving complex land-use systems. It also has practical applications for farmers and land managers. Extensions are under study to account for introduction of agroforestry practices at the farm and landscape level.

References Auclair, D., (ed.) 1996a. Alternative agricultural land-use with fast growing trees. Third annual report, European Commission, D.G.VI. 471 p. Auclair, D., 1996b. In M. Etienne (ed.) Temperate and Mediterranean silvopastoral systems of western Europe. INRA, Versailles, pp. 195-206. Bergez, J.É., 1996. In M. Etienne (ed.), op. cit., pp. 207-220. Thomas et al., 1994. Agroforestry Forum 5(2): 65-72.


THE POTENTIAL OF AGROFORESTRY FOR SAHELIAN COUNTRIES

H. Breman1 & J.J. Kessler2

iDLO Institute for Agrobiology and Soil Fertility AB-DLO, PO Box 14, 6700 AA Wageningen. 2Englaan 8, 6703 EW, Wageningen, the Netherlands

Introduction With the aim of optimizing resource use in semi-arid regions, the surplus value of woody plants in relation to water and nutrient availability has been estimated. Chances for effective use of agroforestry in the Sahel have been identified and defined, taking farmers goal, soil type and climate into account.

Methods A synthesis of more than 500 publications about woody plants in agroecosystems, with an emphasis on the Sahel, has been interpreted using the basic analysis of primary production in Sahelian countries (Penning de Vries & Djitèye, 1991). Taking light absorption by woody plants into account, an impression has been obtained about the maximum profit in relation to water and nutrient availability for herbaceous neighbours (crops or rangeland). A simulation model has been elaborated, which will make it possible to do much more detailed estimations (Conijn, 1995). Fieldwork in the southern Sahel of Mali made it possible to test some of the conclusions about the surplus value of trees, on process level as well as the overall influence on soil and vegetation concernes (Groot et al., in press).

Results The results are presented in Tables 1 and 2.

Conclusions Though processes have been identified through which woody species improve the availability of nutrients and water, it is not easy for farmers to exploit this surplus value: - surplus value is low where most needed, in marginal areas; - woody species compete with crops or herb layer; - labour intensitivity is high. Nevertheless, the following chances for effective use of agroforestry have been identified: 1. Chances for agroforestry in sylvopastoral systems - In case of water limited production, woody cover as high as possible for maximum sustainability

(erosion control). - In case of nutrient limited production, woody cover 15-20%; unpalatable, homogeneously

distributed trees, with high ratio trunk height / crown diameter, for optimum animal production. - For maximum animal production fodder banks of highly palatable woody species at locations

representing optimum growth conditions and high niche differentiation for woody plants. 2. Chances for agroforestry in cropping systems - Windbreaks useful to improve crop establishment on sandy soils in driest parts of area with

nutrient limiting growth (Sahel), where superficial ground-water table is available - In more humid areas of semi-arid region (sudanian savannah), maximum crop production with

woody cover of 15-20% of homogeneously distributed trees, with high ratio trunk height / crown diameter and with restricted exploitation. With fertiliser benefits higher than without!


3. Favourable economic conditions Agroforestry potential positively correlated with wood and fruit prices, negatively with wages. Subsidised agroforestry has to be considered in the upper course of river basins, in view of the buffering functions provided by woody plants. Agroforestry reduces the necessity of subsidies on external inputs, in view of the improved efficiency of the use of water and nutrients.

Table 1. Effects of woody plants on water availability Process rainfall interception stem flow improved soil structure: less run-off* improved storage capacity soil * transpiration of woody plants micro-climatic changes * hydraulic lift * uptake by deep roots

Sahelian zone -+ + 0 -+ 0 +

savannah -++ +++ + -+ 0 ++

0 negligible effects; +, ++, +++ water availability increases with 10-50, 50-100 or >100 mm yr*; - decreased water availability, * perhaps positive influence on herbaceous plants

Table 2. Effects of woody plants on nutrient availability Process redistribution

lateral roots wind animals

reduction of losses decreased wind erosion

-water erosion -leaching -fire

recycling: -internal -external

enrichment uptake by tap roots nitrogen fixation P-uptake through mycorrhiza

Sahelian zone

+ + +

+ 0-+ + + + +

0 0 0

savannah

++ + +

+ +-++ +++ + ++ ++

+ + +

0 negligible effects; +, ++, +++ N increase 1-5, 5-10 or >10 kg ha-1 yr-1; P increase 10% of N increase

References Breman, H. & J.-J. Kessler, 1995. Woody plants in agro-ecosystems of semi-arid regions (with an

emphasis on the sahelian countries). Advanced Series in Agricultural Sciences 23. Springer-Verlag, Berlin.

Conijn, J. G., 1995. Rapports PSS no. 12. Projet PSS. 1ER, Bamako, DAN-UAW, Wageningen, AB-DLO, Wageningen/Haren.

Groot, J.JR., et al (in press). Utilisation des éléments nutritifs et de l'eau par Acacia seyal et Sclerocarya birrea. In: Breman, H. & K. Sissoko (Eds). Intensification agricole au Sahel, KARTHALA, Paris.


SIMULATION OF LONG TERM CARBON DYNAMICS AND NITROGEN YIELD OF AN AGROFORESTRY SYSTEM IN A SEMI ARID REGION

J. G Conijn

Department of Grassland and Vegetation Science, AB-DLO, PO Box 14, 6700 AA Wageningen, The Netherlands

Introduction In tropical areas, agroforestry systems are used because of their potential to maintain soil organic matter at higher levels compared to monoculture cropping systems of annual species. Higher soil organic matter levels have a postive effect on plant production, especially in low input systems. On the other hand trees may reduce the yield of the understorey species by competing for limiting resources. To investigate the relation between soil organic matter level and grass yield, a simulation study has been carried out, in which 4 grass production systems in a semi arid region are compared.

Methods The model RECAFS (Conijn, 1995) calculates the absorption of light, water and nitrogen by an annual grass species and a tree species both in monoculture and in a mixed stand and the dry matter production of both species as a function of the absorbed resources. A soil water and a soil nitrogen balance have been included. The model also simulates the dynamics of carbon and nitrogen in the soil organic matter. The time step of integration is one day. The tree population, as described in the model, is homogenuously distributed. The model has been parameterised with soil and plant data, characteristic for the semi arid region of West Africa. The following grass production systems have been simulated : agroforestry without tree pruning (AF), agroforestry with tree pruning (AFp), grass monoculture with continuous cropping (GM) and grass monoculture with fallow years (GMf). A period of 30 years has been simulated, using actual weather data from Segou in Mali. Total crown cover in both agroforestry systems varies between 15 and 18 % and the leaf area index of individual trees equals on average 4 and 1 rcfi- m~2 for unpruned and pruned trees, respectively. In the agroforestry systems only grass biomass is removed from the field. In case of pruning, tree branches are lopped in the dry season to keep the trees at constant size. Fallow years have been simulated by incorporating grass biomass into the soil at the end of each third year. All production systems have been fertilised with inorganic nitrogen (50 kg ha"' yr"') and with other nutrients at unlimiting supply rates.

Results For both grass monoculture systems the amount of carbon in the soil organic matter declines strongly to 38 % (GM) and 65 % (GMf) of its initial level after 30 years, whereas in the two agroforestry systems the initial level of carbon in the soil organic matter can be maintained during this period (Figure 1). The amount of nitrogen in the harvested grass, produced in the agroforestry system without tree pruning (AF) and averaged over the entire simulation period, is almost half of that from the monoculture system with continuous cropping (GM) : 42 and 72 kg ha~l y r 1, respectively (Figure 2). In both other production systems annual nitrogen yields have intermediate values of 52 (AFp) and 51 (GMf) kg ha"' yr"V


Csom (kg/ha)

25000

20000

15000 --

10000

5000

GM

N yield (kg/ha/yr) 80

60

GMf GMf

AFp 40

GM 20

'AF

1949 1959 1969 1979

Figure 1. Simulated development of the amount of carbon in the soil organic matter (Csom). See text for explanation of the abbreviations.

-500 -400 -300 -200 -100 0 100

dCsom (kg/ha/yr)

Figure 2. Average annual nitrogen yield as a function of the average annual change in the amount of carbon in the soil organic matter (dCsom).

Conclusions In general, the simulated results show a positive relation between nitrogen yield and loss of soil organic matter in the 4 grass production systems at a certain level of nutrient input. Apparently, part of the production capacity of the ecosystem is needed to maintain organic matter in the soil and can therefore not be used for grass production. The difference in organic matter loss between the agroforestry system with tree pruning (AFp : 56 kg ha'1 yr~l) and the monoculture system with fallow years (GMf : 233 kg ha~l yr~l) is mainly caused by the difference in decomposition rates of herbaceous and woody plant litter. Tree pruning is a very effective way to favour grass production in agroforestry systems (increase in grass nitrogen yield is 25 % relative to unpruned trees), without risking high carbon losses from the soil. However, if the prunings are removed from the field, soil organic matter levels may decline much stronger. The effect of unpruned trees on grass production, illustrated by the strong decline in grass nitrogen yield in the agroforestry system AF compared to the grass monoculture GM, is correlated to the poor soil conditions, where competition for limiting resources is intense. Niche differentiation is not possible, because most nitrogen and water is available in the upper soil layers, in which most roots of both species can be found. Next challenge is now to find situations where high yields and high soil organic matter levels coincide as much as possible by minimising the competition for limiting resources.

References Conijn, JG., 1995. RECAFS : a model for resource competition and cycling in agroforestry

systems. Model description and user manual. Rapports PSS no. 12. Projet PSS. 1ER, Bamako, DAN-UAW, Wageningen, AB-DLO, Wageningen/Haren. 101 pp. & appendices.


Radiative climate modelling on virtual coconut stands for predicting the light regime in coconut based farming systems

J. Dauzat1, M. Eroy2, M.L. Girard 1 CIRAD/GERDAT Modelling Unit, PO BOX 5035, Montpellier, France Davao Research Center / Philippines Council Authority, Philippines

Introduction An accurate modelling of the PAR regime is essential to predict the behavior of intercrops in agroforestry systems. This is especially true in coconut based farming systems where it has been demonstrated that, in the absence of strong water deficit, the intercrop yields are more or less proportional to the available PAR. SO far the pertinence of this modelling needs a relevant description of the vegetation. The method described herein consist in performing numerical radiative simulations on three dimensional computer mock-ups.

Methods The geometrical and topological features of plants are modelled in order to create a parameter file which is used by the AMAP software to generate a population of plant mock-ups consistent with the observed population (Reffye et al., 1995). In this study three age groups of Laguna Tall coconuts have been observed at the Davao Research Center. A complete description of the trees has been worked out : height, diameter, inclination of trunks; number of fronds per tree, phyllotaxy, rachis-petiole length and curvature; number and position of leaflets on the rachis and their geometry. The data have been modelled accounting for the inter- and intra-tree variability and the results used to generate stochastically coconuts of each age group. Pruned trees have also been simulated by limiting their frond number to 18 (Figure 1). The generated trees have then been set up to create stands of different densities with a triangular or a square planting pattern. Additional densities have been obtained by thinning.

Figure 1. Simulated mock-ups of 20 (unpruned / pruned), 5 and 40 yr. (unpruned / pruned) trees.

Numerical radiative simulations have been performed with specific programs (Dauzat, 1989) : - the MIR program which calculates the interception of incident radiation; - the TRANSRAD program which calculates the multiple scattering within the stand. The final outputs in concern here are the average PAR transmission rate of the stand and a map of the transmitted radiation at the soil level.


Results Satisfactory simulations of transmitted PAR have been obtained for the 5, 20 and 40 years old observed coconut stands. The diurnal evolution of the transmitted PAR was also correctly restituted (Figure 2).

50

40 -\

30

20

10

0

600

.VA VAj

i i

1 E 1

I i

s s

k -S"

; ' 1

« S 400 u 'S S

fe 200

g OH

0

x.x..

X

20 age groups

40 5 7 9 11 13

time of day (h) 15 17

H measured Ü simulated Figure 2. Left: averaged values on several days.

X measured simulated Right: daily evolution for 20 yr. old stand.

Further results obtained by varying the stand density (Figure 3) lead to the conclusion that the light transmission is appreciably a linear function of the tree density irrespective of the planting pattern. Pruning the lower fronds strongly increases the light transmission and its effect is comparable to a density reduction of about one third. Because the coconut crown development is normally maximal between 15 and 30 years, the PAR transmission is lower under 20 years old trees. Therefore the management of intercropping must be argued against the age of the trees.

60

50

2 40

30

20

X <

-

- thinned stands

X .

A •~ _

pruned trees

A

•

A -

- •

50 -

40 -I

30 •

7 0 -

* •

" ' * - • -

A triangular design

• square design

m

pruned trees

D

A .

• A

70 90 110 130 trees ha"1

150 90 110 130 trees ha

150 170

Figure 3. Light transmission rates vs. density under 20 (left) and 40 yr. (right) coconut stands

Conclusions An original approach was successfully used to simulate the light transmission under 3 coconut stands. The use of computerized coconut mock-ups associated with specific radiative programs ensure that the simulations performed for other densities remain valid as long as the tree architecture is not deeply modified. The results show how light transmission can be fitted by thinning a stand or pruning the lower fronds of the trees. If it is ascertained that the latter practice has no long term detrimental effect on the coconut yield, it could be adopted as an efficient cultural management for intercopping.

References Dauzat, I , 1989. Oléagineux 49 (3): 81-90. Reffye (de), Ph. et al., 1995. Agroforestry Systems 30: 175-197.


ON-STATION EVALUATION OF LEUCAENA, CALLIANDRA, GLIRICIDIA, SESBANIA, SENNA AND ERYTHRINA SPECIES IN ALLEY CROPPING WITH MAIZE IN WESTERN KENYA. A LONG TERM EXPERIMENT: 1988 - 1994

A.M.Heineman

Oxford Forestry Institute, University of Oxford, South Parks Road, 0X1 3RB, Oxford, U.K.

Introduction Leucaena, Calliandra, Gliricidia, Sesbania, Senna and Erythrina were evaluated in a long term alley cropping experiment with maize (Heineman, in preparation). The main objective of the study was to determine which species had positive or negative effects on maize yields and why. Species choice is known to influence the productivity of individual components and overall sustainability of the system. Farmer managed experimental alley cropping has so far not worked in western Kenya. Socio-economic incompatibility of the technique vis-a-vis local expectations was identified as the main cause (Shepherd etal., submitted; Swinkels et ai, submitted). This interpretation might be correct for the specific alley cropping designs used, but this conclusion does not seem to have general applicability. Alley cropping must perform satisfactorily from a bio-physical point of view before it is considered for end-user adaptation and adoption. Farmers should only participate in the process of species selection, when uniformity in research protocols and methodological compatibility across sites is guaranteed. Long-term species evaluation experiments are essential in developing bio-physically functional alley cropping systems. Each species is thought to cause a specific response in maize, which is the outcome of the balance of all complimentary and competitive interactions. Trees should be identified which perform the desired functions best, i.e. nitrogen fixation, nutrient cycling, deep nutrient capture, efficient nutrient transfer and reduced leaching and erosion. At the same time, they must not be too competitive with maize for light, water and nutrients. Bio-physically efficient resource sharing between trees and crops is a mandatory prerequisite for successfully practising alley cropping, both in on-station and on-farm evaluation programmes. An agroforestry system that does not lead to better crop yields will not be perceived by farmers as an attractive innovation, fit for adoption.

Methods A randomised complete block (RCB) design with 8 treatments, replicated 4 times was used. Tree seedlings were planted in April 1988 in double rows in each plots (14,286 trees ha"1) except the controls. In on-farm trials, tree densities are typically 50 to 75 % lower. Trees were managed as hedges after one year, leaf biomass was on average applied five times a year. Maize was sown twice a year (47,619 plants ha"1) for five years. The quantities of N, P and K applied in leaf mulch and the corresponding quantities of N, P and K removed in crop harvest were calculated, using partial nutrient budgeting techniques. Between plot interactions are a potentially disturbing factor in the determination of yields. Considering this, two strategies were followed. Polyethylene mesh root screens were inserted around control plots to prevent penetration by roots from adjacent plots. In addition, a calculation technique was used to verify whether the performance in any treatment was modified by undesirable root competition from neighbours. In a valid trial, treatment related variation in maize yields should be the result of differences in the magnitude and the sign (+, -) of the nutrient balances. Control yields will decline rapidly while its nutrient balances become progressively more negative. In alley cropping, maize yields will ultimately depend on the balance between positive and negative interactions between trees and crops. In this study, the result of the competitive and facilatory forces in alley cropping treatments were expressed in terms of variation in treatment related nutrient use efficiency (NUE).


Results Species differed widely in leaf and wood production as trees in 1988 and as hedges in 1989 to 1993. The amount of N, P and K recycled to alley cropped maize via leaf mulch varied significantly. The application of tree biomass resulted in higher yields of alley cropped maize, compared to the persistently low and declining yields in the 'maize only' controls. The efficiency with which alley cropped maize was able to utilise the additionally recycled nutrients varied between species. Moderately productive N fixing Gliricidia sepium and Etythrina caffra had high NUE's. High biomass production in Calliandra calothyrsus led to competition for water with maize and negatively influenced its NUE. Unintentional below-ground interaction between adjacent plots was ruled out as a cause for the observed treatmental differences and was also not the cause of the consistently low control yields. Thus, the experimental results were not caused by design artefacts. Long term nutrient budgets confirmed that minimum amounts of N, P and K must be recycled to cause positive yield responses in maize (not achieved in S.siamea) but also that if a species is too productive, the balance in alley cropping can shift from net complimentarity to net competition (e.g. C.calothyrsus). These results were used to design a pot experiment to determine whether the differences in recycled N, P and K (varying upto fourfold) could be held responsible for the observed yield patterns. The observed variation in field NUE values was confirmed in the pot experiment, in the absence of tree roots, both in sequence and approximate magnitude. The results from the field and pot studies were positively correlated, using simple linear regressions. Low NUE's of tree-crop combinations in the field corresponded well with low NUE's of identical tree leaf- seedling maize combinations in the pot experiment and vice versa. Species varied significantly in foliar polyphenol concentrations (Palm, 1995). High polyphenol concentrations contributed to a relatively low NUE in alley cropping with C.calothyrsus and low polyphenol concentrations in G.sepium and E.caffra were associated with high NUE's.

Conclusions L.leucocephala and C.calothyrsus have traditionally been used in alley cropping in west Kenya. Farmer adoption of the technique in western Kenya was probably in part disappointing because the bio-physical modalities of species choice and management were not yet well understood when the trials were designed and executed. L.leucocephala and C.calothyrsus can result in low NUE's because competition with maize is usually not sufficiently controlled. Less competitive trees like G.sepium and E.caffra are better choices in managing the delicate balance between competition and complimentarity. Doing exploratory pot trials before field trials are started might be a cost effective way to reduce the long list of potential trees for alley cropping. Then, fewer species need to be considered in the often lengthy and expensive process of field experimentation. Complete characterisation of selected tree species should aid in the formulation of minimum nutritional requirements for tree leaves, including the effects of anti-nutritional compounds (poly-phenolics), which can modify leaf decomposition and nutrient release patterns. The effect of varying the mulching rates can be tested in pots with representative soil mixtures, and may give indications about minimum tree densities to achieve positive nutritional benefits in associated crops.

References Heineman, A.M. (in preparation). Crop production and soil changes in alley cropping systems in the highlands of East Africa: Critical interactions between system components. Oxford, UK, Ph.D. Thesis, University of Oxford. 250 p.

Palm, C.A. 1995. Agroforestry Systems 30: 105-124. Shepherd, KD. et al. (Submitted to Experimental Agriculture). Adoption potential of hedgerow intercropping in maize-based cropping systems in the highlands of western Kenya. I. Background and economic evaluation.

Swinkels, R. etal. (Subm.Exp.Agr.) Adoption potential of hedgerow intercropping in maize-based cropping systems in the highlands of western Kenya. II.Economic and farmers' evaluation.


SEASONAL AND LONG TERM EFFECTS OF LEUCAENA LEUCOCEPHALA HEDGEROWS AND INORGANIC SOURCES OF N AND P ON THE PRODUCTIVITY OF MAIZE - BEAN SYSTEMS IN WESTERN KENYA, WITH COMPARATIVE NUTRIENT USE EFFICIENCIES OF DIFFERENT FERTILISER ALTERNATIVES. A LONG TERM EXPERIMENT: 1988 - 1994

A.M. Heineman

Oxford Forestry Institute, University of Oxford, South Parks Road, 0X1 3RB, Oxford, U.K.

Introduction Many soils in the highlands of East Africa are depleted of soil nutrients, particularly N and P, as a result of decades of subsistence farming without adequate nutrient management. Crop yields are very low. They can only be stabilised and soil fertility restored by returning to the soil the equivalent or more of seasonally removed nutrients in crop harvests and through other losses. East African economies cannot base subsistence farming in large part on imported inorganic fertilisers. Agroforestry techniques, whereby trees are used to recycle nutrients, fix atmospheric N and reduce nutrient losses should also be considered to achieve better subsistence agriculture. However, it is also recognised that trees may not be able to fully provide the quantities of N, P and K to make subsistence cropping systems self sufficient in nutrient requirements. Maize is often fertilised by farmers in western Kenya with small amounts of N and P in the form of diammoniumphosphate (DAP) and calciumammoniumnitrate (CAN), normally well below the recommended dosage. Agroforestry and inorganic fertilisers both have a role to play in the search for better balanced nutrient budgets in maize based systems. An alley cropping experiment was carried out between 1988 and 1994. Its main objective was to compare the seasonal and long-term crop responses to pure and combined use ofL.leucocephala mulch and DAP/CAN fertiliser.

Methods A split plot design was used with 4 main plots (maize monocrop, maize-bean intercrop, maize-L.leucocephala alley crop and maize-bean-Z. leucocephala alley intercrop) and 3 sub-plots (no fertiliser, 30 kg N ha'1 + 15 kg P ha'1, 60 kg N ha"1 + 30 kg P ha'1). The 12 treatments were replicated 4 times (Sub-plot treatment size: 5.0 x 7.5 m). L.leucocephala was planted in April 1988 (density: 10,667 trees ha"1). Crops were sown twice a year in April and September from 1989 to 1993. Hedges were cut 2 to 3 times per season, leaves applied to the crops and wood removed. Yield calculations were in t ha"1 dry matter on an equal area basis, recognising that hedges occupied 20 % of the land area in alley cropping plots. Partial nutrient budgets were constructed for N, P and K. They illustrated for each alley cropping treatment the relationship between nutrients recycled through the hedges and the corresponding additional nutrient harvest in maize and beans. For the unfertilised 'maize only' treatment, similar budgets showed how much N, P and K could be removed without organic or inorganic inputs (figure 1). In the DAP/CAN fertilised systems, budgets showed relationships between additional DAP/CAN inputs and permitted nutrient exports in crop removals. By comparing mulched, DAP/CAN and unfertilised treatments, the relative maize yield contribution ofL.leucocephala mulch and DAP/CAN was determined. By comparing long-term yield trends across cropping systems, the nutrient use efficiency (NUE) ofL.leucocephala mulch, DAP/CAN or the combination was calculated.

Results Maize yields in all cropping systems declined between 1989 and 1994 because the site was former pasture and resident soil fertility declined as the cumulative quantity of nutrients exported increased over time. L. leucocephala systems were on average as productive as maize mono crops or maize-bean intercrops, although maize populations in alley cropping systems were 20 % lower,


because of the replacement of 1 in every 5 maize rows by a L.leucocephala row. The mulch additions to maize in alley cropping directly benefited individual maize plants. They grew taller, stored more nutrients and produced more grain, compensating for the loss in plant population. The beneficial effect of the mulch became less significant as inorganic fertiliser levels increased. On average, it required 3 times the equivalent amount of inorganic N to obtain equivalent maize yield effects through mulched N applications. The average nitrogen NUE of maize, when receiving N via L.leucocephala was 14 %, thus requiring 28 kg of mulch (N = 3.56 %) to export 1 kg of N in maize yields. The N use efficiencies for DAP/CAN in the absence of mulch were considerably higher (figure 1). Similar results were achieved with regards P use efficiencies.

Conclusions The results suggest that alley cropping NUE's were low, because the positive effects of mulch were off-set by some competition between trees and crops. Hedges must reach a minimum mulch productivity in order to be effective but excessive production will lead to increased competition. Only if hedges exert no competitive pressures on maize, NUE's may approach those of inorganic fertilisers. Alley cropping is in terms of yield advantage particularly attractive if inorganic N and P are too expensive to be economic. This experiment was not sited on a slope, thus the soil conservation effect of the hedges could not be demonstrated. Traditional maize mono crops on slopes without adequate nutrient management decline in productivity, because loss of top soil aggravates the decline in productivity as a result of nutrient exports in crop removals. Therefore alley cropping is likely to be more attractive on slopes than on flat lands and most attractive when purchased fertilisers are unaffordable. The long-term results, on which this abstract are based (Heineman, in preparation) offer considerable scope to design factorial experiments to determine what the preferred combination of tree leaf mulch and inorganic fertilisers should be to restore soil fertility, stabilise crop yields and suit the specific needs of farmers on soils of known fertility.

Figure 1

111

— -a

I s

800 Actual N out

Max.possible N out

Min.possible N out

400 800

Total N applied via inorganic fertilisers (kg/ha) between 1988 and 1993

Note: Also shown is the maximum and minimum amount of N that would have been exported if the N use efficiency of the fertilisers had been 100 % and 0 % (coded: Max.possible N out, Min.possible N out, respectively)

References Heineman, A.M. (in preparation). Crop production and soil changes in alley cropping systems in the highlands of East Africa: Critical interactions between system components. Oxford, UK, Ph.D. Thesis, University of Oxford. 250 p.


THE UK NATIONAL NETWORK SILVOPASTORAL EXPERIMENT -A CO-ORDINATED APPROACH TO RESEARCH

G M Hoppe1, A R Sibbald2, J H McAdam1, W R Eason3, M Hislop4 and Z Teklehaimanot5.

'Department of Agriculture for Northern Ireland, Belfast, BT9 5PX, UK. 2Macaulay Land Use Research Institute, Aberdeen, AB9 2QJ, UK. 'institute for Grassland and Environmental Research, Aberystwyth, SY23 3EB, UK. "Forestry Commission, Roslin, EH25 9SY, UK. 5University College North Wales, Bangor, LL57 2UW, UK.

Introduction European Union land use policy is currently targeted at reducing levels of agricultural surplus and reducing a substantial timber product deficit. There is also interest in sustainable land use systems which generate multiple products, enhance landscape diversity and increase biodiversity within the natural environment. The integration of agriculture and forestry practices on the same land area in agroforestry systems offer an opportunity for a phased reduction in agricultural production combined with high quality timber production, afforestation and increased habitat diversity within the landscape. Until relatively recently there has been little research carried out on such systems in temperate Europe and this paper outlines a co-ordinated approach which has been taken within the UK.

The UK agroforestry research discussion forum In western Europe and the UK in particular, agroforestry can be seen as developing along two lines - silvoarable systems where tree rows are intercropped with an arable crop and silvopastoral systems where stock graze pasture between widely spaced trees. Neither system is practised to any great extent in the UK and research on agroforestery systems is relatively recent (Sibbald et al, 1990). Agroforestry systems represent complex interactions between the individual components and research has primarily concentrated on quantifying productivity with lesser resources directed towards the investigation of ecological interactions. Recent interest in agroforestry research in the UK started in the early 1980's with the publication of a number of models e.g. a lowland model by Doyle et al. (1986). It was recognised that the necessary biological research to verify these models would be resource demanding and would require a collaborative approach. As a consequence of this, an informed group of scientists largely within the UK formed the UK Agroforestry Research Forum in 1985. The Forum debates specific areas of research, agrees on a collaborative approach and co-ordinates two national network experiments, the largest of which is the National Network Silvopastoral Experiment.

The national network silvopastoral experiment (NNE) In this experiment a common set of treatments - three replicates of protected Sycamore, Acer pseudoplatanus at two agroforestry spacings (100 and 400 stems ha"1), a woodland control planted at 2500 stems ha"1 and a grazing control in plots 0.4-1 Oha size - are adopted at each of six UK sites - Aberdeen, Scotland (MLURI and FC - funded by the Department of Agriculture, Environment and Fisheries for Scotland); North Wyke, SW England & Bronydd Mawr, S Wales (IGER and FC - funded by MAFF); Bangor, N Wales (UCNW funded); Loughgall & Broughshane, N Ireland (DANI funded). The sites represent a wide range of pasture types from 20 year old swards (the MLURI site) to those sown the year prior to the trials commencing (the DANI, Loughgall site). Management protocols have been agreed for sheep-grazed pasture managed to a constant sward height profile. Trees are given standard protection and pruning, and


an integrated measurement, recording and analysis programme is adopted to quantify all aspects of the output of the system (Sibbald et al., 1990; Eason et al., 1994). Data on tree height and diameter, ewe performance, lamb growth and output, stock carrying capacity and standard pasture and climate variables are analysed on a between-site basis, and published each year (Sibbald et al., 1995). At all sites additional treatments - usually variants of tree species and spacing - have been planted to suit local research requirements e.g. Ash, Fraxinus excelsior, planted at the DANI Loughgall site. It is of particular interest to note that 5 years after introduction of the systems, animal production has not been significantly reduced by any of the agroforestry treatments (Hoppé et al., 1995).

Ecological interactions Additional information on some aspects of ecological interactions occurring within the system has been collected on a sporadic basis from most of the sites. This has included avifauna recording, invertebrate sampling and floristic diversity monitoring, all to protocols that are agreed at the regular NNE managers meetings.

NNE co-ordination and management To co-ordinate and manage the experiment, the managers of the NNE sites meet on at least two occasions each year to discuss progress, problems, modification of the appropriate protocols and joint analysis and publication of the data. Meetings are held on a rotational basis, one meeting (held in July) coincides with the annual UK agroforestry research discussion forum meeting.

EU - ALWAYS project In 1993 the NNE was included in a bid for a 4-year research programme to investigate alternative land use with fast growing trees (See Auclair, this conference). The overall aim of additional scientific research carried out on the network sites is to contribute to biophysical and bioeconomic models of agroforestry systems which help support their adoption on a European scale. As well as the standard data set, the NNE is contributing data on tree root growth and canopy architecture, microclimate modification and sward diversity.

Future Despite separate site funding, the NNE has largely maintained the integrity of its management and scientific output since its conception. This has been widely recognised and has resulted, for example, in the attraction of EU and other external funding. A significant number of postgraduate research students use the sites to study more detailed aspects of the biological interactions. This basic science base helps to underpin the applied nature of the work and provides added value to the sponsors of the NNE sites in terms of scientific output from their investment. The next stage must be to translate the research into demonstration and practice on commercial farms. In N.Ireland a series of on-farm demonstration sites are managed by land owners (with DANI support) to incorporate the basic research findings of the NNE and demonstrate that silvopastoral systems can be a viable land use option on livestock farms in the UK.

References Doyle C. J., et al., 1986. Agricultural Systems 21: 1-32. Hoppé G. M , et al., 1995. Agroforestry Forum 6 (2): 19-22. Eason W R, et al., 1994. In: L. O. Fresco et al. (Ed.) The future of the Land: Mobilising and

integrating knowledge for land use options. John Wiley and Sons Limited: pp 123-128. Sibbald A. R, et al., 1995. Agroforestry Forum 6 (1): 5-8. Sibbald A. R, et al., 1990. Agroforestry Abstracts 3: 149-164.


THE PHYSIOLOGICAL CONSTRAINTS ON CROP GROWTH IN DRYLAND AGROFORESTRY

J.E.Lott1'2, C.RBlack1 and C.K.Ong2

1. University of Nottingham, Department of Physiology and Environmental Science, Sutton Bonington Campus, Loughborough, LE12 5RD. Fax: 0115-951-6334 E. Mail: [email protected] 2. International Centre for Research in Agroforestry, PO Box 30677, Nairobi, Kenya. Fax: 252-2-521001 E. Mail: [email protected]

Introduction Agroforestry has the potential to alter the physiological constraints imposed on crops growing in water-limited environments in ways which may or may not be beneficial for crop yield. This experiment was set up to establish how an overstorey agroforestry system alters the microclimatic conditions experienced by understorey crops and whether the crop physiological responses are modified by the presence of trees.

Methods This experiment was carried out at ICRAF's experimental field site at Machakos, Kenya, using 6 - 8 m tall Grevillea robusta trees planted at a 3 by 4 m spacing and intercropped with maize and beans or cowpea. The climate is semi-arid with a bimodal annual rainfall of 750 mm. Microclimatic parameters were measured at concentric distances from the trees and their influence on the transpiration, photosynthesis, phenology and yield of the understorey crop was examined.

Results Tree shade decreased the mean diurnal temperature range experienced by the crop from 24 °C in the sole crop to 14 °C in the agroforestry system; maximum temperatures were also 7 °C lower in the latter treatment. As a result, thermal time accumulated at a much slower rate in the agroforestry treatment, causing considerable delays in plant development. This delay had two significant effects; the ability of the crop to compete with the trees for water was compromised because of the slower development of the root system, while extension of the growing season increased the period available for evaporation of soil water. Since tree shade only reduced soil evaporation from 50 to 45 % of total rainfall, the overall effect was to increase evaporative losses during the cropping season.

The trees were periodically pruned during the experimental period to maintain a 25 to 35% reduction in total radiation reaching the understorey crop. This reduction in radiation was expected to have very little effect on crop productivity since measurements of the light response of maize grown under artificial shade nets illustrated that photosynthetic rate was hardly affected up to a 35% reduction in PAR (Figure 1). However, when the photosynthetic light responses of both C3 and C4 crops grown under the tree canopy were examined, the rates were found to be only half of those of the corresponding sole crop and




light saturation occurred at 30% of full sunlight. This severe reduction in photosynthetic activity may reflect a combination of water stress and the poorer spectral quality of the radiation under the canopy.

2200

PAR (umol m 2 s"1)

Figure 1. Light response of maize grown as a sole crop in full sunlight or artificial shade and in an agroforestry system.

-r 0.50 1

Ü 0.40-o s ir 0.30-2 s 0.20 • JS §• 0.10' 2 o

' Solecrop

• . . « Agroforest

25% shade

, — - 50% shade

1

I

1

J f

• / ' .

• .

' ' ' ' ^

/ , A

^ f / /

/ /

/ /

—i 1 — — i 4 6 8

Transpiration rate (mmol m2 s') 10 12

Figure 2. Water use efficiency of maize grown as a sole crop in full sunlight or artificial shade and in an agroforestry system.

The water use efficiency of crops grown in the agroforestry system was improved relative to the sole crop (Figure 2), but this was insufficient to compensate for the severe reduction in the quantity of water available to the crop. In addition, competition for water between the trees and crops resulted in more frequent and severe crop water stress.

Conclusions The information obtained can be used to identify areas of future technological development through the selection of better species combinations and improved breeding and management practices to encourage positive interactions.

This work was supported by the Overseas Development Administration under contract R5810.


TREE-SOIL INTERACTIONS IN POPLAR- ARABLE AGROFORESTRY SYSTEMS

J. Park1 and S.M. Newman2

1 Department of Agriculture, The University of Reading, Earley Gate, P.O. Box 236, Reading, UK, RG6 2AT. 2 Biodiversity International Ltd, 35 Nelson Street, Buckingham, UK, MK18 IDA

Introduction Issues associated with soil health and the effect agriculture has on the soil are becoming of increasing interest in sustainable systems research (Haberern, 1992; Thomson, 1992). Silvoarable systems may offer the potential to improve soil quality by increasing the amount and changing the distribution of carbon in soil whilst maintaining the productive capacity of the system. A poplar-arable system in Buckinghamshire.UK forms the basis for this research in which tree-soil interactions are quantified in relation to the lateral distance from tree alleys based on measurements of carbon in both the surface and sub surface horizons.

Methods The research described is based upon a silvoarable agroforestry trial established in March 1988. The soil on the 4 ha site is a river alluvium (Fladbury series; Avery, 1980), clayey silt classified grade 3 which has been subject to a conventional arable rotation. Poplar trees (P. trichocarpa x deltoïdes) belonging to the clones Boelare and Beaupré (Potter, et al., 1990) are planted in rows at 14 m intervals across the field. Following planting the trees established quickly and started to influence annual crop growth (Table 1). It was hypothesised that this was due in part to changes in soil properties in these arable alleys. To quantify the soil effects a number of related measures have been undertaken (Park et al, 1994). In October 1995 a series of soil transects were sampled (within row, lm, 3m and 6m from the tree bases) at two soil depths (0-15 and 15-30cm). These were analysed using the loss on ignition method to provide information on soil carbon at different distances from the tree (Table 2).

Results Table 1. Diameter at Breast Height (DBH) and Top Height (TH) Measurements for Poplar trees since establishment in 1988. Mean Annual Increment (MAI) is the 1994 height divided by 7

Year DBH (cm) TH (m)

1988 - 2^67 1989 - 4.34 1990 6.3 6.60 1991 9.4 9.25 1992 13.1 11.79 1993 16.8 13.8 1994 19.4 15.6 MAI 2.7 2.2


Table 2. Average soil carbon values (%) at different distances from the tree rows and at two depth.

In row lm 3m 6m

0-15cm 3~36 343 3~TÏ 2.99 15-30cm 2.65 2.60 2.03 2.36

Table 2 illustrates a general trend of decreasing carbon levels in samples further from the base of the tree. However, the only significant difference is in the surface 15cm between those samples taken within the tree rows and those taken at 6m ( p<0.011). As expected at each distance from the tree the soil in the surface 0-15cm contained a significantly (p<0.010) greater amount of carbon than that in the sub-surface soil (15-30cm).

Discussion and Conclusions The soil carbon sampling presented here forms part of an on going monitoring programme (Newman, 1994; Park et al., 1994). Recent sampling supports earlier work which suggests that poplar trees can influence soil properties in a relatively short period of time, although continued monitoring is required to provide a clear picture of these changes in time and space. Data collected on soil carbon are presently being used in the construction of a model of carbon flow and distribution in silvoarable systems. This tool will be used to explore the usefulness of fast growing trees in adding carbon to arable systems and the implications this may have for future productivity.

References Avery, B.W. 1980 Soil Classification for England and Wales. Soil Survey Technical Monograph 14, Harpenden, UK Haberern, J., 1992. Journal of Soil and Water Conservation. 47(1): 6 Newman, S.M., 1994 Poplar Agroforestry Studies. Farmer Centred Agroforestry Research and Development in Eastern China, Biodiversity International, Buckingham. Park, J., et al. 1994 Agroforestry Systems. 25, 111-118. Potter, C.J., 1990. The introduction of improved clones from Belgium. Forestry Commission Information Note 181. Thompson, T.R.E., 1992. Biologist. 39(1): 33-34


BELOW- AND ABOVEGROUND RESOURCE CAPTURE IN AGROFORESTRY SYSTEMS

M. van Noordwijk

International Centre for Research in Agro-Forestry, ICRAF-S.E.Asia, P.O.Box 161, Bogor 25001, Indonesia

Introduction Depending on one's definition, agroforestry includes a broad range of land use systems that integrate trees, crops and grasses in the landscape. Trees play a directly productive and/or a supportive role, via effects on soil fertility, soil water balance, microclimate and/or pest and disease incidence. In temperate zone agriculture the major part of traditional agroforestry systems no longer met farmer's targets and has been replaced by simplified systems and landscapes, but new versions of agroforestry are re-invented, based on a direct production value of well-managed trees. In the tropics there is still scope for trees in a supportive role, although competition with crops and grasses makes it unlikely that trees can be maintained that do not have any direct value for the farmer (Van Noordwijk and Purnomosidhi, 1995). A generic view on tree-soil-crop interactions is needed to evaluate the huge variety in agroforestry systems in all there locally adapted forms. A simple equation was developed for quantifying tree-soil-crop interactions (I), distinguishing between positive effects of trees on crop yield through soil fertility improvement (F) and negative effects through competition (C) between tree and crop for light, water and nutrients (Sanchez, 1995). In its simplest form, the tree - crop interaction (I = F - C) is positive and hence the combined tree-crop system may be attractive if F > C, and not if F < C. The simple equation (I = F - C) needs to be expanded to separate the various positive and negative interaction terms directly and to develop a process-based model on water, nutrient and light capture in agroforestry systems (WaNuLCAS) which can be used to 'understand' and thus extrapolate the results (Table 1).

Table 1. A three-step approach to analysis and synthesis of tree-soil-crop interactions

Y, = Y0 + F. + F„ + C + M

Crop yield Crop yield Direct in in fertility interaction monoculture effect

Long term Competi- Competi- Micro-fertility tion for tion for climate effect light water and effects

nutrients

/. Experimental

2. Process-level understanding

3. Synthesis model

+ /- Mulch transfer trial

Litter quality, mineral izat ion rates

W A N U

Residual effect vs pure crop control

Functional SOM fractions (Ludox)

L C A S

+ /-Tree removal, + root barriers

Canopy shape, light profiles

Root barriers

Root architecture (fractal ?)


Methods A long term hedgerow intercropping trial in Lampung (Indonesia) of the 'Biological Management of Soil Fertility' project, in cooperation with Brawijaya University (Malang, Indonesia) is used (Van Noordwijk et a/., 1995). On part of the plots all hedgerows were removed. The fertility term was estimated from the yield on these plots minus that in the pure-crop control. The competition term is based on the yield contrast between these plots and that in alleys.

Table 2. Terms of the tree-soil-crop equation for maize in 6'th year of hedgerow intercropping experiment in Lampung (Indonesia); F = fertility effect, C = competition effect, I = overall interaction; data are expressed as percentage of monoculture crop yield (2.6 Mg ha ' of grain)

Tree species

Leucaena leucocephala

Calliandra calothyrsus

Peltophorum dasyrrachis

Flemingia congesta

Gliricidia sepium

F

152

120

58

37

19

C

-159

-115

-26

-89

-60

I

- 7

+ 5

+ 32

-52

-41

Results The components F and C, as well as the overall interaction term I, differed clearly between five species of hedgerow trees (Table 2). Only the local species Peltophorum dasyrrachis gave a positive overall effect on crop yields. Its positive overall effects is not based on positive F terms, but rather on moderately negative C terms.

Discussion Part of the 'fertility' effect of the tree is based on light, water and nutrient resources which the tree acquired in competition with the crop (Fcomp); another part may have been obtained in complement to resources available for the crop (F„oncomp), e.g. from soil layers to which the crop has no access or at times that the crop is not active. Furthermore, part of the resources acquired by the tree in competition with the crop are recycled within the system, and may thus be used by a future crop (Crecycl). Tree products which are not recycled (Cnoniecyd), may have direct value for the farmer. One may argue that Fcomp is based on the same resources as Crœyci- The question whether or not a tree-crop combination gives yield benefits then depends on: 1) the complementarity of resource use (Fnoncomp), 2) the efficiency of the recycling, and 3) the value of tree products based on Cnonrecycl relative to the value of crop products which could have been produced with these same resources. Integration models on above- and below-ground resource capture and recycling, such as the Wanulcas model allow the exploration of a wide array of management options and predict effects of soil and climate parameters on the performance of tree-crop combinations, ranging from simultaneous 'hedgerow intercropping' to sequential 'improved fallow' systems.

References Sanchez, P. 1995 Agroforestry Systems 30: 5-55. Van Noordwijk, M. and P. Purnomosidhi, 1995. Agroforestry Systems 30: 161-173. Van Noordwijk, M. et al. 1995 In: R.A. Date et al. (eds) Plant-Soil Interactions at Low pH:

Principles and Management. Kluwer, Dordrecht: 779-784

Division 1

Crop physiology, production and management.


INVESTIGATING THE AIR HUMIDITY IN THE ENVIRONMENT OF PLANTS BY USING AN ELECTRIC THERMAL MEASURING TRANSDUCER

S. Alexieva, M. Kilifarska Institute of Soil Science and Agroecology, 7, Sh.Bankja Str., PB 1080, Sofia Bulgaria

Introduction The relative humidity represents the relation of the partial pressures between the saturated water vapour and the unsaturated air with water vapour under a distinct temperature. Conditions exist, under which the water vapour diffusion may be caused by a temperature gradient [Philip, 1957] Such possibilities of similarity determine an error which is not larger than the methodical errors of the well known principle solutions when measuring the humidity. The aim of the investigation was to create conditions, under which it would be possible, through a temperature gradient and some border conditions, to elaborate a method and a schematic solution for measuring the air humidity.

Methods The method of a heated thermosensitive element is one of the possible variants for determining the relative air humidity ç. Grounds for this is the relation between the thermal conductivities of a saturated water vapour Av

J and that of air which is unsaturated with water vapour A, [Philip, 1957]. Av = (p. X* (1). Compared to the thermal conductivity of the dry air Xa under isothermic conditions and temperatures in excess of 40°C Xv begins to grow rapidly and its role in the thermal transfer becomes dominant. This means that under given border conditions Xv will depend both on the temperature gradient and on the humidity. If in a suitable volume a temperature gradient is developed which would cause a gradient in the water vapour pressure, then this is mandatorily connected with a heat transfer. This water vapour stream, with a certain approximation, is proportional to the transfered heats i.e., it is mathematically tied to an increase in the thermal conductivity of the volume. On this basis, the effectivity of thermal conductivity Xe in this volume may be taken as an aggregation of two parts, namely: Xe = Xa + Xv (2). The relations ( 1 ) and (2) are thermophysical regularities and a basis for creating an electrothermal device for determining the relative humidity of the air. For the experimental determination of Av

and the relative air humidity connected with it, in a given volume is needed to be developed a temperature gradient toward the ambient temperature, while Xa of the dry air will serve as a basis of comparison. Figure 1 illustrates the dependences Xe Xv and X', of the relative air humidity in the 0 to 100% range, a pressure of 105Pa and 50"C temperature in the investigated volume. The Xa for this temperature is Xa = 2.91 [W.m'.K1]. The fact that a comparative method is applied for measuring renders possibilities for increasing the precision, because the disturbing factors, namely, temperature changes and velocity of the air stream have been eliminated. These, normally, give rise to noninformative disturbances .The thermosensitive elements in the device are two silicon transistors with metal bodies and similar characteristics. The first one is a measuring transistor, while the second serves as a comparative one. The body of the measuring transistor is perforated while the second one is hermetically closed. The two transistors must preferably be placed next to each other in order to be found under the same atmospheric conditions: ambient temperature, air stream velocity and relative humidity. The thermosensitive elements are heated to nominal power from the source of direct current voltage E, which guarantees a 50"C temperature of the crystal. One of the p - n transition of each one of the transistors serves for heating, while the other one is thermosensitive to the heat release in a dry air and in the investigated medium. The thermosensitive p - n transistors are connected to a

Division 1 641

W/m

29.2

29.1-

M O

K 1

K K A,

O"3

\

y /

X,

SK

^ , M -Ä>

»T,

.-"X "V&"

DA u«>.t I OP | u * ) i©

OP

^V, cri P ^ > Î •\Ur

' ^

Kt = -[2 + R1/R3(1 + U0/U(pt)]

0 20 40 60 80 100 <P %

Fig. 1. Dependences of the thermal

conductivities A,, Av, Av* the relative

humidity, as compared to Ao

Fig. 2. Principle electric scheme of the electrothermal device - Tt -measuring element; T2 - comparative element; DA - differential amplifier; OP - temperature compensating amplifier; E - source of direct electric voltage; Rt - collector resistors; Rh - basic resistor; Rt - thermal resistor.

differential amplifier DA. The exit signal from DA depends on the relative humidity measured and on the ambient temperature t - Up, t. The schematic solution of the electrothermal device is shown on Figure 2. The operational amplifier OP connected to exit DA, contains the temperature sensitive element for the ambient temperature in its reverse connection Rr In this way its coefficient of amplifying varies with the temperature of the ambient air. The nominal value of the amplifying coefficient of this temperature compensating amplifier, Kt is reached at a 20"C mean temperature of the medium. When there is a drop, resp. rise in the temperature, the amplifying changes in specific borders so that the relative humidity may be recorded directly on the voltage meter, connected to the exit OP - Uç. For example: at 20°C the initial voltage of DA is 25 mV, this signifying a relative humidity of 50 %. In this case the coefficient of amplifying OP is 100, i.e., the exit is 2.5 V. If the temperature drops to 10°C, the exit voltage of DA reaches 14 mV. Then the coefficient of amplifying changes to 178, this corresponding to the change in temperature. The exit voltage becomes 2.5 V anew, responding to 50 % humidity. In this way the changes in the ambient temperature do not influence on the graduation of the voltmeter for relative air humidity.

Results 1. With the elaborated electrothermal device at minimal power (30 mW) and 50°C heating of the thermal elements is significant sensitivity and preciseness achieved as a result of the use of temperature sensitive p - n transistors. 2. The effect of the ambient temperature is compensated through change in the coefficient of amplifying of an operational amplifier, whose exit is graduated directly to indicate the relative humidity. The meteorological analysis, recording the effect of the factors disturbing the measuring gives the following results: 1. The methodical error at a calibrated temperature 20"C and a relative humidity 50 % is 1 %. 2. The additional errors from the change in the ambient temperature above and below the calibrated one are recorded thus: - in the temperature range 20-40"C the error increases by 2 %; - in the temperature range 10 - 20" C the error increases by 2.5 %; - for temperatures below 10"C the conditions of thermal transfer deteriorate strongly and the error increases as compared to the above ones.

References Philip, J. R., 1957. Journal of the Meteorological 14: 359 - 366.


STROMAL ENZYMES IN N-DEFICIENT WHEAT: mRNA AND PROTEIN QUANTITIES

S. J. Crafts-Brandner1, R Holzet, U Feller2

1 TJSDA/ARS, Western Cotton Research Laboratory, 4135 E. Broadway Rd, Phoenix, AZ 85040, U. S. A. 2Institute of Plant Physiology, University of Bern, Altenbergrain 21, CH-3103 Bern, Switzerland

Introduction Nitrogen is remobilized from senescing leaves of cereals and translocated to sinks (e.g. developing leaves, maturing grains). A high percentage of the nitrogen present in the mesophyll cells of wheat is located in the chloroplasts (Peoples et al., 1988). During leaf senescence, the photosynthetic capacity declines, proteins are degraded and breakdown products (amino acids) can be exported via the phloem (Crafts-Brandner et al., 1990, Feller et al., 1994). It is well known that nitrogen deficiency accelerates leaf senescence in intact wheat plants, but the sequence of events is not yet satisfactorily identified. In this study we determined the coordination between the abundances of ribulose-l,5-bisphsophate carboxylase/oxygenase (rubisco), rubisco activase and phosphoribulokinase (Ru5P kinase) and their respective transcripts (rbcS, rca and prk for rubisco small subunit, rubisco activase and Ru5P kinase, respectively). The chloroplast ATP-dependent proteolytic system Clp has recently been described (Shanklin et al., 1995). The Clp protease is composed of two unequal subunits (ClpP and ClpC). ClpP (proteolytic subunit) is encoded in the plastome, while ClpC (ATPase subunit) is nuclear-encoded. The functions of this proteolytic system are not yet identified. Especially the role of this protease in the remobilization of chloroplast proteins during senescence is open to discussion. The transcript levels for these two subunits (clpP and clpC) were quantified in the second leaf of N-stressed wheat plants and of control plants throughout the experimental period.

Methods Winter wheat (Triticum aestivum L., cv. Arina) was grown hydroponically (8 plants per pot containing 1 L aerated nutrient medium) in a culture room with a light/dark cycle (14 h light/10 h darkness). The nutrient medium according to Hildbrand et al. (1994) was used at half-strength prior to the beginning of the experiment. After full elongation of the second leaf (14 d after imbibition), the experiment was started and the plants were transferred to full strength nutrient medium for controls (+N) or to nitrogen-deficient nutrient medium (-N). The second leaf was sampled 0, 4, 8, 13, and 18 days after full leaf expansion. The leaf samples were extracted and analyzed for mRNA quantities (Northern blotting), protein quantities (SDS-PAGE and Western blotting), total RNA, total protein and chlorophyll.

Results Beginning at the time of maximum leaf elongation there was a decline in the total RNA and protein contents; the declines were enhanced by removing N from the nutrient solution. These results suggested that senescence of the second leaf was initiated for both controls and N-stressed plants near the time of maximum leaf elongation. In contrast to total RNA and soluble protein, chlorophyll levels remained high during the experimental period. These results indicate that chlorophyll may decline rather slowly and may therefore not be a suitable indicator for leaf senescence. The poor correlation between chlorophyll content and senescence initiation is consistent with previous reports (Hensel et al., 1993, Smart, 1994). The quantity of rubisco closely paralleled the decline in soluble protein for controls and N-stressed plants. Rubisco activase quantity also declined for controls and to a greater extent for N-stressed plants. In

Division 1 643

contrast, Ru5P kinase quantity remained relatively stable over the 18-day period for controls and even under N-stress the protein was much more stable than rubisco and rubisco activase. Declines in rubisco quantity for both controls and N-stressed plants were associated with a large decline in the rbcS transcript per unit fresh weight within 4 days after maximum leaf elongation. Rca transcript quantity remained high throughout the sampling period and was only slightly influenced by N-starvation. Prk transcript levels declined after full leaf expansion less rapidly than those for rbcS and more rapidly than those for rca. In contrast to rbcS and rca, the prk transcript level remained higher in leaves of N-deficient plants than in controls. The transcripts for clpP and clpC were present throughout the sampling period, but after full leaf elongation a slight decrease was observed for clpC, while for clpP an increase to the three-fold level was detected. The transcript levels for the Clp subunits tended to be lower in leaves of N-stressed plants than in controls, but the overall time courses were not markedly affected by the N status. The expression of this proteolytic system was apparently not restricted to senescence suggesting so far unknown physiological functions of this protease throughout leaf development.

Conclusions Leaf senescence in young wheat plants started near the time when the leaf reached its maximal length. One of the senescence symptoms was the precipitous decline in rbcS transcript quantity, which was paralleled by a decrease in the quantity of rubisco protein. For the other stromal enzymes investigated (phosphoribulokinase and rubisco activase), the transcript and protein quantities were not closely correlated. As judged by the protein and transcript quantities, the senescence program in leaves of N-stressed wheat plants was similar to that of control plants with adequate nitrogen supply, but the time courses differed (accelerated senescence under N-stress). The two Clp subunits were constitutively expressed and not only during senescence. Therefore Clp is not a senescence-specific protease. However, it cannot be ruled out that Clp is involved in some way in the remobilization of chloroplast proteins during senescence. The mechanisms involved in the degradation of stromal proteins and the control of these processes are not yet clear and lead to challenging questions for future experiments.

References Crafts-Brandner, S.J. et al., 1990. Photosynthesis Research 23: 223-230. Feller, U. et al., 1994. Crititcal Reviews in Plant Sciences 13: 241-273. Hensel, L.L. et al., 1993. The Plant Cell 5: 553-564. Hildbrand, M. et al, 1994. Journal of Experimental Botany 45: 1197-1204. Peoples, M.B. et al, 1988. Senescence and Aging in Plants. LD. Noodén and A.C. Leopold

(eds), Academic Press, San Diego, pp. 181-217. Shanklin, J. et al., 1995. The Plant Cell 7: 1713-1722. Smart, CM , 1994. New Phytologist 126: 419-448.


IS MOBILIZATION OF PRE-ANTHESIS RESERVES REFLECTED IN DRY MATTER LOSS FROM VEGETATIVE PLANT PARTS OF WHEAT?

T. Gebbing1'2, H. Schnyder1'2

1 Institut für Pflanzenbau, Universität Bonn, Germany 2 Lehrstuhl für Grünlandlehre, TU München, 85350 Freising, Germany (present address)

Introduction The importance of reserves in vegetative plant parts as a source of assimilate for grain filling of wheat has been studied and discussed controversially for many decades (for a review of the subject cf. Schnyder 1993). Reserves already present at anthesis have received particular attention, because they may buffer grain yield against adverse conditions for photosynthesis during the grain filling period (e.g. Bidinger et al. 1977). Balance sheets of dry matter (DM) of the vegetative above-ground plant parts have been used most frequently for estimation of reserve contributions to grain filling. In that approach the net loss of DM from vegetative above-ground plant parts between anthesis and grain filling is equated with the contribution of pre-anthesis reserves to grain filling (Gallagher et al. 1976). Although the method has been subject to criticism (cf Schnyder 1993) the underlying assumptions have not been tested comprehensively. One of the most critical assumptions is that changes in DM of vegetative plant parts between anthesis and end Of grain filling are due exclusively to storage and redistribution of assimilates. The identity of the major compounds mobilized during grain filling is well known. Starch is insignificant (e.g. Kiniry 1993), but large amounts of water-soluble carbohydrates (WSC, e.g. Kühbauch et al. 1989) and proteins (e.g. Austin et al. 1977, Spiertz et al. 1978) may be mobilized in vegetative plant parts during grain filling of wheat. The objective of this study was to test whether DM loss from vegetative plant parts between anthesis and grain filling accurately reflected mobilization of WSC and protein in wheat grown with differential nitrogen supply.

Methods In 1991 and 1992 single plants of two spring wheat cultivars (cv Kadett and Star) were established outdoors with two levels of N fertilizer supply (24 or 48 mg N per plant) at a density of 320 plants m'2. At anthesis selected sets of uniform plants were transferred to a growth cabinet. Growth conditions were set to reproduce the local long term average of weather conditions. Plants were sampled at anthesis and at the end of grain filling. Tillers were severed near soil level and assigned to the main tiller or lateral tiller fraction. Main tillers were dissected into ear, leaf blades, leaf sheaths and stem. In 1992 the roots plus crown were also sampled. After freeze drying main tiller ears were threshed by hand and separated into the grain and non-grain fraction (ear structures). Samples were weighed after drying, ground in a ball mill and analysed for WSC and N content. Protein content was estimated as nitrogen content times 6.25.

Results Total loss of DM from above-ground vegetative plant parts between anthesis and grain maturity was 161 mg per main tiller in 1991 and 389 mg per main tiller in 1992 (cf Table). These losses of DM significantly underestimated the mobilization of reserves (WSC and protein). On average of the different treatments reserve mobilization was 200% of the net loss of DM in 1991 and 121% in 1992. Net mobilization of WSC and protein was equivalent to 16-31% of grain yields (data not shown). Underestimation of reserve mobilization by balance sheets of DM was

Division 1 645

Table: Net loss of DM, protein and water-soluble carbohydrates (WSC) from vegetative plant parts of spring wheat between anthesis and grain maturity. Data are means of two cultivars and two nitrogen fertilization treatments. Negative values indicate accumulation of biomass.

Leaf blades

Leaf sheaths

Stem

Ear structures

Roots plus crown

1991

1992

1991

1992

1991

1992

1991

1992

1992

DM

-- net loss,

57

92

100

107

50

244

-46

-54

Protein

mg per main

— net loss,

292

55

72

26

27

29

33

24

24

WSC

tiller -

7

12

51

74

119

219

12

12

mg per plant —

25 42

mainly related to continued synthesis of structural compounds in stems and ears structures after anthesis. This process had a masking effect on reserve mobilization as estimated from balance sheets of DM. Further, although there were significant effects of cvs and N fertilizer treatments on reserve mobilization (data not shown), these effects were not apparent in balance sheets of DM. A close correspondence between mobilization of reserves and DM loss was only observed in leaf blades and leaf sheaths. DM loss from the roots plus crown fraction was 4.4 times higher than could be accounted for by mobilization of WSC and protein. This was likely due to death and decay of roots. Reserve mobilization in 1992 was much higher than in 1991. This effect was primarily due to higher pre-anthesis WSC accumulation. On average of years, cvs and N fertilization treatments 80% of the protein and 88% of the WSC present in above-ground vegetative plant parts at anthesis was mobilized during grain filling. Stems, leaf sheaths, leaf blades and ear structures contributed 21, 18,44 and 17% to protein mobilization and 66, 25,4 and 5% to WSC mobilization. These relationships were little affected by cultivar and N fertilization.

Conclusions Pre-anthesis reserve mobilization was not accurately reflected in balance sheets of DM of the above-ground vegetative plant parts between anthesis and grain maturity. Balance sheets of dry matter significantly underrated WSC and protein mobilization.

References Austin, R.B. et al., 1977. Journal of Agricultural Science 88: 159-167 Bidinger, F. et al., 1977. Nature 270: 431-433 Gallagher, J.N. et al.,1976. Nature 264: 541-542 Kiniry, J.R., 1993. Agronomy Journal 85: 844-849 Kühbauch, W. et al., 1989. Journal of Plant Physiology 134: 243-250 Schnyder, H., 1993. New Phytologist 123: 233-245 Spiertz, J.H.J, et al., 1978. Netherlands Journal of Agricultural Science 26: 210-231


CONTRIBUTION OF PRE-ANTHESIS RESERVES TO GRAIN FILLING OF SPRING WHEAT: ASSESSMENT BY STEADY-STATE 13CO ƒ 2C02 LABELLING

T. Gebbing1'2, H. Schnyder1'2, W. Kühbauch1

'institut für Pflanzenbau, Universität Bonn, Germany Lehrstuhl für Grünlandlehre, TU München, 85350 Freising, Germany (present address)

Introduction In wheat (as well as in other determinate crops) grain filling takes place during the last phase of the life cycle of the plants. Grains are filled while the photosynthetic apparatus is senescing. From these relationships one should suspect that grain yields would vary strongly according to the environmental conditions during grain filling. Interestingly, however, grain yields seem to be buffered considerably. An important role of pre-anthesis reserves in buffering grain yields against adverse conditions during grain filling has often been discussed. However, the methods used to assess reserve contributions to grain filling have been subject to criticism (e.g. Schnyder 1993). In most studies the pre-anthesis reserve contribution was equated with the loss of dry matter (DM) from above-ground vegetative parts between anthesis and grain maturity. This procedure may result in significant errors (Bidinger et al. 1977, Austin et al. 1977, Gebbing et al. 1996). In a few studies (e.g. Bidinger et al. 1977, Austin et al. 1977) 14C pulse-labelling of photosynthate was combined with growth analysis. This approach likely gives more accurate results. Ideally, however, all reserve pools should be labelled uniformely, a prerequisite not met in pulse-labelling studies. In the present study steady-state labelling of all photosynthate-C fixed during the post-anthesis period was used to determine the contributions of pre- ('non-labelled C') and post-anthesis photosynthate ('labelled C' in mature grains) to grain filling of wheat. Comparison with balance sheets of reserves (water-soluble carbohydrates (WSC) and protein) in vegetative plant parts between anthesis and grain maturity allowed an assessment of the apparant efficiency of pre-anthesis reserve utilization in grain filling.

Methods For information on plant growth and sampling procedures cf Gebbing et al. (1996). Briefly, in 1991 and 1992 single wheat plants were established outdoors in pots. At anthesis plants were transferred to a growth cabinet and all photosynthate fixed during the grain filling period labelled with a 13C02/

12C02 mixture as described by Schnyder (1992). Isotope composition of mature grain-C was analysed by isotope ratio mass spectrometry. Pre-anthesis photosynthate (i.e. pre-anthesis reserves) in mature grains was calculated from grain mass, C concentration and the fraction of non-labelled C derived from C isotope composition of mature grains.

Results Grain yields were similar in both years but the contributions of pre-anthesis reserves to grain filling differed greatly (Table). This effect was mainly due to higher pre-anthesis WSC accumulation in 1992 (Gebbing et al. 1996). Contributions of pre-anthesis reserves to grain filling ranged between 13 and 28% of mature grain mass and were higher at the low N fertilizer level in both years. The pre-anthesis reserve contribution to grain filling was closely related to the amount of reserves mobilized during grain filling. The average apparent efficiency for conversion of mobilised pre-anthesis reserves into grain mass was high (86%, cf Figure). This efficiency estimate would be less if loss of WSC and protein from roots after anthesis were also included in the calculation (approx. 81%) or if turn-over of pre-anthesis WSC by post-anthesis photosynthate had occurred (approx. 80%).

Division 1 647

Table: Main stem grain yields and pre-anthesis reserve contribution (±1SD) to grain filling of two spring wheat cultivars grown with differential nitrogen supply.

Year N supply Cultivar Grain yield Contribution of pre-anthesis reserves to grain filling

1991

1992

(mg N per plant) 24 48

24 48

24 48

24 48

Kadett Kadett

Star Star

Kadett Kadett

Star Star

mg per 1434 1673

1897 2132

1439 1829

1747 2000

main stem 227 173

354 278

408 359

489 428

+24 ±17

±42 ±20

±45 ±17

±25 ±34

% 15.8 10.4

18.7 13.1

28.4 19.6

28.0 21.4

600

<1> CO

a CO

t «

_c §

< 4 ^

o c o

o o. <u Q

*i a C3

H U u,

u

vi c ca M C

400 -

200 -

o -1

y=0.86x

r2=0.90

A low N Ka

A highN Ka

• low N St

a high N St

200 400 600

WSC and protein lost from vegetative plant parts between anthesis and grain maturity (mg per main stem)

Figure: Relationship between pre-anthesis reserve mobilization in above-ground vegetative plant parts of wheat and pre-anthesis reserve deposition in grains (Ka = Kadett, St = Star). The dashed line indicates the 1:1 relation.

Conclusions Pre-anthesis reserves were utilized efficiently and contributed significantly to grain filling of non-stressed spring wheat.

References Austin, R.B. et al., Journal of Agricultural Science 8 Bidinger, F. et al., 1977. Nature 270: 431-433 Gallagher, J.N. et al.,1976. Nature 264: 541-542 Gebbing, T. et al., 1996. this volume Schnyder, H., 1992. Planta 187: 128-135 Schnyder, H„ 1993. New Phytologist 123: 233-245

159-167.


CONTRIBUTION OF CARBOHYDRATES TO WINTER SURVIVAL AND SPRING REGROWTH OF WHITE CLOVER (Trifolium repens L.)

M.P. Guinchard, Ch. Robin

Laboratoire «Agronomie et Environnement», ENSAIA-INRA, BP 172 - F-54505 Vandoeuvre les Nancy, France.

Introduction White clover {Trifolium repens L.) is the most important pasture legume in regions with a cool, temperate climate. The persistence of white clover is partly determined by the winter survival and spring regrowth. Starch is accumulated in leaves and stolons during autumn (Vez, 1961 ; Guckert et al, 1983) and hydrolysed into free sugars during winter. But the role of those reserves on the winter survival and spring regrowth is not well understood. The aim of this study was to determine the contribution of carbohydrates reserves of the stolons on white clover morphogenesis. Two cultivars were tested (Huia and Aberherald) in order to isolate genetics traits of winter survival.

Methods The experiment was conducted in controlled conditions on plants pre-acclimated to low temperatures (10/4°C day/night) before they were submitted to chilling conditions (5/0°C day/night). After 28 days of chilling treatment, all the leaves were cut and plants were submitted to a regrowth period by raising the temperature of 2°C per day until the 20/15°C day/night conditions were obtained. Controlled treatment consisted of setting the plants at 20/15°C immediately after the acclimation until the end of the regrowth period. The photoperiod was 10h at 250mmol.nr2.s-1, with a relative humidity of 70%. Leaf appearance rate, leaf area, petiole length and stolon starch content were determined at the end of the chilling treatment, and after the regrowth period on treated and controlled plants. Starch was analysed with ßamyloglucosidase at 55°C and enzymatically determined (Bergmeyer et al, 1974).

Results Chilling decreased significantly the leaf appearance rate, the petiole length and the leaf area and the stolon starch content in both cultivars (Table 1). During the chilling treatment, Aberherald produced larger leaves than Huia. During the regrowth period, the stolon starch content decreased both in controlled and in plants of the chilling treatment. At the end of the regrowth period, Aberherald showed bigger leaves and a higher stolon starch content whereas there was no difference between the two cultivars in the leaf appearance rate.

Conclusions We confirmed previous studies showing that starch accumulated in stolons of white clover during autumn is hydrolysed during a cold period and during the regrowth (Guckert et al, 1983 ; Bertrand et al, 1991). The cultivar Aberherald produced bigger leaves than Huia during the regrowth following chilling but no differences were observed between cultivars in the leaf appearance rate. A higher dry matter and therefore a better yield could be expected in spring for cv. Aberherald. This better production can be attributed to the higher stolon starch content at the end of the chilling treatment and at the end of the regrowth period.

Division 1 649

Table 1. Leaf appearance rate, petiole length, total leaf area and stolon starch content of white clover (cv Huia and Aberherald) at the end of the chilling (5/0°C) and control (20/15°C) treatments and at the end of the regrowth period.

Leaf appearance rate (leaf.d-1) Chilling Regrowth

Petiole length per plant (mm) Chilling Regrowth

Total leaf area (cm2.pl._1) Chilling Regrowth

Stolon starch content (mg.g-1 ! Chilling Regrowth

CONTROL (20/15°C)

Huia

0.27 0.21

855 140

71 16

DW)

67 30

Aberherald

0.27 0.27

860 161

89 23

92 47

CHILLING (5/0°C)

Huia

0.02 0.18

179 138

20 17

25 9

Aberherald

0.02 0.21

201 192

31 23

39 13

References Bergmeyer, H.U. et al., 1974. Methods of enzymatic analysis (H.U. Bergmeyer, ed), Academic Press, New York, 3 : 625-631.

Bertrand, A. et al., 1991.Canadian Journal of Plant Science 71 : 737-747. Guckert, A. et al., 1983. Supplément de la revue Fourrages 94-95 : 61-86. Vez, I , 1961. Bulletin delà Société Botanique Suisse 71 : 118-173.


CONTRIBUTION OF IN VITRO PLANT CULTURES TO THE STUDY OF MINERAL NUTRITION

H. Lipavskâ, L. Nâtr

Department of Plant Physiology, Faculty of Science, Charles University, Vinicnâ 5, 128 44, Prague 2, Czech Republic

Introduction In vitro techniques are used in many fields concerning plant biology. They also allow to expose plants to specific conditions and determine the plant response that cannot be observed in vivo. One of these possibilities is supplying the plant with exogenous sugars, which enables to support growth of nongreen organs or isolated cells, but also uncoupling of processes that are mutually dependent in intact plant via photosynthesis.

Methods The changes in chlorophyll content (Arnon, 1949) and dry matter accumulation and allocation were determined in in vitro grown rape (Brassica napus L.). Plants were grown 21 days on LS media (Linsmaier etal, 1965) with 0, 1 and 3 % sucrose (treatment 1, 2, 3) and on the medium without inorganic nitrogen, with 1 or 3 % sucrose (treatment 1-N, 3-N) and on LS medium with 1-10% sucrose (chlorophyll content determination) under dark and light conditions (16 h photoperiod, 550 umol m"2s"' ).

Results The enhanced availability of sugar induced an increase in the plant chlorophyll content (Fig. 1), although it was reported that high sugar concentration in the medium restricts chlorophyll synthesis in isolated cells (Neumann, 1973).

o SZ

o

1 2 3 4 5 6 7 8 9 10

sucrose concentration in the medium [%]

Fig. 1 : Effect of exogenous sugar supply from the medium on the chlorophyll content in rape plants grown in vitro

This effect might be connected with preferential dry matter allocation to root favouring the nitrogen availability and thus promoting chlorophyll synthesis. In light the total dry weight of plants grown with sucrose in the medium and without inorganic N (-N) was nearly the same as in the corresponding treatment with full N supply (Fig.2).

Division 1 651

The dry matter allocation, however, differs remarkably. In both cases - in light and dark -the shoot/root ratio decreased with increasing concentration of sugar in the medium, and further decrease was brought about by N deficiency (Fig.3).

o o

0 1 3 N1-N N3-N

treatment

d & M

0 1 3 X1-N X3-N

treatment

Fig.2: Dry matter accumulation in rape grown in vitro on different sucrose and nitrogen concentration in the medium.

Fig.3: The shootroot ratio in rape grown in vitro on different sugar and nitrogen concentration in the medium

Conclusion The non-limiting exogenous sugar supply in combination with N deficiency strongly promoted root system development. Total dry weight of-N variant in dark even exceeded the total dry weight of+N plants grown on the same sugar concentration. It is obvious that in vitro cultivation enabling long term exogenous sugar supply from the medium offers new possibilities to study mineral nutrient effects bypassing their modulation of photosynthesis.

References Arnon, D.I., 1949. Plant Physiology 24: 1-15 Linsmaier, E. etal., 1965. Physiologia Plantarum 18: 100-127 Neumann, K.-H., 1973. Plant Physiology 51: 685-690


APPLICATION OF DIFFERENT FUNCTIONS TO THE DESCRIPTION OF GROWTH OF BUCKWHEAT (FAGOPYRUMESCULENTUMMOENCH)

R. Maciorowski , S. Stankowski1, G. Podolska2, A. Pecio2

Department of Biometry, Academy of Agriculture, Slowackiego 17, 71-434 Szczecin, Poland IUNG Pulawy, Osada Palacowa, Poland

Introduction For the sake of common application of mathematical modelling in agricultural sciences, attempts of approximation of growth processes by means of different mathematical functions become particularly important. From among many mathematical growth functions, the sigmoid curves with asymptotic value of final size, have found a relatively large application in the description of completed growth processes (Causton et al., 1981; Hunt, 1982; Ramachandra Prasad, 1992). In this paper, a usefulness of some S-shape curves for description of accumulation of plant dry matter of buckwheat (Fagopyrum esculentum Moench) was tested.

Methods The glasshouse experiment was carried out in 1992-1994 years in IUNG Pulawy. The objects of research were plants of buckwheat cv. Hruszowska. The plants were grown in optimal conditions of fertilization (N, P, K mg and microelements Fe, B, Mn, Cu) and soil humidity, in Mitscherlich's pots which contained 7 kg loam soil mixed with 2 kg glass sand. The dry matter of green parts of plants was measured every ten days. The mean yearly values of measurements obtained from 15 plants (3 pots with 5 plants each) were used in further calculations. Constant parameters of the estimated equations (Richard -[R], Simple logistic-[L], Gompertz-[G], Janoschek-[J]) were determined numerically, using the quasi-Newton algorithm according to STATISTICA package. After that, other characteristic parameters of the growth function: initial value w0, coordinates of the inflection point of function graph (t;, w,) and characteristic for that point maximal theoretical growth rate (dw/dt)max, were calculated according to previous studies (Zelawski et al., 1980, Gregorczyk, 1994). As a measure of fit precision of theoretical curves to the empirical data, the residual sum of squares S(WJ - Wj) (where: w - empirical values, w -theoretical values, j - number of measurements) and correlation coefficient R were used (Maciorowski, 1995).

Results Results are presented in the Table and in Figures 1 and 2.

The characteristic parameters of the investigated functions, describing the accumulation of plant dry matter of buckwheat

Function w0 t, w, (dw/dt)max R S(WJ-WJ)

[g] [day] [g] [g day"1]

[R]w=24.40(l+959.9e-0128t)1/(1-2104)

[L] w=24.46(l +631.7 e"0123 ')"'

[G] w=25.36 exp(-38.39 e"00768t)

[J] w=24.14(l-exp(-0.01764411441)) 0

0.049

0.039

0

0

52.9

52.5

47.5

53.7

12.4

12.2

9.3

13.0

0.796

0.751

0.716

0.707

0.99

0.99**

0.98**

0.99**

1.01

1.12

4.00

1.76

Division 1 653

Figure 1. The investigated curves as compared with the experimental points.

.-y!/ ' vC--- Figure 2. The theoretical curves ^^><? ^ ~ ^ Z ^ . of growth velocity (dw/dt).

" 0 10 20 30 40 50 60 70 80 90 100 Time of growth -t [day]

Conclusions The investigated functions correctly described accumulation of dry matter of buckwheat plants, because empirical points are located close to the theoretical curves (very small values of residual sum of squares and high values of correlation coefficients). From the functions used, Gompertz model did not show good fit, particularly in the exponential growth stage. The accumulation of dry matter increased exponentially until the beginning of flowering (about the 40th day after sowing). After that character of growth changed into linear. In the full flowering stage (about the 50th day depending on the model) the inflection point appeared on the growth curve (from concave to convex). The maximal theoretical growth rate (dw/dt)max changed from 0.7 to 0.8 (g day" ) and was the highest in the Richards function. From the beginning of maturity phase (the 70th day of growth) exponential decrease in growth rate of investigated buckwheat plants was observed, which corresponded with a relatively small increase of total dry matter.

References Causton D. R. et al., 1981. The biometry of plant growth, E. Arnold Publishers, London, 257 p. Gregorczyk A., 1995. Acta Societatis Botanicorum Poloniae 1: 5-7. Hunt R., 1982. Plant growth curves. The functional approach to plant growth analysis. E. Arnold

Publishers, London, 248 p. Maciorowski R. et al., 1995. Biuletyn IHAR 194/195: 72-81. Ramachandra Prasad T. V. et al., 1992. Journal Agronomy & Crop Science 168: 208-212. Zelawski W. et al., 1980. Acta Physiologiae Plantarum 2: 187-194.


ANATOMICAL AND BIOCHEMICAL CHANGES IN GRASS LEAVES DURING DEVELOPMENT

I. Maurice, F. Gastal

INRA, Station d'Ecophysiologie des Plantes Fourragères, 86600 Lusignan, France

Introduction Several physiological aspects of leaf growth oftall fescue (Festuca arundinacea Schreb.) have been described, mostly in young leaves emerging from the sheath of older leaves: anatomy, cellular dynamics (MacAdam et al., 1989), C metabolism (Schnyder et al., 1987), N metabolism (Gastal et al., 1994), and secondary cell wall deposition (MacAdam, 1988). The objectives of our study were to examine how some of these aspects may change during leaf development, and to evaluate possible consequences for the costs of synthesis and the quality of various segments of the leaf.

Methods Tillers oftall fescue were cut to leave a 5 cm stubble, put in pots containing sand and placed under controlled conditions. They were allowed to grow for 19 days then were transfered to hydroponics at 21°C, 80% RH, continuous light (400 umol.m'ls"1 PPFD) and 7.5 mM N03

solution. After 15 days, tillers which fastest growing leaf was about to emerge into light were identified. Leaves from this population were harvested after 0, 2,4, 6 and 8 days. The leaves were cut into segments of 5, 10 and 20 mm from base to tip. One part of the samples was dried, weighed and analysed for fibres and mineral content with the TDF method (Prosky et al., 1985), the results being expressed as a weight of enzymatic digestion residue. The other part was used to measure the width and the area of cross-sections. Leaf elongation rate (LER) was measured daily. Longitudinal distribution of relative growth rate (REGR) was assessed by making fine holes in the growth zone (Schnyder et al., 1987). Thus, we were able to calculate the pathlines (i. e. lines of displacement) of elements along the leaf (dotted lines on Figs. 3 and 4).

Results LER averaged 1.3 mm.h"1 throughout the experiment, and the length of the growth was consistently 30-35 mm. For each sampling date, the width of the leaf increased along the growth zone (Fig. 1). After a maximum or a plateau beyong the end of the growth zone, width decreased towards the tip. The width of a segment leaving the growth zone increased from day 0 to 8, but the increase was much less after day 4. This can be related to the size of the apical meristem, which progressively surrounds the apex, causing the leaf width to increase. Average thickness (Fig. 2) was obtained by dividing the area of the cross-sections by width

Fig 1: Time course of width Fig 2: Time course of average thickness

DayO Day 2 Day 4 Day 6 Day 8

SO 100 150 200 250 300

Distance from leaf base (mm)

50 100 150 200 250 300


Division 1 655

a,

Fig 3: Time course of density

• Day 2 A Day 4 • Day 8

50 100 150 200 250 300


Fig 4: Enzymatic digestion residue

measured on the same leaf. As for width, average thickness increased along the growth zone, but in the other parts of the leaf, the pattern of thickness changes was different from that of width. From the tip, thickness increased markedly at first, then showed a slower, but steady, increase towards the base. This shows that the meristem was still thickening, whereas it had stopped widening. We also measured the height of ridges of our cross-sections, and found that the increase in thickness near the end of the growth zone was mainly due to an increase in the thickness of the mid-rib (three vascular bundles combining into one ridge). Fig. 3 shows that for each day, dry matter density decreased along the elongation zone (0-35 mm) as elongation results from a water influx that exceeds dry matter deposition, and it increased along the maturation zone (35-100 mm), as secondary cell wall deposition and chloroplasts development occurs (MacAdam et al., 1989). Near the tip of the leaf, dry matter density decreased. Dry matter density also increased with time, not only in growing or maturing parts of the leaf, but also in mature ones, as shown by following the pathlines of individual elements with time (Fig. 3). The residue of the enzymatic digestion (Fig. 4) was low in the growth zone, though it increased on day

8, as cell division must slow down. The pathlines of elements indicate that the rate of entry of fibres and minerals was high within the maturation zone, then stopped around 100 mm from the base.

100 150 200 250 300


Conclusions Dry matter accumulated with time all along the leaf. There must have been an entry of soluble material, as the residue of enzymatic digestion could not account for the increase in dry matter beyond 100 mm from the base. At this point, segments were mature and had emerged from the sheaths, so they would be able to photosynthesise and reduce nitrates. It is likely, especially under continuous light, that a considerable part of these assimilates were being stored. Therefore, analyses of water soluble carbohydrates and the reduced N fraction are being done to attempt to account for this phenomenom. Successive segments increase in width and thickness and become denser. This implies that the costs of production per unit length of leaf must increase. The fact that the proportion of non-digestible material decreases with time has implications for forage quality and should be studied further.

References Gastal et al., 1994. Plant Physiol. 105: 191-197. MacAdam, 1988. Columbia, Missouri, PhD Thesis, University of Missoury, 132p. MacAdam et al., 1989. Plant Physiol. 89: 549-556. Prosky et al., 1985. J. Assoc. Off. Anal. Chem. 68(4): 677-679. Schnyder, H. et al., 1987. Plant Physiol. 85: 290-293. Schnyder, H. et al.,1987. Plant Physiol. 85: 548-553.


STUDIES ON THE ACCUMULATION OF GLIADIN PROTEINS DURING WHEAT GRAIN DEVELOPMENT

N. Mladenov1, N. Przulj1, N. Hristov1, Y. Yan2, S. Prodanovic3, S. Vuckovic3

1 Institute of Field and Vegetable Crops, 21000 Novi Sad, M. Gorkog 30, Yugoslavia 2 Southwest Agricultural University, Chonqing, China 3 Faculty of Agriculture, Belgrade, Yugoslavia

Introduction Protein accumulation during different grain developmental stages is an important area in wheat physiology and cultivation research. It is well-known that the bread-making quality of wheat is related to both protein concentration of grains and the quality of protein (Finney et al., 1948). Gliadins play important role in determination of bread-making quality because they give extensibility to a bread dough (Payne et al., 1984). Damidaux et al. ( 1978) have studied the relationships between gliadin components and viscoelastic properties of durum wheat and they have found a consistent relationship between the presence of particular gliadin components and quality of gluten. Some investigations on differential protein accumulation during grain development were carried out (Bushuk, 1971; Peltonen, 1992). In order to improve our knowledge of wheat storage proteins, we further explore the accumulation traits of gliadin proteins during 12 developmental stages of grain filling in two wheat cultivars.

Methods Materials include two winter wheat cultivars: Prima and NS Rana-2, which were planted in 1995 at Novi Sad. Twelve grain developmental periods studied were those initiated after pollination. Ears were collected 2, 9, 14, 19, 23, 26, 29, 33, 35, 39, 41 and 44 days after pollination. Gliadin electrophoresis was carried out according to the procedures of Lookhart et al. (1978) and Metakovsky et al. (1991) with some modifications. Nine % Polyacrylamide gel was used for gliadin separation. Single seed was extracted with 70% aqueous solutions of alcohol (150 (0.1 [seed1]) for about two hours. For electrophoretic separation, 20 JJ.1 sample solutions were used. The electrophoretic apparature used was DYY-III28A vertical gel former with twelve gel slots (135 x 100 x 1.5 mm). Electrophoresis was performed at a constant voltage (380V) for two and a half hours at a temperature not exceeding 25°C. When the second purple marker dye band of methyl green has migrated to the end of the gel, the power was turned off, and the gel was fixed in 10% Tri Chloro-Acetic acid (TCA) for an half hour and stained with 0.04% Coomassie brilliant blue R250 in 10% TCA for 24 hours. Gliadin electrophoregrams were determined on the basis of method of Bushuk et al. (1978).

Results Results are presented in Figures 1 and 2. The rapid accumulation of gliadin proteins was observed in a short period (about 5 days), namely 19-23 days after pollination. After 23 days of pollination, all gliadin bands became visible on the electrophoregrams and the relative intensities of all bands reached to the maximum. However, from 23 days to full maturity of grains, there existed smaller differences in relative intensities, suggesting that the contents of gliadin components have a slight increase in this period.

Division 1 657

Number of sample

0-

10-

20-

30-

40-

50-

60-

70-

80-

90-

100-

1 2 3 4

=

5 6 7 8 9 10 11 12 Figire. 1. Diagram; of ghadmetoroplioregiai™ at diffavait grain dewloptiHtal stages in Pnnm Number of sample and days after polimtion:

I. 2 days 2 9days 3. 14 days 4. 19 days 5. 23 days 6. 26 days 7. 29 days 8. 33 days 9. 35 days 10. 39 days II. 41 days 12 44 days

Number of sample 2 3 4 5 6 7 8 9 1

0-R e 10-1 a 2°-

! 30-1

v 40-e

50-m 60-o b 70-

| 80-1 90-t y 100-

Figure, 2. Diagrams of gBadin electrophoregrams at different gram developmental stages in NS Rana-2 Number of sample and days after pollination:

1. 2 days 2. 9 days 3. 14 days 4. 19 days 5. 23 days

6. 26 days

7. 29 days 8. 33 days 9. 35 days 10. 39 days 11. 41 days 12. 44 days

Conclusions In this work the accumulation of gliadin proteins during wheat grain development was studied. It was found that after 14 days of pollination some gliadin bands began to appear. Furthermore, some gliadin components appear earlier than others, which is related to then-intensities. Generally, more intensive bands appeared earlier than light bands.

References Bushuk, W. et al., 1978. Canadian Journal of Plant Science 58: 505-515. Bushuk, W., 1971. Cereal Chemistry 48: 448-455. Damidaux, R. et al.., 1978. Hebdomedal Seances of Academy of Sciences, Series D, 287:

701-704. Finney, K. F., 1948. Cereal Chemistry 25: 291-312. Lookhart et al., 1982. Cereal Chemistry 59: 178-181. Metakovsky, E. V. et al., 1991. Journal of Genetics & Breeding 45: 317-324. Payne, P. I. et al., 1984. Philosophic Royal Society, Series B, 304: 359-379. Peltonen, J. et al., 1992. Finlan Agricultural Science 1: 499-506.


COMPARISON OF TWO DESTRUCTIVE METHODS IN THE ESTIMATION OF GRASSLAND PRODUCTION

R. Mosquera, E. Carrai, A. Castelao, E. Lopez, C. Moirón, A. Rigueiro, J. Villarino.

Departamento de ingenierla Agroforestal y Production Vegetal. Escuela Politécnica. Superior. 27002 Lugo. Spain.

Introduction The most important way of measurement of grassland productivity is probably the estimation of dry matter production. There are several methods estimate dry matter production which can be divided in destructive and non-destructive methods. Destructive methods usually are more exact than nondestructive methods. Destructive methods consist of cutting a predetermined area. The size of this area is one of the more important decisions for dry matter production estimation, as well as sample number. Larger cut areas are more precise than smaller ones for dry matter production estimation because variability is reduced, but the harvested areas can not be grazed in grazing experiments and for this reason sample size should be as small as possible. The objective of the present experiment was to evaluate two sample sizes for estimate grass production.

Methods Two destructive methods for estimating grassland production are compared in a established experiment.. The first method tested is usually used when simulating grazing experiments (small plot experiments (Mosquera and Gonzalez, 1996)), and the second one is used in order to study more frequently the grassland dynamic parameters (mean and instantaneous growth rate) because it takes less area and therefore more samples can be taken (Mosquera, 1993). The experiment was conducted in Galicia (NW of Spain), and it is a silvopastoral simulation. Main plot sizes were 16 x 12 square meters and included two different grass mixtures (folium perenne + Trifolium repens + Trifolium prantense and Dactylis glomerata + Trifolium repens + Trifolium pratense), three different types of fertilization ((40 units of Nitrogen) organic fertilizer, inorganic fertilizer and no fertilization), two tree species (Betula celtiberica and Pinus pinaster) and three replicas. The first method applied was cut an area of 2 x 5 square metres per plot and the second one consisted of four samples of 0,3 x 0,3 square metres obtained at the same time. Means from each treatment and method were calculated and different relationships were made. 36 and 144 samples were used in the first and second method respectively. Linear, logarithmic and quadratic relationships were tested in order to study the relation between methods.

Results The linear, logarithmic and quadratic regressions of two methods are shown in Table 1. Linear and quadratic regressions could be seen in Figure 1. The production range was from 1140 to 3553 kg per ha. The best fit between methods was described by a quadratic regression (r=0,85) although the linear regression was good too (r=0,81). Values reported from quadratic and linear regressions are not different at intermediate dry matter production (range between 1700 and 2800) and differences were shown when this parameter rose (above, 300 kg DM /ha). DM values from 0.3 x 0.3 m method between 1500 and 2000 kg DM/ha corresponded to 1500 to 2500 and tolOOO to 2800 for linear and quadratic regression with 2 x 5 m method, respectively. However, higher production values for 0.3 x 0.3 method between 2000 and 3000 kg DM/ha were related with 800 kg DM/ha more with 2 x 5 m method. Differences between methods could be explained because when dry matter production rose smaller size samples were associated with higher grass height and it is very difficult to limit the square borders, and avoid border effects. Bigger size samples are less affected by the border and this

Division 1 659

problem is avoided. An area of 1 cm border meant a 12% and 1 % border of total area for small (30 x 30 cm) and bigger (500 x 200 cm) sample. An other reason could be that the usual variability associated to grassland area is higher when production rises and is compensated in samples with large areas because lower and higher productive areas are represented in the same sample, which does not occur with smaller samples. Relative values of both methods showed that highest production values with 0.3 x 0.3 m methods were related to highest production values with the 2 x 5 m method.

Table 1. Linear, quadratic and logarithmic regressions between DM from 5 x 2 m method and DM' from 0.3 x 0.3 method

Model

DM = a + bDM' DM = a + bDM' + cDM'2

LDM=a + bDM'

Tm DM/Ha

a -1356 -9247.5 -29230

Parameters b

1.93 9.44 4181.16

0,0017 0.81 0.85 0.84

33 375 Tm DM/ha

Figure 1. Linear and quadratic regressions between the two destructive methods. X axis represents DM/ha of 0.3 xO.3 method and Y axis DM/ha of 2 x 5 m method.

Conclusions A larger sample size represents better the production heterogeneity in the cut area than smaller samples, but destroy too much area. Differences between methods increased above 2000 kg DM/ha, a range associated with low grass quality, and therefore it should not be used with grazing experiments, where the small area sampling method should be use. An important correlation between relative values of production results for the two methods were found and both methods can be used depending on objectives, variability and availability.

References Mosquera, R., 1993. Producción y manejo de forrajes en us sistema de producción lechero. Tesis Doctoral. Universidad de Santiago de Compostela. 295 pp Mosquera, 1996. Efecto de la fertilización nitrogenada y potâsica sobre la composición quimica de la pradera. Actas de la SEEP (en prensa).


STUDY OF NON A DESTRUCTIVE METHOD FOR DRY MATTER YIELD ESTIMATION IN DAIRY ROTATIONAL SYSTEM.

M.R. Mosquera-Losada', A. Gonzalez-Rodriguez2

'Departamento de Ingenieria Agroforestal y Producción Vegetal. Escuela Politécnica Superior. 27002 Lugo. Spain 2Centro de Investigaciones Agrarias de Mabegondo. Apartado de Correos n° 10. La Coruna. 15080 Spain.

Introduction The use of height as a predicting method of DM for pasture yield helps the farmer to manage his own land for milk production. It is an easy, cheap and non destructive technique for deciding the target DM for the cows movement in the rotational systems. DM and height relationship is not constant through the year because it is affected by different density, so pasture with low density should be 1 or 2 cm higher in order to achieve the same DM target than higher density pastures (Wright, 1985). Height and DM relationship should be studied in the different seasons because of density changes through the year as well as pasture productivity (Mosquera, 1995).

Methods Samples were taken in pastures grazed by dairy cows in Galicia (North-West of Spain). Cows were managed in a flexible rotational system (Mosquera-Losada, 1993). A rising-plate sward stick method was used in order to determine the sward height. It consisted of a plate which has a scale for height determination as described by Frame (1981). The dry matter production was estimated by the cut of five 0,33 x 0,33 m areas with battery operated shears to 2,5 cm above ground before and after grazing. Samples were dried and weighed individually. Height was estimated in the sampling area before cutting. The correlations were studied during three years (1989,1990 and 1991) and three periods (spring, summer and autumn). Different linear, quadratic and logarithmic models were fitted to the data.

Results The studied relationships between DM production and height are presented in Table 1. There was a high correlation between height and production as found by O'Sullivan et al. (1987). Linear relationship had the highest correlation coefficient (0.78,0.91 and 0.73 for spring, summer and autumn, respectively) as well as the quadratic. Best relationships were found in the summer, spring and autumn in this order. Linear regression had similar slopes for the three studied periods, however changes in dry matter per centimetre are higher in the spring (1531 kg ha"1) and autumn (1388 kg ha" ') than in the summer (1134 kg"') at a target height of 10 cm recommended by Mayne et al. (1984). This higher dry matter change for every centimetre can be explained by the fact that the grassland is less dense during the spring and autumn than during the summer (Mosquera-Losada and Gonzalez-Rodriguez, 1994). Linear correlation was similar to that found by Hoden et al. ( 1991 ) with dairy cows at a stocking rate of 2.3 cows per ha. On the other hand, offered pasture production was very similar for quadratic regressions for the same target height (1487,1497 and 1348 kg ha"1 for spring, summer and autumn, respectively). Linear relationship is preferred in spite of having the same variance explained than quadratic regression because of the simplicity.

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Table 1. Dry matter (DM, kg/ha) and height (H, cm) relationship in the three studied periods (spring, summer and autumn) and mean of the three years

Model

Spring

Summer

Autumn

DM = a DM = a LDM=a DM=a-LMS=a LMS=a DM = DM = LDM= DM= LMS= LMS= DM = DM = LDM:

DM= LMS= LMS=

bH bH bH

bLH-bH bLH +cLH2

a + bH a + bH + cH2

a + bH a + bLH + cLH2

=a + bH + cH2

=a + bLH+cLH2

a + bH

cHz

cLU1

cH2

bHH -bH

c t f a =a a + bLH + cLH2

=a+bH+cH2

=a + bLH +cLH2

a -49.1 142 6.13 1514 5.67 5.10 176 93

6.44 1373 5.93 4.49 1.41 792 6.04 5016 6.29 8.65

Parameters b

155 116 0.1 -1647 0.2 0.85 131 145 0.07 -1361

0.16 1.50 139 -52.41 0.11 -4936

0.05 -2.59

c -1.85 -715 -0.004 0.04 --0.46 -618 -0.002 -0.11 -

r

0.78 0.78 0.81 0.77 0.82 0.83 0.92 0.92 0.85 0.92 0.89 0.91 0.73

10.81 0.75 -1457

0.69 0.75

-0.003 0.69 0.84 0.70

RSD

419 419 -

423 --

343 343 -

348 --

276 269 -

267 --

Conclusions A good relationship between DM production and height in dairy rotational systems was found. Linear correlationship was preferred to quadratic and logarithmic (in spite of having the same variance percentage explained) because of simplicity.

References Frame, J., 1981. Herbage mass. In "Sward measurement handbook" Hodgson et al. (Eds) Grassland Society Hurley Br. Pp:39-69. Hoden, A. et al. 1991. Journal of Agricultural Science, Cambridge, 116,116417-428. Mayne, CS., et al.. 1984. Grass and Forage Science, 42:59-72. Mosquera, R., 1993. Producción y manejo de forrajes en us sistema de producción lechero. Tesis doctoral. Universidad de Santiago de Compostela. 295 pp Mosquera, R. et al. 1995. Estudio de la composición botanica en sistemas lecheros sometidos a distinta carga. Congreso 1995 de la Sociedad Espanola de Malherbologia. O'Sullivan, M. et al, 1987.Irish Journal Agriculture Research, 26:63-68. Wright, I.A., 1985. Forage height and mass in relation to grazing management. En "Emerging technology and management for ruminants". Eds. F.H. Baker, M.E. Miller, M.E. Westuinss Press for Wintock International Boulder, co:341-348.


RESPONSE OF BUCKWHEAT VARIETIES GROWN ON DIFFERENT SOIL TO DIMETIPIN

J.Pawlowska, D.Dietrych-Szóstak, A.Pecio

Institute of Soil Science and Plant Cultivation Osada Palacowa, 24-100 Pulawy, Poland

Introduction Buckwheat is regarded as a one of the most valuable cereal crops due to nutrients in its seeds such as K, P, easily assimilable protein, Fe, Cu and vitamins. The seeds also contain rutin, which is used by pharmaceutics (Kusiorska et al., 1993). The acreage of buckwheat cultivation extends on various soils. The reasons for buckwheat yielding deceptiveness result mainly from its genetics and biology. In order to advance and equate seed ripening the dimetipin growth regulator has been used for several years. In previous studies some differences in di- and tetra-ploid buckwheat varieties response to the chemical were found (Ploszynski et al., 1993; Dietrych-Szóstak et al., 1994; Dietrych-Szóstak et al., 1995). The point of the presented study was to determine the differences between buckwheat varieties (under various soil conditions) response to dimetipin.

Methods The experiment was conducted on plots filled with the eight different types of soils (Table 1) occuring in Poland the most frequently.

Plot nr

1 2 3

4 5 6 7 8

Soil type

black earth brown alluvial soil brown soil developed from loess typical brown soil limestone soil typical brown soil acid brown soil acid brown soil

Soil suitability complex

very good wheat complex (1) good wheat complex (2) good wheat complex (2)

very good rye complex (4) defective wheat complex (3) good rye complex (5) weak rye complex (6) very weak rye complex (7)

Plots were fertilized according to standards (Dietrych-Szóstak et al., 1994). Two buckwheat varieties were tested: diploid-Kora and tetraploid-Emka. Buckwheat plants were sprayed once with Harvade 25 F (500 g dimetpin/ha) at the beginning of full ripening. The control plants were treated at the same time with distilled water. Plants were harvested at the full ripening. Yield were analyzed (g/conted per plant) as well as protein in nuts (%N x 6.25) in automatic Contiflo system.

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Results Results are presented in the Table 2.

Yield of buckwheat seeds and protein content in buckwheat nuts subject to soil conditions after dimetipin application

Plot nr

1 2 3 4 5 6 7 8

Weight of seeds Control Kora Emka

0.82 1.04 0.86 1.02 0.40 0.81 0.22 0.23

0.55 0.79 0.80 0.94 0.44 0.58 0.24 0.30

Dimetipin Kora

1.93 2.15 2.83 3.03 0.53 2.14 0.59 0.53

Emka

1.17 1.16 1.52 1.88 0.80 1.40 1.28 1.03

Protein Control Kora

12.5 12.6 12.1 12.6 11.1 10.6 11.6 11.9

Emka

12.3 12.8 13.1 12.7 11.6 11.1 12.4 12.1

Dimetipin Kora

11.9 12.1 13.4 12.8 11.8 11.6 12.1 11.6

Emka

12.6 12.3 13.8 13.2 12.6 12.5 12.9 12.5

The seed yield of both buckwheat varieties significantly increased after dimetipin treatment due to seed shape improvement. In case of diploid variety Kora, which created more tillers differences were more tangible than in the case of tetraploid Emka. On better soils (complex nr 1, 2, 3, 4, 6) the effect was much more clear than on the poorer soils (complex nr 5, 7, 8) and the seed yield per one plant of Kora was higher than the yield of Emka. On poorer soils Emka was more productive.

Conclusions Growth regulator dimetipin increases buckwheat seed yield by equalization of ripening time and seed shape improvement. The results confirm the previous study of Dietrych-Szóstak et al.,1994. Before making a decision to apply dimetipin, the genetic features of buckwheat varieties should be taken into consideration. The seed yield of diploid variety was higher on better soils, tetraploid one - on poorer soils.

References Dietrych-Szóstak, D., Pawlowska, J.,1994.Fagopyrum 14:59-61. Dietrych-Szóstak, D., Pawlowska, J.,1995.Biological Bulletin of Poznan, Poland, 32:31p. Kusiorska, K.et al.,1993. Acta Academiae Agriculturae ac Technicae Olstenensis 56:229-237. Ploszynski, M. et al.,1993.Materiafy XXXIII Sesji Naukowej Institute of Plant Protection of Poznan, 194-197.


INFLUENCE OF INORGANIC NITROGEN ON SENESCENCE AND PROTEIN REMOBILIZATION IN FLAG LEAVES OF MATURING WHEAT GROWN ON WATERLOGGED SOIL

R. Pfarrer, U. Feller

Institute of Plant Physiology, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland

Introduction Various stresses, such as nutrient depletion, drought, heat or waterlogging can influence senescence in plants (Noodén, 1988). Waterlogging causes oxygen deficiency and affects the availability of nutrients for the plants (Ponnamperuma, 1984). Limited oxygen availability in the soil alters the energy metabolism in plant roots (Reggiani et al., 1985; Saglio et al., 1980). Waterlogging during the grain filling period may reduce uptake of nutrients by the roots and translocation of nutrients from senescing leaves to the maturing grains and as a consequence also grain yield (Cannell et al., 1980; Stieger et al., 1994a; Trought et al., 1980; Watson et al., 1976). Plant roots are therefore directly influenced by waterlogging, whereas the shoot may be affected indirectly by changes in root activities and in the composition of the xylem sap. Protein remobilization is accelerated in wheat leaves on flooded soils. The supply of nutrients to the soil can modify plant responses to waterlogging. Nitrogen can alleviate the adverse effects of waterlogging on shoot growth, but nitrogen alone could not improve shoot growth if the supply of other ions became limiting (Woodford et al., 1948; Garcia-Novo et al., 1973; Drew, 1991). In the work presented here, the influence of additional inorganic nitrogen on leaf senescence and protein remobilization was investigated in winter wheat {Triticum aestivum L., cv. Arina) grown on waterlogged soil.

Methods Winter wheat {Triticum aestivum L., cv. Arina) was grown in large polyethylene pots (0.36 m diameter, 0.38 m high) embedded in the field. The soil in intact pots was flooded permanently from anthesis to maturity, while in control pots with holes in the bottom the soil was well aerated throughout the maturation period (aerated controls). Nitrate (chloride for controls) was fed via a flap into the stem below the flag leaf node (10 ml solution per plant, containing 10 mM Ca(NOs)2 or 10 mM CaCl2). Feeding started at the same time as flooding. Each leaf lamina was homogenized in 10 ml 20 mM sodium-phosphate buffer pH 7.5 with a polytron mixer. The homogenate was filtrated through Miracloth (Calbiochem, San Diego) and was used directly for chlorophyll determination and after centrifugation for the quantification of soluble proteins and free amino acids in the supernatant (Stieger et al., 1994b and references therein).

Results The fresh weight of the flag leaf lamina was reduced in all flooded plants as compared to control plants on well aerated soil. This effect was less pronounced when the flooded plants were fed with additional nitrate via a stem flap below the flag leaf node. Flag leaf senescence - as judged by the net protein and chlorophyll degradation - was accelerated in wheat plants by flooding. The loss of chlorophyll and protein started later and proceeded more slowly in the flag leaf lamina of plants fed with additional nitrate, while chloride was totally ineffective. No major increase in the content of free amino acids in the flag leaf lamina was observed during the rapid senescence caused by waterlogging in absence of additional nitrate. This result indicates that the free amino acids, deriving from protein catabolism, were efficiently exported via the phloem. On the other hand, the level of free amino acids increased initially in the flag leaf lamina

Division 1 665

of plants fed with additional nitrate and decreased again two weeks after the treatment. The level of soluble protein was higher in the flag leaf lamina of plants fed with additional nitrate than in the other treatments (chloride feeding / no feeding) on flooded soil. This result indicates that the additional nitrate was at least partially assimilated and used for amino acid and protein synthesis. In summary, calcium nitrate fed via stem flap below the flag leaf node partially compensated in the flag leaf lamina the senescence promoting effect of waterlogging while calcium chloride was not effective. These findings indicate that inorganic nitrogen (nitrate) influenced in these plants the time course of senescence, while the accompaning cation (calcium) or another anion (chloride) caused no major effect.

Conclusions Nitrification is reduced and denitrification is stimulated in soils under hypoxia, causing higher ammonium (mainly sorbed to soil particles with cation exchange properties) and lower nitrate contents. In general, inorganic nitrogen is less available for crop plants grown on flooded soil and may cause anticipated senescence. Nitrate fed in a high concentration directly into the xylem below the flag leaf node delayed the rapid senescence in the flag leaf lamina after flooding. This result indicates that the flux of inorganic nitrogen to the leaf can serve as a signal in the system. However, the effect of waterlogging was only partially compensated by additional nitrate, indicating that other signals from the roots (e.g. phytohormones) are still effective (Neumann et al., 1990). Therefore inorganic nitrogen may be a relevant, but not the only regulating factor in this system.

References Cannell, R. Q. et al., 1980. Journal of Science of Food and Agriculture 31: 117-132. Drew, M. C, 1991. In " Plant life under oxygen deprivation" (Eds. Jackson, M. B. et al.),

Academic Publishing, The Hague, 303-316. Garcia-Novo, F. et al., 1973. New Phytologist 72: 1031-1039. Neumann, D. S. et al., 1990. Journal of Experimental Botany 41: 1325-1333. Noodén, L. D., 1988. In "Senescence and aging in plants" (Eds. Noodén, L. D. et al.), Academic

Press, San Diego, 1-50. Ponnamperuma, F. N., 1984. In "Flooding and plant growth" (Ed. Kozlowski, T. T.), Academic

Press, London, 9-45. Reggiani, R. et al., 1985. Journal of Experimental Botany 36: 1698-1704. Saglio, P. H. et al., 1980. Plant Physiology 66: 1053-1057. Stieger, P. A. et al., 1994a. Plant and Soil 160: 87-95. Stieger, P. A. et al., 1994b. Plant and Soil 166: 173-179. Trought, M. C. T. et al., 1980. Plant and Soil 56: 187-199. Watson, E. R. et al., 1976. Australien Journal of Experimental Agriculture and Animal

Husbandry 16: 114-122. Woodford, E. K. et al., 1948. Annuals of Botany 12: 335-370.


WATER DEFICIT AND POLLINATION POTENTIAL OF WHEAT (Triticum aestivum L.)

K. Streiff, A. Blouet, A. Guckert

Laboratoire Agronomie-Environnement / INRA Ecole Nationale Supérieure d'Agronomie et des Industries Alimentaires 2, avenue de la forêt de Haye, 54 500 Vandoeuvre lès Nancy, France

Introduction The recent use of CHA (Chemical Hybridizing Agent) has allowed the commercial production of hybrid wheat. But the success of hybrid seed production depends greatly on the aptitude of the pollinator variety to spread a lot of viable pollen grains. Many environmental factors affect the pollen quality and quantity (Stephenson et al., 1992). One of the major factor seems to be the water stress (Saini and Aspinall, 1981).

Methods After 6 weeks of vernalization, individual plants of winter wheat (var. Virlor) developed in a growth chamber with constant day/night temperature (respectively 16°C and 12 °C), 75 % relative humidity and 16 hours daylength (500 u.mol. m-2.s-l). Plants were grown in individual pots containing a mixture of peat, sand and perlite (50/30/20, v/v/v). Plants were subjected to a short water deficit by withholding the water supply during pollen meiosis. Pollen viability was investigated by microscopic examination of pollen stained with a solution of FDA (Heslop-Harrison and Heslop-Harrison, 1970). A coloration with DAPI was used to test the nuclear conformity of pollen grains (Coleman and Goff, 1985). To determinate anther length and number of pollen grains per anther, 10 anthers were analysed by the method suggested by De Vries (1974). To test the germinability of pollen grains, excised stigmas from emasculated flowers were transferred to petri dishes containing a medium of Brewbaker and Kwack (1963) and were pollinated. The percentage of germinated pollen grains was determinated after a staining with anilin blue (Kho and Baër, 1968). Data were subjected to statistical analysis using the procedure one way ANOVA of the SYSTAT package. Means were compared by the Tukey test .Values significantly different (p=0,01) are indicated by a different letter.

Results 0

•a

g -I

a

-3

»=«=

rewatenng

16 o- 2 4 6 8 10 12 14 Days from withholding water supply

Figure 1. Course of the 7th leaf water potential. Open symbols represent the control values. Each value is a mean of 5 repetitions. Vertical bars indicate the standard deviation.

Division 1 667

The water potential of the leaf decreased slowly and it reached - 2 MPa during the stage of pollen meiosis.

Table 1 . Effects of water stress on mean of 10 repetitions.

Treatment

Control Water stress

Plant height (cm)

47.4 a 36.5 b

the plant height and

Number of spikelets per spike

19,8 a 18,2 b

on pollen production

Anther length (mm) 3,18 a 2,66 b

. Each value is a

Number of pollen grains / anther

2580 a 1820 b

All the measured parameters were significantly affected by the water stress (Table 1). The height of the plant was reduced by 23 %. This is particularly unfavourable for the hybrid seed production because it has been showed that the pollen transport was better when the pollinator plants were higher than the male sterile one (De Vries, 1972). The number of pollen grains per anther decreased also by 29 % when the plants were stressed.

Table 2 . Effects of water stress on the Treatment Control

Water stress

Pollen viability (%) 81.8 a 62.9 b

pollen quality. Each value is a mean of 10 repetitions Pollen conformity (%)

91,3 a 71,2 b

Pollen germinability (%) 22,9 ±15 8,3 ±9,8

The pollen quality was also strongly affected by the water deficit (Table 2). The percentage of non viable and nuclear abnormal pollen grains increased by 20 % on stressed plants. These results agreed with those found by Saini and Aspinall (1981). The effects on pollen could be attributed to an increase in endogenous abscissic acid ( Morgan, 1980; Saini et al., 1984). Water stress reduced the pollen germinability non significantly by 63 %. Finally, the production of viable pollen per spike (i. e. the pollination potential) was reduced by 50 % on stressed plants.

Conclusions This study showed that even if the water deficit lasted only 7 days, the pollination potential was strongly affected. And, in the field, it has been showed that the limiting factor for the hybrid seed production was the quantity of viable pollen disseminated (Khan et al, 1973). So, in countries where water stress can occur during the sensitive stage of pollen meiosis, it would be necessary to irrigate in order to optimize the hybrid seed production.

References Brewbaker, J. L. and Kwack, B.H., 1963. Pollen physiology and germination-International

symposium. University of Nijmegen. Ed. H. F. Linskens, 143-151. Coleman, A. W. and Goff, L. J , 1985. Stain Technology 60 : 145-153. De Vries, Ph., 1972. Euphytica21 : 185-203. De Vries, Ph., 1974. Euphytica23 : 11-19. Heslop-Harrison, J. and Heslop-Harrison, Y., 1970. Stain Technology 35 : 225-227. Khan, M. N. et al., 1973. Crop Science 13 : 223-226. Kho, Y. O. and Baër, J., 1968. Euphytica 17 : 298-302. Morgan, J. M., 1980. Nature 285 : 655-657. Saini, H. S. and Aspinall, D. 1981. Annals of Botany 48 : 623-633. Saini, H. S. et al., 1984. Australian Journal of Plant Physiology 11 : 243-253. Stephenson, A. G. et al., 1992. Ecology and evolution of plant reproduction : a new approach.

Wyatt R. (Ed), Chapman and Hall, New York, 119-136.

Division 2

Agroclimatology and modelling.


ESTIMATING ZERO PLANE DISPLACEMENT AND ROUGHNESS PARAMETERS IN A SUNFLOWER CROP

V. Magliulo1, F. De Lorenzi1, L. Lustrini1, A. Pitacco2

1 CNR-Irrigation Institute, P.O. Box 101, -80040- S. Sebastiano al Vesuvio (Naples), Italy 2University ofPadova, Via Gradenigo,6 -35131- Padova, Italy

Introduction Roughness lenght (zj and zero flux plane displacement height (DJ are required parameters for both crop modeling and irrigation scheduling purposes (Smith et al., 1991). Wieringa (1992) recently reviewed roughness estimates for various crops and terrain types. Reported values for crops ranged between 0.05 and 0.18 (as a function of crop height), but no papers deal with sunflower, and few authors monitored the above parameters covering a full growth cycle. The present paper reports data for a sunflower crop starting from a height of 0.5 m until maturity

Methods A sunflower crop (cv Mimosa', maturity group I) was sown in Vitulazio (Caserta, Southern Italy) on June 13, 1995 at a density of 5.5 plants per square meter. Fertilization consisted of 200 kg Tons per hectare of urea and 500 kg per hectare of superphosphate, broadcast before sowing. The crop was cultivated following establishment. It was necessary to apply irrigation at regular intervals during the cycle of the crop. Volumetric soil water content throughout the experiment was assessed by means of a neutron probe. The field had a surface area of 2.5 ha and the rows were spaced 0.75 m apart and oriented north-south. The fetch in the prevailing wind direction (south-west) was about 120 m. A commercial apparatus (Bowen ratio system, Campbeil Sei. Ltd, Shepshed, UK) was used to monitor temperature and vapor pressure at two heights in the canopy boundary layer. To assess energy balance equation terms, measurements of net radiation were made at 1 m height above the canopy with a Fritschen-type net radiometer (Model 3032, Weathertronics, West Sacramento, California, USA), soil heat flux with two plates (HFT-1, Rebs, Seattle, Washington) and mean soil temperature in the soil layer above the plates with thermocouples. Wind profiles were established by monitoring wind speed at four heights, 0.2,0.4,0.8,1.6 m above the top of the canopy, by AM101 low treshold cup anemometers (Vector Instruments, Rhyl, United Kingdom). All measurements were performed by a 21X micrologger (Campbell Sei. Ltd, Shepshed, U.K.) at maximal intervals of 10 seconds and the averages stored every 30 minutes. Crop height (He) and LAI were monitored at regular intervals visually with a meter, and with an LAI-2000 Plant canopy analyzer (Li-COR, Lincoln, Nebraska, USA) respectively. Data were filtered by deleting records featuring limiting fetch and a wind speed at the top height lower than 1.5 m-sec'. Only profiles established in neutral conditions were considered, so that situations with a Richardson number > 10.01 J were also purged. The lowest height was discarded when falling outside the logarithmic sublayer, according to Raupach et al. criterion (1980). Surviving observations were processed in a worksheet, by the mean of two macros. The first one was aimed to produce graphs of the wind profiles to evidence anomalies. The second macro was used to calculate zero flux plane displacement (DJ and roughness lenght for momentum (zj with the graphical approach. The logarithm of the distances above the zero plane displacement level were regressed against wind speeds, for 6 different values of 5, spanning 0.7, and the values of the regression coefficients corresponding to the best fit (evaluated on the basis of the r2) were selected. The value of delta used was then taken as the estimate of D, and the intercept as the logarithm of z0. The procedure was then

Division 2 671

repeated, in a second step, for each group of the D parameters, this time with 6 values of <5,spanning the value previously found.

Results D and z0 parameters estimated between Day of Year (DOY) 199 and 258 are reported in the figure. A maximum crop height of 2.2 m and LAI of 4.59 were reached on DOY 235, declining thereafter D was a decreasing fraction of crop height throughout the expeiiment (from 0.8 He to about 0.73), but the correlation was poor (r=0.34). Z0 increased from about 0.04 to almost 0.12 He (r=0.56). No correlation for any of the 2 parameters was found with wind direction, so that the effect of row orientation was unimportant, since the crop was a fairly uniform surface already when LAI was 2.0 (Hc=0.9 m).

1.6

1.4 -|

1.2

1.0

E 0.8

0.6

0.4

0.2

0.0 0.4 0.6 0.8

DZO +D

1.0 1.2 1.4

crop height (m)

1.6 1.8 2.0

Figure: Calculated D and z0 parameters as a function of crop height.

Conclusions D and z0 parameters for a sunflower crop ranging in height between 0.5 and 1.85 m, resulted a decreasing and increasing fraction of crop height, respectively. The proposed relationships are the following: D[m] =-0.092+0.154 He 1 =0.43 z„[m] = -0.097+0.671 He 1 =0.79

References Smith, M. et al., 1991. Report of the expert consultation on procedures for revision of FAO guidelines

for prediction of crop water requirements. UN-FAO, Rome, Italy, 54p. Wieringa, J., 1992. Boundary Layer Meteorology, 63: 323-363. Raupach, M.R. et al., 1980. Boundary Layer Meteorology, 18: 373-397.

Division 3

Plant-soil relations.


RESULTS FROM AN INVESTIGATION ON THE HEAT FLUX DENSITY IN SOIL ON THE BASE OF THERMOELECTRIC AND CONDUCTOMETRIC TRANSDUCERS

S. Alexieva Institute of Soil Science and Agroecology, 7, Sh.Bankja Str., PB 1080, Sofia Bulgaria

Introduction The heat flux density q in the root zone soil layer generalizes the kinematics of the liquid soil phase which includes not only moisture but also easy soluble compounds presenting mineral salts. The isothermity of the soil profile and the intensity of thermomoisture exchange give a reason the moisture migration and the salts dissolved in it to be followed. On the other hand this makes it possible to reach a decision upon preserving the water balance through an alternation of a well cultivated upper layer and a more dense lower one [Globus, 1983].

Methods The temperature gradient (grad T) in the root zone is measured by cylindrical drill with thermoelectric battery, whose heat terminals are at a depth 50 cm. The generated thermoelectric tension from the battery E is gauged by nanometer type "Keitly" model 197 - sensitivity 10 nv. The temperature difference A T is calculated from this read values of E (E = k. A T). By means of conductometrical transducers placed at given sections in the soil profile the electrical resistance Re of each section is measured. On the base of the electrothermal analogy the heat resistance Rt and the measured Re are comparable according to the expressions: R=AT/P (1) and P = Re.I2 (2), where: / - the direct current of the ohmmeter for the respective band; P - electrical power. After differentiation of ( 1 ) and (2) could be determined AP/AT= \IRt = AAS, /Al,, (3) where: A is the heat conductivity of the soil type, and 5, and /( - heat surface and heat line of the investigated section. Replacing the expression for A from (3) it results in the following dependency for the heat flux density in Fourier principle q = -(A/Rt)gradT, (4) where A - coefficient and is defined by the size of the investigated section. In the summer of 1995 the following measures on a soil type leached chernozem of a maize crops under conditions of no watering were made:

- for A T with thermobattery of 25 thermocouple (chromel - alumel) whose heat terminals are at / = 50 cm and the cold ones, through a thick - walled pipe, are under conditions of a surface temperature; the values for grad T are calculated by the measured E of the thermobattery with a nanometer;

- by the conductometrical transducer and a ohmmeter Re and the current are substituted in the expressions (1), (2) and (3) is calculated and q from (4).

Results The heat flux density (thermodiffusion) calculated with formula (4) generalizes the migration of the liquid soil phase in which grad T plays extremely important part, especially the values over 0.2"C.cm '. Under higher values of grad T the thermodiffusion reaches layers under 50 cm (Figure 1 - curve lines 1, 2). The level of the stationary soil profile, however, depends on the influence of the moisture gradient (Figure 1 - curve line 3).

Division 3 675

The lower values of grad T define the ceasing of the thermodiffusion till / = 20 cm (Figure 1 - curve lines 4, 5).

Table 1. The measured values by the thermoelectrical and the conductometrical transdusere

Date E[mV]

Re[kQ] I = 10 cm

Re[kQ]

I = 30 cm

Re[kQ] I = 50 cm

22.06.95 0.536

1.19

4.7

186

30.06.95 6.07.95 0.398 0.613

1.5 1.1

14.3 21

136 50

10.0795 0.035

1.55

50

136

23.08.95 0.134

11.1

72

392

Calculated values

grad T ["C/cm]

0.27 0.2 0.31 0.02 0.07

q I = 10 cm I — 10 cm I = 10 cm I =10 cm I =10 cm [W/cm] 1-76 2.4 1.76 2.48 0.71

IQ'3 I = 30 cm I = 30 cm I = 30 cm I = 30 cm I = 30 cm

0.3 0.92 0.02 0.03 0.05 I = 50 cm I = 50 cm I = 50 cm I = 50 cm I = 50 cm

0.12 0.9 0.03 0.09 0.03

4[W/cm2].10"3 gradT[ C/cm]

Figure 1. The dynamical of q in the different layers depending on grad T

50 / [cm]

References Globus A. M., 1983. Physics of non-isothermal soil moisture transfer.Monograph: Hydrometeoizdat, Leningrad, 260 p.


RELATIONS BETWEEN STABILITY OF TUNDRA SOILS AFFECTED BY MECHANICAL IMPACTS AND PLANT COMMUNITY COMPOSITION

N.P. Buchkina, TS. Zvereva

Agrophysical Research Institute, 14 Grazhdansky prospect, St.Petersburg 195220 Russia

Introduction Agricultural lands in the typic tundra of the Yamal Peninsula are pastures for the reindeers. Decreasing the areas of pastures as related to a rapid development of the gas- and oilfields causes higher mechanical impacts on the remaining agricultural territories. The study reported here was conducted to ascertain a mechanical stability of the cryogenic peaty soils and cryozems with different composition of plant communities.

Methods The mechanical stability was considered as an ability of soils to resist both normal and shear stresses induced by the tracked vehicles. The shear and normal stress resistances of soils with different plant communities were determined using a Amarjan's vane device (Amarjan, 1990) and a Reyjakin's penetrometer (Bahtin, 1969). The morphological properties, moisture content, bulk density, and texture of the soils studied were measured by conventional methods (Vadjunina et al., 1986). The coefficients of resistance were calculated on the basis of data on strength properties (shear and normal stress resistances), depth of the seasonally-thawed layers and organogenic horizons, locations of biogeocenosis on a relief. A range of variations in the parameters studied (except a location on a relief) was established using a 10-estimates scale. The visual investigations were used to evaluate the location of biogeocenosis on a relief. The dimensionless coefficients of resistance (P) were calculated using the following formula:

PeXlOO P = — ,

where Pe - a sum of estimates for the parameters of biogeocenosis;

Results In the soils of typic tundra of the Yamal Peninsula, the normal stress resistances ranged from 0.5±0.1 to4.5±1.3 MPa. These values were defined only by soil properties (moisture content, bulk density, and texture), if these soils had a very poor plant cover. In this case, the loamy cryozems and cryogenic peaty soils showed the greatest and lowest normal stress resistances ranging from 2.6±0.5 to 3.5±0.6 MPa and from 0.9±0.2 to 1.7±0.3 Mpa, respectively. The thixotropic horizons of mineral soils had a lower normal stress resistance (by 20-40%) compared to the unthixotropic horizons. A presence of rhizome plants (Carex sp., Eriophorum sp.) in the plant communities led to increasing the normal stress resistances by 12-15% and 22-30% in the upper horizons of loamy and sandy cryozems, respectively. In the profiles of cryogenic peaty soils, the root horizons had essentially greater normal stress resistance than those without roots. Similar relationships were observed for the soil shear resistance which also was defined by physical properties of soils with a poor plant cover. In this case, the cryogenic peaty soils showed the lowest ability to resist shear stresses. The shear stress resistance of this soil ranged from 1.7±0.1 to 2.5±0.5 kPa at the high and low values of moisture content. The high values of shear

Division 3 577

stress resistance of 3.0±0.2 kPa were determined in the dried loamy cryozems. The highest values of shear resistance in the cryogenic peaty soils (3.2±1.2 kPa) and waterlogged loamy cryozems (3.1±0.8 kPa) were induced by the rhizome plants in the phnt community composition studied. These soils indicated the same ability to resist the shear stresses as compared to the dried loamy cryozems.

Conclusions The coefficients of resistance can range from 5 to 100. In the soils of typic tundra of the Yamal Peninsula, these coefficients were equal to 31-69. Based on the values of coefficients of resistance, the tundra soils studied were divided into five groups. The cryogenic peaty soils of the sedge bogs with thick rhizome horizons had the highest resistance to mechanical impacts (P = 62-69), while the cryogenic peaty soils of the sedge-moss bogs and the dried clay loam cryozems were included into the second group (P = 54-61). The loamy sand and loamy cryozems with rhizome plants, the cryogenic soils without root horizons and the peaty cryozems were grouped into the third group (P = 46-53). The fourth group included the cryozems formed on slope and flat sites with shallow organogenic horizons (P = 38-45). The lowest resistance was observed in the waterlogged cryogenic peaty soils without rhizome plants (P = 31-37).

References Amarjan, L.S., 1990. Properties of unconsolidated grounds and methods of their studies,

Moscow, 254 p. (in Russian). Bahtin, PU., 1969. Studies on mechanical and engineering properties of main types of soils in

USSR, Moscow, 271 p. (in Russian). Vadjunina, A.F. et al., 1986. Methods of investigations of soils physical properties, Moscow,

416 p. (in Russian).


FACTORS DETERMINING THE VALUES OF FORCES NEEDED FOR PULLING OUT SUGAR BEET ROOTS FROM THE SOIL

M. Bzowska-Bakalarz

Institute of Agricultural Mechanization, University of Agriculture, 20-612 Lublin, Gieboka Street 28, Poland

Introduction From the viewpoint of cultivation, harvest and transport processes of sugar beets, the main physical traits of roots are geometrical dimensions, height of root protruding over the soil surface and force for pulling the inexcavated roots out of the soil (Byszewski et al, 1978). The limit values of these forces are the basic parameters for working out the constructional needs of agricultural machines. The influence of meteorological and soil conditions on geometrical dimensions of roots and on their growth over the soil surface is known. Neverthless, no researches into the direct influence of those conditions on the pulling out force value have been made yet. (Bzowska -Bakalarz et al, 1987).

Methods The value of forces for pulling out sugar beets Fw was estimated for three varieties cultivated at two nitrogen fertilization levels. The plants were cultivated on the same type of soil (loess) with the same agrotechnical measures. In years 1981-1983 the correlation between the pulling out force value and the root shapes and dimensions was examined. In 1984 and 1985 the pulling out force values were measured for only two varieties (Table l).The experiment was carried out in 50 replication. An instrument equipped with 1st class of precision dynamometer, earlier described by the author (Bzowska - Bakalarz et al, 1987) was used in the experiment. Soil moisture and soil strength were measured in all experimental plots (Fig. 1). The description of meteorological conditions was based on the data from the local meteorological station' and thus the Sielianinov coefficient(SC) for the thirty-days period before harvest was evaluated (Molga, 1972).

Soil strenght [MPa]

3 4 5 6 7 10 11

^ \

• 1981 • > > ^ ^ ^ • SC- 1.51 •"*.. \ • M - 9.98% •»>

\

~ ^ s 1985 " " - » ^ SC- 1.24

L M - 15.69%

\K ^ "--.._

1983 SC-0 .12 M - 2.69%

" ~ ^ - ^ ^ ^ ^ 1984 "• SC-2 .55 M - 14.7%

-V.

1982 SC-0.61 M - 5.15%

\ \ \

"K _—-.

0

50

I 100

£ 150

Q200

250

300 Fig.1. The curves of changes of soil strength; SC-Sielianinov coefficient, M-soil moisture

Results In the Table 1 average values of measured forces for particular combinations are presented. The average values of these forces amounted from 272.5 N to 794.3 N, and they were very differentiated, which was due to high variation coefficients (w) and standard deviations (Se). As the author's research implies, the values of the forces for pulling out the roots are correlated with maximum root diameter (D) [correlation coefficient 0.3855] and length (L) [correlation coefficient 0.4568]. Significantly less force was needed (by 11.5%) for pulling out the roots of multi-seed AJ3 variety with shorter roots than for pulling out the roots of mono-seed varieties.

Division 3 679

The variety differences in force values for pulling out the roots are related to the variety differences in root dimensions (length and diameter of the root) but, first of all, they are correlated with the soil moisture and strength. A significant, but not consistent, effect of nitrogen fertilization dose both on the root dimensions and on the force values Fwwas noted.

Table. 1. The values of the forces Fw [N] needed to pull out sugar beet from the soil

Study object

Variety:

Fertilization N

In 1981 r.:

In 1982 r.:

In 1983 r.:

Years:

Variety:

Years:

AJ3 PN Mono 1 PS Mono 4

[kg/ha]: 160 280

160 280

160 280

160 280

1981 1982 1983

PN Mono 1 PS Mono 4

1984 1985

Average^ [N]

489,63 552,21] 537.94J

527,81 526,05

289,16 327,94

652,00 515,00

642,25 734,53

308,55 583,83 688,39

375,46 399,00

483,54 350,91

.55,94

.38,78

• 137,00

.92,28

.275,28 .339,84

.104,56

•23,54

•72,63

LSD[N]

44,21

-

28,81

67,22

53,53

44,21

21,89

21,89

Estimation of error

Se = 231,37 N w = 43,91%

Se = 136,92 N w = 35,3%

« -Significant difference; LSD - the Least Significant Difference

For instance, in 1982, the roots of plants cultivated at higher fertilization doses (280 kg/ha) were shorter and the forces for pulling out the roots were lower. So, fertilization level influenced the root dimensions (length and diameter) and had an effect on the values of forces for pulling out the inexcavated roots. The ranking of the years according to soil strength (high strength at the depth corresponding to the root length) as well as the forces for pulling the inexcavated roots out of the soil is given in Table 2.

Table 2. The forces for pulling the inexcavated roots out of the soil Year

1983 the highest soil strength 1982 1984 1985

1981 the lowest soil strength

Force for pulling out the roots 688.39 N 583.89 N 423.54 N 350.91 N 308.55 N

Conclusions As a result of the studies it can be stated that the most significant factor affecting the values of the pulling out forces are soil properties (strength and moisture). The variety and the nitrogen fertilization level are secondary factors that determine only indirectly the values of these forces by variability of root dimensions (length and diameter).

References Byszewski, W. et al., 1978. Zesz. Probl. Post. Nauk Rol. 203: 391-397 Bzowska-Bakalarz, M. et al., 1987. Zesz. Probl. Post. Nauk Rol. 316: 9-24 Molga, M, 1972. Meteorologia rolnicza, PWRiL, Warszawa, 200p.


EFFECT OF SOIL COMPACTION ON NODULE STRUCTURE IN SOYBEAN

H.V. Halmajan, L. Ungurean, A. Dobrescu, V. Stefan, I. Savulescu

Bucharest University of Agronomical Sciences and Veterinary Medicine, Bd. Marasti nr. 59, 71331 Bucharest, Romania

Introduction Research reports (Tricot et al., 1990, Tu and Butter, 1988) have shown opposite effects of soil compaction on nodule growth and nitrogen fixation in soybean (Glycine max) and pea (Pisum sativum). In our previous experiment soil compaction enhanced nodulation and did not affect the pod yield (Halmajan et al., 1995). The objective of this work was to observe the effect of soil compaction on nodule structure in long and short day-length growing conditions and the influence of carbon addition on nodulation in compacted soil.

Methods Soybean plants were grown in glasshouse conditions in 1995, with two levels of soil strength: no compaction ( 1.1 g cm"3) and strongly compacted ( 1.6 g cm"3). The seeds were sown in two different periods (on the 25 April for spring planting and on the 20 August for summer planting). The plants were harvested in mid pod filling stage (early July and respectively early October). The seeds were inoculated with Bradyrhizobium japonicum USDA 110. Two weeks before seeding in spring planting case, 1.5 g C as sucrose per kilo of soil were added to the soil. The structure of nodules was observed using an optic microscope (M.C. 7). Paraffin sections were obtained using Heidenhein's method (Sass, 1966).

Results Results are presented in the Table. Total nodule number as well as nodules dry weight tended to be enhanced by soil compaction for both sowing periods. Soybean nodulation was much higher in spring planting. Plant metabolism was also influenced by planting dates, physiological measurements registering higher values for spring planting. The larger values of nodule dry weight in compacted soil are sustained by ion content and respiration. Photosynthesis and transpiration had different trends according to the planting period. The shape and the structure of nodules were observed. The nodules had a round shape. Nodule diameter was bigger in non compacted soil in spring planting and in compacted soil in summer planting. Large differences were observed in the anatomic structure, where two trends were noticed. The first one is that the soil treatment strongly influenced the development of the parenchyma and the periderm cells as well as the cell walls diameter of the endodermis and of the infected cells containing bacteroids. Due to the soil pressure in compacted soil, the parenchyma and the periderm tissues, which have protective functions, are much more developed. Also the sclereids from endodermis are longer in control, but cell walls are thicker in compacted soil. The infected cells containing bacteroids are larger in the nodules from the compacted soil, the biggest difference being noted for the diameter of the nuclei. The second trend is that nodule size was correlated with the dimensions of the cells involved in oxygen regulation ("subcortex" and interstitial cells). Interstitial cells divide the nodule in several parts, being important oxygen regulators. They are longer in bigger nodules. "Subcortex" cells (Day et al., 1991), which are also involved in oxygen regulation, acting as a physical barrier, are smaller in larger nodules.

Division 3 681

Soil compaction and planting date influence on plant development and nodule structure in soybean

The variable

Extract conductivity (us g'1) Respiration (mg C02 kg"1 h'1) Photosynthesis (ml O2 dm"2 h"1) Transpiration (mg dm'2 h"1)

Nodule number per plant

Nodule dry weight per plant (g)

Nodule diameter (mm)

Parenchyma + periderm cells (urn)

Endodermal cells (sclereids) length (urn) width (urn) cell wall diameter (urn)

Subcortex cells (urn)

Cells containing bacteroids length (urn) width (urn) nucleus diameter (urn)

Length of interstitial cells (urn)

Control

1200 b 450 b 627 a 259 c

72 c

0.28 c

3.8 a

28 b

83 a 60 a 4b

127 b

36 b 36 a 5.7 b

28 a

Spring planting

Compact

1500 a 544 a 229 c 268 b

102 b

0.41b

3.1b

60 a

65 b 56 a 10 a

150 a

46 ab 34 a 7b

24 a

Compact + Carbon

1470 a 557 a 319b 333 a

148 a

0.58 a

2.4 c

54 a

50 c 40 b 9a

150 a

60 a 38 a

11.8a

24 a

Summer

Control

850 n 527 n 265 n 447 m

16n

0.09 n

1.1 n

80 n

52 m 48 m 3n

61m

32 m 26 m 8n

12 n

planting

Compact

950 m 630 m 313m 280 n

27 m

0.17m

1.7m

120 m

37 n 28 n 5 m

47 n

36 m 34 m 12 m

18 m

Means in the same row followed by the same letter are not significantly different at P < 0.05.

Conclusions Irrespective of the planting date, soil treatment (compacted and non compacted) induced different nodule formation and development (number, dry weight and structure) on the soybean taproot system. Carbon addition increased very much nodule number and nodule dry weight, but the structure of the nodules was less affected.

References Day, D.A. et al., 1991. Plant Physiology and Biochemistry 29: 185-201. Halmajan, H.V. et al., 1995. Proceedings of The Second European Conference on Grain Legumes, Copenhagen, 68-69.

Sass, JE., 1966. Botanical Microtechnology. Iowa University Press, 218 p. Tricot, F. et al., 1990. Proceedings of The First ESA Congress, Paris, 51-53. Tu, J.C. et al., 1988. Horticultural Science 23: 722-724.


EVALUATION OF POTASSIUM STATUS OF SOILS

J. Matula

Research Institute of Crop Production, 16106 Prague 6, Czech Republic

Introduction The intensive and unbalanced application of fertilisers during the last few decades in the Czech Republic, has resulted in both an excess and a large range of potassium levels in soils, causing an imbalance of other nutrients, especially a deficiency of magnesium. Recently, however, the consumption of industrial fertiliser has decreased dramatically. The restoration of appropriate levels of potassium in soils is the keystone to balanced soil fertility, which is needed for maintaining both profitability and high dietary quality of crops, as well as respect for the environment.

Methods Two approaches were used to evaluate the potassium reserve of soils: (a) a correlation study between ordinary soil potassium tests and concentration of potassium in soil solution, and (b) a growth chamber study of the bioavailability of potassium. The first research was conducted with a set of 349 soil samples, taken from plough depth of different sites in the Czech Republic. The soils were analysed by the method Mehlich 2 ( (Mehlich, 1978) and the KVK-UF method (Matula, Pirkel, 1988); the soil solution being separated from water saturated soil paste using centrifugation. For the growth chamber study, spring barley (cv Akcent) was grown in 600g of soil per pot (from a range of 20 soils of markedly different agronomic qualities) over four weeks, using 3 replicates of each soil. The growth regime was 16h/20°C days at an effective photosynthetic radiation of 500 umol m"V and 8 h/15°C nights, with fertiliser (as a solution of NH4NO3) added in 6 doses to provide 150 mg of N per pot during cultivation. The shoots were harvested after 28 days, immediately dried at 65°C (to constant weight) and analysed for nutrient content by routine procedures. To evaluate the appropriate level of potassium in soil, the index efficiency (IE) of potassium was used (Matula, 1985), calculated by the formula: IE = dry matter yield of shoots / % K in shoots. Data were statistically analysed using regression analysis software (Statgraphics, version 7, Manugistics, inc, USA).

Results The possibility to predict potassium concentration in a soil solution (from more easily measured soil testing parameters) is shown in the Table below.

Table. Correlation between K concentration in soil solution and parameters of two soil tests

Soil testing parameters

(n = 349) Mehlich 2 [mgK/kg] Ratio K/VCa+Mg (Mehlich 2) KVK-UF [mgK/kg] Ratio K/VCa+Mg (KVK-UF) % ekv. K saturation CEC (KVK-UF)

Correlation coefficients Models

Linear 0,5250 0,5757 0,5778 0,6192 0,7511

Multiplicative 0,5413 0,5911 0,5911 0,6208 0,7676

The closest relationship suitable to predict the concentration of potassium in the soil solution from current data of soil testing methods, was found after transformation of the values of exchangeable

Division 3 683

potassium (determined by method KVK-UF) into its equivalent saturation of cation exchange capacity, followed by the ratio K/VCa+Mg. The best correlation between soil potassium and potassium content in plants was found in the case of exchangeable potassium in soil. Any other adjustments of exchangeable potassium by other characteristics of soil (i.e. K concentration in soil solution, K- reserve determined by method of boiling nitric acid extraction, KT fixation capacity), did not improve the correlation of relationships.

x a> •o c

ID

o a.

110

100

90

80

70 -

60

50

40

30 -

20

9865

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900

Exchangeable potassium in soils determined by KVK-UF

Figure. The use of the concept of potassium efficiency index, to define the suitable level of potassium in soil.

The scatter diagram suggested that these sets of soils can be classified into three groups (A, B, C) due to their different desorption characteristics and buffering power. From the shape of the curves the effective levels of potassium were estimated: 70, 140 and 220 mgK.kg"1 respectively, for soil groups A, B, C.

Conclusions The possibility of predicting the potassium concentration of soil solutions from more easily measured parameters of routine soil testing, can contribute to optimise the potassium status of soils together with parameters of water regime of the exact plot. The short-term plant soil trials in a growth chamber enabled to distinguish of soils of different potassium availability when the concept of potassium efficiency index was employed.

The research was supported by GA CR through the project 503/94/0021

References Matula, J. - Pirkl, J. 1988. AO c. 272804, Praha, Üfad pro vynâlezy a objevy Matula, J. 1989. Rostlinnâ Vyroba, 35 (12) : 1283-1292 Mehlich, A. 1978. Communications in Soil Science and Plant Analysis, 9, 6 : 477-492


EARTHWORMS PRESENCE AS AFFECTED BY TILLAGE SYSTEM IN CLAY SOIL

M. Mazzoncini, E. Bonari, M. Ginanni, S. Menini, F. Sancarlo

Dipartimento di Agronomia e Gestione dell'Agro-Ecosistema, University of Pisa, via S. Michèle degli Scalzi 2, 56124 Pisa, Italy.

Introduction Fragmentation of organic matter, channelling and mixing of soil components are key roles by which earthworms increase microbial decomposition activity, soil macroporosity, movement of air and water in the soil matrix and aggregate stability. Earthworms presence is very important in sustainable agricultural systems based upon nutrient cycling stimulation and conservation tillage techniques. In this cases, earthworms may alleviate compaction of untilled soil by burrowing and may facilitate residue incorporation into the soil. Many researchers (House et al., 1985; Mackay et al., 1985) found that the adoption of conservation tillage techniques (reduced and no - tillage) increase earthworms and arthropods presence.

Methods A field experiment was carried out from December 1994 to November 1995 to monitor earthworms presence on a clay soil (Tipic Xerothent) of a hilly site representative of Central Italy where shallow ploughing (25-30 cm -CT), disk harrowing (10-15 cm - RT) and no tillage (NT) were compared in a long term experiment. The experimental design was a randomized complete block. Since 1991 durum wheat (Triticum durum L.) was cultivated as monoculture. Durum wheat was sown 14.10.1994; herbicides were sprayed 2.12.1994 (chlortorulon) and 22.3.1995 (dichlofop - methyl). After wheat harvest, CT and RT were performed on 1.8.1995 and 19.10.1995 respectively. Earthworms presence was monitored on five dates: 15.12.1994, 16.03.1995, 22.05.1995, 22.09.1995 and 26.10.1995. At each date twelve soil cubic samples were extracted from each tillage system by means of a spade after having dug a trench to isolate the soil block to sample; samples were cubes of standardized volume (30 x 30 x 30 cm). Soil samples were placed on a black plastic sheet to improve the visual detection of earthworms and than crumbledby hand. After extraction earthworms were plunged and conserved in a hydro-alcoholic solution (90%). After three days of conservation, earthworms were counted, weighed and classified by means of a binocular microscope.

Analysis of variance

Treatments Tillage system Sampling date Interaction

Total earthworms

m"2 biomass

n.s. **

O. complanatus

m"2

**

n.s.

n.s.

A. rosea

nv2

n.s. **

n.s. **significantatPs0.05

Results Both total number and total biomass of earthworms were affected by tillage systems and sampling date, as shown in the Table. On an average, earthworms number found in NT plots was 5 and 2.6 fold greater than that of CT and RT respectively (Figure 1). No significant differences were observed between CT and RT. Variations in earthworms population density among sampling periods seem to be related to seasonal climatic changes. Earthworms biomass was influenced by tillage systems only in December and March while no significant differences were found in May, September and October probably due to the preponderant presence of juvenile

Division 3 685

Eec Mr. My Spt. Oct. Man

Figure 1. Total earthworm density recorded at each sampling date in the three tillage systems. CT=conventional tillage, RT= reduced tillage, NT= no-tillage. Bars labelled with the same letter are not significantly different at P<0.05 (DMR test).

individuals, whose weight is limited. When the effect of tillage system was significant, earthworms biomass was greater under NT than under CT and RT (Figure 2). The two dominant species recorded in all tillage systems during the whole sampling period were Allolobophora rosea (Savigny, 1826) and Octodrilus complanatus (Dugès, 1828). Tillage systems influenced the behaviour of these two species differently. In fact, while O. complanatus density was greater with NT (22.8 individuals m"2 on average) than with RT and CT (8.0 and 1.9 respectively), A. rosea presence was affected only

by sampling date.

Conclusions Soil matrix modifications related

to CT and RT reduce earthworms abundance with respect to NT. The response of earthworms species to tillage systems vary in relation to their customs. Species such as O. complanatus, which live in mineral soil but feed on soil surface residues (anecic species)

„. „ „ ^ . j . , , . . . . i seem to be more sensitive to any Figure 2. Total earthworm fresh biomass recorded at each .. ,. , i... it ° ,. , , . „ . ,.„ , soil disruption due to tillage than sampling date in the three tillage systems. , . . . . „~ v & .. , t.,, n T , j , ..,, x™ endogeic species such as A. rosea CT=conventional tillage, RT= reduced tillage, NT= no- ( c * g t J j 9 Ç 2 . w ^ ^ tillage. Values labelled with the same letter are not „„„ „ , V ' / _ '' • -c *i A-tv L *n n n c / i c n . +\ 1992). The burrows of O.

significantly different at P<0.05 (LSD test). , , . .. ^ r

° J v complanatus, larger than those of A. rosea and more vertically oriented, may facilitate water infiltration and reduce soil erosion. As a consequence, O. complanatus presence may be useful for NT system in hilly clay soils characterized by low hydraulic conductivity.

May Sept.

References Curry J. P. et al., 1992. Soil Biology and Biochemistry 24: 1409-1412. House, G.J. et al., 1985. Soil and Tillage Research 5: 351 - 360. Mackay A.D et al, 1985. Soil Biology and Biochemistry 17: 851 - 857. Wyss E. et al, 1992. Soil Biology and Biochemistry 24: 1635-1639.


EFFECT OF TOXIC METALS ON THE GERMINATING ABILITY OF WINTER WHEAT

L. Szabó

Agricultural University, Faculty of Agronomy, Department of Crop Production, Gyöngyös Hungary

Introduction Nowadays, as environmental pollution is becoming a huge problem, more and more attention is paid to the potentially toxic matters, and, among these, a particular attention should be paid to the dangers associated with heavy metals. Soils with high heavy metal contamination indicate a fundamental environmental problem since many elements, remaining in the topsoil, have a potentially polluting effect (Szabó and Kâdâr 1994a, Szabó and Kâdâr 1994b, Szabó 1995a, Szabó 1996a). Soil contamination makes it impossible to grow food crops in the area in question. Another problem can be that the toxic element accumulates in the seed as a consequence of the heavy metal load on the sou, which is detrimental to the germinating ability of the seed. The objective of our experiment was to find out how the germinating ability of winter wheat seeds changed if they were grown on soils treated with heavy metals.

Methods The experiment was set on brown forest soil prone to acidification (pH 6.5) in the autumn of 1994. Number of treatments was 24 (8 elements times 3 doses). With 3 series, number of all plots was 72. The elements applied were AL As, Cd, Cr, Cu, Hg, Pb and Zn. The doses of application were 0/30, 90, 270 kg/ha as per element. Winter wheat "Mv 25" was used as an indicator crop. Seeds were grown on contaminated plots, harvested and tested for germination. Germination test was carried out according to the Hungarian Standard MSZ 6354-3: 1992. 4x100 wheat seeds/plot were placed out for germination in an environment of crepe filter paper soaked with distilled water at 20°C temperature.

Results During the experiment the seeds evaluated were divided into four separate classes as defined below: - healthy seeds with normal germination,

- swollen seeds with no germination, - rotten seeds, - infertile seeds.

On the untreated control plots, germinating ability (rate) of the wheat seeds was as high as 97.3 %. When treated with Cd, Pb, Hg, As or Al, germinating ability proved somewhat poorer as compared to the control plots, varying between 95 and 96 % with minimal differences between doses. Among the 8 elements, only Cu, Cr and Zn produced a harmful effect on germinating ability (see Table). It is clear from the Table that Zn proved to be most harmful for the germinating ability of wheat seeds as described by the mean of 91.8 % of the 3 treatments. It is clear, too, that germinating ability decreases parallelly with increasing doses of Zn. As compared to the control of 97.3 %, germination rate was 94 % and 90.5 % by treatments with 30 kg/ha and 270 kg/ha, respectively. With Cu, the germination rate fell also from 95.6 % to 91 % with increase of the dosis of treatment. With Cr, germination percentages were 96 % (30 kg/ha) and 92.5 % (270 kg/ha).

Division 3 687

Ratio of rotten seeds proved 6-7.5 % at 270 kg/ha level of treatment, which is 3-4 times as high as in the control. This fact gives evidence of the germ killing effect of the 3 metal salts.

Table. Effect of soil treatment with different doses of different heavy metals on the germinating ablihty of winter wheat seeds

Element

Cu Cr Zn

Control

30 healthy

95,6 96 94

Doses of heavy metals 90

seeds with normal germination, % 92,5 94 91

270

91 92,5 90,5

Mean

93 94,2 91,8 97,3

swollen seeds with no germination, % Cu Cr Zn

Control

0,2 -

0,2

---

-5 -

0,1 1,7 0,1 -

rotten seeds, % Cu Cr Zn

Control

2,5 2,8 5

6 4

6,6

6 6

7,5

5 4,3 6,4 2,5

infertile seeds, % Cu Cr Zn

Control

1,7 1,2 0,8

1,5 2

2,4

3 1,5 2

2,1 1,6 1,7 0,2

Conclusions Getting into the soil, heavy metals may become detrimental (harmful) to the organisms living in the soil, and, as such, to the germinating plant. Our investigation underlines that the application of different doses of different heavy metals has an impact on the germinating ability of the wheat seed grown there. By treatments with Cu, Cr or Zn, germination rate of the seeds became reduced by 3-5 %. More elevated doses resulted in more reduced germination rates. Germ killing effect of the 3 metal salts is evident. Cd, Pb, Hg, As and Al treatments gave very similar results to the control, and also, effect of the different doses proved to be almost equal.

References Sâri, P., 1996. Nehézfémekkel végzett kisérletek eredményei barna erdötalajon. Tudomânyos

Diakköri Dolgozat, GATE Mezögazdasagi Föiskolai Kar, Gyöngyös, 53. p. Szabó, L. and Kâdâr, I., 1994a. Nehézfémek a talajban, növényben. Agrarökonómiai

Tudomânyos Napok, GATE Mezögazdasagi Föiskolai Kar, Gyöngyös, 2. kötet, 419-422. p. Szabó, L. and Kâdér, I., 1994b. Effect of heavy metal loand on soil and erop. XXXVI.

Georgikon Napok, PATE Keszthely, 146-153. p. Szabó, L., 1995a. Nehézfémek viselkedése a talaj-növény rendszerben, Müszaki Kémiai Napok,

MTA VEAB Veszprém, 64-66. p. Szabó, L., 1995b. Talajok mikroelem ellâtottsâgânak kömyezeti összefüggései, GATE

Fleischmann Rudolf Mezögazdasagi Kutató Intézet, Kompolt, 56-61. p.


TRACE ELEMENT SUPPLY OF THE ARABLE LAND IN HUNGARY

L. Szabó

Agricultural University, Faculty of Agronomy, Gyöngyös, Hungary

Introduction The purpose of the study was to obtain a general picture of micronutrient status, to locate problem areas with deficiency and excess, and to give guidelines for solving the problems in practice. The project was started at the end of 1974 in cooperation with FAO and was financed by the government of Finland. Altogether 30 countries took part in the project by collecting and sending soil and plant samples for analysis to the laboratory of the Institute of Soil Sience, Finland.

Methods Wheat and maize were used as indicator crops. Wheat samples were taken at mid-tillering stage, maize samples at the 4-6 leaf-stage with parallel sampling of the soil from plowlayer. The soil available trace elements were determined generally by using extradants AAAc + EDTA (Lakanen and Erviö, 1971). The plant total element content was determined as follows:

B - azomethin-H method Ca, K, Mg, P, Cu, Fe, Mn, Mo, Zn, Co - dry ashing + HCl solved Cd, Pb - wet ashing with cc HNO3 Se - dry ashing with Mg(NÛ3)2 as described by Siemer/Hagemann

The 250 sampling sites, including 144 wheat-soil and 106 maize-soil sites in Hungary were well distributed across the country and soil properties therefore varied widely. About half of the soils sampled were classified as Phaeozems (n=125). Main soiltypes commonly found were chernozems (n=46), Luvisols (n=25), Vertisols (n=15), Cambisols (n=10) and others (n=29). The texture, pH, CEC, EC and CaCC"3 equivalent showed on average values as those of the international material (n=3783) and the ranges of variation were almost as wide as those internationally. Organic matter content in Hungarian soils is relatively high and more uniform.

Results The Hungarian soils and crops contained high N, Ca and P values and were among the three highest national mean values recorded in this study. The exchangeable K contents of most Hungarian soils were well below the international mean. The average level of K fertilization in Hungary was exceeded only by that of Belgium. This is likely to explain the unagreement between the K content of soils and plants as well as the wide variation of K % in plants. Exchangeable Mg contents of soils and crops were very close to the international average but high Mg contents are typical of Hungarian maize. According to these data a response to Mg fertilization seems unlikely (acid sandy soils have low Mg status, but with no maize production).

Boron. The B status of the soils and corresponding plants were in general at a satisfactory level. Copper. The plant/soil Cu contents corresponded closely to the respective international values. Iron. In general, the Fe status of Hungarian soils and plants seems to be quite normal. Manganese. The soil/plant Mn values vary widely because of the varying pH of the soils. Molybdenum. The soil/plant Mo values vary widely parallel with the varying pH of the soils. Zinc. Hungary is among the 7-9 countries with the lowest mean soil and plant values. At some locations response to Zn fertilization can be expected.

Division 3 689

Cadmium. About half of the Cd values fall in the highest plant/soil zone and the other half in the middle zone. The variation ranges of both plant Cd and soil Cd are relatively narrow. Lead. Only three countries (Belgium, Italy and Malta) have higher Pb median values than Hungary. Cobalt. The plant/soil Co median is clearly on the high side in the international Co field, but there is considerable variation in Co data. Selenium. Hungary shows average values for the Se status of soils.

Conclusions The Hungarian soils included in this FAO study varied widely with regard to texture, pH, CEC, EC, CaC03 equivalent and somewhat less with regard to OM content. The N, Ca and P contents of soils and plants were generally high. Most of the K and Mg contents of soils were below the international average but those of plants were at an average level or above. The soil and plant contents of most macronutrients varied widely, partly because of generally high though varying N, P, K fertilizer application. The micronutrient contents of soils/plants were commonly at the "normal" international level: B slightly on the high side, but Cu, Fe, Mn, Mo, Zn were on the low side. Compared to other micronutrients the variation ranges for B and Mn are wide, both low and high B and Mn values were recorded. Concerning the new analytical data, Cd and Pb soil and plant data indicate higher contamination in acid regions, while Co and Se status seems to be at a satisfactory level (Sülanpää, 1982, Sülanpää and Jansson, 1992). Other investigations within the last two decades in Hungary, both soil and plant analyses and field trials with microelements, support the findings quoted above. Good responses could often be recorded by applications of, first of all, Zn fertilizers. In vineyards, there is a need for Fe, Mn and Zn treatments. Not much is known yet about the contamination of soils and plants with harmful elements and toxic heavy metals. However, there seems to be a high Cd and Pb load in Hungary which endangers the whole soil-plant-animal-human food chain (Kâdâr, 1993, 1994, 1995, Szabó andKâdâr, 1994a, Szabó and Kâdâr, 1994b, Szabó, 1995a,b)

References Kâdâr, I., 1993. Agrokémia es Talajtan. 43:291-304. Kâdâr, I., 1994. Acta Agronomica Hungary 42:155-161. Kâdâr, I., 1995. Contamination of the soil-plant-animal-human food chain with chemical elements

in Hungary. Regicon Kft. Nyomda, Kompolt (Handbook printed in Hungarian). Lakanen, E. and Erviö, R., 1971. Acta Agronomica Fennica 123:223-232. Sülanpää, M., 1982. Micronutrients and the nutrient status of sous: a global study. FAO Soils

Buüetin. N. 48. Rome. Sülanpää, M. and Jansson, H., 1992. Status of cadmium, lead, cobalt and selenium in sous and

plants of thirty countries. FAO Sous Bulletin. N. 65. Rome. Szabó, L. and Kâdâr, I., 1994. Nehézfémek a talajban, növényben. In: IV. Agrarökonómiai Tud.

Napok. Szerk: Magda, S. - Radó, A. 2:419-422. Gyöngyös Szabó, L. and Kâdâr, I., 1994. Effect of heavy metal load on sou and crop. XXXVI. Georgjkon

Napok PATE. Georgjkon Mezôgazdasâgtudomânyi Kar, Keszthely, 146-153. p. Szabó, L, 1995. Nehézfémek viselkedése a talaj-növény rendszerben. Müszaki Kémiai Napok

MTA VEAB Veszprém, 64-66. p. Szabó, L., 1995. Talajok mikroelem eUâtottsâgânak környezeti összefïiggései. GATE

Fleischmann Rudolf Mezógazdasagj Kutató Intézet Kompolt, 56-61. p.

Division 4

Crop quality and post-harvest physiology.


MIXED CEREAL-VETCH FORAGE AS A SILAGE CROP IN SUSTAINABLE FARMING

F. Borowiec1, E. Pisulewska2, K. Furgal1

1 Animal Nutrition Department, Krakow Agricultural University, 30 - 059 Krakow, Poland 2 Crop Production Department, Krakow Agricultural University, 31-120 Krakow, Poland

Introduction Cereals, grown on arable lands, are increasingly used as green forage or silage crops for ruminants (McCartney, 1993). Intercropping cereals with legume species improves the nutritive value of resulting forage and benefits cropping systems, mainly by increasing soil N supply for the next crop (Ostrowski, 1993). In the environmental conditions of Southern Poland, intercropping cereals with legume species is cosidered to be an alternative to maize as a silage crop, in small sustainable farms. Methods The forages of winter cereals (rye, wheat, and triticale) and their intercrops with hairy vetch as well as forages of spring cereals (wheat and triticale) and their intercrops with spring vetch were used. The vetch was planted at 0, 30, and 60% of the recommended rate. The forages were harvested following the stage of shooting (cereals) and at the begining of flowering (vetch). The material was swathed, chopped 2 - 3 cm, and ensiled in 6L-plastic containers (0.7 kg fresh matter per L), in four replicates. The fresh and ensiled material was anaysed for gross chemical composition (Kaminski et al, 1995) and water-soluble sugars (Deriaz, 1961). In addition, the fresh forages were analysed for their buffering capacity (Playn & McDonald, 1966), and the ensiled forages for VFA, on a Varian -3400 gas-chromatograph, and ammonia. The silages were evaluated according to Flieg & Zimmer (Kaminski et al., 1995). Results Ensiling the same cereals with hairy or spring vetch improved the ensiling process and the quality of the silages, on the condition that the percentage (wt/wt) of vetch in the ensiled forage did not exceed 50% (Tab. 1.). Conclusions 1. The mixed forages of spring and winter cereals with vetch, containing less than 50% (wt/wt) of vetch, produce silages of good quality and high nutritive value (i.e. an improved energy : protein ratio). 2. The cereal-vetch forages due to their environmental and technological quality are a viable sustainable alternative to maize as a silage crop, in small farms.

References Deriaz, RE., 1961. Journal of the Science, Food, and Agriculture, 2: 152-160. Kaminski, J. et al., 1995. In: „Methods in Animal Nutrition", Krakow Agric. Univ., 1995. McCartney, D.H. et al., 1993. Jornal of Animal Science, 71: 91-96. Ostrowski, R.,1993. Roczniki Naukowe Zootechniki, 20. 157-169. Playn, M.J. et al.,1966. Journal of the Science, Food, and Agriculture, 17: 264-268.

Division 4 693

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EFFECT OF ENVIRONMENTAL FACTORS, GENOTYPE AND PERIOD OF HARVEST ON POST-HARVEST RIPENING OF SUNFLOWER

J. Crnobaracl, B. Marinkovicl

^Faculty of Agriculture, Institute of Field and Vegetable Crops, Dositeja Obradovica 8, 21000 Novi Sad, Yugoslavia

Introduction It is necessary to be familiar with dynamics of seed maturation and post-harvest ripening

for the purpose of shortening breeding processes. The objective of this study was to determine the earliest time of acquiring high and stable reproductive ability of the sunflower seed as influenced by different environments and genotypes.According to Nikolajeva (1982), the sunflower is characterized by weak dormancy, due to low embryo activity and low permeability of the grain coat. The latter is also emphasized by Chandler et al.(1985), Csresnyes (1979) and others. Dormancy occurs 19-21 days after fertilization (Fursova, 1989). According to Voskobojnik et al. (1989), the beginning of seed filling is at the same time the beginning of dormancy, because of the accumulation of inhibitors and hardening of the grain coat.

Methods In a three-year trial established both in a field and a greenhouse, the harvest of the mother component of the hybrids NS-H-26 and NS-H-27 and the variety VNIIMK-8931, which started 10 and ended 52 Days After the Beginning of Flowering (DABF), was performed each third day. Beforehand, the plants were marked with respect to the beginning of their flowering. The seed obtained was tested for its germination in rolls of filter paper 15, 20, 25, 30, 40, 50, 60, 80 and 100 days after the period of harvesting to determined seed dormancy. The data were statistically processed as a three-factorial split block design. Nevertheless, since there were actually five factors (years, environments, genotypes, time of harvest and dormancy), two of them were left out by means of using the mean values of their treatments . After the effect of the factors was estimated using the F-test, the degree of a particular factor's influence on germination was determined on the basis of the percentage share of its sum square in the total sum square . With regard to the average of the rest of the factors, the dynamics of germinability during the stage of maturing and post-harvest ripening was presented as a Contour plot (Origin 3.5).

Results According to the F-test, all tested factors were significantly effective. The harvesting

period showed to be decisive factor on since its share in total variability of the trial was 80.4-82.4%. The share of post-harvest ripening was 9.9-10.1% while the share of other factors (year, agroecological environment and genotype) ranged from 0.5 to 0.1%. The germination over 90% is achieved 19 DABF and with seed moisture of 69.3%. At first harvest, the period needed for post-harvest ripening was a 100 days while at the end of the harvest period, it decreased to 25 days. The earliest seed vitality is achieved 51 to 58 days after flowering (the sum of days to harvest and days for dormancy). The optimum harvest period is 25 to 31 DABF in which case post-harvest ripening lasts 25 to 30 days (Fig.1.). In greenhouse the seed harvested up to the 28th DABF has less moisture and shorter period of post-harvest ripening. The seed harvested in 1985, which was the warmest year, had the fastest maturation, but weakest post-harvest ripening because of higher germination level at the beginning of harvest. The variety VNIIMK-8931 had higher germination rate and shorter period of post-harvest ripening than the hybrids, although the water concentration was higher than in hybrids in the period of harvesting (Fig.2.).

Division 4 695

Conclusions The harvesting period and the post-harvest ripening were the two decisive trial factors. The duration of dormancy during the first harvests was 100 days, while at the end of the harvest, it decreased to 25 days. The earliest satisfactory seed germination is achieved 51 to 58 day after flowering. The optimum harvest period is 25 to 31 DABF, in which case post-harvest ripening lasts 25 to 30 days. The fastest maturation was observed in the seed from the greenhouse and that from the field in the warmest year. However, these seeds had the weakest post-harvest ripening, because of a higher germination level at the beginning of harvesting. The variety VNIIMK-8931 had a higher germination rate and a shorter period of post-harvest ripening than the hybrids.

Fig. 1. Effect of harvesting period on sunflower seed germination in the period of post-harvest ripening

Harvest (days after the beginning of flowering)

Fig. 2. Differences between the rate of seed germination affected by year, environment and genotype

. JTfci. AVERAGE YEAR

W A R M EST YEAR

"F"

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Dormancy (days afterthe period of harvesting 15 I I 20 ^m 25 MM 30 MM 40 ^ ^ 60 |

References Cseresnyes, Z., 1979: Seed Science and Technology 7 (2): 179-188. Chandler, J.M. et al., 1985: Crop science 25: 356-358. Fursova, D. B., 1989: Tehniceske kulturi 1: 8-9. Nikolaeva, M.G., 1982: At Kann, A.A., : Physiology and biochemistry of dormancy and germination of seed, "Kolos", Moskva: 72-96. Voskobojnik, L.K. et al., 1989: Sb. N. I. rabot "Semenovedenije i standardizacija maslicnih kultur", VNirMK, Krasnodar: 35-38.


RELATIONSHIP BETWEEN SOIL NITRATE CONTENT AND GRAIN PROTEIN CONTENT IN MALTING BARLEY (HORDEUM VULGARE ssp DIST1CHVM)

M. Malesevic1*, Lj. Starcevic2', Bogdanovic Darinka2), N. Przulj" 1) Institute of Field and Vegetable Crops, 21 000 Novi Sad, M. Gorkog 30, Yugoslavia 2) Faculty of Agriculture, Novi Sad, Yugoslavia

Introduction: Malting barley grain of good quality is very difficult to attain on fertile soils, such as chernozem. The primary indicator of quality in malting barley is protein content. Grain protein content and protein structure are especially variable in semi-arid climatic regions, such as the Vojvodina Province. Under the same conditions, protein content is somewhat higher in winter than in spring malting barley. The reason for this, in addition to genotype properties, can be that the two forms have growing seasons of different length (01 October - 25 June in winter and 01 March - 05 Jury in spring barley (Malesevic et al., 1992). A result of this is a different capacity of the root system to utilize N, P, K, water and other substances. Since the root system of winter barley develops deeper into the soil than that of spring barley (Garz et al., 1983), the effect of residual N on grain yield and quality is greater in the former. On the other hand, the NO3-N content and distribution in the soil depend on climatic factors, up until the beginning of intensive N uptake. In barley, protein synthesis is dependent on temperatures during the heading - maturing period and the level of N03-N supply (Foster et al., 1987).

Methods: The effect of N on grain yield and quality in winter and spring malting barley was studied in the period between 1985 and 1995. The trials were conducted on a chernozem sou rich in N, P and K. At the Fe-2 stage (Feekes - scale), the following fertilizer N (Nf) rates were applied: 0, 30, 60, 90 and 120 kg ha"1. Prior to this, Nmin content was analysed up to the depth of 120 cm. After the harvest, grain protein content was determined (% N x 6.25). The connection between particular parameters was determined using correlation and regression analysis.

Results: NO3-N sums significantly varied on a year to year basis. The protein content in the NfO treatment was shown to correlate with the sum of NO3-N in the soil (up to 120 cm in winter and 60 in spring barley) at the end of winter (Table 1). Additions of Nf (30... 120 kg ha'1 ) affected the grain yield and protein content, the extent of change depending on the level of NO3-N (Figures 1 and 2).

Table 1. Relationship between N03-N in the soil and grain protein content in tretment with no N.

Malting barley

Winter barley

Corr. coeff.

Spring barley

Corr. coeff.

Protein in

grain (%) NO

12.9

11.9

0-60

67

0.44

61

0.95**

NO3-N

0-90

101

0.75**

100

0.79**

sums, kg ha"1,

0-120

143

0.87**

129

0.67*

soil depth

60-90

34

0.71*

39

0.59

90-120

72

0.65*

65

0.61

*, ** significant at 0.05 and 0.01 (n = 11)

According to these results, it may be concluded that the grain protein content could be well predicted before the harvest (Figure 2). The control of soil nitrate N could help avoid the cultivation of malting barley in soils with excessive NO3-N levels.

Division 4 697

Figure 1. Effect of N03-N sums (kg ha1) in soil 0-60 cm for spring and 0-120 cm for winter barley and N-fertiHzer on yield and protein content.

Yield

180

160

140

120

100

80

60

Yield

%

No

| Spring bailey | ——•" <40

0-60 cm

N . 40-60

>60

30 60 90 120 150 Nf.kgh»-1

<130

130-150

>150

120 150 NC kg ha "I

Protein content 16

Protein content 16

120 150 Ntkgha '

Figure 2. Relationshrp between N03-N in soil (0-60 cm spring barley, 0-120 cm winter barley) and grain protein content in marring barley.

Protein content, (%) 16 15 14 13 12 11 10 9 8 7

| Spring barley | "

0-60 cm f ^

y = 6.24 + 0.094x r = 0.954**

| Winter barley |

• ^ ^ ^ " 12.5

y = 8.59 + 0.028x r = 0.864**

30 60 90 120 150 NO 3

180 210 N.kgha ''

Conclusions: Our study has shown malting barley to be very sensitive to residual Nmin. Overall status of NO3-N has had a greater influence on protein content than the fertilizer N.

References: Foster, E., et al., 1987. In "Nutritional Quality of Cereal Grains" (Ed. Olson R A and Fray K S),

Pub Medison Wisconsin, USA, pp 337-396. Garz, J., et al., 1983. Wissenschaftliche Zeitschrift Univ. Haue 4: 99-110. Malesevic, M, et al., 1992. In "Malting Barley and Malt" (Ed Lazic V) Faculty of Agricult. Novi

Sad pp 14-52.


EXAMINATION OF THE ORGANIC GROWTH OF FIVE SILAGE MAIZE VARIETIES BY APPLYING STATISTICAL APPROACHES

Istvân Pâlinkâs

Senior Lecturer, Candidate of Agrarian Science, UASG College of Agriculture, Gyöngyös

Summary From the points of view of feeding and knowledge of varieties, we deem important to examine how and to what extent the nutritive values accumulate in the fodder-plant during its growth, in relation to time elapsed. In order to determine this, we conducted an experiment in the site of the model farm of College of Agriculture in 1994, involving 5 varieties (Variety 1: Pioneer 3965A MTC, variety 2: Pioneer 3732 SC, variety 3: DEMA-210 TC, variety 4: SzDC-488, variety 5: HS-50) of silage maize so that we can describe the process of their development in time (organic growth) in possesion of adequate data, in form of trend functions.

We described the 15-member condition-time tendency resulting from the examined parameters /height (cm), raw protein x 10 (kg tonna), dry substance x 102 (MJ tonna"1), net energy content x 10 (MJ tonna" )/ of the individual varieties under survey, by applying cubic trend functions. The reason why we used cubic function differring from the special literature where the change is depicted by exponential function, by growth stages, is that, this way, by one function, the organic growth of the individual nutritive values can be provided as being easier to handle and better matching, in respect of both growing and declining phases, at a time. We provided the trend functions in the following form: Yy = b 0 +b r t+b2- t

2+b3- t3 where t

means the time in terms of weeks.

Our Figure attached hereto shows the trend and diagram of all examined factors for the variety 1, selecting the trend values and emasuring units so that they can be depicted in a system of co-ordinates. From them, one can monitor the development of the individual nutritive values in time, the place and size of its maximum and the proposed interval for harvesting.

In appointing the interval for harvesting, we applied the basic principle accepted by the special literature whereas the silage maize is advisable to be harvested from the point of view of feeding when its dry substance content is between 35 and 40%. By varieties, it takes place in the following intervals (weeks):

variety 1 11.9 < t < 13.1 variety 2 12.5 < t < 13.8 variety 3 12.4 < t < 13.5 variety 4 12.7 < t < 14.15

As regards variety 5, this did not occur in the period under survey since this is a late repening, long growing variety: its dry substance content was of 33.7% at the 15th sample-taking.

Division 4 699

Values

2 3 4 5 6 7

4 1 1 Time 9 10 11 12 13 14 15 (weeks)

• HEIGHT (cm) -DRY SUBSTANCE x 10 (kg/tonne)

RAW PROTEIN x 10 (kg/tonne) NET ENERGY CONTENT x 10 (MJ/tonne)

Trends of maize for silage (variety 1) and their diagram


METABOLIC ENGINEERING OF LIGNIN THROUGH FLUX CONTROL IN THE PHENYLPROPANOID BIOSYNTHETIC PATHWAY

Vincent J.H. Sewalt, Jack W. Blount, Richard A. Dixon

Plant Biology Division, The Samuel Roberts Noble Foundation, P.O. Box 2180, Ardmore, Oklahoma 73402, USA

Introduction Forage lignin content and composition are under control of several genes in lignin biosynthesis and are, therefore, amenable to genetic engineering (Figure 1). We aim at reducing lignin concentration or lignin methoxyl content in alfalfa to increase the nutritional value of this forage legume important to the dairy industry. We have demonstrated the potential for metabolic engineering of the lignin pathway by suppression of phenylalanine ammonia-lyase (PAL) or caffeic acid O-methyltransferase (COMT) in tobacco (Elkind et al., 1990; Bate et al., 1994; Ni et al., 1994). In addition, tobacco plants with suppressed cinnamate 4-hydroxylase (C4H) and caffeoyl CoA O-methyltransferase (CCOMT) have been generated (Masoud et al., unpublished; Sewalt et al. unpublished). To investigate which enzymes constitute physiological control points in phenylpropanoid and lignin biosynthesis, selected transgenic plants with down-regulated PAL, C4H, and COMT were analyzed for lignin characteristics.

Phenyalanine "°yP «>y.° V "S"0 ™^° P A L1 C 4 H X Ç3H X C O M T I _FSH. f COMT

CinnamicAcid^O ß^L^ t C l . ^ HO-^QCH, c^o^f "COM, CH OH CH CH CH

4CL 4CL 4CL

C C A - S O CcA-S O CoA-S O « - S O CoA-S O

, fccoAH jCCOMX j ^ CCOMT [

p o~~ 6"'""""'""*jo '"* jo Y Y^CH Y ° C H j HO^f^CCH, CHjO Y^CCH,

Phytoalexins OH CH en OH OH

Peroxidase

Lignin Figure 1. Lignin biosynthetic pathway

Methods Plant material originated from several independent transgenic experiments. PAL phenotypes evaluated were control, severely sense-suppressed (primary transformants), recovering from sense-suppression (T5 plants), and sense-suppressed plants turned into PAL-overexpressors (Bate et al., 1994; Howies et al., 1996). C4H phenotypes were primary transformants, generated by introducing anti-sense and sense C4H constructs into control plants (Masoud et al., unpublished). COMT-suppressed plants were obtained by antisense expression (Ni et al., 1994); plants evaluated were controls, primary transformants, and Tl-progeny from one of the transformants. Middle stem sections (internodes 10 and 11 for PAL and COMT plants, internodes 8 to 11 for C4H plants) were sampled and ground under liquid nitrogen. PAL, C4H, and COMT activities were confirmed according to standard procedures. Freeze-dried material was used for isolation of cell walls using the detergent fiber procedure, and subsequent determination of Klason lignin (modified from Kaar et al., 1991) and lignin methoxyl groups (TAPPI, 1972).

Division 4 701

Results Suppression of PAL and C4H activities resulted in plants with substantially reduced lignin concentration (50% and 65% of wild-type, respectively). Severely PAL-sense suppressed plants produced low levels of lignin with drastically increased methoxyl content, indicative of a shift from predominantly guaiacyl-type lignin with small amounts of syringyl units to almost exclusively syringyl-type lignin. Contrary to the situation with severe PAL-suppression, lignin methoxyl content was not affected by suppression of C4H. Overexpression of neither enzyme resulted in changes in lignin, indicative of downstream control points in the lignin biosynthetic pathway.

DKL BOCH3 jCOMT ^ <£,

Figure 2. Lignin concentration and methoxyl content in tobacco plants down-regulated in COMT

COMT suppression resulted in slightly reduced lignin concentration (80-95% of wildtype) but with a concomitant increase in lignin methoxyl content (Figure 2). The effects of moderate COMT suppression reported here agree with previously published results obtained with less rigorous lignin analyses (Ni et al., 1994), but are at variance with the effects of severe COMT suppression (reduced syringyl:guaiacyl ratio, no reduction in lignin content) reported by other groups. The variable results from different COMT-antisense experiments can be potentially explained by the existence of parallel methylation pathways involving free hydroxycinnamic acids or their CoA thiolesters in which distinct enzymes, COMT and CCOMT, catalyze functionally identical reactions.

Conclusions Although the most drastic results are obtained by PAL or C4H suppression, lignin manipulation via suppression of O-methyltransferases bears more practical relevance for forage improvement due to possible pleiotropic effects associated with altering enzymatic steps earlier in the phenylpropanoid pathway. Our current transgenic approach is the separate and simultaneous down-regulation of COMT and CCOMT in tobacco and alfalfa to dissect the relative importance or redundancy of the two enzymes, and to obtain a more thorough suppression of OMT activity.

References Bate et al., 1994. Proceedings of the National Academy of Science U.S.A. 91: 7608-7612. Elkind et al., 1990. Proceedings of the National Academy of Science U.S.A 87, 9057-9061. Howies et al, 1996. Proceedings of the National Academy of Science U S A (in review). Kaar et al., 1990. Journal of Wood Chemistry and Technology 11: 447-463. Ni et al., 1994. Transgenic Research 3: 120-126. TAPPI, 1972. Methoxyl content of pulp and wood. T 209 su-72, TAPPI, Atlanta GA.

Division 6

Agriculture-environment relationships.


THE EFFECT OF DIFFERENT FORMS OF NITROGEN FERTILIZERS ON THE ACCUMULATION OF CADMIUM AND ZINC IN PLANT TISSUES

J. Balik, P. Tlustos, J. Szakova, V. Vanek

Department of Agrochemistry and Plant Nutrition, Czech University of Agriculture in Prague, 165 21 Prague 6 - SuchdoL, Czech Republic

Introduction The rate of nitrogen fertilizers and their forms have an important effect on the composition of soil solution and composition of cations (macronutrients) in plant tissues ( Balik et al., 1990 ). Therefore the influence of different nitrogen fertilizers on the accumulation of Cd and Zn in plants was studied.

Methods Three year ( 1992 - 1994) model pot experiments were used in this study. Two crops were planted on different soils. Oat was planted at soil Prestanov and maize at soil Cerveny Ujezd. Oat was harvested as silage crop ( about 28% d. w.) and maize at plant height of 100 cm ( about 13% d.w.).

Main parameters of used soils

Soil type Soil texture pH/KCl Cox. ( % ) CEC (mval/lOOg) V ( % ) Cd (HN03) (mg.kg"1 )

Zn (HN03) (mg.kg" )

Cd (TOT) (mg.kg ' ) Zn (TOT.) (mg.kg"1 )

Soil - Prestanov Ortic Luvisols sandy loam 5.1 2.30 23.0 55.7 0.50 54.2 0.57 128.4

Soil - Cerveny Ujezd Ortic Luvisols loamy 6.7 1.35 14.8 94.6 0.20 36.7 0.27 73.5

Ammonium sulphate (SA), urea (V), ammonium nitrate (AN), calcium nitrate (CaN), and sodium nitrate (NaN) were used as nitrogen fertilizers. Chemical compounds were applied as soil solution and mixed thoroughly with the soil before the sowing of grains. Rate of applied nitrogen was 300 mg.kg"1 ofsoilforoat and 800 mg.kg"1 for maize.

Results Experiments showed nonsignificant effect of applied fertilizers on the yield of both crops. The maize slightly increased yield on the ammonium sulphate treatment. Figures 1 and 2 showed the increased Cd and Zn concentration in both growing plants at treatments of acid derived fertilizers. Plant uptake of N03" caused the release of OH" into soil solution. The hydroxyl anion together with rest of calcium in the soil solution led to higher pH at the treatments of calcium and sodium nitrate. Opposite processes were observed after application of ammonium sulphate. Soil pH dropped in 4.49 at (SA) treatment and rose on 5.36 at (CaN) treatment after the oat harvest. The results of maize experiment confirmed the same pattern. pH was 5.43 at (SA) and 6.70 at (CaN) treatmens. Significant pH differences were mainly caused by high nitrogen rates in pot experiments. Eriksson ( 1990 ) found higher concentration of Cd in ryegrass, wheat and oat after apphcation of acid fertilizers and Wu et al. (1989) at ryegrass experiment. Results of Balik et al. (

Division 6 705

1994) confirmed the lower Cd uptake by spinach using mild extradant ( 0.01 mol.1 CaCl2 )• The content of available soil Cd was lower at (CaN) treatment compared to (SA) treatment.

Figure 1 The Cd concentration (bars) in plants and pH-KCI in soil

120

100

60

40-

20-

100% = 528 ppb

rM

%

100%=803ppb

$ 1 1 1 1 ^ 1 AN SA CaNNaN SA V CaN

m o

5.5 * X Q.

5

Figure 2 The Zn concentration in plants

100%=82ppm 100%=169ppm

AN SA CaN NaN SA V CaN Conclusions Three year model pot experiments were used for study of behaviour of different forms of nitrogen fertilizers on the Cd and Zn uptake by oat and maize. Application of ammonium sulphate and ammonium nitrate caused the lugher accumulation of Cd and Zn in plant tissues. Calcium nitrate and ammonium nitrate treatments showed opposite effect in both plants.

References Balik, J. etal., 1990. Proc. Stickstoff-Dungemittel-Boden-Pflanze, Praha: 84-88. Balik, J. et al., 1994. Prague, Czech Republic, Report 01, Czech University of Agriculture, 262p. Eriksson, J.E., 1990. Uppsala, Sweden, PhD Thesis, 120 p. Wu, Q. T. et al., 1989. Paris, France, CR. Acad. Sei., 309, s. Ill: 215-220.


EFFECT OF TOXIC ELEMENTS ON WINTER WHEAT ON BROWN FOREST SOIL

L. Fodor

Gödöllö University of Agricultural Sciences, College of Agriculture Gyöngyös Mâtrai St. 36, 3200 Gyöngyös, Hungary

Introduction The contamination of the agricultural environment and arable land with heavy metals and other possible toxic elements is more and more dangerous. The pollutants come from metal-mining, industrial production, traffic, industrial and communal waste waters, acid rains, etc. (Csathó, 1994, Szabó, 1995). The toxic elements appear in the soil and water and they become available for the plants. The cultivaited plants - as primary and secondary biomass - serve as human food directly or indirectly. It's very important to know how the toxic elements can move in the soil, in what way they get into the plants and in what quantities they accumulate in the vegetative and generative organs of the plants (Szabó et al., 1994, Kâdâr, 1995). Relation between toxic elements, soil and plant may be studied in an objective manner on arable land. The aim of our experiment is to describe the effects of some toxic elements on brown forest soils, cultivated plants and thus on the food chain.

Methods This is a field study, wich is being conducted on a slightly acid brown forest soil (pH=6,2) at the College Farm in Gyöngyös. The experiment is conducted in split-plot design with three replications on 35 m2 field plots. Effects of 8 toxic elements (Al, As, Cd, Cr, Cu, Hg, Pb, Zn) were examined on tree levels (0/30, 90, 270 kg element • ha"1) using soluble salts. The first year (1985) we used winter wheat as a test plant. Toxic effects and effectiveness of treatments were appraised and analysed during tillering and harvest. Fresh weight of green shoot samples was determined and the toxic element content in green sprouts was analysed by ICP-technique. At harvest the grain yield was determined on each plot.

Results

Results of the first year of the experiment are presented in tables 1 and 2.

Table 1. Effect of treatments on element content in green sprout during tillering

Symbol of elements

Al Zn Hg Cu As Cd Cr Pb

treatments 1% 0 30

element 90

•ha 1

270 element content in green sprout mg 135 31 0 8

0,0 0,1 0,5 0,5

-34 5 9

0,4 1,0 4,6 1,7

208 38 19 8

2,0 1,7 2,7 2,6

74 39 86 11

2,8 2,2 13,1 3,0

LSDS-A

kg 1

n.s. 9

25 3

1,2 0,9 8,8 2,7

Mean

139 37 37 9

1,7 1,6 6,8 2,4

Division 6 707

Table 2. Effect of treatments on fresh matter during tillering and on grain yield at harvest

Symbol of

elements

Al Zn Hg Cu As Cd Cr Pb

treatments kg 0

1357 1357 1357 1357 1357 1357 1357 1357

30 element per ha

90 green sprout g per

-1294 1119 1019 903 1179 1116 985

981 910 1244 503 799 1224 1153 602

270 m

2 m 1059 890 989 160 760 948 1096 397

L S D 5 %

397

Mean

1132 1031 1117 561 821 1117 1122 661

grain yield t per ha Al Zn Hg Cu As Cd Cr Pb

4,88 4,88 4,88 4,88 4,88 4,88 4,88 4,88

-5,45 5,42 5,19 5,34 5,18 5,10 4,79

4,80 4,72 4,35 4,90 4,43 5,11 5,17 4,32

4,40 4,19 5,13 2,65 3,31 4,80 4,61 2,48

1,3

4,69 4,79 4,97 4,24 4,36 5,03 4,96 3,86

Conclusions Toxic effects of Cr, Zn, Ag, Cu could be traced during both tülering and harvesting. Cd, As, Hg and Cr showed considerable enrichment in green sprout, which demonstrated their intense mobility on slightly acid brown forest soil. In the case of higher Cd, Cr, As, Hg contaminations the green sprouts of winter wheat are qualified as toxic according to Hungarian standard (4/1990. (II. 28.) MEM decree) so they musn't be used as fodder-crop.

References Csathó, P., 1994. Contamination of the environment with heavy metals and its consequences on

agricultural production, MTA TAKI, Budapest, 176. p. Kâdâr, I., 1995. Contamination of the soil-plant-animal-human food chain with chemical elements

in Hungary, MTA TAKI, Budapest, 388. p. Szabó, L. et al., 1994. Heavy metals in the soil and plants, GATE, Gyöngyös, 419-422. p. Szabó, L., 1995. Environmental aspects of micro element content of soils, GATE, Kompolt, 95-

102. p.


GROWING THE PLANTS ON THE SOIL POLLUTED BY HEAVY METALS

N.Kharitonov,M.Bulgacova,V.Pashova,I.Onuphrieva Agroecology Institute, Agrouniversity,Voroshilov st.25,Dnepropetrovsk, 320027, Ukraine

Introduction It was established that zone of technogenical contamination of soil in the Dniepropetrovsk region is 10-15 times bigger than area of land disturbed by mining. For example, in the Krivoy Rog iron ore deposition dust post blusting cloud are main source of heavy metals pollution. Thus, it is necessesary to undertake the steps connect with improvement of biological activity contaminated soil, reduction of heavy metals moving in the soil-plant system.

Methods The investigations were conducted in the conditions of laboratory, vegetative,micro-field experiments. The coefficient of quarry dust fitotoxicity ( c ) was determined by the mathematical equation c=m<>-mi/mo. The meaning of mathematical symbol for m» is a bioproductivity of plant on the untread soil, mi is a bioproductivity of plant on the heavy metals contaminated soil. Salts of metals (Fe, Co, Pb and Cd) were brought into the soil in doses which were equivalent to technogenic load. For the soil protection from the toxic action of redundant elements the biohumus and huminate preparation were introduced on the experimental plots of land in barley crops in dose 0,6 and 0,01 kg m-2.The huminate preparations application was made in the several variants(A-introduction in soil,B-treatment of seeds before sowing,C-treatment of sowing).

Results Results are presented in the Table 1-3.

Table 1 Maximum meaning of the heavy metals composition in the quarry dust, ppm

Denomination Fe Mn Zn Cu Ni Co Pb Cr Cd

Quarry dust of the primary cloud 15000 800 80 32 25 25 20 8

Quarry dust of the secondary cloud 385 210 259 67 14 63 35 37

Division 6 709

Table 2 Coefficient of fitotoxic action of heavy metals and quarry dust

Plant

Barley Soya

Dose

1 % 1 %

Sand

0,1 0,07

Substrat

Sand/Clay

0,25 0,12

Table 3 Influence of the huminate preparations on the barley growth on the soil contaminated by heavy metals,g m -2

Variant

Control A A+C A+B

A+B+C A+B

A+B + C A+B

A+B + C A + B

A+B + C LSD

Raw material in method B application, country

Brown coal, Kazakhstan

Brown coal, Ukraine

High-moor peat

lowland peat

Bioproductivity

315 435 392 419

255 343

331 348

300 288

275 46

Conclusions Technoggenic pollution of soils by heavy metals lead to increasing of its migration on trophical chains. Reduction of biological activity of technogenically contaminated soils evoke developing their degradation processes. Improvement of soil condition is possible thanks to realization such rehabilitation steps as using sorbents, vermicompost and huminate preparations.


THE ACCUMULATION AND DISTRIBUTION OF CADMIUM, ZINC AND ARSENIC BY POPPY

D. Pavlikova, V. Vanek, J. Szakova, J. Balik

Department of Agrochemistry and Plant Nutrition, Czech University of Agriculture in Prague, 165 21 Prague 6 - SuchdoL Czech Republic

Introduction Heavy metals can enter into the food chain through their uptake by plants. One of high Cd accumulators, poppy, has long been cultivated in Czech Republic for popularity of the seeds. The degree of Cd and other heavy metals uptake by plants is influenced by factors such as soil pH, organic matter, sesquioxide content etc. (Oliver et al., 1994, He et al., 1994). Therefore poppy has been planted on the different polluted soils treated with remediated materials to find their effect on the uptake of heavy metals by seeds and the metals distribution within the plants.

Methods Poppy (Papaver somniferum L.) was cultivated on three soils with different contents of heavy metals in pot experiments from 1992 to 1995. Some properties of these soils are presented in Table 1. Lime, farmyard manure and bentonite were applied in the first year of this experiment. Direct and subsequent effect of used materials was investigated. Fertilizer (NPK) was applied every year. The yield of poppy seeds and capsules was determined. Plant tissues were analysed for content of Cd, Zn and As. Heavy metals were analysed by flame and graphite furnace AAS. Certificate materials RM 12-02-03 Lucerne was used for quality tests of analyses.

Results The yields of poppy seeds were not effected by the application of all three materials, but minor effect of lime application was observed on acid soil. Our results confirmed that content of heavy metals in soil is the main factor influencing their uptake by plants. The highest content of Cd (4.64 mg .kg'1) and As (0.146 mg.kg"1) in seeds was determined on the most polluted soil Kbely. The effect of lime, farmyard manure and bentonite application on the uptake of metals differed with elements and tested soils (Table 2). Positive effect of applied materials on Cd, Zn and As concentration was not observed on soil with the lowest heavy metal contents (Cerveny Ujezd). Lime application made positive effect at the cadmium accumulation on the acid soil (Prestanov). Cd concentration was decreased by 40 % in seeds and by 59 % in capsules over the whole experiment. The strong decrease in cadmium after adding lime is significant (P < 0.05). Application of farmyard manure also reduced Cd concentration by 18 % in seeds and by 25.5 % in capsules in mean of two studied soils (Prestanov and Kbely). Zn content in seeds was not significantly reduced in seeds, but its content in capsules was reduced by 36 - 59 % at all treatments on acid soil Prestanov. Seed content of arsenic was effected only on the most polluted soil at lime treatment (by 16 % in seeds and 28 % in capsules) and at farmyard manure (by 14 % in seeds and 8 % in capsules). Metal distribution in poppy plants differed in elements. More than 50 % of cadmium was accumulated in seeds, but 83 % of arsenic was accumulated in stems and leaves (Table 3).

Conclusions The uptake of cadmium, zinc and arsenic by poppy was mainly effected by their contents in soils. The effect of used materials on the uptake of metals differed in elements and soils. Application of lime showed the highest drop in heavy metal accumulation in seeds and capsules. Cadmium was mostly found in seeds, but arsenic was more accumulated in stems and leaves.

Division 6 711

Table 1. Selected properties of the used soils

Sou

Cerveny Ujezd Prestanov

Kbely

pH/KCl

6.8 5.1 7.3

P K Mg Ca mg.kg"1

137 21 95

266 132 2780 200 244 2380 275 152 6090

Cox % 1.35 2.10 2.09

Cd Zn As mg.kg"1

0.33 85.7 0.76 179.9

17.50 179.2

19.7 19.7 16.7

Table 2. Concentration of Cd, Zn and As in poppy seeds (mg.kg1)

Treatment

0 lime

bentonite farmyard manure

Sou

C. Ujezd Prestanov Kbely Cd concentration

0.432 2.842 0.520 1.717 0.411 2.340 0.521 2.339

4.463 5.103 4.246 3.648

Zn concentration 0

lime bentonite

farmyard manure

70.69 108.89 77.04 102.67 75.90 109.77 72.14 108.00

80.70 89.74 84.83 75.47

As concentration 0

lime bentonite

farmyard manure

0.093 0.053 0.098 0.062 0.083 0.055 0.067 0.061

0.146 0.122 0.149 0.126

Table 3. Distribution of Cd, Zn and As in poppy plants (%)

Cadmium Zinc

Arsenic

Seeds 54.9 43.8 6.5

Capsules 12.3 9.2

10.5

Stem+leaves 32.8 47.0 83.0

References Oliver, DP. et al., 1994. Journal of Environmental Quality 23: 705-711. He, Q. B. et al., 1994. Water, Air and Sou Pollution 74: 251-265.


HEAVY METALS AND DIFFERENTIATION OF PERENNIAL GRASSES IN THE PATHOGEN RESISTANCE CHARACHTER

VA. Pozdnyakov, A. Kudums, A.I. Drizhachenko

Department of Perennial Grass Selection, SZ NPO "Belogorka", 188231 Leningrad Gatthina locality, Russia

Introduction In recent 3 decades in Russia processes of a biodiversity elimination were increased. Environment pollutions by industrial outputs icluding heavy metals (HM) is one of basic factors affecting on environment conditions negatively. However nature of plant resistance to HM is not studied. There is not clear differences in the resistance of both plants species and their hybrids. As was shown by Fenic et al. (1995) detoxication of HV by plants carries by participation of organic acids, metalothioneins, phytohelatins and tonoplast transferase emergence.ln addition many metals are necessary to plants as unchangeable microelements for their viable. These are Fe, Co, Mn.Mb, Se, Cu. Enzymes containing H M iones often carry out protection functions (Zarubina et al., 1988).

Methods xFestulolium hybrids have been synthesized by authors due to crosses of tetraploidy cv.Orlinskij plants (Lolium perenne L.) belonging to the Western-European variety-type group (Shutova, 1977) with plants of the cv.Baltica (Festuca arundinacea Schreb.) selected from the VIR collection island Sahalin sample. Female parent plants were emasculated,unripe hybrid embryoos were grown on the Randolf-Kox medium. Methods for an estimation of resistance hybrids to Erysiphe graminis DC.f.festucae Jacz. .Puccinia coronifera Kleb.f.fectucae Eriks. and the local rust population has been described (Pozdnyakov,Drizhachenko, 1983;Pozdnyakov et al., 1986). Analysis of the microelement content in the plant green mass was carried out accoding to Sillanpaa (1990). The statistic analysis of evidences in heredity of pathogen resistance plant properties was carried out according to Wolf(1966) and Rokitskij(1974).

Results Our experiments demonstrated German cultivars of Festuca pratensis L. had a few of Fe-contents (58-85+26,3 mg/kg of dry matter)in leaves of the second cutting plants than the Russian cv. Lubava, wich affected by local population of leaf spot plant pathogens. Hybrides of xFestulolium of our selection (1983-3 F5, 1982-52 F3) differencing on resistance to rust fungi and powdery mildew were remarkable for Fe-contents (78-104+26,3 mg/kg). The same hybrides had also high contents of Cu (6.0-9.1+3,6 mg/kg). It may suppose cells and tissues of the plants have more activity of Fe- and Cu-containing ezymes. Differences on Mn-content were not found.

Conclusions Data of our experiments are of interest to studying rules of geographic variability of plants, as according to Petuchov (1995) unusual plant appearence had found in places of the large breakes of continents, ex. at Africa or at the Middle and the Far East.

Division 6 713

References

Fenic S.J.,Trophymjak T.B.,Blum Ja.B., 1995. Progress in modern

biology,pp.261-275. Petuhov l.,1995.S.-Petersburg: Institure of Geochemistry. PozdnjakovV.A.,Drizhachenko A.I.,Kostitsin V.V., 1986. Bul.bot.,gen.and plant breed. 103:67-70. Pozdnjakov V.A.,Drizhachenko A.I.,1983.Improve of the plant defence in the Pribaltic and Belorus.Riga.Thesises,pp.60-61. Rokitskij P.F., 1974.The statistic genetics.Minsk. ShutovaZ.P., 1977. Bul.bot.,gen. and plant breed. 59:70-87. Sillanpaa M.,1990. FAO Soils Bull.48 VolfV.G. 1966. Statistics,Kolos,Moskow. Zarubina M.A. et al.1988. Bull.ofVIZR 70:59-72.


THE EFFECT OF SOD. REMEDIATION TREATMENTS ON PLANT UPTAKE OF CADMIUM, ZINC AND ARSENIC

P. Tlustos, J. Bahk, J. Szakova, D. Pavlikova

Department of Agrochemistry and Plant Nutrition, Czech University of Agriculture in Prague, 165 21 Prague 6 - SuchdoL Czech Republic

Introduction Lime, farmyard manure and bentonite are used extensively as soil treatments to improve soil structural properties and decrease the mobility of heavy metals. Alloway (1990) summarized published results and found lower availability of Cd in soils with higher pH, except one source. Lune (1985) confirmed lower Cd uptake by plants at limed soils. Acidification ofthat soils increased Cd and Zn uptake again. Higher soil sorption showed lower Cd content in oat biomass (Haghiri, 1974). The higher content of organic matter and sorbent materials decreased accumulation of heavy metals in carrot roots but did not effect content in ryegrass and spring wheat (Hasselbach, 1990).

Methods The effects of lime, farmyard manure and bentonite application on crop yields and heavy metal accumulation were investigated using pot experiments over a 4 year period. A loamy soil from a polluted area of Northern Bohemia (Czech Republic) was used in this experiment. Parameters, pH-KC1 = 6.80, amount of available nutrients P = 195, K = 504, and Mg = 269 mg.kg1 and total concentration of Cd = 0.60, Zn = 154.0 and As = 39.5 mg.kg' were determined in mentioned soil. Bulk soil was sieved and four treatments were established, phis lime, dry chopped manure and bentonite. Remediation materials were applied only before first planting in 1992. Fertilizer (NPK) was applied before each crop. The rates of fertilizers differed from growing crop. The same crop rotation was grown in each treatment. Silage oat was planted in 1992, silage maize in 1993, spring barley in 1994, and poppy in 1995. The yield of fresh and dry matter and the concentrations of Cd, Zn, and As were determined for each treatment, crop, and location within the plant. Each soil treatment was analyzed every year after harwest for amount of available metals by three different extractants ( 2 moll"1 HNO3, 0.005 mol.1"1 DTPA, and 0.01 moLl"1 CaCl2( Tlustos et al, 1994). Heavy metals were analyzed by flame and graphite furnace AAS. Certificate materials BCR -142 Light Sandy Soil and RM 12-02-03 Lucerne were used for quality tests of analyses.

Results The application of all three compounds had a positive effect on the yield of the first two crops, the oat and maize. The yield increase was approximately 13 % in bentonite, 10 % in manure, and 5 % in lime treatments. The following crops barley and poppy, showed a slightly reduced yield. The accumulation of heavy metals differed by crop and spatial location within the plant ( Table 1, 2, 3). Cd was more accumulated in stalks than in grain. Arsenic followed similar pattern, except maize with the lowest As concentration. Higher Zn contents were found in seeds as compared to stover, again with the exception of maize with the highest concentration of Zn. The effect of lime, bentonite and farmyard manure application on the uptake of metals differed by element and crop. Cd uptake was decreased by each treatment probably through reducing the amount of Cd in solution. The highest effect was found in the manure treatment ( Table 1). The mean concentration of Cd in plants fell by 25 % in this treatment ( mean of all four crops). The concentration of Zn in soil was about one hundred times higher than Cd ( Table 2), the application of remediated compounds had no positive effect on Zn uptake by crops. Plant uptake of As was slightly affected, positive mean effects were found in the manure and bentonite treatments.

Division 6 715

The amount of extractable elements depended on the strength of solution. The concentration of all three elements decreased in row HN03 > DTPA > CaCl2 of used extract solutions. Different element uptake by plants has not been detected at soil remediation treatments by chosen three extractants.

Table 1. The Cd content in the dry matter of subsequently growing plants (mg.kg"1)

Treatment

Zero Lime Sorbent Manure

Oats

0.368 0.350 0.203 0.213

Maize

0.953 0.819 0.803 0.494

Barley Grain

0.162 0.129 0.136 0.147

Straw 0.378 0.450 0.411 0.450

Poppy Seed

0.213 0.130 0.305 0.188

Capsule 0.259 0.202 0.197 0.123

Table 2. The Zn content in the dry matter of subsequently growing plants (mg.kgJ)

Treatment


Oats

23.20 24.91 22.39 22.39

Maize

87.40 159.20 99.60 100.89

Barley Grain

31.58 32.52 32.30 32.31

Straw 30.40 28.88 33.08 25.90

Poppy Seed

59.19 57.53 71.18 48.69

Capsule 10.84 14.01 17.99 11.59

Table 3. The As content in the dry matter of subsequently growing plants (mg.kg')

Treatment


Oats

1.883 2.040 2.093 2.167

Maize

0.731 0.648 0.691 0.718

Barley Grain

0.622 0.731 0.698 0.772

Straw 1.740 1.764 1.944 1.666

Poppy Seed

1.610 1.814 1.093 1.336

Capsule 5.772 3.821 3.418 2.787

Conclusions The concentration of heavy metals in biomass was effected by growing crop. Higher concentration of Cd and As was mostly found in stalks, Zn was more accumulated in grain. Application of lime, manure, and bentonite decreased the Cd accumulation in the first and second crop, and slightly decreased As content over all four crops. The highest decline of heavy metal accumulation was found at farmyard manure treatment.

References Alloway, B. J., 1990. Heavy metals in soils. J. Willey and Sons., New York, 331 p. Haghiri, F., 1974. Journal of Environmental Quality 3: 180 - 183. Hasselbach, G., 1990. Verband Deutscher Landwirtschaftlicher Untersuchungs und Forschungsanstalten, Reihe Kongressberichte 30: 281 - 286. Lune,P., 1985. Rapport, Instituut voor Bodemvruchtbaarheid, No. 13/85, 45 p. Tlustos, P. et al., 1994. Rostlinnâ vyroba 40: 1107 - 1121.


EVALUATING THE IMPACT OF PESTICIDES ON THE ENVIRONMENT USING AN INDICATOR BASED ON FUZZY CODED VARIABLES

H.M.G. van der Werf and C. Zimmer

INRA, Station d'Agronomie, BP 507, 68021 Colmar, France. Email [email protected]

Introduction The use of pesticides in agriculture causes undesirable effects on the natural environment. We propose an indicator of the environmental impact of a pesticide application (L^,) as a decision aid tool for farmers. The environmental impact of a pesticide largely depends on: a) the amount applied, b) its rate of degradation, c) its partitioning to the air, the surface water and the groundwater, d) its toxicity to the species in those environmental compartments (Van der Werf, 1996). Several methods have been proposed to estimate pesticide environmental impact (Levitan et al., 1995; Van der Werf, 1996). None of these methods aggregates the four criteria mentioned above into a single output parameter. To assess pesticide environmental impact three types of input variables are available: a) pesticide characteristics (e.g. toxicity to water organisms), b) characteristics of the environment (e.g. the runoff risk of the field), c) characteristics of the pesticide application (e.g. the site: on the crop, on the soil, in the soil). For some of the input variables the values available are certain and precise (e.g. rate of application). However, often the values are imperfect: their validity may be doubtful (e.g runoff risk), or they may be imprecise (e.g. soil half-life). The effect of the input variables on the risk of environmental impact can be expressed in every-day language (e.g. If the runoff risk of the field is large and the pesticide is applied on the soil and the pesticide is toxic to aquatic organisms then the risk of surface water contamination is large). We have based our indicator on an expert system using a collection of fuzzy membership functions and decision rules. This technique is robust when uncertain or imprecise data is used and allows the use of knowledge which is expressed in every day language (Bouchon-Meunier, 1993).

Methods The value of L^, depends on four variables: P (presence, reflecting amount and persistence), Rgro (risk of groundwater contamination), Rsur (risk of surface water contamination) and Rair (volatilization risk). The value of each of these intermediairy variables depends on two to four input variables according to fuzzy decision rules which will not be presented here. For all variables the membership to a fuzzy set F (Favorable) and a fuzzy set U (Unfavorable) has been defined using values from the literature (Van der Werf, 1996). The value of F depends on the rate applied and its soil half-life. The value of Rgro depends on the mobility of the pesticide, the site of application and the month of application and its toxicity to man. The value of Rsur depends on the runoff risk of the field, the site of application and its toxicity to aquatic organisms. The value of Rair depends on the volatility of the pesticide and its site of application. For the air the toxicity is not taken into account because an appropriate variable is not available. L^, can take values between 0 (no risk of environmental impact) and 1 (maximum risk of environmental impact). Its value is determined according to a set of 16 decision rules, 6 of which are given below as an example:

a) If f is F and Rgro is F and Rsur is F and Rair is F then Ipest is 0.0 b) If P is F and Rgro is F and Rsur is F and Rair is U then 1^, is 0.1 c) If f is F and Rgro is F and Rsur is U and Rair is U then Ipest is 0.3 d) If f is F and Rgro is U and Rsur is U and Rair is U then Ipesl is 0.5 e) If P is U and Rgro is F and Rsur is F and Rair is F then IP<!S, is 0.5 f) If P is U and Rgro is U and Rsur is U and Rair is U then Ipest is 1.0

The risks for the environmental compartments are considered to be additive, volatilization risk is given less weight than groundwater and surface water contamination risks (rules a to d). The presence of an active substance is considered as an environmental risk, even when the risk for each of the environmental compartments is nil (rule e).


Division 6 717

Results Results are presented in the table and the figure.

Sensitivity of !„«, to variation of input variables

0.25

- Crop cover

-A Toxicity - human

• Month

S Soil mobility

-O Soil half-life

•—Amoun t applied

H Volatility

-A Toxicity - aquatic

+ — Runoff risk

- H — 80 20 40 60

% of the transition interval 100

Analysis of the sensitivity of 1, , to variation of input variables. Each input variable is varied over its transition interval from favorable (0%) to unfavorable (100%), while the other input variables are kept at their median value, or, for crop cover, at unfavorable.

The values of P, Rgro, Rsur, Rair and Ip,, rate in a field with medium runoff risk.

for a number of pesticides applied at their recommended

Pesticide Rimsulfuron Parathion Cyfluthrin 2,4-D EPTC Carbofuran Glyphosate Alachlor Atrazine Isoproturon Lindane

Site of application plant/soil, crop cover 50% plant/soil, crop cover 100% plant/soil, crop cover 100% plant/soil, crop cover 50% in the soil in the soil plant/soil, crop cover 100% plant/soil, crop cover 0% plant/soil, crop cover 0% plant/soil, crop cover 10% in the soil

Month June Aug. July April April April April April April Jan. April

P 0.00 0.07 0.07 0.12 0.50 0.35 0.66 0.52 0.56 0.55 0.88

Rgro 0.00 0.00 0.00 0.32 0.00 0.69 0.00 0.45 0.84 0.89 0.60

Rsur 0.46 0.20 0.20 0.38 0.19 0.20 0.10 0.69 0.69 0.67 0.20

Rair 0.00 1.00 0.95 0.00 0.00 0.00 0.00 0.00 0.00 0.18 0.00

Ipest 0.09 0.13 0.14 0.19 0.28 0.36 0.38 0.49 0.58 0.59 0.61

Conclusions The IpeSl indicator can be used as a decision aid tool by farmers or extension officers to compare the environmental impact risk of pesticide treatments.

References Bouchon-Meunier. B., 1993. La logique floue. Presses Univ. de France, Paris, France, 128 p. Levitan, L. et al., 1995. Agriculture, Ecosystems and Environment 55: 153-168. Van der Werf, H.M.G., 1996. Agriculture, Ecosystems and Environment, submitted.

Author index


Author index

Abad, A 514 Acutis, M 86 Agüera, F 130, 132, 134, 172 Agarwal, A 496 Alavoine, G 222, 276 Aleton, B 434 Alexandrescu, A 298 Alexieva, A.S 640,674 Altimirska, R.A 320 Amaducci, M.T 198 Amigues, J.P 112 Angelini, L.G 516 Angonin, C 528 Annerose, D.J.M 74, 106, 118 Antûnez, M 322 Appel, T 324 Àrendâs, T 236 Arsène, G.G 362 Asanome, N 174 Auclair, D 618 Aufhammer, W 564 Aveline, A 326 Aydin, M 518 Babich, N 412 Baier, J 252 Baker, J.M 504 Balashov, E.V. 224 Balîk, J 704, 710, 714 Balko, Ch 76 Ballesta, A 328 Bannayan Awal, M 20 Bänziger, M 164 Bara-Herczegh, 0 332 Barben, P 136, 520 Bartosova, M.L 446 Baudet, D 530 Bavec, F 138, 330 Bavec, M 138, 330 Beblik, A.J 490 Bellocchi, G 226 Benincasa, P 554 Berecz, K 332 Bernardes, M.S 24, 160 Berti, A 348 Berzsenyi, Z 140 Bezdushny, M 572 Bindi, M 54 Black, CR 632 Blâha, L 142 Blâzquez, R 386 Blouet, A 666

Blount, J.W 700 Bobyleva, N.I 212 Bockstaller, C 228,414 Bogdanovic, D 230,696 Boixadera, J 322 Boixadera Llobet, J 340 Boizard, H 488 Bolanos, J 164 Bonari, E 226,684 Bonciarelli, F 444 Bondarenko, N.Ph 114 Bonet-Torrens, M 78 Bonhomme, R 190 Bonnet, A.-C 92 Booth, E.J 144,540 Borin, M 348 Borowiec, F 692 Bos, H.J 146 Bosch-Serra, A.D 78,340 Bouthier, A 526 Braga, R.P 148, 196 Breman, H 620 Brink, M 150 Brownlow, M.J.C 424 Bruckler, L 356 Bryson, R.J 522 Buchkina, N.P 676 Bujân, M 524 Bujak, K 470 Bulgakova, M 708 Bullock, P 14 Burda, V 302 Bürgi, H 410 Butcher, CS 416 Bzowska-Bakalarz, M 678 Cabelguenne, M 112, 498 Cabrera, F 544 Canarache, A 448 Carrai, E 658 Castelao, A 658 Castelao, A.M 524 Castellvi, F 80, 116 Castillon, P 526 Castrignanô, A 450, 452 Cazanga Solar, R 186 Ceccarini, L 516 Ceotto, E 258, 454, 492 Chapman, P.J 310 Chapot,J.Y 334 Chassin, P 238 Chaussod, R 372

Author index 721

Chauvel, B 528 Chiang, C 372 Clark, W.S 522 Cleyet-Marel, J.C 326 Colbach, N 456, 458, 528 Colnenne, C 336, 588 Colomb, B 530 Colucci, R 576 Conde, J.R 200 Conijn, J.G 622 Connor, D 72 Convertini, G 232, 234, 450, 452 Copchyk,Z.M 532 Cosentino, V 46, 56 Costea, M 298 Coutinho, J.F 288, 294, 368 Couture, S 112 Crafts-Brandner, S.J 642 Crnobarac, J 694 Crout, N.M.J 20 Crozat, Y 326 Csajbók, J 82 Csathó, P 236 Cupina, B 152 Cyran, A 62, 64 Czerednik, A 154 Daamen, C.C 598 Dal Rio, M P 358 Dauzat, J 624 David, C 418, 430, 586 de Barros, J.M.C 156 De Cock, L 158 De Giorgio, D 234 De Jaeger, 1 158 DeLorenzi, F 84,670 De Ruijter, F.J 534 de S. Câmara, G.M 24, 90, 160 de Toledo, V.C 240 Debaeke, P 498,600 Debreczeni, K 338, 460 Deflune, G 536 Dekkers, Th.B.M 290 Delmas, R 32 Delphin, J.-E 462 Delprat, L 32, 238 Demotes-Mainard, S 538 Denys, D 276 Dietrych-Szóstak, D 662 Dijkstra, P 22, 60, 62, 64 Dines, L.J 162 Dirks, B.O.M 40 Dixon, R. A 700 Djukic, D 152

Dobrescu, A 680 Domingo-Olivé, F 78, 340 Dominguez Giménez, J 172 Donatelli, M 86, 342, 454 Doneva, E.V 88 Doughty, K.J 540 Dourado-Neto, D 24, 90, 160 Dragovic, S 110 Drizhachenko, 1 712 Dubrulle, P 530 Dumanovic, Z 26 Durand, J.-L 92 Durkic.M 542,558 Eason,W.R 630 Edmeades, G.0 164, 166 Edwards, A.C 310 Eiland, F 390 Elgersma, A 188,242 Elings, A 164, 166 Ercoli, L 136, 182, 244, 246, 262, 344, Eric, P 152 Eroy, M 624 Etchebest, S 92 Ewert, F 168 Fabre, B 418 Falcimagme, R 68 Fancelli, A.L 24 Fardeau, J.C 312 Fayet, G 530 Fedeli, A.M 100 Feil, B 464 Feller, U 642, 664 Fereres, E 72 Fernandes, M.L.V 288, 294 Fernandez, J.E 544 Fernândez-Boy, E 544 Ferri, D 232, 234, 450, 452 Filcheva, E 266 Fischer, A 256 Fismes, J 546 Flotats, F.X 322 Flotats Ripoll, F.X 340 Fodor, L 706 Fornaro, F 506 Fotyma, E 548, 550 Fotyma, M 548,550 Fraser, AR 310 Frenda, A.S 350 Friesen, D.K 304 Frossard, E 304, 308, 312 Fuhrer, J 58 Füleky, Gy 292 Furgal, K 692


Gaetani, M 610 Gahoonia, T.S 296 Gak,E.Z 28 Gak,M.Z 28 Galan, M 552,572 Garcia Ruiz, R 172 Garibay, S.V 464 Gastal, F 92, 654 Gaunt, J.L 318 Gautronneau, Y 430 Gebbing, T 644,646 Ghesquière, M 92 Giardini, L 348 Gigout, M 530 Ginanni, M 520, 684 Giorio, P 84 Girard, M.L 346, 624 Girardin, P 228,414 Giupponi, C 348 Glaude, E 222 Gómez-Macpherson, H 170 Gonzalez, M.A 248, 274 Gonzalez-Rodriguez, A 660 Goudriaan, J 184, 306 Goulding, K.WT 496 Grandi,S 358 Greco, P 450,466,482 Grevsen, K 48 Grichanov, 1 412 Gristina, L 350, 370 Groenwold, J 22,60 Grossi, N 610 Grub, A 58 Guckert, A 546, 666 Guiducci, M 554,602 Guiking, F.C.T 468 Guinchard, M.P 648 Halmajan, H.V 298, 494, 680 Hammer, G L 44, 104, 184 Hansen, S 390 Harrison, R 250 Hassink, J 220,242 Haverkort, A.J 512, 534 Hay, M.J.M 300 Heineman, A.M 626, 628 Heiander, CA 420 Hellebrand, H.J 256 Hengsdijk, H 422 Hensen, A 40 Herzog, F 424 Hislop, M 630 Hölzner, R 642 Hoppe, G.M 630

Hristov,N 656 Hütsch, B.W 30 Huzsvai, L 108, 580 Ibanez, M 80, 116 Ikeda, T 174 Iwama, K 94 Jambert, C 32, 238 Janâcek, J 142, 302 Jansen, D.M 468 Jansen, M 62, 64 Jansen, M.J.H 22 Janssen, B.H 282 Jarvis, S.C 496 Jedruszczak, M 470, 612 Jeuffroy, M.-H 352, 538 Jolânkai, M 556 Jones, P 176 Jouan, B 570 Jovanovic, 0 34, 178, 280 Jovic,M 194 Juric, 1 542,558 Justes, E 276 Käding,H 256 Kalinowska-Zdun, M 392,592 Kaneko, T 94 Karvonen, T 96 Kaul, H.-P 354 Kawashima, H 94 Keane, E.M 176 Keating, B.A 44, 104, 184 Kessler, J.J 620 Kharitonov, N 708 Kilifarska, M 640 King, J.A 250 Kiniry, J.R 584 Kiriyama, H 254 Kirkham, M.B 126 Kleemola, J 96 Kieps, C 98 Klir, J 252 Knezevic, M 542, 558 Koeijer, T.J 426 Kolodziej, J 472 Kosovan, S 446 Kovâcs, G.J 580 Kozmiüski, C 36 Kren, J 560, 562, 582 Kresovic, B 208 Kruse, M 564 Kubât, J 220, 252 Kudums, A 712 Kuida, C 254 Kujira, Y 254

Author index 723

Kulig, B 566, 614 Kühbauch, W 646 Kurtener, D 38 Kyriakopoulus, K 10 La Loggia, F 84 Lafolie, F 356 Lamascese, N 574 Lange, A 568 Langeveld, CA 40 Langeveld, J.W.A 474 Lantinga, E.A 188, 428, 502 Lap, D.Q 140 Laruccia, N 86 Lascano, C E 304 Lasserre, F 570 Laureti, D 100 Leakey, R.R.B 2 Ledent, J.F 186 Lee, H.C 240, 536, 270 Leenhardt, D 356 Leffelaar, P.A 502 Leipnitz, W 256 Lemeur, R 158 Leterme, Ph 362 Lewis, C 540 Linères, M 238 Liniewicz, K 42, 472 Lipavskâ, H 650 Lipavsky, J 302 Lisova, N 552, 572 Lloveras, J 328,514 Lombardo, V 370 Longobucco, A 54 Lopez, A 386 López, E 658 Lopez-Real, J.M 270, 536 Losavio, N 574 Lötscher, M 300 Lott, J.E 632 Ludva, L 302 Lustrini, L 670 MacGillivray, C.W 18 Maciorowski, R 652 Madry, W 392, 592 Magliulo, V 84, 670 Maiorana, M 576 Maja, C 230 Malesevic, M 110, 230, 696 Mallo, F 386 Mambelli, S 358 Manzi, G 466 Marchetti, R 102, 258, 342, 454, 492 Marinkovic, B 694

Marinova Garvanska, S 260 Mariotti, M 136, 182, 244, 246, 262, 344 Mariscal, M.J 180 Marras, G 100 Martelo, J.M 202 Martignac, M 68 Martinez-Cob, A 80 Martorana, F 136, 182, 226 Maruhnyak, A.Y 532 Mary, B 216, 222, 362 Masoni, A 246,344 Matin, M.A 264 Matthews, K.B 416 Matula, J 682 Maurice, 1 654 Mazurek, J 50 Mazzoncini, M 226, 516, 520, 684 McAdam, J.H 630 McCartney, H.A 540 Meinke, H 44, 104, 184 Menconi, M 46, 54, 56 Mengel, K 286 Menini, S 520,684 Mészâros, 1 580 Meynard, J.M 336, 408, 458 Michalska, B 36 Michelena, A 514 Miele, S 610 Miglietta, F 54 Migni, M 554 Mihailovic, V 152 Mikkelsen, G 478 Millard, P 382 Minguez, M.I 200,512 Misa, P 476 Mitchell, D.T 604 Mitchell, R.D.J 250, 360 Mitova, T 266 Mladenov,N 110,656 Mladenovic, G 194 Moirón, C 658 Moreno, F 544 Moriondo, M 54 Morvan, T 362 Mosquera-Losada, R 660 Mouraux, D 186 Muhr, L 500 Mulholland, B.J 168 Murillo, J.M 544 Nâdasy, E 578 Nagy, J 122, 580 Najmanova, J 384 Nakeseko, K 94


Nalborczyk, E 154 Nassiri, M 188 Nâtr, L 650 Navari-Izzo, F 46 Neeteson, J.J 216 Neudert, L 582 Neumann, R 8 Newman, S.H 634 Nicolardot, B 222, 276 Nielsen, N.E 296 Nijland, G.0 596 Nocquet, J 430 Norton, G 540 Nwalozie, M.C 74, 106, 118 Oberson, A 304 Odinga, J.J 268 Olesen, J.E 48 Ong, CK 632 Onofri, A 602 Onuphrieva, 1 708 Orgaz, F 130, 132, 134, 180 Osborne, B.A 176, 604 Otegui, M.E 190 Overbosch, G.B 474 Paasonen-Kivekäs, M 96 Pâlinkâs, 1 698 Pantone, D.J 584 Papini, R 342 Pardini, G 610 Park, J 634 Pashova, V 708 Patyka,V. 572 Paveley, N.D 522 Pavlikova, D 384, 710, 714 Pavlyshyn, M.M 212 Pawlowska, J 662 Paz, A 248,274 Pechovâ, M 142 Pecio, A 192, 652, 662 Perez, P 116 Perez, P.J 80 Perovic, D 194 Peters, M 500 Petö, K 108,480 Pfarrer, R 664 Pietkiewicz, S 154 Pilbeam, C.J 364,598 Pinochet, X 326 Pinto, P.A 148, 196 Pinxterhuis, J.B 268 Piro, F 482 Pisulewska, E 692 Pisulewska, E.K 484

Pitacco, A 670 Podolska, G 50, 652 Pogorecky, A 572 Poma, 1 350,370 Popa, G 190 Popovic, T 34 Porceddu, E 6 Porta, J 322 Porter, J.R 18, 168 Posca, G 608 Poulik, Z 590 Pozdnyakov, V.A 712 Pritoni, G 198 Prodanovic, S 194, 656 Promayon, F 586 Przulj.N 110,656,696 Pucaric, A 486 Puech, J 112 Putaric, V 52 Rabbinge, R 6, 44, 104, 428, 436 Ragab, A.Y.R 140 Ragasits, 1 332 Rapini, R 492 Raschi, A 46, 54, 56 Reau, R 336,588 Recous, S 352 Richard, G 488 Richner, W 410 Richter, G.M 366, 490 Richter, J 490 Richter, 0 366 Richter, R 590 Ridao, E 200 Riedo, M 58 Rigueiro, A 658 Rikanovâ, J 590 Rinaldi, M 452, 506 Rivoal, R 570 Rizzo, V 232, 234, 452, 506 Robin, Ch 648 Rodriguez, D 306 Rodrigues, M.A.R 368 Rodrigues, M.S 270 Rokhinson, E.E 114 Roostalu, H 66 Rosell, J.1 80, 116 Rosset, M 58 Rossing, W.A.H 408 Roy-Macauley, H 74, 106, 118 Rozbicki, J 392,592 Rubaek, G.H 308 Ruiz-Nogueira, B 202, 204 Ruzicka, M 302

Author index 725

Ryan, J 364 Sâinz, M.J 524 Sail, M 118 Sancarlo, F 684 Sanchez, P 2 Santoalla, M.C 386 Sârdi,K 272 Sarno, R 350,370 Sau, F 202, 204 Savulescu, I 494,680 Sayre, K.D 510, 594 Sbaï, A 372 Scalabrelli, G 610 Scarpa, G.M 100 Schapendonk, A.H.C.M 22, 60 Scherer, H.W 374, 568 Schjönnig, P 390 Schneiders, M 374 Schnyder, H 644, 646 Schouls, J 596 Schultze-Kraft, R 500 Schvartz, Ch 372 Sciazko, D 62,64 Scofield, A.M 536 Scott, R.K 162 Seddig, S 76 Segers, R 40 Serça, D 32 Serio, F 574 Setatou, H.B 376, 378, 380 Sewalt, VJ.H 700 Sgherri, C.L.M 46 Shand, CA 310 Shopski, N 88 Sibbald, A.R 416,630 Sibbesen, E 308 Silvestri, N 226,520 Simünek, P 536 Simmonds, L.P 598 Simonis, A.D 376, 378, 380 Sinaj, S 308, 312 Sisak, 1 272 Skoric, M 120 Smith, J.W 500 Smith, S 310 Smolyar, E.1 28 Solcan, E 298 Soldati, A 410 Somers, B.M 432 Sousa, J.R 288 Sovero, M 144 Spallacci, P 102, 258, 342, 454, 492 Spasova, D 34

Stamp, P 410 Stankowski, S 62, 64, 652 Starcevic, Lj 230, 696 Stefan, V 494, 680 Stefanescu, D 298 Stockdale, E.A 496,318 Stockle, C.0 388, 498, 600 Stojsic, M 120 Streiff, K 666 Struik, P.C 444 Svendsen, H 390 Sylvester-Bradley, R 162 Szabó, L 686, 688 Szakova, J 704, 710, 714 Szalai, T 556 Szentpétery, Z 556 Szundy, T 314 Taboada, M.T 248, 274 Tabourel-Tayot, F 206 Tamâs, J 122, 580 Tamm, T 66 Tarawali, G 500 Tarawali, S.A 500 Tei, F 602 Teira,M.R 322 Teittinen, M 96 Teklehaimanot, Z 630 Thornton, B 382 Thorup-Kristensen, K 606 Tiessen, H 304 Tischner, T 314 Tlustos, P 384, 704, 714 Tolimir, M 208 Triboi, A.M 68, 434 Triboi, E 68,434 Trinsoutrot, 1 276 Tsadilas, CD 124 Ulasik, S 62, 64 Ungurean, L 680 Vago, D 298 Valentine, A.J 604 Valgus, T 66 van Dam, A.M 502 van de Geijn, S.C 18, 22, 60, 62, 64 van den Boogaard, R 606 van den Pol-van Dasselaar, A 40 van der Putten, P.E.L 608 van der Werf, H.M.G 716 van der Werff, P.A 290 vanderWilk, C 594 van Dijk, G 10 van Evert, F.K 504 van Ittersum, M.K 422, 436


van Keulen, H 44, 104, 278 van Noordwijk, M 636 Vandiepenbeeck, M 186 Vanek, V 384, 704, 710 Vanhoutvin, S 168 Varga, B 486 Vasic, G 26,208 Veerman, C 10 Végh, K.R 236,314 Veithof, G.L 40 Ventrella, D 506, 576 Venturi, G 198, 358 Vereijken, P 404 Veskovic, M 178, 280 Vidal, M 386 Videnovic, Z 26 Villalobos, F.J 130, 132, 134, 170, 172, 180, 210 Villar, J.M 80, 116, 388 Villar, P 116, 388 Villarino, J 658 Villette, C 530 Vintner, F.P 390 Voijslava, M 110 Volterrani, M 610 von Fragstein, P 438 Vonella, A. V 574 Vong, P.C 546 Vos, J 318, 502, 608 Vuckovic, S 194, 656 Wagner, D 588 Walker, K 540 Walker, K.C 144 Watt, T.A 240 Webb, J 250,360 Werner, A 256 Wesolowski, M 470, 612 White, J 166 Whytock, G.P 144 Wijnands, F.G 440 Witkowicz, R 484 Wolfert, J 502 Wood, M 364 Wossink, G.A.A 426 Wozniak, A 508 Wyszynski, Z 392, 592 Yan, Y 656 Yang, H.S 282 Zajac, T 484 Zayats, O.M 212 Zebrowski, J 154 Zelinschi, B 298 Zhang, J 126 Ziólek, W 566,614

Zimmer, C 716 Zugec, 1 558 Zvereva, T.S 676

Subject index


Subject index

abiotic stress 142 absorption 362 acid savannas 304 advection 80 agricultural development 6 agricultural production systems 436, 620 agricultural soils 248, 274, 366, 688 agro-ecosystems 220 agro-ecological indicator 228, 414 agro-ecological zones 14 agroforestry 424, 618, 620, 622, 630

632, 634, 636 air humidity 640 air temperature 42 alternative crops 574 alfalfa 46 alien cytoplasm 176 allelopathy 536 alley cropping 626, 628 Alopecurus myusuroides 528 alternative land use 424 amaranth 564 ammonia volatization 474 anatomy 654 arable farming 512 arbuscular mycorrhizal fungi 290 aridity index 52 aspargus 524 associative diazotrophs 572 atmospheric precipitation 42 atrazine 462

bambara groundnut 150 barley 66, 386, 714 bio-dynamic 536 biological recultivation 260 Bradyrhizobium japonicum 326 Brassica napus 276 bread wheat 514, 594 breeding 166 broom-rape 172 buckwheat 192, 564, 652, 662 bulk density 264 buried seed 144

cadmium 710, 714 calcium sulfate 254 canopy model 50 canopy resistance 84 canopy structure 146, 154, 188 carbohydrate 648

carbon dioxide 22, 40, 46, 54, 56 60,64,222

carbon-partitioning 206 castor 100 catch crop 334, 466, 502, 482 cauliflower 48, 606 cereals 296, 562, 590, 692 CERES-barley model 66 CERES-rice model 148, 196 CERES-sorghum model 452 CERES-wheat model 450 chilling 648 chlorophyll 642 Cinderella trees 2 climate 18,52,356 climate change 18, 22, 58 cocklebur 584 coconut based farming system 624 coenosys 556 composting 256, 270 computer modelling 122, 624 conductometric transducer 674 continuous cropping 178 copper deficiencies 526 cotton 124,518 cover crop 334, 370, 464 cowpea 74, 106 crop growth 18,336,490 crop growth analysis 140, 606 crop growth chamber 68 crop growth enhancement 22 crop growth model 14, 108, 156, 186, 206

388,480,502 crop juvenility 160 crop management 582 crop modelling 96, 202 crop protection 8 crop residues 216, 250, 360 crop rotations 82, 178, 232, 266, 428

434, 444, 466, 470, 482 crop species 136 crop water consumption 98 crop-livestock systems 500 cropping system 444, 454, 458, 476, 486

504,506 CropSyst 342,498 cultivar mixture 494 cumulative ryegrass P uptake 292 cytoplasm 176

dairy manure compost 240

Subject index 729

dairy rotational systems 660 decision aid tool 228, 414 decision rules 112 decision support system 416 decomposition 222, 276 defoliation 382,606 denitrification 238, 390 detoxication 708 development 6, 150, 170 dimetipin 662 disease resistance 594 drainage 96 drainage system 88 drought 120, 164, 524 drought adaption mechanism 74 drought duration 34 drought resistance 118 drought stress 76 drought tolerance 94 dry matter 392,574 dry matter partitioning 156 dryland 632 durum wheat 350,450,466,514 dynamic optimization 318

early vigour 132, 134 earthworms 684 ecological 144, 420 ecological cultivation 524, 562 ecological systems 478 ecophysiology 130 ecosystem 28 efficiency 426 electrothermal device 640 emission 32 emission of gasses 256 energy balance 84,476,562, 582 environmental impact 14, 430, 716 EPIC 446 eternal frozen soil 38 Europe 6 évapotranspiration 80 extractable organic N 324 eyespot 456

farming systems 228, 404, 408, 414, 420 farmyard manure 384, 710 fatty acids 540 fertilization 82, 280, 352, 372, 434

532, 580, 614 fertilizers application technologies 590 Festuca rubra 382 finite elements method 116

food quality 536 forage 692 forage systems 500 forecasting 20 forest soil 248 fungicides 522 furrow-irrigated 510 fuzzy logic 716

gas exchange 68 gaseous nitrogen losses 338 gene flow 458 genetic engineering 700 genetic inputs 148 genotypic variation 300 germination 118, 686, 694 gliadin 656 global warming 38 grain development 656 grain filling 644, 646 grain nitrogen content 346 grain protein 696 grain quality 62, 64, 110 grain yield 194 grapevine 54 grass cover 610 grassland 268,658 grassland ecosystem 58 green bulk 212 green leaf area 522 green pea 578 greenhouse effect 30 ground cover 472 ground water reserve 472 groundnut 118 groundwater 348

Henin-Dupuis model 226 halophytes 158 heat flux density in soil 674 heating 380 heavy metals 686, 706, 708, 710, 712, 714 herbicides 556 Heterodera avenae 570 horse bean 566 humic substances 224 humus 230 hypocotyl 134

I-WHEAT 44 immobilization 362 improved pastures 304 in vitro cultures 650


inbred maize lines 542 »identification index 182 indirect selection criteria 76 infiltration 264 informatie programme 98 infrared spectroscopy 310 inoculation 320 inorganic fertilisers 628 input-output combinations 426, 436 integrated crop protection 440 integrated farming 440 integrated management 570 integrated systems 478 intensive and low input management 592 interactive development of sustainable farming systems 432 intercropping 484 intraplant competition 560 irrigated maize 328 irrigation 100, 122, 356, 518, 580 irrigation water 114

Kenya 626 kernel number 538 kernel set 190

land use 618,630 land use allocation 416 land use technology 422 leaching 114,344,496,544 leaf 654 leaf area index 542 leaf emergence 168 leaf expansion 608 leaf growth 92 leaf photosynthesis 554 learning processes 432 legumes 484, 568 light absorption 554 light interception 162, 184 lignin 700 linear programming 408 Lolium multiflorum L 410 Lolium perenne L 60, 382 long-term experiments 196, 230, 278, 308 long-term fertilization 460 lucerne 492

magnetic field 114 maize 26, 84, 122, 124, 140, 164

178, 186, 208, 236, 238 240, 246, 280, 330, 376 460, 464, 486, 516, 520

26, 544, 580, 698, 704 maize genotypes 314 malting barley 110, 696 malting quality 110 manure 386 manuring methods 612 maturity 694 meiosis 666 methane 32, 40 methane evolution 254 methane oxidation 30 methods 86,658 micro-elements 614 microbial activity indexes 258 microbial biomass 372 micrometeorology 670 mineral nitrogen 384 mineralizable nitrogen 384 mineralization 250, 318, 350, 354, 360

364,370,380 minirhizotron 410 Mitscherlich equation 236 mixed fanning 428 modelling 44, 48, 58, 72, 166, 192, 226

278, 282, 346, 338, 390, 408 456, 458, 446, 490, 600

modular growth 560 mole drainage 88 molecular mass distribution 332 morphogenesis 648 mRNA 642 mulch 468 mutants 212 mycorrhizal infection 604

NAR 152 new modes of action 8 nintrification inhibitor 546 nitrate 340, 348, 370, 462, 544, 578 nitrate leaching 322, 356 nitrate reductase activity 358 nitrate-N 696 nitrification rate 378 nitrogen 104, 164, 182, 244, 246

250, 262, 270, 318, 340 344, 352, 354, 360, 380 428, 486, 496, 502, 538

572,578,664

nitrogen availability 372 nitrogen balance 386, 492 nitrogen compounds 32 nitrogen critical concentration 602 nitrogen deficiency 336, 528

Subject index 731

nitrogen dynamics 252 nitrogen economy 564 nitrogen fertilization 30, 332, 338, 368, 514

518, 548, 550, 566, 588, 704 nitrogen fixation 568 nitrogen fixing bacteria 320 nitrogen losses 474 nitrogen mineralization 216, 240, 324 nitrogen nutrition 298, 586, 650 nitrogen recovery 334, 376 nitrogen requirements 490, 600 nitrogen supply 468 nitrogen uptake 392 nitrogen use efficiency 368, 512 nitrous oxide 40 nodulation 326, 470, 680 nodule structure 680 nonexchangeable NHt+ 374 nutrient accumulation 272 nutrient availability 288, 294, 302 nutrient balance 444, 454 nutrient contents 274 nutrient dynamics 242 nutrient use efficiency 314, 474, 626, 628 nutrient utilisation 142 nutrients 248, 534, 596 nutrients dynamics 322

object-orientation 504 oilseed rape 336, 540 olive orchard 180 on-farm research 418 onion 78 open top chamber 62 optimal input 596 organic amendments 246 organic carbon 238 organic farming 418, 430, 438, 586 organic farming system 290 organic fertilization 350, 368 organic manuring 282 organic matter 220, 224, 266, 310 organic soilP 304 oriental tobacco 482 osmotic potential 126

particle-size fractions 312 peanut 74 peas 152,614 perennial grass 206 permanent fallow 366 pesticides 440, 716 pH 704

phenology 198,202 phenylpropanoid biosynthesis 700 phosphate 286,290 phosphate availability 292, 308, 312 phosphorus 244, 262, 296, 306, 310, 530 phosphorus distribution 300 phosphorus test 288,294 photoperiod 150 photoperiodism 160 photosynthesis 126, 158, 176, 516, 604, 608 photosynthetically active radiation 190, 210 phyllotaxis 174 phytic acid 298 phytotoxic 706 pig slurry 322,340,342 Piracicaba 24 plant ecosystem 28 plant canopy analyzer 210 plant community composition 676 plant densities 138 plant growth analysis 652 plant morphology 146 plant nitrate test 330 plant pathogen 712 plant protection 508 plant residues 222,276 planting date 204 planting systems 138 pod yield 106 policy 2 poplar 634 population dynamics 570 potassium 530,682 potato 76,94,534,608 potato cyst nematodes 534 potential yield 186, 196 precipitation 26, 42, 120 production estimation 658, 660

protein content 484 prototyping farming systems 404

radiation interception 200, 210 radiation model 180, 624 radiation use efficiency 48, 306, 574 rain intensity 102 rainfall 24 rape 56, 546 ratio N/S 546 redox potential 374 reduced tillage 510 relative growth rate 602 residual nitrate 328 residue 596


resource capture 636 resource use 560 Rhizobium strains 552 rice 254 risk benefit 8 root density 264 root distribution 78, 410 root growth model 78 root mass 256 root system 142 rotational fallow 366 roughness parameter 670 row orientation 208 runoff 102 ryegrass 188, 242

Sahel 620 salinity 158 saturated conductivity 102 seed quality 540 seed yield 192,662 senescence 642, 664 sensitivity analysis 148 silage 692 silvopastoral system 618, 630 simulation 28, 108, 354, 388, 480

504, 584, 622 simulation model 130, 132, 172 Slovakia 446 sludge 260 slurry 362 soil analysis 530 soil C and N 232,234 soil conservation 464 soil drying-rewetting 324 soil evaporation 598 soil fertility 230, 232, 252 soil fertility replenishment 2 soil management 348 soil microclimate 38 soil moisture 36, 488, 576 soil nitrate 328, 342, 492 soil nitrogen 330 soil organic matter 216, 226, 280, 282, 622 soil parameters estimate 86 soil phosphate 268, 286 soil physical properties 224 soil properties 272 soil solution 462 soil strength 576 soil temperature 168 soil testing 268 soil tillage 234, 488, 558

soil volume 262 soil water 390 soil water content 82 soil water deficit 516 soil water depletion 106 soil water potential 94 soils 258, 260, 288, 302, 308

312, 364, 448, 634, 682 686,688

solar radiation 154 sorghum 126,452 sowing rates 532 sowing term 50 soybean 174, 202, 204, 298, 326

470,584,680 spatial distribution 36 spectral component analysis 200 spectral properties 136, 182 spring barley 532, 548 spring wheat 168, 194 stability 194,676 stochastic simulation 24 stockless systems 438 stored soil water 90 subsurface irrigation 96, 244 SUCROS 20 sugarbeet 358,392,612 sugarbeet roots 678 sulphur 568 sunflower 130, 132, 134, 156, 172

670,694 sustainability 278, 422, 434 sustainable farming system 448 sustainable pest management 412 sustainable production techniques 426 sweet pepper 138, 602 synchronization 468

tall fescue 654 technogenic influence 52 temperature 378 thermal conductivities 640 thermoelectric transducer 674 thermoperiodism 160 tillage 520,684 tobacco 554 toxic elements 706 trace element 688 transgenic rapeseed 144 transpiration 598 trend analysis 302 tropical maize 166 tundra soils 676

Subject index 733

underplant crops 508 zinc deficiencies 526 upland farming systems 416

validation 196 variability 274 variety 152 vineyard 610 volcanic soils 294

wastewater 124 water balance 68,90, 116,548,550 water deficit 34, 92, 666 water infiltration model 116 water infiltration rate 576 water limitation 72 water management 112, 498 water potential 92 water relations 46, 54, 56 water soluble carbon 258 water use 506 water use efficiency 314,506,512, 598 water-soluble carbohydrates 644, 646 waterlogged soils 88 waterlogging 664 weed control 542 weed level 558 weed species 136 weed tolerance 556 weeds 520 West Africa 500 Western Europe 424 wetland rice 374 wheat 20,44, 104, 146, 170

176, 184, 270, 306, 346 352,364,494,510,538 644, 646, 656, 666, 684

wheat competition 528 wheat flour proteins 332 white clover 188, 242, 300 winter barley 212 winter hairy vetch 552 winter oilseed rape 198, 588 winter triticale 154,508, 592 winter wheat 50, 62, 64, 162, 236

344, 456, 460, 550, 558 582,586

workability 488

xFestulolium 712

yield 26, 174, 198,204,208,522 552, 566, 572, 594, 612


List of national representatives

Albania Sulejman Sulce Tel: +355 42 25500 Fax: not known

Belgium J.-F. Ledent Tel: +32 10 473458 Fax: +32 10 473455

Cyprus I. Papastylianou Tel: +357 2 305101 Fax: +357 2 316770

Czech Republic J. Kubat Tel: +42 2 360851 Fax: 42 2 365228

Denmark N.E. Nielsen Tel: +45 32283496 Fax: +45 35283460

Finland Païvi Nykänen-Kurki Tel: +358 55 230028 Fax: +358 55 178628

France A. Guckert Tel: +33 83 595837 Fax: +33 83 595804

Germany W. Aufhammer Tel: +49 7114592386 Fax: +49 7114592297

Greece A. Simonis Tel: +30 31471280 Fax: +30 31471280

Hungary G. Fuleky Tel: +36 28 330737 Fax: +36 28 310804

Ireland T. Storey Tel: +353 1 2693244 Fax: +353 1 2837328

Italy G. Zerbi Tel: +39 432 558618 Fax: +39 432 558603

National Representatives 735

The Netherlands S.C. van de Geijn Tel: +31317 475850 Fax: +31317 423110

Poland M. Fotyma Tel: +48 81 863421 Fax: +48 81864547

Portugal P.J.C. Aguiar Pinto Tel: +351 1 3637970 Fax: +351 1 3637970

Slovak Republic J. Vidovic Tel: +42 838 22311 Fax: +42 838 26306

Slovenia F. Bavec Tel: +386 62 226611 Fax: +386 62 23363

Spain M. Ines Minguez Tel: +34 15491122 Fax: +34 1 5449983

Switzerland A. Soldati Tel: +4152 339120 Fax: +41 52 332706

U.K. G. Rüssel Tel: +44 316671041 Fax: +44 316672601

North America M.J. Goss Tel: +1519 8244120 Fax: +1519 8245730


ESA Executive Committee

President:

Secretary:

President Elect:

Dr. Hubert Spiertz Research Institute for Agrobiology and Soil Fertility (AB-DLO) P.O. Box 14 NL-6700 AA Wageningen THE NETHERLANDS Fax: +31 317 423110

Dr. Philippe Girardin INRA, Laboratoire d'Agronomie P.O. Box 52 68001 Colmar Cedex FRANCE Fax: +33 89 72 49 33

Prof. Miroslav Zima Department of Plant Physiology Faculty of Agronomy University of Agriculture Nitra SLOVAK REPUBLIC Fax: +42 87 511593

Past president: Prof. L. Giardini Istituto di Agronomia generale e coltivazioni erbacee Universistà di Padova, via Gradenigo 6 35131 Padova ITALY Fax: +9 49 8070850

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