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Management of Organic Wastes for Crop Production :Kapoor, K. K., Sharma, P. K., Dudeja, S. S. and Kundu, B. S. (Eds.) 2005 pp. 193-203

Department of Microbiology, CCS Haryana Agricultural University, Hisar – 125 004

193CHAPTER 22

IS HIGH YIELD POSSIBLE WITH BIOLOGICAL

APPROACHES ?

O. P. RUPELA1, A. P. GUPTA

2and K.K. KAPOOR

3

1 International Crops Research Institute for the Semi-Arid Tropics, Patancheru - 502324,

Andhra Pradesh2 Department of Soil Science, CCS Haryana Agricultural University, Hisar-125004

(Superannuated March, 2004)3 Department of Microbiology, CCS Haryana Agricultural University, Hisar-125004

ABSTRACT

Biological approaches such as crop residues and biomass as surface mulch; growing

Gliricidia sepium on field bunds as source of nitrogen for crops; compost,

vermicompost and microbial biofertilizers as soil-building elements; and sources of

crop nutrients, and microbial and herbal biopesticides to protect crops have been

widely reported as valuable for crop production. Scope of these approaches to meet

crop nutrients and crop-protection needs in place of chemical fertilizers and pesticides

was examined. Published literature and websites were scanned to look for logically

sound comparisons, particularly at on-farm scale. Because farmers using organic

farming practices were the major users of some (not all) of the biological approaches,

we ended up comparing organic and conventional farms. Experiments with treatments

of biological versus conventional inputs (e.g. chemical fertilizers) within a given

experiment were the other source of relevant data for comparative performance.

Discussion in this paper is restricted to marginal and small farmers in rain fed areas.

From the limited evidence, it was apparent that yields comparable to conventional

agriculture were harvested by using biological approaches. In addition, a substantial

improvement in soil quality due to the biological approach was reported suggesting

that these yields would also be sustainable.

INTRODUCTION

A crop production system involving inputs of chemical fertilizers, pesticides,machinery for tillage and irrigation water is expensive. In addition, it threatens energy

and water security for future generations and contributes greatly to pollution,particularly when these inputs are inappropriately managed. Agriculture as practiced inthe early 20th century, without the modern inputs, is widely regarded as having lowproductivity. Practices such as no-tillage, green-manuring and use of farmyard manure(FYM); important features of the old agriculture, are also important ingredients of organic farming. These can be made more efficient by value-addition through thescientific knowledge gained in the later half of the 20th century. Crop production maythen be more sustainable without sacrificing productivity, the important concern of



Biological Approaches & Crop Yield194

those responsible for food security of a given country. This expectation is due to thepositive effects of practices such as conservation tillage, value-added composts (e.g. vermicompost, P-enriched compost), biofertilizers and biopesticides, as evident frompublished literature.

Use of chemical fertilizers is generally linked to the availability of water andmore so with irrigation (Sharma and Gupta, 2001) but use of chemical pesticides ismuch more wide-spread, including in rain fed areas and is generally determined by agiven crop. For example, raising of cotton crop uses over 40% of synthetic pesticides inIndia (Vijayaraghavan, 1995), and much of it is grown as rain fed. Local availabilityof these inputs is also an important determinant of their use. Villages not linked to citiesare likely to use relatively less of the purchased inputs than those close to cities or

linked by roads (Parthasarathy Rao et al., 2004). As per 1991 census, 78% of farmers inIndia are either marginal (owning <0.4 ha) or small (owing 0.4 to 1.4 ha). It is thesefarmers who may least afford the purchased inputs. But if there is sufficient evidencethat using the biological approaches, as used in organic farming, high yields or incomeare possible then these farmers would be the major beneficiaries.

Organic farming taken in strict sense, particularly when a farmer is looking fora certification by some agency (FAO, 1999), essentially most of the inputs have to begenerated on-farm. In this paper we are not touching this aspect of organic farming oreven organic farming as such. Focus here is to examine the scientific soundness of harvesting high yield using biological approaches. Comparisons where given betweenorganic farming and conventional farming are by default, because less number of experiments, particularly on-farm, were available for assessing the value of biologicalapproaches. Also, low-cost and biological approaches using locally available resources(including microorganisms) have been dealt as synonymous with the practices used inorganic farming.

LOOKING FOR EVIDENCES OF HIGH YIELD

Much of the information and some data that can be accessed on the topic of organic farming per se are through reports from farmers (Fukuoka, 1978) or farmer-groups (Murakami, 1991; IFOAM, 2004) with ideological approach. These groups alsoclaim that many organic farmers are harvesting yields at par their neighbor conventionalfarmers who use modern inputs. In the absence of sufficient data without the routinescientific rigor, such claims are not taken seriously by the scientific community. The

other sources of information noted through literature search were the reports onevaluation studies executed by governments (USDA, 1980) or by institutions withinterest and/or mandate on social and environmental issues (Harris et al., 1997). Allsuch evaluation reports generally supported the long-term sustainability of organicfarming, in view of economic viability of organic farms and improvements in soilhealth over time. Recent reviews (Stockdale et al., 2001; Delate and Cambardella,2004) have indicated good value of agro-practices used by organic farmers and haveindicated a scope of harvesting high yields on organic farms. Using no-tillage, biomassas surface mulch, microbial inoculants, compost as soil building element and



Management of Organic Wastes for Crop Production 195

biopesicides for protecting crops – overall called low-cost systems by Rupela et al. (2005a) resulted in similar or higher yield (Fig. 1) than the control treatment in all thefive years except year one. The control or mainstream agriculture treatment receivedchemical fertilizers and pesticides at levels recommended for a given crop in the region.The experiment comparing four crop husbandry systems was initiated in June, 1999 ona rain fed medium-deep Vertisol with annual mean rainfall of 783 mm.

Fig. 1. Yield and net income (in Rupees) over years from the four different systems of cropproduction (LS1, LS2, MA, MA+biomass) in a long-term experiment at ICRISAT, Patancheru,India. Intercrops taken in the different years were sorghum/pigeon pea in 2000/01 (year2),cowpea/cotton in 2001/02 (year 3), maize/pigeon pea in 2002/03 (year 4) and cowpea/cotton in2003/04 (year 5). Income was calculated by putting a price (common across all treatments) foreach item (both input and output). Per-day labor was priced at Rs. 75/- not distinguishingbetween farmer and family members. (1 US$ = ca. 45 Rupees).

Source: Rupela et al., 2005a.

0

1

2

3

45

6

7

8

LS1 LS2 MA MA+biomass

-10

0

10

20

30

40

50

2000/01 2001/02 2002/03 2003/04

Year

Net income (1000- Rupees)

Yield (total economic mass) t ha-1




Note : Low-cost system 1 (LS1) – received rice-straw (first 3-years only) as surface mulch(no-tillage), beneficial microorganisms and herbal extracts to protect crops from pests; compostas sources of nutrients; low-cost system 2 (LS2) – received farm waste in place of rice-straw, theother inputs were same as in LS1; conventional agriculture (MA) - received tillage, chemicalfertilizers and pesticides as recommended for a given crop by research institutes in the region,compost and loppings of Gliricidia were added to all the four treatments; conventionalagriculture plus biomass (MA+biomass) – received tillage and chemical fertilizers and pesticidesas in MA and quality and quantity of biomass as LS2.

Crop Nutrient Needs

If a crop has to yield, its nutrient need has to be met. The major question to be

debated is whether the nutrients needed for a high-yielding crop can be met throughsources other than chemical fertilizers or not. And more importantly, are thosealternatives available or can be made available to the crop and how? Indeed, biomass isthe engine of productivity of an organic farm. Critics have always indicated non-availability of large quantity of biomass needed to supply the nutrients for harvestinghigh yields, particularly for a non-legume crop. While respecting the view that biomassis indeed difficult to access for crop production, it is argued that large quantities can begenerated on-farm. Also, as an interim, the large quantities available near cities andfrom agro-based industries (Beri et al., 2003) can be transported to farm for priming afield before sufficient biomass is generated on-farm. Transporting of this resource maybe linked to drives to keep cities clean to offset costs. Rupela et al. (2005a) reported useof biomass from external sources for first three years. After that it was generated at the

field using different strategies. Production of over 10 t ha

-1

crop residues bysorghum/pigeon pea intercrop was measured at ICRISAT Patancheru (Rupela et al., 2005b). Leaf fall of pigeon pea, was measured to add another 3.1 t ha-1 which contained22 kg N and 2 kg P ha -1. Strategically selected crops in a system can thus be a source of biomass and nutrients. It was argued that if the crop residues were needed as cattle feedor as fuel, then either the cattle excreta after composting or equivalent quantity of othernon-economic biomass may be returned to land. In the on-going long-term experimentdescribed above, Rupela et al. (2005a) also reported production of 4.5 t ha-1 (dry mass)of loppings from Gliricidia grown on field bunds in year five. The bunds accounted for6.1% of the total area. Addition of the loppings to a field meant application of 103 kg Nand 6.7 kg P ha-1. This obviously means that a farmer need not depend on fertilizer Nfrom year five, at least in some types of soils and in areas receiving up to 783 mm rains.Contributions from biological agents such as microorganisms (both in soil andphyllosphere) for providing nutrients such as N from air and soil macro fauna, e.g. earthworms for playing important roles in nutrient cycling and crop production can besignificant and need quantification studies.

Soil Quality

Reganold et al. (1993) studied 16 pairs of farms in New Zealand. Each pairhad a farm using Biodynamic Agriculture (a type of organic farming) and a neighboring




conventional farm having similar crop, plantation or animal production system. Theorganic farms in most cases had significantly greater microbial activity, better soilstructure, more earthworms, lower bulk density and easier soil penetrability (Table 1).However, the results of the soil chemical analyses were variable. On per ha basis thefarms using organic farming practices were as often financially viable as theirneighboring conventional farms. Reganold et al. (1993) reported significantly moreorganic matter aggregated (both 0.5 to 3.0 mm and 0.25 to 10 mm size) in soil samplesfrom organic farms than conventional farms. In the ongoing long-term experimentRupela et al. (2005a) reported 17-27% more soil respiration, 28-29% more microbialbiomass C, 23-28% more microbial biomass N, and 5-13% more acid and alkalinephosphatase activity, and 3 to 6 t ha-1 of more organic carbon in top 20 cm profile at theend of year five, in the low-cost treatments using biological approaches as the major

inputs than the control treatment receiving recommended levels of chemical fertilizersand compost.

Table 1. Mean values of aggregated soils data from 16 pairs of farms each with

organic (bio) and conventional (con) farming

Soil Property All ‘bio’ farms All ‘con’ farms

Bulk density (Mg m-3) 1.07 1.15*

Penetration resistance (0 to 20 cm)(MPa)

2.84 3.18*

Carbon (%) 4.84* 4.27

Respiration (µl O2 h-1 g-1) 73.7* 55.4

Mineralizable N (mg kg-1) 140.0* 105.9

Ratio of mineralizable N to C (mgg-1)

2.99* 2.59

CEC (cmol kg-1) † 21.5* 19.6

*= significantly different at p<0.01, †= Cation exchange capacity in centimoles of cation charge(+) per kilogram of soil.

Source: Reganold et al., 1993.

Labor Needs

An important criticism of organic farming and thus on use of biologicalapproaches, and rightly so, is its high labor requirement. But it is argued that most smalland marginal farmers, may have a greater access to labor (family members) than to cashrequired for modern inputs. Important point to be considered is whether cost for thelabor will be compensated or not. Also, such farmers can potentially be viewed as self employed. Information on website (www.ifad.org/events/organic) of the InternationalFund for Agriculture Development (IFAD) based on evaluations done in Latin Americaand Asia suggested that organic farming offers a new opportunity for small farmers in




developing countries. It would, however, need supportive government policies thatfoster development in this sector.

BIOLOGICAL APPROACHES

Animals, (e.g. cattle and poultry) are an important component of a small farm(<0.4 to 1.4 ha) family in the semi-arid tropics – focus of this paper. For appropriate useof biological resources, the crops and animals need to be integrated. This section brieflydescribes the different biological approaches that can help poor farmers havesustainable yields and livelihoods.

Crop Residues/Biomass

Nutrients when added as biomass are not in a readily available form for cropsand need to be mineralized by microbial activity. It is widely accepted that only aportion of the N applied as biomass to the soil through soil incorporation is recoveredby the crop (Schomberg et al., 1994; Thönnissen et al., 2000). According to T. J. Rego,ICRISAT, this portion under Patancheru conditions would be about 10% in year one(unpublished data). Thus nutrients from a given quantity of biomass added in a year areavailable over several years. Also, a given quantity of biomass applied as surface mulchversus as incorporated in soil is likely to have different value and may take differenttime for degradation. Placed on soil surface the biomass serves as mulch and potentiallyhelps prevent loss of soil moisture (Hajare et al., 1997) and prevent soil degradation. Itmay also result in favorable conditions for microbial activity. The apparent differentniche with the two methods of biomass use – incorporation versus surface mulch,resulted in lower soil temperature (Rupela et al., 2005b) compared to conventionalagriculture treatment and is likely to have a different soil microbial and macro faunadiversity with a bearing on crop productivity and is an important researchable topic. Asindicated earlier, substantial quantity of biomass is possible if crops and cultivars areselected strategically such that biomass is produced without sacrificing on over allproductivity of the cropping system. In year 2001, Rupela et al. (2005b) harvested 4 tha-1 by thinning of cowpea (cv C-151) in a cowpea/cotton intercrop (sown as 4-rowscowpea, 1-row cotton), leaving the other two-rows for grain production. Non-removalof two-row of the fast-growing cowpea cultivar would have adversely affected thegrowth of cotton.

Composting

Virtually every crop residue can be composted. Composts are an importantinput for an organic farm. A farm dependent on composting and recycling the cropresidues is potentially more sustainable. Compared to the traditional pit method, theaerobic composting with addition of cellulose degrading plus P-solubilizingmicroorganisms such as Aspergillus awamori has been found efficient particularlywhen rock-P is added (Kapoor et al., 1990; Rupela et al. 2003b). Phosphocomposts –the composts having rock-P additions during composting and thus rich in P are also




available commercially. Partially decomposed composts are a good feed for earthworms.Compost prepared involving earthworms is referred as vermicompost and is generallyrich in plant growth promoting substances besides other values generally stated forcomposts. The different types of composts should be viewed as soil-building elementsdue to their richness in potentially beneficial microorganisms, besides being a source of nutrients.

Gliricidia

Gliricidia sepium is a leguminous tree and can be grown on field bunds withoutapparent negative effect on a crop growing in its vicinity. After an initial care in yearone, particularly during summer, the tree may survive dry periods in several soils and

rainfall regions and need to be evaluated. It is a potential source of nitrogen for cropsand a fodder for cattle. Grown on field bunds, banks of percolation tanks and nearmechanical structures in Thanh Ha watershed, Hoa Binh province, Vietnam, largequantity of biomass was harvested that resulted in 100 to 200 kg N ha-1 when applied toa field.

Biofertilizers

Any organic farm is likely to be rich in several different types of agriculturallybeneficial microorganisms particularly those with traits of cellulose degradation,nitrogen fixation (both symbiotic and asymbiotic), P solubilization, plant-growthpromotion and biocontrol. But in initial years their addition is highly recommended.India has over 100 companies engaged in manufacture and marketing of microbialinoculants with these traits. A knowledgeable farmer should use these inputs for use atleast in the first three years. There is, however, a need of policy support to ensure thatfarmers receive good quality inoculants.

Biopesticides

Several herbs with ability to manage insect-pests are known to farmers. Societyfor Research and Initiatives for Sustainable Technologies and Institutions (SRISTI) hasdone a commendable job of preparing a database on these and other knowledge itemsrelevant to rural trades. A good number of these can be viewed on their website(www.sristi.org). There is an ever-growing interest in the different types of biopesticides (Grzywacz et al. ,2005). Neem seems the most studied herb (Singh and

Saxena ,1999). There are over one hundred biopesticides patented globally, most of these in USA. Farmers, generally in developing countries seem to be busy in preparingtheir own recipes for managing pests, and at times with good results. For example, acurd-based recipe has been reported to manage cotton-pests in Maharashtra, India(Amin ,2002). It may be noted that curd has four different human-friendlymicroorganisms (Hanniffy et al., 2004) known to produce organic acids which maychange phyllosphere pH potentially unfavourable to insect-pests. In the low-costtreatments of the long-term experiment Rupela et al. (2005a) successfully used a




protocol for crop protection involving two microorganisms Bacillus subtilis BCB 19and Metarhizium anisopliae (both research products of ICRISAT with ability to kill Helicoverpa larvae), wash of compost of two herbs (neem- Azadirachta indica andGliricidia sepium) and two items of traditional knowledge. The same protocol was usedsuccessfully in protecting cotton from insect-pest in on-farm experiments in Adarshawatershed of village Kothapally, Medak district, Andhra Pradesh in 2003/04 and2004/05 seasons and in village Chawad, Valia taluka, Bharuach district in Gujarat in2004/05 season. The results have been encouraging. Most farmers harvested yield of cotton at par or more when the half acre plot (1 ha = 2.42 acres) was protected withbiopesticides than the other half acre protected with chemical pesticides. Some moreinformation on the Kothapally experience is available in ICRISAT (2005).

Termites

Biologically, termites are detritivores meaning feeding on dead biomass buthave been occasionally noted to damage live plants. They have a very important role inthe overall cycle of life. But in conventional agriculture practices these have beenprojected as enemies attracting chemical pesticides .In the long-term experiment statedby Rupela et al. (2005a), termites were successfully managed by digging termitaria insearch of queen and killing it. After the queen was killed in the eleven termitaria notedin year one of the trial on a one ha area, only 1 to 3 new termitaria were noted annuallyin the subsequent five years. No need of any pesticide was felt to manage termitesduring six-year (Jan 1999 to March 2005) life of the ongoing experiment despite thefact three of the four treatment, received lot of biomass. Termites can be valuable not

only in forest ecosystems but also in the crop production system. In Africa, farmerscollect and apply termitaria soil to cropped fields as this is believed to enhance cropgrowth. Rupela et al. (2003a) reported bacterial population of 4.72 log10 g-1 termitariasoil with ability to suppress disease-causing fungi. Termites are thus a biologicalresource with potential to enhance crop production.

CONCLUSIONS

Indeed, maximum yields in the long-term experiments in India have beenreported from treatments receiving both chemical fertilizers generally recommended forthe different crops in a given region, and composts – the treatment is generally calledintegrated nutrient management (Yadav et al., 2000; Singh et al,. 2004). Data shared inthis paper also suggested highest yield in the treatments receiving both types of

nutrients. But for small and marginal farmers in the rain fed areas, inputs of suchtreatments may not be affordable and at times not even accessible. The low-costbiological approach (es) discussed here are indeed organic farming plus and may be anattractive choice particularly when their strategic application results in yield levels atpar conventional agriculture. Such a system of crop husbandry with yields comparableto conventional agriculture may be more acceptable to policy makers as it can alsogenerate employment and can potentially address the problem of human migration fromvillages to cities. It also offers a challenge for the agricultural fraternity who should




evaluate such an approach in different climatic regions and soil types. For those withinterest and stakes (e.g. NGOs and public-sector organizations committed to povertyalleviation) in the indicated biological resources, it is an opportunity worth investing.

Acknowledgements: We thank the watershed team at ICRISAT led by Dr S.P. Wanifor help in collecting some information from their on-going work; P. Humayun, P.V.S.Prasad and J. Nalini for collecting literature and typing the manuscript.

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