research compendium - central west farming...

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RESEARCH COMPENDIUM 2016

2 CENTRAL WEST FARMING SYSTEMS Harvest Compendium 2016

“Farmers Advancing Research”

Central West Farming Systems Research Compendium 2016

Published by: Central West Farming Systems, June 2016

CWFS Staff Involved: Diana Parsons, Dr Neil Fettell, John Small, Helen McMillan, Jamie Thornberry, Nick Hill, Scott Chamney, Debbie Anderson, Diana Fear, Julie Low, Glen Forbes, Mitchell Coote and Neil Williamson.

Technical Editing: Dr Neil Fettell & Dr Nigel Wilhelm

Feedback on this publication is welcome. Please contact Diana Parsons CWFS CEO on (02) 6895 1015 or email [email protected]

Disclaimer: The information presented in this compendium should not be taken as advice and may not apply to your circumstances. Readers must obtain their own advice and conduct their own investigations and assessments of any proposals they are considering, in light of their own individual circumstances. Information is subject to change without notice and neither CWFS nor its staff or third party authors accept any liability from the interpretation or use of the information set out in this document.

Please acknowledge the author and CWFS if any information contained in this publication is reprinted.

www.cwfs.org.au www.cwfs.org.au/cwfs_blog

@CWFSystems

@Central West Farming Systems

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Introduction 04Executive Committee 04Sponsors & Funding bodies 05Foreward 06Chairman’s report 07CEO’s report 08Farming systems 09Maintaining profitable farming systems 09 Risk management strategies for growing canola 11 Comparing break crops performance in SA Mallee 15 Are green manure cover crops a viable option 21 Seeding rate by row spacing 25 Sowing early to maximize wheat yield on low fallow 31 Area cultivated during the summer fallow has increased on recent years 37Livestock grazing behaviour 40Stubble and soil management 44Soil acidity 44Seasonal effects of strategic stubble treatments on Wheat & Barley 53 Stubble efficiency, stubble grazing Condobolin 60 Seasonal effects of strategic stubble treatments on nitrogen response 66 Good stubble, bad stubble 71CWFS Long Term Trial 2015 80Weed management 88Using sowing direction & row spacing for weed management 88Row orientation & weed competition 94Advertising 98Membership Form 109

TABLE OF CONTENTS

CONTENTS


Central West Farming Systems - Executive Committee 2016Chairman Peter StuckeyVice Chairman Paul Adam

Vice Chairman Sarah JacobsonSecretary David McDonaldTreasurer Bruce Patton

Committee Member Lawrence HigginsSteven HodgesRuth KlingnerGeorgie LuelfGraham McDonaldDavid Watt

Skills Based Rep—Graham Centre Toni NugentSkills Based Rep—AgnVet Matt McRaeSkills Based Rep—NSW DPI Ian Menz

Acknowledgment to co-operating farmersCWFS would like to acknowledge the support provided by the co-operating farmers, without their in-kind support the trials would not have been possible.

CENTRAL WEST FARMING SYSTEMS EXECUTIVE COMMITTEE 2016

EXECUTIVE COMMITTEE

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CWFS MAJOR FUNDING BODIESGrains Research and Development Corporation (GRDC)Federal Department of AgricultureLandcare AustraliaCSIRO

CWFS PLATINUM SPONSORGrainCorp

CWFS DIAMOND SPONSORSADM (Archer Daniels Midland)NSW Department of Primary IndustriesGrainGrowers

CWFS SILVER SPONSORSFarm Oz (ADAMA)

CWFS BRONZE SPONSORSAuswestAWBCBH GrainHeritage SeedsEmerald GrainFarmanco

CENTRAL WEST FARMING SYSTEMS SPONSORS & FUNDING BODIES

SPONSORS & FUNDING BODIES


There has been a lot of change in the Grains Research and Development Corporation’s (GRDC) over the past twelve months. Firstly a restructure of the three representative panels so that the Northern Region Panel are now responsible for the entirety of New South Wales and Queensland. This realignment has meant that the Northern Panel can now more efficiently oversee regional investments, particularly with our state based partners and concentrate on investments that local and practical solutions to growers’ production challenges.The second change has been the opening of two regional offices, one in Toowoomba Qld and one in Dubbo NSW increasing the staff based in the region from one to five with plans to further decentralise roles in the future. This will allow more regional touchpoints and ensure that local and regional issues are incorporated into future investments. A third has been the development and recognition of the regional network of R&D nodes across the Northern Region at Emerald, Darling Downs and Goondiwindi in Queensland, and Narrabri, Tamworth, Trangie, Condobolin, Wagga Wagga and Yanco in New South Wales.Each node has a combination of research agronomists and technical staff and the necessary equipment to conduct detailed trials, which vastly increases the scope and resourcing for R&D projects and allows for better pooling of data to fast-track results.

In my particular workspace, regional grower services role is to ensure that R&D from the nodes is validated on a local level and then through investments in extension and communications delivered to growers. Change is occurring here as well, as GRDC increases its focus on local communication and extension, tailored to the local audience.Grower groups such as Central West Farming Systems are pivotal to the effective extension and communication of research to grower membership. We can ‘know’ from statistically significant research results that a practice or technology is the best recommendation for growers, but often that research needs to be demonstrated in the local farming systems to give the confidence to make a change. When taking the results from complex research to integrate into a local farming system we have to be aware that group learning, local knowledge and practical experience are all required to move along the pathway of adoption. I am proud to introduce the CWFS compendium which includes locally relevant research that is funded by your grower levies and I look forward to working with you in the future to ensure that the results of the most cutting edge grains R&D are available to you to implement change on a paddock level.

Sharon O’Keeffe GRDC Manager Regional Grower Services – North

GRAINS RESEARCH AND DEVELOPMENT CORPORATION FOREWARD 2016

“I am proud to introduce the CWFS compendium which includes locally relevant research that is funded by your grower levies”

FOREWARD

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A promising start to 2015 unfortunately gave way to a tough finish.Favourable sowing conditions at the start of the season became hampered by minimal moisture in the latter part of the season. This, of course, resulted in poorer yields around the district.The aim of CWFS is to develop and implement strategies which address the challenges of farming. In 2015 CWFS continued to offer this support through their many projects incorporating a range of field days, workshops and information updates.Strong attendance at field days highlights not only the need for relevant and constructive information, but also CWFS’ regard as a reputable and respected organisation within the farming community.CWFS has continued to recognise the valuable role women and youth play in agriculture by hosting a variety of workshops and excursions aimed at this audience. These events were particularly well received with a high level of enthusiasm and engagement. Innovative farming practices were also popular with events including farming and drones field days.CWFS has embraced the digital world with podcasts and Twitter accounts. However, we appreciate that not all members can access these services due to internet constraints. For those in this situation the newsletter is a vital means of communication and one in which many people contribute to.

This year we welcomed Helen McMillan to the CWFS team. I also extend thanks to our hard working staff, led by our CEO, Di Parsons, for whom without her dedication and passion, CWFS would not be the credible organisation it is today. Thank you to NSW DPI, GRDC and all our funding partners for their ongoing support. This support ensures our continual growth and security of our organisation.I also acknowledge our executive members for their time and commitment to CWFS.We look forward to another promising year for CWFS.

Peter Stuckey Chairman Central West Farming Systems

CENTRAL WEST FARMING SYSTEMS CHAIRMANS REPORT 2016

“Strong attendance at field days highlights not only the need for relevant and constructive information, but also CWFS’ regard as a reputable and

respected organisation within the farming community”.

CHAIRMANS REPORT


CWFS staff and executive have had another exciting and successful year, with successes at both a regional and national level, and a full suite of projects. We welcomed Helen McMillan to the CWFS team as our new Agronomist Team Co-ordinator. Helen was previously employed as a Pastoral Production Officer with the Northern Territory Department of Primary Industry & Fisheries based in Tennant Creek. Helen replaces Nick Hill who moved across to NSW DPI, and we wish him well in his new role and thank him for his efforts whilst a member of our team.CWFS has spent a great deal of time developing the Lachlan Irrigation Research Facility (formerly LIRAC) site in the past twelve months. 2015 saw approximately 7000 trial plots located at the site, which is becoming valuable resource for not only CWFS, but also for industry stakeholders (including CSIRO and a number of universities), and for the Central West NSW region. We are committed to continuing to develop it as a regional resource. In addition, the commercial crops which are also grown at the site are aimed at assisting CWFS become partly self funding. CWFS was also excited to include a livestock component to our suite of projects, and look forward to working with the livestock industry stakeholders in the future. We welcome input or suggestions from members to ensure future livestock RD&E activities are locally relevant.Our regional site program remains a valuable asset for CWFS and I would like to thank the co-operators and project partners for their ongoing support. Our spring field days, ‘Barley to Beer’ evenings and numerous workshops continued to be popular, and I would like to thank everyone involved in these events. Examples of some of the workshops included technologies (eg

drones), women & youth, being an instigator of a social media pilot project with CSU and GRDC Updates in Parkes, Nyngan and Cowra. In addition, CWFS was invited to participate in some exciting opportunities to showcase our projects. CWFS was heavily involved in the two day 2015 Agribusiness Today Forum – Mixed Farming Systems of the Future which was held in Forbes. Topics ranged from tropical grasses in the central west, future technologies and climate scenarios, with a field trip to Dan Mattiske’s shearing shed to learn about developing livestock technologies and management systems. CWFS was invited to be part of the feature exhibit at the Australian National Field Days in Orange, and hosted a group of USA university students mid-year.At a national level, CWFS showcased a number of projects being undertaken. These included two scientific papers which Neil Fettell co-authored; the first being a paper which was presented at the Australian Society of Agronomy Conference 2015 titled “Novel wheat genotypes for early sowing across Australian wheat production environments”; and the second was a presentation at the GRDC Research Update, Wagga Wagga titled “Early sowing in 2014 – how did it go?” John Small also presented a paper “Good stubble bad stubble” at the GRDC Grower Update in Parkes.I would like to thank our funding bodies and members for your continued support. Without this support, CWFS would not be as successful as it would be in delivering relevant RD&E to the Central West NSW region.

Diana Parsons Chief Executive Officer Central West Farming Systems

CENTRAL WEST FARMING SYSTEMS CEO’S REPORT 2016

“2015 saw approximately 7000 trial plots located at the site, which is becoming valuable resource for not only CWFS,

but also for industry stakeholders”.

CEO’S REPORT

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MAINTAINING PROFITABLE FARMING SYSTEMS WITH RETAINED STUBBLE.

The GRDC initiative, Maintaining Profitable Farming Systems with Retained Stubble, or the “Stubble Initiative”, is a five year program to address the issues encountered by growers when retaining stubbles from one year to the next.Based in the southern cropping region, the initiative involves farming systems groups in Victoria, South Australia, southern and central New South Wales and Tasmania collaborating with research organisations and agribusiness to explore and address issues for growers that impact the profitability of cropping systems with stubble, including pests, diseases, weeds, nutrition and the physical aspects of sowing and establishing crops in heavy residues.The initiative aims to address the issues with stubble retention, quantify the effects that these issues are having on yield and profitability, develop practical solutions and then extend the knowledge to grain growers and their advisers.The farming systems groups involved are developing regional guidelines and recommendations that growers can implement on-farm to help them to consistently retain stubbles. The ultimate goal is to provide southern growers with practical information to guide their crop management, underpinned by results from local trials across the southern cropping region. While each grower group is investigating their own locally relevant issues, there are common issues across the region that are also being addressed in a consistent manner by the groups, with the support of the CSIRO research team led by Dr John Kirkegaard.The groups and organisations involved are BCG, on behalf of Southern Farming Systems, Victorian No Till Farming Association and Irrigated Cropping Council; Mallee Sustainable Farming Systems Inc; Riverine

PROFITABLE FARMING


Plains Inc; Central West Farming Systems; Farmlink Research Limited; Eyre Peninsula Agricultural Research Foundation; Lower Eyre Agricultural Development Association; MacKillop Farm Management Group; Upper North Farming Systems; and Yeruga Crop Research, on behalf of the Mid North High Rainfall Farming Systems Group and the Yorke Peninsula Alkaline Soils Group. Hart Field Site group is also participating in the initiative, with South Australian Grains Industry Trust (SAGIT) funded trials (H0113 and H0114).Research support is being provided by CSIRO, and SA Research and Development Institute’s Naomi Scholz has been appointed to assist with co-ordination and communication. For more information, contact your local grower group or Naomi Scholz, SARDI [email protected] (08) 8680 6233.GRDC Project codes: BWD00024, CWF00018, EPF00001, CSP00174, LEA00002, MFM00006, MFS00003, RPI00009, UNF00002, YCR00003, DAN00170.

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RISK MANAGEMENT STRATEGIES FOR GROWING CANOLA IN THE LOW RAINFALL ZONE.

Michael Moodie1 Mick Brady2 Andrew Ware3 Therese McBeath4

1MSF, Mildura 2DEDJTR, Mildura 3SARDI, Port Lincoln 4CSIRO, Adelaide

WHY DO THE TRIAL?For canola to be a sustainable, long-term break crop option for low rainfall farmers, low risk management systems need to be investigated. This project was undertaken to identify strategies that minimise the risk of canola production in the low rainfall zone. This will improve the long term profitability of canola in low rainfall farming systems.

HOW WAS IT DONE?Two trials were established in the low rainfall zone in 2015; at Ouyen in the Victorian Mallee and Minnipa on the Eyre Peninsula. Treatments were a combination of three factors: • Timing of Sowing-early (21-22 April) or later (6-7 May) sowing; • Variety- Hybrid (Hyola 450) or open pollinated (stingray) variety;• Timing of nitrogen (N) application- N applied either at seeding,

early post emergent, bolting or flowering.

KEY MESSAGES• Contrasting canola yields were observed at two sites in 2015

highlighting both the potential and the risks of growing canola in the southern Australian low rainfall zone.

• Sowing at the earliest opportunity and applying N at seeding or early in the crop’s development produced the highest grain yields.

• Purchasing hybrid canola instead of using farmer retained open pollinated canola provided no advantage in 2015.

RISK MANAGEMENT STRATEGIES


BACKGROUNDRecent research and farmer experience throughout the southern Australian low rainfall zone has demonstrated the benefits that canola can have as a break crop within intensive cropping rotations. Through a reduction in root disease and weed burdens, cereal crops following canola in the low rainfall zone have consistently yielded up to 0.4 t/ha more than maintaining continuous cereal. While the rotational benefits provided by canola have been evident, many growers in the low rainfall zone have been frustrated by the highly variable profitability of canola as a stand-alone crop. Over the past five years, the productivity and profitability of canola has been impacted by dry springs, high input costs and episodic pest incursions. For canola to be a sustainable, long-term break crop option for low rainfall farmers, low risk management systems need to be investigated. Therefore, trials were established at two locations (Ouyen, Victorian Mallee and Minnipa, Upper Eyre Peninsula) in 2015 to identify if management strategies could be employed to lower the risk of growing canola in the low rainfall zone while enhancing the profitability of canola as stand-alone crop. These trials are part of the GRDC funded Optimising Canola Profitability Project currently underway across New South Wales, Victoria and South Australia (CSP00187).

METHODOLOGYIn 2015 replicated trials were established at Ouyen (Victoria) and Minnipa (South Australia) were established using a common set of treatments. Treatments were a factorial combination of the following management strategies:• Time of sowing: fixed date (sowing regardless of moisture in mid-late April) or waiting until after the break

of the season.• Variety: open pollinated (low cost grower retained seed) seed compared to hybrid (higher cost) seed.• Timing of N application: Four N application timings: at sowing, post emergent; bolting and flowering. Sowing occurred at Ouyen on the 22nd of April and 7th May for the early and late sowing dates respectively. Sowing at Minnipa occurred exactly one day earlier for sowing treatments. Canola was sown at a seeding rate of 2.5 kg/ha with treatments sown to either the hybrid variety Hyola 450 or the open pollinated (OP) variety Stingray. Both varieties are triazine tolerant (TT) and stingray seed, which was graded to extract large seeds (>1.8 mm), was sourced from a farmer near to the Minnipa site.Nitrogen was applied as urea at the same rate (150 kg urea/ha) at all application times. At Ouyen, concerns about the likelihood follow up rainfall post application led to N being applied simultaneously for the both early and late sowing dates of sowing treatments for each of the three in-crop application timings. The in-crop N application dates for Ouyen were the 26th May (post emergent), 10th July (bolting) and 31st July (flowering) with at least 4 mm of rain falling in the two days following each N application. At Minnipa, N timing matched the target growth stage for each time of sowing treatment. Nitrogen was applied to the fixed sowing date treatments on 12th June, 7th July and 21st July and the later sowing date on 7th July, 31st July and 10th August for the respective post emergent, bolting and flowering N application.Both trials received 100kg/ha of single superphosphate at sowing to supply phosphorus and sulfur. Weeds were controlled in each trial using group A, C and D herbicides. Multiple products were used during the season to control insects including aphids in spring.

RESULTSBoth sites received timely rainfall to ensure moist seeding conditions and good establishment for both sowing dates. The Ouyen site received 35 mm of rain in April and a further 23 mm in May while 35 mm of rainfall also fell at Minnpa in April with a further 16 mm in May. However, growing season rainfall (GSR) was vastly different between the two sites. At Ouyen, GSR was 140 mm which is approximately 50 mm below the long term average. Minnipa received 250 mm of GSR of which is close to the long term average. Both sites experienced extreme temperatures in October with maximum temperatures above 35oC for 5 days at Ouyen and 7 days at Minnipa.Canola yields at Minnipa were nearly five times greater than at Ouyen with an average of 1.55 t/ha and 0.33 t/ha respectively across all treatments. However, despite the vast yield differences, similar treatment effects were observed at both sites.Early time of sowing of improved yields at both sites (Figure 1) although this was only significant at Minnipa. A two-week delay in sowing at Minnipa resulted in a yield reduction of 0.27 t/ha or 16%. At both sites, variety choice made little difference to grain yield (Figure 2) even through the hybrid variety had produced significantly

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more biomass by mid flowering than the open pollinated variety. Early application of N produced higher grain yields at both sites (Figure 3). At Ouyen, applying N at seeding resulted increased yields by 18% relative to the other timings. There was no significant difference in grain yield between the other N timings. At Minnipa, seeding and post emergent N applications improved yields by 0.2 t/ha or 12% over the later timings.

Figure 1: Canola grain yield for Ouyen (A) and Minnpa (B) for the fixed (early) and break (late) sowing dates. The bars represent the standard error off the mean with Ouyen (n.s.d) and Minnipa (P=0.037).

Figure 2: Canola grain yield for Ouyen (A) and Minnipa (B) for Hyola 450 (hybrid) and Stingray (open pollinated) varieties.


The bars represent the standard error of the mean with Ouyen (n.s.d) and Minnipa (P=0.017).Figure 3: Canola grain yield for Ouyen (A) and Minnipa (B) for the seeding, post emergent, bolting and flowering nitrogen applications. The bars represent the standard error of the mean with Ouyen (P=0.01) and Minnipa (P<0.001).

IMPLICATIONS FOR COMMERCIAL PRACTICEThe aim of these trials was to test if the risk of growing canola can be reduced in the low rainfall zone. Sowing at the earliest opportunity and applying N at seeding or early in the crops development produced the highest grain yields at both Ouyen and Minnipa despite vastly different yields at the two sites. This limits the ability to reduce risk by waiting for yield potential in response to seasonal conditions to be better understood as yield is compromised by delaying management decisions and inputs. However, using a hybrid variety provided very little benefit at these sites in 2015, suggesting that hybrid canola does not provide large enough production benefits to justify the significant cost of seed in the low rainfall zone.This paper summarises the yield outcomes from these trials, however an important consideration is the impact on profitability. Similar experiments are continuing at these sites in 2016 with the trial program also expanding into the South Australian Mallee at Karoonda. The combined dataset from 2015 and 2016 will form the basis for an economic analysis to determine the profit-risk trade-offs of management decisions when growing canola in the low rainfall zone.

ACKNOWLEDGEMENTSThank you to the Grains Research and Development Corporation (GRDC) for providing the funding. Thank you to Alan Crook and the Minnipa Agricultural Centre for providing the land to the trials. Thank you to Dr. Ray Correll (Rho Environmetrics) for completing the statistical analysis for these trials. ATR Stingray is a registered variety of Nuseed Pty Ltd. Hyola 450TT is a registered variety of Pacific Seeds.

FURTHER INFORMATIONMichael Moodie, Mallee Sustainable Farming Email: [email protected] Phone: 0448612892

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COMPARING BREAK CROP PERFORMANCE IN THE SA MALLEE.

Michael Moodie1 Todd McDonald1

Nigel Wilhelm2 Ray Correll3

1Mallee Sustainable Farming, Mildura 2SARDI, Waite Campus 3Rho Environmetrics Pty Ltd, Adelaide

WHY WAS THE TRIAL WAS DONE?Trials were implemented to compare break crop productivity and profitability on major soil types in the northern South Australian Mallee. This information will help farmers in this region to select the most appropriate break crop for their farming system.

HOW WAS THE TRIAL WAS DONE?Trials were established at Waikerie and Loxton with two trials implemented at each site on contrasting soil types. At the Waikerie site, one trial was located on a sandy loam and the other on a shallow heavier soil with limestone while at Loxton trials were located on either a red loam or a deep sand. The break crops represented in the trial were field pea, vetch, chickpea, lentil, lupin and canola. In 2015, the Loxton site was sown on 28 April and the Waikerie site on 1 May.

KEY MESSAGES • Break crops faced a range of tough environmental conditions in

the Mallee in 2015 including multiple frost and heat shock events.• Timely rainfall in April and hence early sowing resulted in excellent

biomass production with most crop options producing on average more than 2 t DM/ha and several break crop options producing greater than 2.5 t DM/ha.

• The highest grain yields tended to be crops with the quickest maturity such as lentils (0.73 t/ha), vetch (0.64 t/ha) and field peas (0.63 t/ha).

• High value crops such as lentils and vetch were highly profitable due to both excellent prices and reasonable grain yields.

BREAK CROP PERFORMANCE


• Break crop productivity and profitability was very different between common Mallee soil types.

BACKGROUNDMallee farmers are looking to increase the proportion and diversity of broadleaved break crops in their paddock rotations, however very little localised information is available to support break crop selection and management in low rainfall environments. Furthermore, there is extreme soil type variability between Mallee paddocks, which adds additional complexity when selecting an appropriate break crop for these farming systems. To address these knowledge gaps, Mallee Sustainable Farming Inc, with funding from SAGIT, commenced a three-year project in 2015 to compare broadleaved break crop performance across four soil types in the northern Mallee of South Australia (SA). The aim of these trials is to provide farmers with information on the relative productivity of legume break crops in this low rainfall Mallee region.

ABOUT THE TRIALThe trials are located at Waikerie and Loxton in the northern Mallee of SA with one trial located on each of two contrasting soil types within the same paddock. A brief description of each of the four trial sites is provided below:• Loxton Flat: Red loam located in a swale• Loxton Sand: Deep yellow sand located on the top of an east-west dune• Waikerie Flat: Heavy red-grey soil with limestone from 20-30 cm below the surface• Waikerie Sand: Red sandy loam located mid slopeEach trial has nine different broadleaved crop options replicated four times. Table 1 shows the crop type, variety, target plant population and seeding rate used for each treatment. Each treatment at each site was managed independently to ensure that it had every opportunity to reach its potential. Agronomic management differences included herbicide choice, fertiliser rates and fungicide and pesticide applications.The Loxton sites were sown on 28 April 2015 and the Waikerie site on 1 May 2015. All plots received 100 kg/ha of single super phosphate banded below the seed and all legumes were inoculated just prior to seeding with their specific Rhizobian strain using a peat inoculant. All canola received an additional 100 kg/ha of urea applied immediately prior to sowing and incorporated by the sowing operation. Pre-emergence herbicide packages and rates were specific for each treatment and soil type. Grass weeds were controlled with an application of clethodim and haloxyfop on 26 June. Broadleaved weeds were controlled to an acceptable level by the knockdown and pre-emergence herbicide applications. Cowpea aphids at the Loxton trial sites were controlled by an application of omethoate on 9 July. Cabbage aphids and native budworm were controlled at all sites on 12 September using a mixture of pirimicarb and alpha-cypermethrin.Crop performance was assessed by measuring establishment, peak crop biomass and grain yield. The trials were machine harvested across three dates from late-October to mid-November to ensure grain yield was measured soon after crops matured. Rainfall was recorded at both locations using automatic rain gauges and temperature was recorded at hourly intervals using iButton temperature loggers. One logger was placed at a height of 1.2 m above ground level (similar to official met gauges) and the other at 0.5 m to reflect crop canopy height.Gross Margins were calculated for each treatment using the Rural Solutions Farm Gross Margin and Enterprise Planning Guide. The January grain prices from the 2016 guide were used to undertake the economic analysis (Table 1).

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Table 1: Break crop treatment details for Loxton and Waikerie trial sites.

CROP VARIETY TARGET PLANTS (m2) SEEDLING RATE (kg/ha) PRICE ($/t)Field Pea PBA Wharton 45 90 550Vetch Rasina 60 40 850Narrow-leaved Lupin PBA Barlock 50 90 380Albus Lupin Luxor 35 120 380Faba Bean PBA Samira 20 140 560Lentil PBA Hurricane 120 50 1340Desi Chickpea PBA Striker 45 100 950Kabuli Chickpea Genesis 090 35 120 1050Canola Stingray 40 2.5 530

WHAT HAPPENED?Seasonal ConditionsRainfall in 2015 was below average at both sites with 193 mm recorded at Loxton and 220 mm recorded at Waikerie from November 2014 to October 2015. Growing season rainfall was also below average with Loxton receiving 145 mm and Waikerie 133 mm. However, both sites received timely rainfall of approximately 40 mm in mid-April and a further 30-40 mm in the month of September.Both trials were impacted by extremely low and high temperatures during the flowering and grain filling period (mid August – mid October) (Table 2). The coldest temperatures were recorded on 30 and 31 August when minimum temperatures were between -4 and -5oC at the Waikerie and Loxton flat sites respectively. There were fewer frost events at both sand sites due to their higher elevation within the paddock with minimum temperatures of -1 and -2.4oC recorded at the respective Waikerie and Loxton sites at the end of August. Both sites were also subject to a number of heat events during the flowering and grain fill period (Table 2) with three consecutive days of near or above 40oC at the beginning of October.Table 2. Number of days between 15 August and 15 October 2015 with a minimum temperature below 0oC or a maximum temperature above 30 oC and 35 oC at each trial site. Note: Temperature loggers were placed at 50 cm from ground level to reflect crop canopy height.

Biomass productionField pea produced the greatest biomass with an average of 3.1 t DM/ha across all four trial sites and no less than 2.7 t DM/ha at any one (Table 3). Canola, vetch and lentil produced similar levels of biomass with 2.5 – 2.7 t DM/ha on average while desi chickpea, narrow leaved lupin and faba bean produced 2.1 – 2.3 t DM/ha across all sites. The lowest levels of biomass were produced by kabuli chickpea and albus lupins. Each crop produced its greatest biomass at the Loxton flat site with the exception of narrow leaf lupin and canola which performed best on the Loxton sand. The biomass produced by vetch was least on the Waikerie flat (<2.5 t DM/ha) than at the other three sites.

Table 2: Number of days between 15 August and 15 October 2015 with a minimum temperature below 0oC or a maximum temperature above 30 oC and 35 oC at each trial site.

Note: Temperature loggers were placed at 50 cm from ground level to reflect crop canopy height.

SITE DAYS <0oC DAYS >30oC DAYS >35oCLoxton Flat 12 17 9Loxton Sand 3 15 5Waikerie Flat 9 16 8Waikerie Sand 4 14 5


Table 3: Peak biomass (t DM/ha) for each trial site and as an overall average across all sites

Table 3: Grain yield (kg/ha) for each trial site and as an overall average across all sites.

Grain YieldAcross all sites (Table 4), lentils had both the most consistent and the highest average grain yield (0.73 t/ha). Field peas only averaged 0.64 t/ha despite having the highest individual yield at any one site of 1.2 t/ha at the Waikerie sand. Field pea yields were particularly affected by frost on the Loxton and Waikerie flat sites. Vetch grain yields were also good with 0.63 t/ha while narrow leaf lupins, canola and faba bean yielded similarly at 0.5 – 0.53 t/ha. The later maturing crops, chickpeas and albus lupins, performed the worst in 2015 with average yields below 0.5 t/ha. Very low yields were obtained from these crops on the soils with the lowest water holding capacity at each site; Loxton sand and Waikerie flat.

TREATMENT LOXTON FLAT LOXTON SAND WAIKERIE FLAT WAIKERIE SAND OVERALLAlbus Lupin 1.62 1.22 1.28 1.59 1.43Kabuli Chickpea 2.17 1.30 1.48 1.58 1.63Desi Chickpea 2.74 1.57 1.85 2.19 2.09Narrow-leaved Lupin

2.56 265 1.97 1.71 2.22

Faba bean 3.01 2.09 2.20 1.94 2.31Lentils 3.28 2.62 2.10 2.19 2.55Vetch 3.41 2.97 1.80 2.55 2.68Canola 2.49 2.96 2.94 2.40 2.70Field Pea 3.57 3.30 2.67 3.00 3.14

p value <0.001 <0.001 <0.001 <0.001 <0.001lsd (5%) 0.54 0.63 0.46 0.42 0.50

TREATMENT LOXTON FLAT LOXTON SAND WAIKERIE FLAT WAIKERIE SAND OVERALLAlbus Lupin 0.28 0.14 0.02 0.30 0.18Kabuli Chickpea 0.43 0.22 0.05 0.45 0.29Desi Chickpea 0.55 0.30 0.09 0.77 0.43Narrow-leaved Lupin

0.71 0.60 0.20 0.49 0.50

Canola 0.52 0.69 0.20 0.66 0.52Faba bean 0.83 0.55 0.29 0.46 0.53Vetch 0.77 0.86 0.19 0.69 0.63Field Pea 0.58 0.71 0.16 1.21 0.66Lentils 0.96 0.64 0.48 0.82 0.72

p value <0.001 <0.001 <0.001 <0.001 0.001lsd (5%) 0.12 0.19 0.09 0.09 0.23

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ProfitabilityLentils were the most profitable break crop option on all soil types in 2015, and averaged nearly $800/ha profit across all sites (Figure 1). This is a reflection of the extremely high price of $1340/t and high and constant yields across all sites relative to the other break crops. Vetch grain which also had a relatively high price was also a profitable option on all soils except the Waikerie flat. Field pea, faba bean and chickpeas returned $75 - $200/ha across all sites while canola and narrow leaf lupins usually broke even. Albus lupins was not a profitable option at any site.

Figure 1: Gross margin for each break crop at the four trial sites and for the overall average yield across all sites.

WHAT DOES THIS MEAN?In 2015, break crops faced a range of tough environmental conditions in the Mallee, however some options still proved to be both productive and profitable. Timely rainfall in April and hence early sowing resulted in excellent biomass production with most crop options producing on average more than 2 t DM/ha and many break crop options producing greater than 2.5 t DM/ha. This is an important consideration where farmers are looking to increase nitrogen levels in their soil because every tonne of above ground legume dry matter is likely to result in 15-25 kg N/ha added to the soil (where legumes are well undulated). The highest grain yields tended to be crops with the quickest maturity such as lentils, vetch and field pea which handled the hot dry finish to the season better than later crops such as chickpea and lupins. High value crops such as lentils and vetch were highly profitable due to excellent prices and reasonable average grain yields. A high grain price also helped both chickpea crops (desi and kabuli) to be profitable despite poor grain yields (although quality was not considered and may have been an issue at some sites). Field pea and chickpea have been the most profitable break crop options in recent trials in the Victorian Mallee where they were the highest yielding treatments in kinder seasons (Moodie et al., 2015).These trials highlight significant variability in the productivity and profitability between the break crop options that may be considered by Mallee farmers. Furthermore, there was large variation in break crop productivity and profitability between the soil types commonly found in Mallee paddocks. Trials are continuing at all four sites in 2016 and 2017 to evaluate break crop performance across seasons and provide Mallee farmers with greater confidence when selecting break crops for inclusion in their farming system.


ACKNOWLEDGEMENTS South Australian Grain Industry Trust (SAGIT) for providing funding for this project.Matt Whitney (Dodgshun Medlin) for providing advice on trial management.Todd McDonald (MSF) and Peter Telfer (SARDI) for their technical assistance on the trial.Brenton Kroehn and the Lowbank Ag Bureau for assistance in selecting and setting up the Waikerie site and Bulla Burra staff for assistance at the Loxton site.

REFERENCES AND LINKSMoodie, M., Wilhelm, N and McDonald, T (2015). Productive and profitable pulse crops in the Northern Victorian Mallee. Mallee Sustainable Farming Results Compendium 2013. http://msfp.org.au/wp-content/uploads/2015/02/Moodie_Pulse-Crops-in-Vic-Mallee.pdfRural Solutions SA (2015 and 2016). Farm Gross Margin and Enterprise Planning Guide http://www.grdc.com.au/FarmGrossMarginGuide


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ARE GREEN MANURE COVER CROPS A VIABLE OPTION TO REDUCE THE USE OF AGROCHEMICALS IN THE LOW RAINFALL MALLEE?

PROGRESS REPORT 2016BACKGROUNDCover crops can be used to achieve 100% weed seed set control by terminating the crop with glyphosate prior to the development of viable seeds of the target weed. Using herbicides to kill both the cover crop and weeds is termed “Brown Manure”. However, this management practice still relies on appreciable herbicide inputs which can be a significant input cost and there is a long term threat of the development of resistance to glyphosate.

A management alternative is to use cultivation to terminate both the cover crop and weeds which is termed green manure. This practice potentially has some benefits over brown manure, such as:

• an alternative to herbicide inputs to control weeds,

• increased decomposition of cover crop residues which may influence soil nutrient supply,

• increased soil water storage as crop growth is terminated more quickly, and

• improved seeding and crop establishment of the following crop.

However, in low rainfall farming systems such as the Mallee, the threat of reducing ground cover levels below critical levels and increasing the risk of erosion is ever present. Therefore if green manure cover crops are to become viable management option, the change in ground cover and agronomic benefits such as increased nitrogen supply, soil water changes and subsequent crop yield need to be quantified.

GREEN MANURE COVER CROPS


TRIAL DESIGNThe aim of this trial is not to measure how effective cover crop termination is at controlling weed seed set, but rather is a green manure a viable management option (in terms of maintenance of ground cover and other agronomic benefits) as we know that terminating cover crops will result in 100% seed set control providing that the crop is effectively killed at an appropriate time.

A factorial trial design with the factors of cover crop choice x termination methods:

• Cover crop choice: Vetch (legume) and Oats (non legume)

• Termination methods:

1. Herbicide (brown manure),

2. Herbicide + Hay cut,

3. High disturbance cultivation (Offset Disc),

4. Moderate disturbance cultivation (Chopper chain),

5. Low disturbance cultivation (Blade Plough).

The site will be sown to a cereal (wheat or barley) to quantify the impact of the previous management techniques on grain production in the second year, 2016.

PROGRESS AGAINST 2015 ACTIVITIES

ACTIVITY TIMINGPre sowing soil nitrogen and water content measurements

April 2015 Completed See attached graphs

Sowing Oats and Vetch plots May 2015 CompletedCover crop establishment plant counts

June 2015 Completed

Cover crop termination treatments1. Herbicide (brown manure),2. Herbicide + Hay cut,3. High disturbance cultivation (Offset Disc),4. Moderate disturbance cultiva-tion (Chopper chain),5. Low disturbance cultivation (Blade Plough).

September 2015 CompletedSee attached Photos

Ground Cover assessment Immediately after termination CompletedLive plant counts (1 square mtr quadrants)

1 week post treatment Completed No live plant

Live plant counts (1 square mtr quadrants)

1 month post treatment Completed No live plants

Ground Cover assessment. Using ground cover assessment guide photos in “Stubble Management – A guide for Mallee farmers”

December 2015 CompletedSee attached graphs

INTERIM RESULTSAll of the treatments were implemented as described in the trial design (see figure1).

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Figure 1: Treatments at site (Oats top and Vetch below)

The nitrogen status of the sites was captured prior to the treatments being implemented as a baseline for the nitrogen impact of the treatments in the second year crop (see figure 2).

The groundcover impact of each of the treatments has been assessed in December 2015 and February 2016 (See figure 3). The data already indicates that a number of the treatment will not be viable as they resulted in a less than 50 % groundcover which will increase the risk of erosion of Mallee sand to an unacceptable level. At this stage the only viable options that reduce chemical usage are the cutting for hay and the use of a blade plough to terminate the crop and associated weeds.

Figure 2: Soil and Plant nitrogen status for the cereal (1) and legume (2) sites prior to treatment.


Figure 3: Groundcover status of treatments

2016 ACTIVITIES

Activity TimingGround Cover assessment February 2016 - completedGround Cover assessment April 2016Pre sowing soil nitrogen and water content measurements April 2016Sowing barley or wheat in line with farmers preference May 2016Early crop vigour: NDVI and biomass cuts (Z22, Z30) June and July 2016Biomass cuts at flowering September 2016Grain yield and quality measurements November 2016

EXTENSION ACTIVITIESThere was a Field Day held on the 7th of October with 68 people attending the site. However with the trial at an early stage participants were only shown the trial and introduced to its purpose. Subsequent field days will involve communication of the results.

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SEEDING RATE BY ROW SPACING FOR BARLEY GRASS MANAGEMENT.

Amanda Cook Wade Shepperd Ian Richter Nigel Wilhelm

SARDI Minnipa Agricultural Centre

KEY MESSAGES • 18 cm (7”) systems showed better plant establishment in a drier

seeding than the 30 cm (12”) system. • Higher seeding rates resulted in higher grain yield but also higher

screenings and lower protein. • Grass weeds were lower in the higher seeding rate and in the 18

cm row spacing indicating crop competition is a non-chemical weed reduction method.

• Single row or spread row seeding boots showed little differences in plant establishment, grain yield and quality or grass weed competition.

WHY DO THE TRIAL? Controlling barley grass in upper EP low rainfall farming systems is becoming a major issue for growers, due to the development of herbicide resistance and changing ecology of the weeds such as delayed emergence of barley grass populations.

There are effective but sometimes costly chemical options for grass weed control using pre-emergent and post emergent herbicides. However for longer term sustainability a range of management techniques, not just reliance on chemicals, is required to address the issue. One of the potential non-chemical options for managing barley grass in a crop is increasing crop competition by reducing row spacing and increasing sowing rate. This research is funded as part of the GRDC Overdependence on Agrochemicals project.

HOW WAS IT DONE?A replicated trial was established at the Minnipa Agricultural Centre

SEEDING RATE BY ROW SPACING


(MAC) (paddock S4) with Mace wheat sown at three seeding rates (targeting 60, 120 or 240 plants/m2) on two different row spacings of 18 cm and 30 cm with two different seeding boots, a single row Harrington point and an Atom-Jet spread row seeding boot with press wheels. The paddock was very grassy in 2013 followed by a pasture with moderate levels of grass weeds present in 2014. In 2014 alternative chemicals for spray topping grass weeds in pastures were used in this paddock as potential small patches of herbicide resistant barley grass had been located in the paddock.

In 2015 the trial was sown on 21 and 22 May with minimal moisture with the 18 cm (or 7”) treatments being sown first, then the 30 cm (or 12”). A base fertiliser rate of 60 kg/ha of 18:20:0:0 was applied for all treatments. The trial was sprayed with a knockdown of 1.5 L/ha of TriflurX, 1 L/ha of Roundup Powermax and 80 ml/ha of Nail and broad-leaved weeds were controlled with 750 ml/ha Tigrex and 100 ml/ha Lontrel on 23 July.

Trial measurements taken during the season included soil moisture, PreDicta B root disease test, soil nutrition, weed establishment, weed seedbank germination, crop and weed establishment, crop and weed biomass (early and late), light interception in crop rows (using AccuPAR PAR/LAI Ceptometer), grain yield and quality.

Soil samples were taken on 21 April. Initial paddock weed counts were done on 20 May and soil taken for weed seed bank germination, with monthly assessments on emergence over the next 12-18 months. Plant establishment and weed counts were taken on 18 June. The Leaf Area Index (LAI) measurements were taken on 18 September using an AccuPAR PAR/LAI Ceptometer (model LP-80), taking the average of 5 readings per plot placed at an angle across the crop rows as per the manufacturer’s instruction manual. The measurements were taken at Zadoks growth stage Z49-51, aiming for maximum crop canopy. Late weed counts were taken on 7 October. The trial was harvested on 9 November. Harvest soil moisture measurements of selected treatments were taken on 27 November.

Data were analysed using Analysis of Variance in GENSTAT version 16.

WHAT HAPPENED?The soil analysis showed the trial site is alkaline, with a pH (CaCl) of 7.9. Cowell P measured 46 mg/kg (0-30 cm). Soil mineral N was 76 kg/ha in the top 100 cm. The soil has a moderate phosphorus buffering index of 150 (0-30 cm). At this site, salinity increases down the profile but is still relatively low. The initial soil moisture was 158 mm within the profile to 100 cm depth. The initial PreDicta BTM inoculum level indicated a high risk of Rhizoctonia disease (214 pgDNA/g soil) but low Take-all and Pratylenchus thornei risk. Sowing occurred on the 21 and 22 May with minimal moisture and the next significant rainfall event was 40 mm on 15 June resulting in uneven crop germination, with some plants at Zadoks growth stage Z12 (2-3 leaf stage) and others plants just germinating. The trial was direct drilled into a pasture paddock, so the plots were quite cloddy due to the dry moisture conditions and seed placement was not ideal. In the dry seeding conditions all seeding rates resulted in lower plant establishment numbers than expected and the 30 cm system achieved much lower germination and plant establishment than 18 cm. In the 30 cm row spacing some seed on the side of furrows germinated then died due to the dry conditions at seeding and potentially seeds being placed within the chemical zone.

Figure 1: Left, 30 cm (12”) ribbon @ 60 plants/m2 and right, 18 cm (7”) ribbon at 240 plants/m2.

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The initial barley grass weed pressure within the trial area was much lower than expected with all plots having less than 10 plants/m2. This weed density is considered to be below what is required for adequate grass weed pressure (for reliable measurement) within a grass weed trial (B Fleet, pers. comm.). No barley grass weeds germinated in the weed seed bank trays despite this site being selected due to high barley grass weed numbers in 2014, while ryegrass and broadleaved weeds both had 31 plants/m2. Wild oats became a more prevalent weed in the 2015 season due to later rainfall events and later germination after the soil applied chemicals at seeding became inactive. Table 1: Grass weed density and canopy measurements taken in seeding rate and row spacing trial sown with Mace wheat at Minnipa, 2015.

SEEDING RATETARGET PLANTS/M2

ROW SPACING (CM)

EARLY BARLEY GRASS(PLANTS/M2)

EARLY RYE GRASS(PLANTS/M2)

LAI (UMOLS)

LATE GRASS WEEDS DM (T/HA)

LATE BARLEY GRASS(PLANTS/M2)

LATE RYEGRASS(PLANTS/M2)

LATE WILD OATS(PLANTS/M2)

60 18 0.7 0.6 60 0.48 15.5 3.4 34.418 ribbon 0.7 0.6 59 0.19 2.3 3.7 13.8

30 2.9 0.4 51 0.67 15 6.3 45.130 ribbon 1.2 1.6 53 0.86 12.9 7.4 62.5

120 18 2.1 0.7 66 0.19 8.0 1.0 14.818 ribbon 0.7 1.0 67 0.16 6.6 0.9 11.9

30 5.3 4.0 54 0.58 20.0 6.7 33.930 ribbon 4.1 1.9 59 0.91 9.6 4.3 77.3

240 18 6.3 2.5 67 0.13 0 0.4 12.218 ribbon 2.8 0.7 67 0.22 1.4 0.9 20.7

30 5.3 1.2 61 0.18 12.0 2.6 5.230 ribbon 5.3 1.2 59 0.21 25.2 0.5 7.9

LSD (P=0.05) row

spacing x seeding rate

ns ns ns ns ns ns ns

18 3.1 1.3 64 0.27 7.8 1.6 20.518 ribbon 1.4 0.8 64 0.19 3.4 1.8 15.5

30 4.5 1.9 56 0.48 15.7 5.2 28.130 ribbon 3.6 1.6 57 0.66 15.9 4.1 49.2

LSD (P=0.05) row

spacing

ns ns 2.5 0.25 ns 2.8 21.7

60 1.4 0.8 56 0.55 11.4 5.2 38.9120 3.1 1.9 62 0.46 11.0 3.2 34.5240 5.0 1.4 64 0.19 9.7 1.1 11.5LSD

(P=0.05)seeding rate

ns ns 2.2 2.1 ns 2.4 18.8


Table 2: Wheat growth, yield and grain quality measurements taken in seeding rate and row spacing trial sown with Mace wheat at Minnipa, 2015.

SEEDING RATETARGET PLANTS/M2

ROW SPACING (CM)

PLANT ESTAB-LISHMENT(PLANTS/M2)

EARLY DM (T/HA)

LATE DM (T/HA)

YIELD (T/HA)

PROTEIN (%)

SCREEN-INGS (%)

TEST WEIGHT (KG/HL)

60 18 64 0.32 8.1 2.88 11.6 10.7 80.018 ribbon 57 0.26 8.7 2.79 11.8 10.0 79.5

30 31 0.16 5.8 2.03 12.1 11.5 79.530 ribbon 27 0.15 7.0 2.03 12.3 11.7 79.0

120 18 109 0.47 8.8 3.34 11.5 7.6 80.018 ribbon 114 0.53 8.9 3.36 11.4 8.5 79.7

30 59 0.27 6.5 2.29 12.2 10.5 78.930 ribbon 67 0.26 6.9 2.40 12.2 10.9 79.2

240 18 194 0.65 9.1 3.56 11.4 8.4 79.518 ribbon 186 0.71 8.1 3.54 11.3 7.1 80.2

30 106 0.42 8.0 2.78 11.6 8.2 79.730 ribbon 103 0.41 7.6 2.64 12.2 9.9 79.6

LSD (P=0.05) row

spacing x seeding rate

19 ns ns ns 0.3 ns ns

18 122 0.48 8.7 3.26 11.5 8.9 79.818 ribbon 119 0.50 8.5 3.23 11.5 8.5 79.8

30 66 0.28 6.7 2.37 12.0 10.1 79.330 66 0.27 7.2 2.36 12.2 10.9 79.2

LSD (P=0.05) row

spacing

10.7 0.25 0.7 0.09 0.16 1.8 ns

60 45 0.22 7.4 2.43 11.9 11.0 79.5120 87 0.38 7.7 2.85 11.8 9.4 79.4240 147 0.55 8.2 3.13 11.6 8.4 79.8LSD

(P=0.05) seeding rate

9.3 0.22 ns 0.08 0.14 1.6 ns

Seeding rate increased the number of plants/m2 however no rate achieved the targeted plant densities due to the dry seeding conditions. The 18 cm row spacing achieved higher plant density than the 30 cm row spacing, but the seeding system boots had no impact on plant numbers (Table 2). There were no differences in early weed numbers for row spacing or seeding rates (Table 1).

Early crop dry matter was greater in the 18 cm row spacing than in the 30 cm, likely due to higher plant numbers. By 7 October the dry matter differences were not present in seeding rate, however the row spacing effect was still present with the 30 cm and 30 cm ribbon system having lower dry matter than the 18 cm treatments (Table 2).

LAI (the area of leaves per unit area of soil surface) increased with seeding rate. The 18 cm row spacing had a higher LAI than the 30 cm row spacing (Table 2). Head emergence was faster with higher seeding rate and 18 cm row spacing (data not presented).

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The total dry matter and numbers of the late grass weeds for ryegrass and wild oats was lower in the higher seeding rate. The 18 cm row spacing showed the same trend with late grass weed dry matter and ryegrass and wild oat plant numbers compared to the 30 cm row spacing. Late barley grass numbers did not change with treatments (Table 1).

Grain yield increased with seeding rate (Figure 2). The 18 cm row spacing also out-yielded the 30 cm row spacing but there were no differences between the two seeding boots. This yield difference between the 18 cm and 30 cm system may be due to the difference in initial plant establishment.

Grain protein showed the opposite trend to grain yield with protein increasing with the lower seeding rate and increasing with the 30 cm system compared to the 18 cm, and again the different seeding boots showed no differences. Higher screenings occurred in the lower plant density treatments, 11% to 8.4% from low to high seeding rates. The 18 cm system had an average of 8.9%, with 8.5% on 18 cm ribbon, 30 cm 10.0% and 30 cm ribbon 10.9%. There were no differences in test weight.

Figure 2: Plant establishment and grain yield at Minnipa in 2015.

There were no differences in harvest soil moisture between the highest and lowest seeding rates (60 and 240 plants/m2) at the different row spacing after harvest (data not presented).

WHAT DOES THIS MEAN?This trial aimed to target barley grass weeds but numbers were much lower than expected due to dry early seasonal conditions, however wild oat numbers were higher than expected and some ryegrass was present. There were no differences in early weed numbers in the row spacing of 18 cm (7”) or 30 cm (12”) or the 60, 120 or 240 kg/ha seeding rates this season in moisture limited conditions.

The seeding rate increased the number of plants/m2 but no rate achieved the targeted plant densities due to the dry seeding conditions affecting seed placement and possibly chemical damage. The 18 cm row spacing achieved higher plant numbers than the 30 cm row spacing but the ribbon seeding system boots showed little impact on plant numbers.

Overall this season the 18 cm (7”) systems showed better plant establishment in a drier seeding which resulted in plant numbers closer to the targeted seeding rates than the 30 cm (12”) system. The higher seeding rates resulted in higher grain yield but also higher screenings and lower protein due to stressful conditions at the end of the season resulting in poor grain filling.

The total dry matter of the late grass weeds significantly declined with the higher seeding rate in the narrower 18 cm row spacing compared to 30 cm, indicating higher seeding rates and narrower row spacing increased crop competition and lowered grass weed numbers. The late barley grass numbers did not show differences (possibly due to the low starting numbers, as discussed previously) however ryegrass and wild oat did, both showing the same trend as the late weed dry matter with lower weed numbers in the higher seeding rate and


in narrower row spacing compared to wider. The reduction in ryegrass and wild oat grass weed numbers demonstrates the potential for barley grass reduction.

The 2015 results show crop competition by using narrow row spacing and increasing plant density is a non-chemical method to reduce grass weed numbers in current farming systems, however the seeding system boots showed little differences. The trial will be repeated for another two seasons hopefully with better initial crop establishment and greater barley grass weed numbers so more information on crop competitiveness and barley grass seed set can be collected.

ACKNOWLEDGEMENTS Thank you to Sue Budarick for doing the weed counts and managing the weed germination trays. Funded by the GRDC Overdependence on Agrochemicals project (CWF00020).Registered products: see chemical trademark list.Agrochemicals project (CWF00020), which is led by CWFS

LOCATION: MINNIPA AGRICULTURAL CENTRE PADDOCK S4Rainfall Av. Annual: 325 mm Av. GSR: 241 mm 2015 Total: 333 mm 2015 GSR: 258 mmYield Potential: (W) 3.0 t/ha Actual: 2.8 t/ha Paddock history 2015: Mace wheat 2014: Spray topped medic pasture 2013: WheatSoil type Red loamPlot size 20 m x 2 m x 4 reps

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SOWING EARLY TO MAXIMISE WHEAT YIELD ON LOW FALLOW

GRDC project code CSP00178

Neil Fettell Central West Farming Systems

Barry Haskins AgGrow

Rachael Whitworth AgGrow

James Hunt Bonnie Flohr Tony Swan Brad Rheinheimer Laura Goward ALL CSIRO

KEY MESSAGES Early sowing is essential in order to maximise yield of wheat crops grown on long (18 month) fallow. Long fallowing and early sowing are complementary practices, as the fallow reduces weeds and diseases which can be difficult to control in early sown crops, and early sowing with slow developing cultivars allows the crop to better use soil water that is stored during the fallow. Stored soil water also helps to establish early sown crops when there is minimal autumn rainfall. This fact sheet outlines how farmers can maximise wheat yield on long fallow by sowing early with slow developing cultivars, and is based on two years of GRDC funded research conducted by AgGrow Agronomy, CWFS and CSIRO in western NSW.

AIM FOR THE OPTIMAL FLOWERING WINDOWIn environments such as western NSW that have a cool winter and hot summer, one of the main drivers of wheat yield and quality is flowering time. When selecting a cultivar and sowing time combination, the intention is to match plant development with seasonal pattern and most importantly get the crop to flower during the optimal period for yield. In southern NSW the optimal flowering period varies from late August in the west to early October in the east (Table 1). This period is a trade-off between increasing drought and heat, and declining frost risk. There is no ‘perfect’ time to flower where these risks are nil, only an optimal time where they are minimised and yield on the balance of probabilities is maximised. Optimal flowering time tends to be earlier on heavy clay soil types more prone to drought than on sands (Table 1).

EARLY SOWING


OPTIMAL FLOWERING PERIOD LOCATION OPEN CLOSE PEAK MEAN YIELD

(T/HA) AND CORRESPOND-INGFLOWERING DATE

MEDIAN SOWING DATE FOR CORRESPONDING PEAK MEAN YIELD (MID-FAST CULTIVAR E.G. SUNTOP)

Nyngan 26 Aug 29 Aug 2.2 / 27 Aug 2 MayMerriwagga 27 Aug 10 Sep 2.6 / 31 Aug 27 AprSwan Hill (clay) 1 Sep 10 Sep 2.8 / 5 Sep 27 AprSwan Hill (sand) 1 Sep 20 Sep 3.7 / 5 Sep 6 MayCondobolin 11 Sep 19 Sep 2.4 / 15 Sep 7 MayMathoura 15 Sep 22 Sep 2.3 / 18 Sep 3 MayBogan Gate 18 Sep 1 Oct 3.7 / 21 Sep 13 MayUrana 18 Sep 29 Sep 3.3 / 23 Sep 8 MayYarrawonga 25 Sep 2 Oct 3.6 / 28 Sep 8 MayTemora 25 Sep 10 Oct 3.0 / 3 Oct 13 MayCootamundra 6 Oct 20 Oct 4.3 / 12 Oct 20 May

Table 1: Optimal flowering periods, peak of the mean of frost-heat adjusted APSIM yield and corresponding flowering date and sowing date range for a mid-fast cultivar for 51 years (1963-2013) for locations in southern NSW (taken from Flohr BM, Hunt JR, Kirkegaard JA, Evans JR 2016 Drought, radiation, frost and heat define the optimal flowering period for wheat in south-eastern Australia. Journal of Experimental Botany. In review).

SOWING TIME AND CULTIVAR COMBINATIONS TO MAXIMISE YIELD.In the majority of seasons, yield will be maximised when wheat cultivars are sown so that they flower during the optimal period. The sowing dates required for cultivars commonly grown in south western NSW to achieve the optimal flowering date for the region are given in Table 2. In very dry seasons, yield is maximised when crops flower earlier than the optimal time and the opposite is true in very wet seasons.

Table 2: Recommended sowing times for south western NSW of different development classes to flower during the period. On long fallows, yield of winter and slow developing cultivars sown early is higher than faster cultivars sown later.

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In the presence of stored soil water such as is found following long fallow, winter and slow developing spring cultivars sown early yield more than faster cultivars sown later (Tables 3 & 4). This is because the longer growing season available to early sown crops allows them to grow deeper roots and extract more water, reduce evaporation and produce more biomass. However, if there is no stored soil water for growth around anthesis and grain filling, early sown crops can hay off and will yield the same or in some cases less than faster developing cultivars sown later.

GRAIN YIELD (T/HA)CULTIVAR DEVELOPMENT SPEED 15-APR 14-MAYWedgetail Winter 6.2 4.9Kiora Slow spring 6.1 5.1LPB11-0140 Winter 6.0 5.2Wylah Winter 6.0 5.0Bolac Slow spring 5.9 4.3V07041-39 Very slow spring 5.9 5.1Lancer Slow spring 5.8 4.9Gregory Mid spring 5.3 4.0Sunvale Slow spring 5.3 4.8Eaglehawk Very slow spring 5.1 4.5Condo Fast spring 3.0 4.7

P-VALUE <0.001LSD (P=0.05) 0.5

GRAIN YIELD (T/HA) STEM FROST DAMAGE (% STERILE TILLERS)

VARIETY 17 APRIL 22 MAY 17 APRIL 22 MAYWedgetail 5.8 4.6 1 0Osprey 5.3 4.8 1 -1Lancer 4.5 4.5 27 0Eaglehawk 4.4 4.4 8 1Sunvale 4.2 4.7 44 -1Suntop 4.0 4.4 18 0Gregory 4.0 4.9 29 0Bolac 3.8 4.6 30 0Dart 3.5 3.9 43 0Spitfire 3.4 4.1 42 0

P-VALUELSD (P=0.005)

<0.0010.4

<0.0017

Table 3: Grain yield for a range of cultivars of different development rates sown on two dates on long fallow at Rankins Springs in 2015.

Table 4: Grain yield (t/ha) and stem frost damage (% tillers frosted) for a range of cultivars of different development rates sown on two dates on long fallow at Rankins Springs in 2014. This trial suffered severe damage from stem frosts in July and August which reduced yield in slow developing spring cultivars sown early.


Growers with long fallows should keep either a winter or slow spring cultivar in order to maximise yield in seasons with a sowing opportunity in April. They also need to keep either a mid-fast or fast cultivar to use on non-fallow paddocks, and in seasons where there is no establishment opportunity until May. Winter, slow and mid-developing cultivars should not be sown dry, even on long fallows. If these cultivars are not established at their optimal time they will flower too late and suffer yield loss due to drought and heat stress. In seasons with a late break where an establishment opportunity has not arrived by the start of May, yield will be maximised by dry sowing as much wheat area as possible to a mid-fast or fast developing cultivar.Keeping a winter cultivar (e.g. Wedgetail) gives the greatest range of potential establishment dates, but is of more value to mixed farmers who can graze these crops in the vegetative phase (typically for ~1000 DSE/ha grazing days). Because they take longer to reach stem elongation, winter cultivars are also less susceptible to stem frost than slow spring cultivars (Table 4). There is unlikely to be a yield advantage of sowing winter cultivars intended only for grain production before early April as the extra vegetative biomass production will not contribute to grain yield. Winter cultivars will be more attractive once cultivars better adapted to western NSW become available in 2018.

OTHER AGRONOMYFallow management, root and foliar diseasesThe yield benefits of summer and winter fallow weed control in western NSW are beyond doubt, but controlling fallow weeds is particularly important for early sown crops for several reasons. Firstly, having as much stored soil water as possible helps establishment of early sown crops when breaking rains are marginal. Secondly, spraying summer weeds conserves N which is necessary to support the higher yields of crops growing on long fallows. Thirdly, early sown wheat crops are more vulnerable to a range of diseases that can be hosted by weeds and volunteers growing during the fallow e.g. barley yellow dwarf virus (BYDV), take-all, Rhizoctonia, wheat streak mosaic virus (WSMV). Making sure fallows are kept weed free from at least August in the fallow year up until sowing reduces the risk of these pathogens attacking early sown crops. BYDV in particular can be very damaging to early sown crops. This virus is spread by aphids in autumn, and crops need to be protected from infection with insecticides. An effective insecticide program should start with a seed dressing product registered for aphid control (e.g. imidacloprid), and needs to be backed up with a foliar insecticide (e.g. lambda-cyhalothrin) at GS13 (3 leaves emerged) if aphids persist past this time. If planning on grazing, check stock withholding periods on any insecticides used.Some slow developing cultivars also have low levels of resistance to foliar fungal pathogens such as stripe rust, and appropriate monitoring and protection with fungicides is required.

Grass weedsSowing wheat early requires clean paddocks free of grass weeds. It is rarely possible to achieve a good knockdown of grass weeds if sowing in April, as most grass weed populations have evolved a greater degree of dormancy and will not emerge until later in May. This also means that many pre-emergent herbicides used when sowing early will have lost residual activity by the time grass weeds begin to emerge. If sowing early into paddocks with grass weed pressure, it is worth using pre-emergent herbicides with a higher level of residual control (e.g. Sakura).Given the yield penalties associated with delayed sowing in western NSW, it is worthwhile keeping grass weed seed banks low so crops can be sown on time without relying on knockdown and pre-emergent herbicides for grass weed control. One year of long fallow alone is not sufficient to drive down high grass weed seed banks. Crop (including hay), pasture and herbicide rotation in conjunction with long fallows and harvest weed seed control (chaff carts, narrow windrow burning, seed destructors etc.) are the most effective way of reducing seed bank numbers and keeping them low.

Seeding ratesTwo years of trials at Rankins Springs have shown no significant yield benefit from reducing seeding rates below 90-100 plants/m² in early sown crops. Trials conducted by BCG in the Victoria Mallee as part of the Early Sowing project showed that even in extremely dry years there was no yield benefit from reducing seeding below 90 plants/m² (Table 5). However, previous trials by NSW DPI at Condobolin have shown a yield benefit from reducing plant densities to ~30 plants/m² in early sown wheat (Tables 6). The BCG trials also showed that in the presence of weeds, lower crop densities do not yield any less but they are less competitive with weeds and allow greater weed biomass production and seed set (Table 5). If paddocks

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are free of grass weeds, plant density can be reduced to 30-60 plants/m² which reduces establishment costs and increases sowing work rate and may provide a yield benefit in some seasons. If planting into paddocks with any level of grass weed pressure or intending to graze, seeding rates should be maintained at 90-100 plants/m² in order to provide even establishment, greater crop competition and early dry matter for livestock. Check seed size and viability in order calculate and appropriate sowing rate in kg/ha.

QUAMBATOOK 2014 (SOWN 1 APRIL)

BERRIWILLOCK 2015(SOWN 9 APRIL)

Target wheat plant density (plants/m²)

50 150 50 150

Actual wheat plant density (plants/m²)

38 88 56 109

Weed biomass (t/ha) 5.4 1.3 0.7 0.4

Grain yield (t/ha) 2.0 2.0 1.3 1.3

Table 5: Plant density of early sown Wedgetail grown in the presence of a model weed (tame oats) with corresponding weed biomass and grain yield. At each site wheat density and weed biomass means are significantly different from each other (P<0.05), but wheat yield means are not.

GRAIN YIELD (T/HA) 2011 2012VARIETY & SOW DATE 30 PLANTS/M² 90 PLANTS/M² 35 PLANTS/M² 80 PLANTS/M²Eaglehawk (mid-April) 3.4 3.1 3.2 2.6

Bolac (late-April) 3.3 2.9 3.4 3.5

Gregory (early-May) 3.6 3.2 3.4 3.0

Lincoln (mid-May) 2.8 3.0 3.0 2.6

Axe (late-May) 2.1 2.6 - -

P-value 0.029 <.001

LSD (p=0.05) 0.4 0.4

Table 6: Grain yield (t/ha) of wheat cultivars of different development speed sown at appropriate times to flower on the same date (~18 September) at two plant densities at Condobolin in 2011 and 2012.

NITROGEN MANAGEMENTThe higher yield potential of early sown crops on long fallows needs to be supported with nitrogen (N). Dryland wheat crops need to see ~40 kg/ha mineral N per tonne of grain yield at 11% protein. A 6 t/ha crop at 11% protein needs a total N supply of 240 kg/ha N. Some N is available in the soil at the start of the season, some will mineralise during the growing season, and the remainder needs to be supplied as fertiliser. The amount available can be determined from soil cores (deep N) prior to sowing. N can leach in long fallows so it is important to sample as deeply as possible (>1 m) and segment cores into depths to get a more accurate estimate of available N (e.g. 0-10, 10-30, 30-60, 60-90, 90-120 cm). Mineralisation is dependent on a lot of variables (organic carbon content of soil, moisture, temperature, surface residue) and is very hard to predict. It can range from >80 kg N/ha following a legume pasture in years with good spring rainfall, to <0 kg/ha following a cereal crop with a large stubble load in a dry spring.In early sown crops that aren’t to be grazed, most N should be top-dressed to avoid excessive early growth. On acid soils in S NSW urea can be top-dressed ‘by the calendar’ in July when soil is cold, crops are generally at Z30 and have covered the soil surface. N losses under these circumstances are minimal.


ACKNOWLEDGEMENTSThis factsheet has been prepared as part of GRDC Project CSP00178. The local project team includes Neil Fettell (CWFS), Barry Haskins, Rachael Whitworth (AgGrow Agronomy) James Hunt, Bonnie Flohr, Tony Swan, Brad Rheinheimer and Laura Goward (CSIRO Agriculture). The project team gratefully acknowledges the guidance of local farmers, particularly Michael Pfitzner who hosted Rankins Springs trials in 2014 and 2015.

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IN SOME DISTRICTS, THE AREA CULTIVATED DURING THE SUMMER FALLOW HAS INCREASED ON RECENT YEARS

John Small Central West Farming Systems

GRDC project CWF00018 – Maintaining profitable farming systems with retained stubble in Central West, NSW

KEY MESSAGES • From reports received it appears that the area of cultivated fallow

has generally increased by 20 to 30% this summer. Specific district increases are reported below.

• Different motivations for cultivating fallow are reported from different districts but generally relate to either; weed management, physical soil condition issues or ending or starting a pasture phase. Producers ability to sow into current stubble loadings was not a major driver of cultivation.

• Cheaper diesel was not a major driver for cultivation but it appears to have made the decision to cultivate easier.

• Producers will burn to reduce stubble loads for sowing if needed.

• Farmers generally reported higher cultivation activity than crop consultants.

BACKGROUNDDuring February a common discussion point was the apparent increase in cultivation of fallows this year.

On 26 February simple question was emailed to producers and consultants;

“Hope you can help. I am just collecting up some information as part of CWFS’s Rain n Grain n Stubble project. If you could quickly just reply this email to me and answer the following questions.

“It appears that in some districts this year more fallows have

CULTIVATING FALLOW


been cultivated than in previous recent years.”

1/Do you think this statement is true?

2/Can you put any amount of hectares the statement?

3/If more cultivation has occurred what is driving this decision:

a/ summer rainfall b/ hard to kill summer weeds c/ cheap diesel d/ all of the above e/ something else. Please nominate.

4/What districts are represented by your response?”

RESULTS It is estimated that the reported responses represent between 150 000 and 170 000 ha, question 2 in the email was poorly structured. 62 email responses were received and further targeted conversations and telephone calls to producers and consultants were made in CWFS districts were few response had been received. Overall about 80 individuals were contacted. Comments made about practises outside of traditional CWFS districts may not by reliable as it commonly relies on only 2 responses.

West of Forbes including Jemalong, Corinella, Gunning Gap districts generally reported a 20 to 30 % increase with the changing from a pasture phase to a cropping phase and hard to kill summer weeds being the main motivation.

Trundle, Tullamore districts provided mixed reports from nil increase to 30%. It appears that cultivation of vetch cover crop residue and windmill grass incursions resulted in any increase.

Lake Cargelligo, Euabalong, Tullibigeal districts reported an increase of between 15 and 30%. These districts reported the most diverse range of motivations for an increased level of cultivation. Ending of a pasture phase was common. Other reasons provided included hard to kill summer weeds and an inability to use 2,4, D because of nearby susceptible crops, lime incorporation and fire mitigation. This was the only area to suggest fire mitigation but it followed practical considerations of cultivating paddocks that fronted the major roads and a matrix across the farm to allow for safe refuges for stock and machinery in the event of a major fire.

North West of Condobolin, Euabalong West and north to Tottenham Interestingly individual producers felt that there was an increase across the district in cultivation but they themselves had generally not changed. Those reporting increased cultivation on their properties citied recent research highlighting benefits of strategic tillage. Some committed continuous croppers felt much of the cultivation observed was related to tradition (one even suggesting genetics) rather than agronomic benefit.

North of Forbes, Tichborne, Parkes, Alectown, Peak Hill reports varied from nil to 50%. Consultants reported a significant increase in “stubble cultivation using chains and small discs” as opposed to soil cultivation. Windmill and barnyard grass, increased areas of lime application and incorporation, preparation of a seedbed for reliable use of triflualin and sakura herbicides were the main factors reported. Some producers had purchased speed tillers and a speed tiller contractor had also established in the area. Similar to cheaper diesel the use of these machines made the decision to cultivate easier rather than be the primary reason to cultivate.

Tottenham north to Nyngan no change reported

Rankins Springs, Binya, Myall Park. Reports suggested no general increase with cultivation being used for specific issues such as levelling and renovation of paddock surface.

Hillston, Merriwagga Reports suggest a small increase above the traditional area of long fallow normally

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cultivated. This appears to have been driven this year by January rainfall and producers not spraying quickly, resulting in stressed weeds and poor spraying results.

Non-traditional CWFS district reportsLockhart, Yerong Creek, The Rock Increased cultivation of fallows using speed tillers. Producers citied planned trifulalin use, attempting to increase N mineralisation and removing old pastures as the main drivers.

Harden, Boorowa, Cootamundra, Junee mixed responses. If an increase has occurred bringing areas back into cropping, lime incorporation and weed management are the suggested reasons.

Temora, Barmedman, Wyalong. Limited response but suggest a 25% increase on average citing insect pests and increased N mineralisation as reasons.

East of Forbes No general increase reported but wider usage of “stubble cutters” rather than soil cultivation. Heavy stubble loads maybe burnt as sowing approaches.

East and North of Dubbo Increased cultivation reported due to summer weeds not being sprayed earlier enough in January and then becoming stressed.

Liverpool Plains - No change

Brewarrina - No change

Moree, Gwydir, Namoi districts Reports suggest a 10% increase in long fallow country which had sealed off due to low level of ground cover. Hard to kill summer weeds were also mentioned.

Upper North South Australia reports suggest an increase due to heavy rains during January which resulted in hard to kill stressed weeds but no more than in previous years were January rain has been received.

ACKNOWLEDGEMENTSThe author would like to thank everybody who took the time to respond to his email, without your support important industry data could not be collected.


LIVESTOCK GRAZING BEHAVIOUR IN LARGE MALLEE PADDOCKS.

Michael Moodie¹ Zac Economou² Mark Trotter² Ali Frischke³ James Murray³

¹Mallee Sustainable Farming, VIC, ²University of New England, NSW, ³Birchip Cropping Group, VIC

WHY WAS THE PROJECT DONE?The integration of cropping and grazing remains a major management challenge in the Mallee. Technology such as portable fencing systems and virtual fencing potentially offer a solution to improve grazing management in large Mallee paddocks with high soil variability. However, to effectively design and deploy these innovative grazing techniques, the grazing behaviour of livestock in these paddocks needs to be understood and quantified.

ABOUT THE PROJECTA flock of two-year-old merino ewes (approximately 200) grazed a 107 ha paddock near Nandaly during summer (barley stubble) and then again in winter grazing (vetch) in 2015. Prior to the commencement of grazing, 25 animals within the flock were fitted with UNE Tracker II GPS collars (Figure 1). Livestock monitoring was supported with on-ground assessment of vegetative soil cover and feed quantity over both grazing periods. At the conclusion of each grazing period, the collars were removed and the data downloaded from the GPS devices. Data was then analysed for the purpose of quantifying variable grazing pressure.

KEY MESSAGES• For the first time sheep grazing behaviour in a Mallee paddock

was monitored and mapped using GPS tracking collars • Sheep grazed the entire stubble paddock as they sought out

spilt grain during the summer fallow, but they preferred to graze on sandy soil types first

• While grazing a vetch pasture in the same paddock, livestock spent 50% of the time grazing only 25% of the paddock and 25% of the paddock was not utilised

LIVESTOCK GRAZING BEHAVIOUR

41

• At least $4000 profit was foregone from the paddock through the under-utilisation of the vetch pasture • Within-paddock fencing technology in large Mallee paddocks has the potential to capture this potential

profit by improving feed utilisation

BACKGROUND Livestock are an integral component of Mallee farming systems. However, the integration of cropping and grazing remains a major management challenge, as paddock sizes tend to be large to benefit efficient cropping practices. Furthermore, Mallee paddocks are also characterised by extreme soil variability and these variable soil types support different levels of feed availability and have different susceptibilities to soil erosion. As a result, farmers report that they are not able to utilise all of the feed on offer within a paddock without reducing groundcover below critical levels. In situations in which farmers are forced to extract maximum productivity, soil erosion often results on the most vulnerable soil types such as sand dunes.Advances in technology such as portable fencing systems and virtual fencing potentially offer a solution to the issue of grazing large Mallee paddocks with high soil variability. However, to effectively design and deploy these innovative grazing techniques, the grazing behaviour of livestock in these paddocks needs to be understood and quantified. This project has begun to address this knowledge gap by quantifying livestock (sheep) grazing habits in a large Mallee paddock with variable soil types.

METHODOLOGYA flock of two-year-old merino ewes (approximately 200) was monitored over a summer and winter grazing period during 2015 using Global Positioning System (GPS) tracking collars. Prior to the commencement of grazing, 25 animals within the flock were fitted with UNE Tracker II GPS collars. Livestock monitoring data was supported with on-ground assessment of vegetative soil cover and feed quantity over both grazing periods. The project was undertaken in a 107 ha paddock near Nandaly in the Victorian Mallee which had a range of soils (deep sands to clay loams) commonly associated with Mallee paddocks. The summer grazing period commenced on 14 January 2015 and concluded on 24 February 2015. The paddock was sown to barley in 2014, and livestock grazed the stubble and grain from lodged heads and grain spilt during harvest. No green plants (volunteer barley or summer weeds) were present when the livestock were introduced into the paddock. The paddock was sown to a vetch pasture in autumn and the flock was re-introduced into the paddock on 28 July 2015. The sheep grazed the paddock until 17 September 2015.At the conclusion of each grazing period, the collars were removed and the data downloaded from the GPS devices. Data was then analysed for the purpose of quantifying variable grazing pressure. Speed thresholds from behavioural modelling techniques were developed to identify when the sheep were grazing, travelling or camping.

RESULTSSummer grazingUtilisation of paddock zones (light, moderate and heavy soil types) was compared at 5-day intervals over the summer grazing period (Figure 1). Initially the sheep spent most of their time grazing the lighter soil types in the paddock before moving on to the other zones. This may suggest preferences for certain zones or soil types before feed became limiting and utilisation of other areas became necessary. By the end of the summer period, paddock utilisation was relatively even.During summer, grazing speeds and distance travelled were very high as the sheep constantly searched for spilt grain. The amount of spilt grain declined from around 80 kg/ha when the sheep were introduced, to approximately 20 kg/ha when they were removed 40 days later. Very little green pick was available during the grazing period and as a result ewes lost condition over this time. There also appeared to be a change in animal behaviour, with an approximate 5% decrease in daily time spent grazing when spilt grain levels dropped to around 40 kg/ha. There may be some value in using this type of data (assuming it could be delivered in real-time) for managing livestock in stubbles where the feed value of spilt grain is difficult to determine.There was a very slight decline in groundcover over the summer grazing period, but on average, groundcover levels remained well above critical levels of 50%. There were already some parts of the paddock at 50% when the sheep were introduced and in an ideal system, grazing would have been avoided in these zones to reduce the risk of erosion.


Winter grazingGrazing intensity was much more spatially variable on the sown vetch pasture in winter than on the cereal stubble in summer. Figure 2 shows that the sheep concentrated grazing on the western end of the paddock during the first 10 days after which paddock utilisation by the livestock slowly increased over time. However, during any 10-day period, livestock spent 50% of the time grazing only 25% of the paddock and a further 25% was not utilised.

Figure 1: Cumulative utilisation of the three soil type zones (light, moderate, heavy) over the summer grazing period.

Figure 2: Grazing residency index (hours spent grazing) in 30x30 m cells for 10 day intervals over the winter grazing period.

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Implications for commercial practiceFarmers already recognise that livestock graze large Mallee paddocks unevenly, however this project has began to put some hard numbers on the extent of the variability in spatial utilisation of a paddock. During summer, when feed was limited, the paddock was fully utilised but means that large areas were very lightly grazed, with animals travelling long distances across the field. This contrasted with the winter grazing period in which sheep concentrated 50% of grazing on 25% of the paddock. A further 25% of the paddock was left unutilised which represents a significant economic opportunity foregone that could be addressed using cost-effective within-paddock fencing or virtual fencing. Two hundred ewes with lambs at foot grazed the paddock, or 5.6 Dry Sheep Equivalent (DSE) per hectare. However, as grazing occurred on only 75% of the area, the stocking pressure on the utilised part of the paddock was 7.3 DSE/ha. It is logical that, with improved grazing management an additional 65 ewes with lambs could have been fed. Alternatively, a quarter of the paddock could have been cut for hay. If 1.5 t/ha of vetch hay were cut from 25% of the paddock, an additional $150/ha of profit would have been made on a quarter of the paddock or the equivalent of approximately $4000 additional profit.Currently there is no easy solution to overcoming the problem of uneven grazing by livestock in large paddocks. Management actions such as moving water points, increasing mob sizes and rotating sheep in and out of paddocks regularly are likely to improve paddock utilisation but will not fully resolve the issue. Rapid fencing systems such as portable electric fencing have been used effectively by some Mallee farmers, but require resources to erect and dismantle. The development of such new technologies as virtual fencing could drastically improve the utilisation of large Mallee paddocks and the data from this project can start making an economic case for investing in more flexible fencing technologies.


ACKNOWLEDGEMENTSThis project is supported by the Mallee Catchment Management Authority, Mallee Sustainable Farming, University of New England and BCG through funding from the Australian Government’s National Landcare Programme. GRDC funded Grain & Graze 3 provided additional support.

Spatially variable grazing led to under-utilisation of pasture on the eastern end of the paddock. Figure 3 shows vetch dry matter accumulation at two of the 29 monitoring locations. On the western edge (site 12), dry matter did not accumulate between the first four monitoring dates, probably because grazing intensity matched pasture growth rate. However, on the eastern end of the paddock (site 16) dry matter accumulated at a consistent rate and when the sheep were removed, approximately 2.5 t/ha vetch still remained. This represents a significant under-utilisation of the feed base with a subsequent loss of potential income from either increased stocking rates or harvest of the excess feed for fodder.

Figure 3: Dry matter accumulation of vetch over the grazing period at monitoring site 12 and 16 which are located on the respective western and eastern ends of the paddock.


SOIL ACIDITY - CROP YIELD IMPACTS AND MANAGEMENT IN CENTRAL WESTERN NSW.


Key Words: ph, acidification, lime, management

GRDC Project: CWF00119 Soil acidity and pH management for central west farming districts.

KEY MESSAGES • Soil acidification is a natural process accelerated by high crop yields,

fertilizer use and potentially direct drilling and stubble retention. It is an unseen cost of doing business.

• To maintain a good soil pH profile producers should aim for a pH(CaCl) above 5.0 in the 0-10cm of topsoil or 5.5 if subsoil acidity issues are present. The target in the 10-30cm zone is greater than pH (CaCl) 4.8.

• Retesting during 2015 of historic soil pH datasets confirms soil profiles continue to acidify.

• Left unmanaged sub soil acidification is likely to occur in most Central West NSW soils.

• Liming needs to be thought of as a farm input, like checking and changing the oil in the tractor, (maintaining capital) rather than buying urea (dollars returned per dollar invested).

• Cost in managing soil pH are easier to quantify than returns.

BACKGROUNDSoil acidification is the natural process accelerated by agriculture. Most produce (grain, meat, fibre) is alkaline and harvesting it causes an increase in acidity. Agriculturally generated sub surface soil acidity is a threat to the sustainability of intensive cropping in low rainfall districts. Preventing sub surface acidity is the preferable option, as the cost of attempting amelioration after sub surface acidification has occurred is time consuming, expensive and most likely cost prohibitive. The vast majority of research on ph management, liming response and economics has been conducted in the medium and high rainfall grain production zones in eastern Australia or in Western Australia.

SOIL ACIDITY

45

Unfortunately the risk reward scenario for producers in low rain areas of NSW, where pH is likely to be a developing issue, means these research findings and economic models are not readily transferrable. Soil acidification is not as obvious as other soil issues such as salinity, erosion or structural decline. Symptoms are less visible, production declines are gradual and these changes are often attributed to other factors such as weather. To maintain a good soil pH profile producers should aim for a pH (CaCl) above 5.0 in the 0-10cm of topsoil or 5.5 if subsoil acidity issues are present. The target in the 10-30cm zone is greater than pH (CaCl) 4.8.In soils where aluminium is present a small drop in pH can result in a large increase in soluble aluminium which retards root growth, restricting the crops ability to access water and nutrients. At harvest this results in a yield penalty and smaller grain size, usually most noticeable in seasons with a dry finish as plants have restricted access to stored subsoil water for grain filling.The rate of acidification will depend on the pH buffering capacity of the soil, its initial pH, cumulative crop yields and the frequency of use of acidifying fertilisers and production of legume crops. Heenan et al reported that a higher rate of acidification was observed with direct drilling and stubble retention at Wagga Wagga. These findings are not a reason to stop stubble retention or using legume break crops, as there are other indicators that business profitability and soil health are significantly improved by these practices. The key message is to be conscious of a gradual decline in soil pH and to take a proactive approach towards limiting the decline.

PH TRENDS IN THE CENTRAL WESTThe GRDC funded “CWFS Soil acidity and pH management for central west farming districts” project involved identifying and retesting historic pH monitoring sites from previous publically funded projects. New monitoring sites were also established and GPS located for future reference. A problem encountered in retesting historic sites was accurately identifying the paddock locations and precisely where samples were collected. GPS locating of sample sites was not a technological option when these sites were originally tested. Six sites were confidently identified and the results of testing are shown in table 1. The critical observation is that pH has generally declined in the 14 years since initial testing. At 3 of the farms topsoil pH is more than likely resulting in a yield penalty. Changes in land use practise may help in explaining the observed change in pH. The Nymagee site had changed from cropping to native pasture. Cropping programs at Tottenham and Euabalong West remained relatively unchanged in mixed farming systems. The sites at Wirrinya, Ungarie and Condobolin West have become more intensive cropping enterprises with more fertilisers and legumes in the cropping cycle, pH at these sites would be likely limiting grain production and sub surface acidification is imminent. 2014 pH at depth data is presented in figure 1. The observed increase in pH at depth is typical of the red brown soil types of the region. Comparisons for pH at depth from 2000 and 2014 are difficult due to the differences in sub sampling depth increments used. Averaging pH readings per depth increment, (practically what happens in the field during sub sampling) and reassigning soil depth increments gave some comparable data. Using the resulting rate of change for pH over the last 14 years, projections have been made for possible readings of Condobolin in 2028 and they indicate a difficult soil environment for cropping. Results are presented in figure 2. The projections need to be considered with caution. Heenan, et al, demonstrated that when a crop system is established, based on a relatively stable long term rotation and management programs, soil pH drop and after a period of time soil pH tend to stabilise or at very least the rate of soil acidification slows. It appears the time before the pH stabilises depends heavily on the paddock history prior to the management change.

NYMAGEE WIRRINYA UNGARIE CONDOBOLIN WEST

TOTTENHAM EUABALO-NG WEST

2000 pH (CaCl)0-10 cm

4.8 4.9 5.2 4.8 5.2 5.7

2015 pH (CaCl)0-10cm

5.7 4.4 4.6 4.5 5.0 5.9

Table 1: Observed changes in pH at 6 locations between 2000 and 2015


Figure 1: 2015 observation of soil pH at depth for 3 selected historic monitoring sites

Figure 2: Observed and projected soil pH at Condobolin west site (2000-2028).

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IS LIMING WORTHWHILE IN CENTRAL WEST DISTRICTS?The application of lime to manage soil pH is not new science, it has been known since Roman times. Current knowledge clearly identifies that to maintain a good soil pH profile producers should aim for a pH (CaCl) above 5.0 in the 0-10cm of topsoil or 5.5 if subsoil acidity issues are present. The target in the 10-30cm is greater than pH (CaCl) 4.8. The economics of applying lime in low rainfall environments is not as clear cut as in medium to high rainfall districts where yields are generally higher and more consistent, resulting in potentially quicker acidification due to product removal, a potential higher dollar loss in production per hectare over time and higher land values which support and or justify more intensive maintenance liming programs. Agriculturally induced soil acidification is using up the capital in your farming system. A fundamental mindshift is required in low rainfall districts so the application of lime is considered an integral part of maintaining the system’s financial and environmental capital base rather than being considered a stand alone crop input. If a yield response to liming is observed the reality is that production has historically been lost to soil acidity. Where there is no response but liming was undertaken on the basis of pH and soil testing to determine rates, the liming was not wasted but acting to maintain a good soil pH profile and will prevent yield decline in the future. pH management and the application of lime should be considered similar to changing the oil in the tractor motor according to the manufacturers specifications to maintain reliability and asset value as opposed to purchasing a crop input, like nitrogen fertiliser, to improve yields or protein and receive a dollar return for the investment in a cropping cycle. Other GRDC supported initiatives have produced models and computer based decision support tools to aid producers planning. Two calculators may be of use and are available at the following web address’s;http://soilquality.org.au/calculators/lime_benefit -this calculator is relatively simple and requires a nominated yield improvement over time to be nominated from liming to calculate the $ return. Such an approach is very simplistic. It does not allow for a yield reduction over time if soil pH is allowed to decline. As suggested earlier where there is no response but liming was undertaken on the basis of pH and soil testing results, the activity is about maintaining farm capital rather than considering the application of one variable crop input over another.http://www.liebegroup.org.au/lime-profit-calculator/- this calculator was developed in Western Australia by the Liebe Farming Systems Group which represents some low rainfall cropping areas of the state. It is very indepth and naturally focused on Western Australian conditions but is potentially useful for local producers. The CWFS “Soil acidity and pH management for central west farming districts” project creates partnerships with the Western Australian owners of the calculator and the intention is to develop a similar model suitable for low rainfall cropping districts in NSW, but this a few years away. As stated previously a change in thinking is required in low rainfall districts so the application of lime is considered an integral part of maintaining the system’s financial and environmental capital base rather than considered a stand alone crop input. Remember more like justifying changing the oil in the tractor rather than justifying buying urea. If this occurs there are clearly two opportunities when liming should be considered. Firstly following those financially rewarding years when returns allow for replacement and improvement in capital items on the farm (soil is part of the farms capital equipment). Secondly in stubble retained systems where the trend is for “strategic” cultivation in the rotations. Lime incorporated into the topsoil acts quicker than surface applied lime. Is should be noted that the impact of take-all disease appears greater immediately following liming so if the disease is a likely concern inoculum levels should be managed in the paddock in the seasons prior to lime applications and wheat production.

DEVELOPING AND COSTING OF A SOIL PH MANAGEMENT PROGRAMThe cost and returns of a pH management program is not as comparable between farms as are operations such as sowing, spraying or harvesting; no relevant benchmarks for low rainfall districts likely exist. Individual business’s will need to develop their own programs and subsequent costings using accurate soil testing and interpretation as the basis. Generally returns are more difficult to quantify than costs.Figure 3 provides a quick reference to an individual paddock’s pH and its likely impact on crop performance. Understanding the effects of pH levels on crop performance in a particular paddock requires accurate spatial information about soil chemistry across that paddock and an understanding of what of the limiting factor of crop performance pH is influencing. For example if acidification is resulting in increasing availability of aluminium than response to liming is likely to be seen quite quickly. If alternatively decreasing pH was making phosphorus less available then economic return would more than likely be lower and slower to achieve. pH management is about maintaining the farms capital value. Unfortunately it does not readily show up in a valuation like other long term investments such as a silo complex or new fencing. It is reasonable to expect


though that an ability to demonstrate good soil pH management would add to a property’s value if it was sold. If on the basis of historical soil test declining pH levels are observed a time line for remediation could be developed. Figure 4 is a decision support tree that highlights likely responses. A guide to application rates is presented in Table 2 but it is critical that final rates be determined on the basis of sound soil sampling procedures and interpretation of test results.Costs are easier to quantify then returns and fall into 3 basic variables, namely-1/ Cost of collecting and interpreting accurate spatial soil chemistry data. Results to any amelioration of soil pH will only be as good as the data used to develop application rates. Over liming, particularly on light soils can lead to nutrient tie up issues and create as many agronomic problems as the liming was attempting to resolve. Approaches to data collection vary from basically spending time in the field with a simple soil pH indicator kit to rapid pH assessments across a paddock on a fee for service basis from commercial suppliers.2/ On farm cost of lime. Lime quality and freight cost from source need to be considered to establish a cost per hectare. A simple measure of lime quality or purity is its neutralising value. It is a measure of the amount of acid on a weight basis the lime will neutralise. The higher the value the lower the rate of lime per hectare required to achieve the same change. The use of neutralising value to develop application rates per hectare is a similar concept to using fertiliser analysis in developing application rates.3/ Cost of spreading. Obviously only consider lime sources that physically can be spread using owned machinery or contractors available in the district. Some “manufactured granular” as opposed to mined and sieved lime products are becoming available. Generally they are more expensive per tonne but may offer significant advantages in terms of material handling and application for some producers. Careful consideration and costing of the options based on the aims of your pH management programme could lead to significant savings in cost over time.

Figure 3: The likely impact of liming. (Dept of Food & Agriculture Western Australia).

49

SOIL TESTECEC(CMOL(+)/KG)

LIME REQUIRED (T/HA) TO LIFT PH IN TOP 10 CMFROM 4.0 TO 5.2 FROM 4.3 TO 5.2 FROM 4.7 TO 5.2 FROM 5.2 TO 5.2

1 1.6 0.8 0.3 0.22 2.4 1.2 0.5 0.43 3.5 1.7 0.7 0.54 3.9 2.1 0.9 0.65 4.7 2.5 1.1 0.76 5.5 3 1.2 0.87 6.3 3.3 1.4 18 7.1 3.8 1.6 1.19 7.9 4.2 1.8 1.210 8.7 4.6 1.9 1.315 12.5 6.7 2.8 1.9

Figure 4: A decision support tree to aid liming decisions (Dept of Food & Agriculture Western Australia).

Table 2: A basic guide to application rates of lime (fine lime,NV>95%) required to alter soil pH. (NSW DPI Soil acidity & liming Agfact)


SOIL PH MANAGEMENT AND PRECISION AGRICULTURE TECHNOLOGIESSimilar to most soil characteristics spatial variability of soil pH can be significant, particularly in the large area paddocks common in the low rainfall zone. The development of management zones and use of variable rate technology in lime application is already commercially available. A distinct advantage with using variable rate application technology in liming is that it limits the potential for higher than required application rates in some areas of the paddock that would occur in a blanket single rate application. Excessive rates can impact crop performance similarly to not managing pH at all.The starting point to development of management zones is quality paddock mapping. Commercial providers of rapid pH assessments across the paddock are operating in NSW. Figure 4 and 6 below are examples of commercially available services. They were supplied by a cooperating farmer in the project and form the basis for their pH management.

Figure 5: Results of pH assessments across a paddock. Note spatial variability.

51

REFERENCES Heenan, D.P., McGhie W.J., Conyers M.K. “Soil pH change over time in relation to rotation, N fertiliser, stubble management and tillage”. 1998

ACKNOWLEDGEMENTSThe research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC. The author would like to thank them for their continued support.

I would also like to acknowledge the support of Nick Hill, former CWFS project manager who was responsible for the data collection reported in this paper.

Figure 6: Management zones developed from pH assessments in figure 4.


CONTACT DETAILSJohn Small Central West Farming Systems PO Box 171, Condobolin 2877

Ph: 02 951009, 0488 951 001 Email: [email protected]

Helen McMillan Central West Farming Systems PO Box 171, Condobolin 2877 Ph: 0437 612 140 Email: [email protected]

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2015 SEASONAL EFFECTS OF STRATEGIC STUBBLE TREATMENTS ON WHEAT AND BARLEY IN CWFS DISTRICTS; YEAR 3 OF A 5 YEAR INVESTIGATIONJohn Small Central West Farming Systems


KEY MESSAGES • During 2015 stubble treatments involving late burning or cultivation

resulted in significantly different yields in wheat and barley in 2 of 3 trials conducted at Tottenham, Weethallee, and Mumbil Creek.

• The stubble treatments had no effect on cultivar rankings or grain quality at any site.

• The effects of stubble treatments observed during 2015 were similar to the effects observed during similar trials in 2013 and 2014. The trend emerging is best summarised;

• “Cultivation late in fallow to reduce stubble loads for sowing is the most likely option to reduce yield unless it resolves a physical soil constraint such as compaction or established hard to kill weeds. Burning late in fallow to reduce stubble loads for sowing is unlikely to significantly improve yields compared to sowing into district typical standing stubbles. Burning maybe a good last minute option where despite good planning stubble is still interfering with sowing.”

BACKGROUNDCWFS are conducting trials at its regional sites that • Investigate the impact of different stubble treatments (burning,

cultivation or standing stubble) imposed towards the end of the fallow have on the yield of wheat and barley

• Evaluate any cultivar responses within crop species to the impact of the different stubble treatments.

During 2013 and 2014 CWFS has conducted similar trials at 12 locations Tottenham, Euabalong, Weethalle, Rankins Springs, Wirrinya,

SEASONAL EFFECTS: WHEAT & BARLEY


Nyngan, Alectown, Gunning Gap, Lake Cargelligo, Ungarie and Tullamore (2 trials) which have been reported previously. Small statistically significant differences in yield due to stubble treatments were observed at 8 of the 12 trials. No cultivar responses to stubble treatments have been observed.

Ongoing trials during the CWFS “Rain n Grain n Stubble” project will hopefully allow responses to be predicted pre-sowing rather than just measured at harvest.

AGRONOMIC ISSUESStubble retention during fallows within cropping systems in CWFS districts is a common practice. The 2013 CWFS farmer survey (representing 47 producers managing 207000 ha) highlighted that 70 % of producers regularly maintained stubble cover over summer whilst 20% regularly maintained fallows by cultivation alone. No simple relationship between farm size and stubble management practice could be determined. Anecdotally, the reliance on herbicide for weed control in stubble retained systems, and the increasing threat to system profitability posed by herbicide resistant and hard to kill summer weeds, have seen the adoption of more integrated weed management programs including a reversion to stubble burning and cultivation. CWFS members are asking about short and longer term impacts of using chemical fallows, cultivation and burning in more seasonally specific dynamic combinations to resolve agronomic problems such as weeds, pests, disease or crop nutrition issues with the aim of increasing profitability.

TRIAL DESIGNThe trial was 12 ranges and 10 rows, and consisted of 4 replicates. Each replicate was 3 ranges. The trial was a split plot with varieties nested in (stubble x crop) nested in replicates. There were 3 stubble treatments; standing, burnt and cultivated. There were 2 crop species, wheat and barley. For each crop species there were 5 varieties tested. They were selected on the basis “farmer interest” and type (early, late, disease response etc).

Figure 1: 2015 trial plan 2015 trial sites:

55

TRIAL SITE Weethalle The trial at the Wirrinya regional site suffered significant herbicide damage and will not be reported.

TRIAL SITE Mumbil Creek

CO-OPERATOR Jeff and Tim Bennett

PADDOCK HISTORY 2012 to 2014 wheat no till

SOIL TYPE Sandy loam

STUBBLE TREATMENTS IMPOSED

March 2015

SOWING DATE 7 May Seeding rate 40 kg/ha, 63 kg/ha MAP fertiliser into moist seedbed

HARVEST DATE 16 November

SPECIAL NOTES Cultivation treatment imposed with offset discs. Stubble conditions at sowing was 80% cover generally about 300mm high with an average load of 2 t/ha, ranging from 1.5 to 3 t/ha. The amount of standing stubble varied from 85 to 70% of total load. Available N to 120cm across the replicates varied from 57 to 84 kg/ha. 0-10 cm Cowell P values varied from 11 to 13 across the replicates with the 10-30cm varying from 3 to 4. PredictaB tests rated crown rot infection below detectable levels.

RESULTS There was a yield response and no grain quality response to stubble treatment in wheat. The yield response showed burnt better than cultivation but not standing stubble and standing stubble was no better than cultivation. No grain yield response to stubble treatment was observed in barley. No differences in crop performance were observed between treatments when considering plant emergence or biomass.The dry spring and heatwave conditions the trial experienced during early October more than likely limited any potential yield advantages from either stubble treatments or variety selection. It is suggested that the yields obtained despite these difficult spring conditions are a reflection of the timely fallow management undertaken by the cooperating farmer prior to sowing.

WHEAT TRIAL STUBBLE

YIELD (T/HA)

Burnt 1.76Cultivated 1.53Standing 1.60Lsd 0.20

BARLEY TRIAL STUBBLE

YIELD (T/HA)

Burnt 2.12Cultivated 2.19Standing 2.28Lsd ns


TRIAL SITE Weethallee

CO-OPERATOR Leuff family “Malonga Park”

PADDOCK HISTORY Rotation is fallow with one cultivation, followed by wheat, followed by barley no till, then back to fallow. 2014 crop wheat.

SOIL TYPE Red sandy loamGSR; 243mm


March 2015

SOWING DATE 11 May. Seeding rate 40 kg/ha, 63 kg/ha MAP fertiliser into moist seedbed


SPECIAL NOTES Cultivation treatment imposed with offset discs. Stubble at sowing about 300mm high with an average load of 2 t/ha, ranging from 1.5 to 3 t/ha. The area between last years’ rows was generally bare. Available N to 120cm across the replicates varied from 113 to 145 kg/ha. 0-10 cm Cowell P values varied from 26 to 31 across the replicates with the 10-30cm varying from 6 to 7. PredictaB tests rated crown rot infection below detectable levels.

RESULTS There was no yield or grain quality response to stubble treatment in wheat. No grain yield response to stubble treatment was observed in barley. No differences in crop performance were observed between treatments when considering plant emergence or biomass.The dry spring and heatwave conditions the trial experienced during early October more than likely limited any potential for impact of stubble treatments. The very small difference observed in wheat yields and no difference in barley yields is most likely related to seasonal influence.

WHEAT TRIAL STUBBLE

YIELD (T/HA)


WHEAT YIELD (T/HA) PROTEIN (%) SCREENINGS (%)Condo 1.65 10.1 8.3Gregory 1.58 9.9 8.4Livingston 1.69 10.2 9.4Spitfire 1.53 10.6 9.1Suntop 1.69 10.2 11.8Lsd 0.1 ns 2.3

BARLEY YIELD (T/HA)

Buloke 2.17Commander 2.03Compass 2.21Latrobe 2.46Oxford 2.11Lsd 0.16


YIELD (T/HA)


57

TRIAL SITE Tottenham

CO-OPERATOR Paul Adam

PADDOCK HISTORY 2012 lupins, 2013 wheat, 2014 wheat

SOIL TYPE Red sandy loam

GSR; 148 mm


March 2015



SPECIAL NOTES Cultivation treatment imposed with offset discs. Stubble at sowing about 300mm high with an average load of 3 t/ha, ranging from 1.5 to 4 t/ha. Stubble cover over the ground was generally 100% and the standing stubble represented about half the total load. Available N to 120cm across the replicates varied from 50 to 75 kg/ha. 0-10 cm Cowell P values varied from 15 to 16 across the replicates with the 10-30cm varying from 4 to 5. PredictaB tests rated crown rot infection below detectable levels.

RESULTS There was no yield or grain quality response to stubble treatment in wheat at the accepted 95% confidence level. At 92.5% a response between grain yield and stubble treatment became evident. A grain yield response to stubble treatment was observed in barley. No differences in crop performance were observed between treatments when considering plant emergence or biomass and winter crop growth considered good. The dry spring and heatwave conditions the trial experienced during early October more than likely limited any potential impact of stubble treatments and most likely contributed to the high screenings observed. The final yields were also heavily influenced by the Spring conditions. Low protein levels reflect low soil nitrogen levels at sowing and the very limited N applied as starer fertiliser.

WHEAT TRIAL STUBBLE

YIELD (T/HA)


WHEAT YIELD (T/HA) PROTEIN (%) SCREENINGS (%)Condo 2.20 9.4 5.8Gregory 2.16 9.5 5.1Livingston 2.40 9.4 7.1Spitfire 2.20 9.7 6.9Suntop 2.49 9.4 5.6Lsd 0.21 ns 0.9

BARLEY YIELD (T/HA)

Buloke 2.69Commander 2.76Compass 2.64Latrobe 2.60Oxford 2.58Lsd n.s.


YIELD (T/HA)

Burnt 2.11Cultivated 1.79Standing 1.98Lsd 0.27


WHEAT YIELD (T/HA) PROTEIN (%) SCREENINGS (%)Condo 1.59 9.5 9.7Gregory 1.56 10 12.5Livingston 1.65 9.9 14.6Spitfire 1.63 10.2 12.6Suntop 1.59 10.1 14.6Lsd ns 0.32 1.78

BARLEY YIELD (T/HA)

Buloke 2.11Commander 1.90Compass 2.14Latrobe 1.99Oxford 1.69Lsd 0.23

2ND YEAR EFFECTS OF 2014 TRIALSThis series of trials has been run over 2013, 2014 and now 2015. During 2014 the 2013 wheat replicates at trial sites were monitored for any second year effects by collecting biomass samples during the spring. At most sites there was a visual difference in the crop performance across the stubble treatments. Statistically at all sites and all stubble treatments there was no significant difference between the biomass production achieved during the Spring 2014.During the 2015 spring, 2014 sites were visited and little visual difference between the wheat replicates could be observed. Based on the previous years’ results little benefit could be identified by collecting further samples and no further data was collected.

DISCUSSION There is no evidence from the 2015 trials that variety yield ranking changes with stubble or tillage treatment for either wheat or barley. Overall 2015 produced similar results to 2013 and 2014 findings. All years have experienced in producer terms a “good start”, “good winter rain” then a “disappointing dry Spring” (heavily edited). The 2015 Spring was perhaps the most “disappointing” and limiting for crop performance since it was a combination of high temperatures and dry conditions. Based on observations made during 2013, 2014 and 2015 it maybe concluded that yield of any of the cultivars tested cannot be improved by pre sowing stubble management when a dry Spring is encountered. This may not be the case in a wet spring when foliar disease may impact crop performance. Again as in 2013 and 2014 the seasonal conditions this year did not bring short term agronomic benefits or risks associated with stubble conservation, burning or cultivation into play. The autumn break was timely and all trial sites were sown with good seed bed moisture. Therefore, the potential benefit of retained stubble providing a more favourable seedbed for an extended sowing time was again not observed. Given the sowing speeds and efficiencies that modern sowing equipment can achieve this perceived benefit of stubble retention may not be as important as when stubble retained systems were initially being developed.During 2015 at Mumbil Creek wheat and Tottenham barley sites a significant relationship existed between yields and pre sowing stubble treatments. The burnt treatment yielded statistically higher than cultivation but not the standing stubble although statistically the standing stubble was not better than the cultivation. This statement has been generally supported by 2013 and 2014 trials were yield responses have been observed except at sites where physical soil constraints to sowing such as soil compaction and established weeds were reduced due to the cultivation treatment.Considering the implications to crop management in CWFS districts of this trial during the years 2013, 2014 and 2015 the following key points emerge• At sowing the best option in terms of yield is to sow the cultivar with the highest yield potential for the sowing

window • Cultivation late in fallow to reduce stubble loads for sowing is the most likely option to reduce yield unless it

resolves a physical soil constraint such as compaction or established hard to kill weeds• Burning late in fallow to reduce stubble loads for sowing is unlikely to significantly improve yields compared to

sowing into district typical standing stubbles. Burning maybe a good last minute option where despite good planning stubble is still interfering with sowing.

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• Burning may not be a cheap option. The cost of burning stubble needs to be considered both in terms of dollar labour cost and lost nutrients. Costs of compliance with burning regulations, WHS and insurance should not be underestimated.

ACKNOWLEGDMENTSCWFS would like to acknowledge the support provided by the co-operating farmers, without their in-kind support the trials would not have been possible. The author also thanks Neil Fettell for his support in compiling this report.


STUBBLE EFFICIENCY STUBBLE GRAZING CONDOBOLIN 2015

Ian Menz Research and Development Agronomist, Condobolin

Nick Moody Technical Officer, Condobolin

Daryl Reardon Technical Officer, Condobolin

February 2015

KEY MESSAGES • Treatment 1, Nil grazed, moderate stubble yielded the highest,

(2.18 t/ha)• No significant difference in Total Plant Available Water, majority of

stored water was below the 50 cm depth.• There was a significant difference between the eight treatments

when comparing available soil nitrogen.• There was a significant difference in grain quality attributes between

the eight stubble treatments.

TRIAL AIMThis trial is part of a series of trials aimed to investigate how differing summer farming practices influence stored water and how plant available water may influence grain yield potential and grain quality attributes in the low rainfall area in central NSW. The summer farming practices that were investigated included stubble and weed management.Stubble was managed either through full or partial removal with sheep, other stubble treatments involved the stubble left standing or stubble being burnt prior to sowing. In addition when stubble was retained the effect of weed control through sprays treatments. As studied in previous year, the effect of stubble, grazing and spray management over the summer period was measured through its effect on plant available water at sowing and flow on effect in grain yield and quality parameters.

STUBBLE EFFICIENCY

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TRIAL DETAILSSoil type: Red Sandy LoamCrop 2014: Twilight field peas and Mannus oats, brown manuredCrop 2015: Livingston wheatSowing rate: 30 kg/haSowing Date: 20th May 2015Fertiliser: 50 kg MAPSeeder type: DBS Parallelogram Hydraulic tyne seeder, with disc cultersRow spacing (cm): 25.4 cmHarvest date: 9th November 2015

TREATMENTS1. Nil graze, as is moderate stubble retain2. Nil graze, as is moderate stubble retain, burnt late3. Nil graze, high stubble retain4. Nil graze, mown stubble removed5. Stubble moderate graze, stubble retention, sprayed for weeds6. Stubble moderate graze, sprayed for weeds, burnt late7. Stubble heavy graze stubble retention, sprayed for weeds8. Stubble heavy graze, stubble retention, one missed sprayGrazing treatments were imposed on the 20th January 2015, when 330 merino ewes were placed on plots. Moderately grazed trial plots had a stocking rate of 727 sheep/ha for one day and were excluded on the 21st January 2015. The heavily grazed trial plots had a stocking rate of 727 sheep/ha for one day and 1455 sheep/ha for an additional day, the sheep were excluded on 22nd January 2015.

SEASONAL REVIEWThe seasonal condition experienced at Condobolin Research and Advisory Station, Condobolin during 2015 year had profound influence on the trial results. The trial was sown into good moisture and established very quickly and evenly. Weed control was exceptional, and the trial was very even throughout the season. The rainfall for the growing season (May to October) was just below average, with Condobolin Research and Advisory Station recording 198.7 mm during the growing season (Table 1), with the Long Term Average (LTA) during the growing season rainfall of 209 mm. Good rainfall fell in June, July, August and October. Rainfall during both May (11.6 mm) and September (6.2 mm) were well below the long term average of 34.4 mm and 29.1 mm, respectively. In addition to lower than expected rainfall in September, high daytime temperatures in the mid to high thirties were experienced, in conjunction with hot strong winds occurred during the first week in October. Combination of high daytime temperatures, hot winds and low rainfall produced a hard finish for the crop.

DEC 14

JAN 15

FEB 15

MAR 15

APR 15

MAY 15

JUN 15

JUL 15

AUG 15

SEPT 15

OCT 15

NOV 15

DEC 15

TOTAL IN-CROP

88.8 59.2 35.2 0.2 64.7 11.6 31.8 41.6 42.3 6.2 65.2 67.3 28.5 454.4 198.7

Table 1: Monthly rainfall (mm) at Condobolin Research and Advisory Station, Condobolin during 2015.

Trial resultsSoil plant available water and nutrient testsSoil tests were taken just prior to sowing at the soil depths of;


0-10cm10-30cm30-50cm50-70cm70-90cm

Plant available waterThe application of the eight stubble treatments over the summer season did not result in any difference to total plant available water for the eight stubble treatments when soil was taken to a depth of 90 cm. The amount of plant available water to a depth of 90 cm was low and ranged from 43mm to 82 mm over the eight treatments. When plant available water was divided into depths there were increasing amounts of stored moisture at lower depths. The majority (69 %) of the little plant available water stored in the profile was below 50 cm in depth. This moisture was beyond the capacity of seedlings or moderately sized plants to exploit.

Soil NitrogenThere was a significant difference, at the 5 % level, between the eight treatments when comparing the total available soil nitrogen (kgN/ha) as well as available soil N for soil depths of 0-10 cm, 10-30 cm prior to sowing the trial in 2015. There was no difference in soil N between the eight treatments at depths lower than 30 cm.Total soil nitrogen levels varied significantly dependant on the stubble management treatment in the previous year. Highest total residual soil nitrogen level, prior to sowing, were recorded for stubble treatment 7 (146.5 kgN/ha), whilst treatment 5 (126.9 kgN/ha) and treatment 2 (121.7 kgN/ha) were similar. These three treatments had stubble retention with weed control through spraying or burning (Table 2.). The lowest total available soil nitrogen prior to sowing was treatment 8 with only 84.4 kgN/ha (Table 2.).Soil nitrogen levels at the 0 to 10 cm depth ranged from 24.5 kgN/ha to 58.7 kgN/ha (Table 2.). The highest level of available N in the 0 to 10 cm depth was 58.7 kgN/ha for treatment 7, with 52.7 kgN/ha for treatment 5 and with 45.9 kgN/ha for treatment 2 similar in value (Table 2.).

STUBBLE TREATMENT 0 TO 10 (CM) 10 TO 30 (CM) TOTAL N (CM)1. Nil graze, moderate stubble retain 44.7 16.0 101.02. Nil graze, moderate stubble retain, burnt late 45.9 27.0 121.73. Nil graze, high stubble retain 30.1 18.8 91.84. Nil graze, mown stubble removed 37.6 19.0 114.95. Stubble moderate graze, stubble retained, sprayed 52.7 29.3 126.96. Stubble moderate graze, sprayed for weeds, burnt late

36.6 25.3 100.9

7. Stubble heavy graze, stubble retained, sprayed 58.7 29.0 146.58. Stubble heavy graze, stubble retained, one miss spray

24.5 19.8 84.4

l.s.d. (p=0.05) 13.7 6.0 26.2

Table 2: Available soil nitrogen (kgN/ha) for soil depths of, 0 to 10 cm, 10 to 30 cm and total profile prior to sowing for eight stubble treatments at Condobolin in 2015.

Soil nitrogen levels at the 10 to 30 cm depth ranged from 16.0 kgN/ha to 29.3 kgN/ha (Table 2.). The highest level of available N in the 10 to 30 cm depth was 29.3 kgN/ha for treatment 5, with 29.0 kgN/ha for treatment 7, with 27.0 kgN/ha for treatment 2 and with 25.3 kgN/ha for treatment 6 being similar (Table 2.).

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Figure 1: Grain yield (t/ha) for the eight stubble management treatments conducted on the stubble grazing trial at Condobolin in 2015.

Grain Yield and Quality There was significant difference between the eight treatment grain yields of Livingston (Figure 1.). Treatment 1 (Nil grazed, as is moderate stubble retain) achieved the highest grain yield with 2.18 t/ha. Other treatments that also achieved similar yields were treatment 3 (2.13 t/ha), treatment 4 (2.11 t/ha), treatment 5 (2.07 t/ha) and treatment 6 (2.06 t/ha) (Figure 1. and Table 3.). The lowest achieved grain yield was achieved for treatment 8 (stubble heavy graze, one missed spray) at 1.74 t/ha (Figure 1. and Table 3.). This is a reduction in grain yield of approximately 20 % when compare to the highest achieved grain in treatment 1.There were differences, at a 5% significance level, in grain quality attributes between the eight stubble treatments when comparing grain protein, test weight and screenings (Table 3).The highest grain protein, was achieved in treatment 7, heavy grazed; stubble retained and weeds sprayed (11.7 %), this treatment had the highest total available soil nitrogen (146.5 kgN/ha) (Table 3.). Grain protein levels for treatment 4 (11.1 %), treatment 5 (10.9 %), treatment 8 (10.5 %) and treatment 6 (10.4 %) were similar to that achieved for treatment 7 (Table 3.). There was a significant difference between treatment 7 and treatment 1, treatment 2 and treatment 3, with 9.4 %, 10.3 % and 9.5% respectively (Table 3.).The grain nitrogen removal ranged from 40.9 kgN/ha for treatment 4 to 31.6 kgN/ha for treatment 8 over the eight stubble treatments (Table 3.). There was no significant difference between the highest five grain nitrogen removal values. The top five rates of grain nitrogen removal were 40.9 kgN/ha, 40.3 kgN/ha, 38.9 kgN/ha, 37.7 kgN/ha, and 36.9 kgN/ha for treatment 4, treatment 7, treatment 5, treatment 6 and treatment 2, respectively (Table 3.).


TREATMENT GRAIN YIELD (T/HA)

GRAIN NITROGEN REMOVAL (KGN/HA)

PROTEIN (%)

TEST WEIGHT (KG/HL)

SCREENING (%)

TILLER NUMBER (M2)

AVAILABLE SOIL NITROGEN (KGN/HA)

1 2.18 35.6 9.4 75.3 23.1 181.9 101.02 2.01 36.9 10.3 73.9 28.2 229.4 121.73 2.13 35.4 9.5 75.7 28.5 201.9 91.84 2.11 40.9 11.1 72.8 42.8 234.4 114.95 2.07 38.9 10.9 73.1 36.9 265.6 126.96 2.06 37.7 10.4 73.6 36.6 221.6 100.97 1.98 40.3 11.7 72.4 52.6 234.9 146.58 1.74 31.6 10.5 73.7 43.4 227.1 84.5l.s.d. (p=0.05)

0.14 4.7 1.3 1.2 12.2 31.1 26.2

Table 3: Grain yield (t/ha), grain nitrogen removal (kgN/ha), grain protein (%), test weight (kg/hl), screening (%), tiller number and total available soil nitrogen (kgN/ha) for the eight stubble management treatments conducted on the stubble grazing trial at Condobolin in 2015.

Variation between stubble treatments was evident when examining test weight, yet even with this difference none of the samples were in excess of the acceptable GTA standard of 76 kg/hl. The highest test weight was obtain from treatment 3, nil grazed high stubble retained (75.7 kg/hl), treatment 3 was similar to treatment 1, nil graze, moderate stubble retain (75.3 kg/hl) but greater than all other stubble treatments (Table 3.).Differences in screening was observed between the eight stubble treatments, yet as with test weight all values were well over the acceptable GTA standard of 5 %. Screenings ranged from 23.1 % for treatment 1 to 52.6 % for treatment 7. Treatment 1 achieved the lowest screening with 23.1 %, with not statistically difference at the 5 % level between treatment 1 and treatment 2 (28.2 %) and treatment 3 (28.5 %). The nil grazed, retained stubble treatments (treatments 1, 2 and 3) achieved the lowest screenings (23.1 %, 28.2 % and 28.5 %, respectively), in conjunction these treatments also had the highest test weights (75.3 kg/hl, 73.9 kg/hl and 75.7 kg/hl, respectively) (Table 3.).Stubble treatment 5 had the largest number of tillers with 265.6 tiller/m2, whilst treatment 1 had the lowest with 181.9 tiller /m2. Plant tillers for stubble treatment 7 were similar to that of treatment 5 (Table 3.).

DISCUSSIONSeasonal conditions resulted in a short dry spring resulting in a fast, hot grain fill in and around the Condobolin region in 2015. These seasonal conditions resulted in high screenings and low test weights that fell below the GTA standard of 76 kg/hl and 5 % screenings for any grade ASW1 and above.Nil grazing stubble treatments, did not affect overall plant available water but did on average improve grain yield to over 2 t/ha, screenings and test weight when compared broadly to stubble treatments that grazed the stubble treatments. The nil grazing treatment with exception of treatment 2, (nil graze, moderate stubble retain and burnt late), achieved the highest grain yields (Table 3. and Figure 1.). It appears that the effect of burning stubble on treatment 2 may have had an influence on the grain yield as this was the difference between treatment 1 and treatment 2.Sheep grazing on stubble over the summer period in moderate intensity lead to similar grain yield than the nil graze stubble treatments yet the grain quality parameters of test weight were lower and screenings were higher (Table 3.). If grazing intensity was increased from moderately too heavy a reduction in grain yields were observed. In conjunction, increased grazing intensity reduced test weight and increased screening. Removal of stubble, either by grazing, mowing or burning increased the number of tillers counted in a unit area. Under more normal conditions higher tiller numbers would in increase grain yield potential. The hot dry spring may have reduced productivity from each tiller causing many small pinched grains, resulting in low test weight and high screenings. Higher screenings and test weights in both moderately and heavily grazed may have resulted from increased tillers during the growing season.

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In contrast, treatment 1, nil grazed, moderate stubble retained, had the highest ground cover over summer, the lowest number of tillers during the growing season. This caused the highest grain yield, high test weight and low screenings.Under hot and dry spring conditions, highest grain yields and test weights in conjunction with the lowest protein and screenings were observed when paddocks were not grazed and at least a moderate level of stubble cover was maintained over summer.

ACKNOWLEDGEMENTThe contributions of GRDC and CWFS in funding this trial are gratefully acknowledged. The contribution of the Operational staff at Condobolin Agricultural Research and Advisory Station, CondobolinContribution of Dr Neroli Graham for the statistical analyses and paper review© State of New South Wales through Department of Primary Industries 2012. You may copy, distribute and otherwise freely deal with this publication for any purpose, provided that you attribute NSW Department of Primary Industries as the owner.Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (December 2012). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of NSW Department of Primary Industries or the user’s independent adviser.


2015 SEASONAL EFFECTS OF STRATEGIC STUBBLE TREATMENTS ON NITROGEN RESPONSE IN WHEAT



KEY MESSAGES • The seasonal conditions experienced during these trials had a

profound impact on the trial results.• During 2015 stubble treatments imposed late in fallow had no

impact on N response.• Similar to 2014, during 2015 generally farmers were unable to

predict final yield before sowing when the season experienced extreme weather conditions.

• During 2015 split N applications did not improve yields and had only a very minor impact on grain quality.

• During 2015 split N applications was not a way to reduce financial risk as opposed to all N fertiliser upfront since crop outlook at Z30 was positive.

BACKGROUNDCWFS are conducting trials at its regional sites that: • Investigate the impact of different stubble treatments imposed

towards the end of the fallow have on nitrogen response (applied as urea) in wheat yield and quality

• Evaluate any interaction between pre sowing stubble treatment and topdressing timing

During 2015 CWFS conducted these trials were conducted at 4 locations Mumbil Creek, Weethalle, Tottenham and Wirrinya.During 2014 CWFS conducted a similar trial at 6 locations Nyngan, Alectown, Gunning Gap, Lake Cargelligo, Ungarie, and Tullamore. These trials have been previously reported.

NITROGEN RESPONSE IN WHEAT

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AGRONOMIC ISSUES The nitrogen demand for maximum yield and protein of dryland crops in Central West NSW is unpredictable until late crop development because of variable spring weather conditions, particularly rainfall. Potentially nitrogen fertiliser can be one of the largest variable costs in wheat production. These two issues have seen farmers adopt topdressing with urea as an important management strategy to balance the seasonal risks and rewards of nitrogen fertilizer. Various approaches to N budgeting have been developed that assist growers to justify how many dollars in the form of nitrogen to risk in an attempt to maximise returns in any one year. A common rule of thumb used to determine crop nitrogen topdressing rates is 20kg/ha of actual N per tonne of expected grain yield. In agronomic N accounting logic this benchmark assumes unrealistic N recover rates from soil and fertilizer. The number also fails to account for any soil N at sowing or any N that may have mineralised incrop. Nevertheless, it continues to be a widely used “number” during the in-season decision making process to topdress crops were growers are not using computer based decision support tools to decide topdressing rates. Growers using the benchmark consider observations of crop performance, a “gut feel’ about how the season will finish, and a knowledge of their business position and market expectation to decide to spend (risk) money on N fertilizer. Organic N in the soil profile provides the basis for N mineralisation in addition to the crop residues that are cycled near the soil surface. Recent research (Angus, CSIRO, 2013 Forbes GRDC Update) suggest that organic N declines by 2-3% in continuous cropping systems. Fertilizer applications or growing grain legumes reduces the rate of decline but does not maintain the level. To maintain yields with continuous cropping, it is suggested that the application of N fertiliser will need to double over the next forty years. Currently urea fertilizer manufacture requires a significant amount of natural gas with modern manufacturing facilities approaching thermodynamic maximum. The outlook is that whilst the availability of natural gas is unlikely to limit N fertiliser supplies, the cost of manufacturing will not fall due to improved production efficiency.These two individual issues alone are pushing producers to use N fertilizer more efficiently. Testing the 20 kg/ha per tonne benchmark under a range of stubble conditions over a number of seasons will either confirm the number for Central West Farming Systems districts or help develop options for more efficient benchmarks.

TRIAL DESIGNThe trial is 12 ranges and 3 rows, and consisted of 4 replicates. Each replicate is 3 ranges and 3 rows. There are 3 stubble treatments; standing, burnt and cultivated. The wheat cultivar is Suntop. Sowing rate was 35 kg/ha, 40 kg/ha of MAP (4.4 kg N per ha) was also applied to all treatments to (try to) ensure phosphorus was not limiting.At each site 3 treatments were developed based on the cooperating farmers yield expectation for the trial site. Each treatment represented a different application timing for urea topdressing based on 20 kg of N per tonne of expected yield/ha. This rate is a commonly used farmer/advisor benchmark across the region. The treatments were; 1: all urea applied at sowing, 2: a 50/50 split upfront and Z21 and 3: split 3 way upfront, Z21 and Z30.

2015 TRIAL SITES AND RESULTS:

TRIAL SITE Wirrinya The trial at the Wirrinya regional site suffered significant herbicide damage and will not be reported.

TRIAL SITE Mumbil Creek

CO-OPERATOR Jeff and Tim Bennett

PADDOCK HISTORY 2012 to 2014 wheat no till

SOIL TYPE Sandy loam


March 2015

SOWING DATE 10 June. The trial was resown after a trial sown 7 May failed to establish due to seeder problems. Seeding rate 40 kg/ha, 63 kg/ha MAP fertiliser into moist seedbed



SPECIAL NOTES Cultivation treatment imposed with offset discs. Stubble conditions at sowing was 80% cover generally about 300mm high with an average load of 2 t/ha, ranging from 1.5 to 3 t/ha. The amount of standing stubble varied from 85 to 70% of total load. Available N to 120cm across the replicates varied from 57 to 84 kg/ha. 0-10 cm Cowell P values varied from 11 to 13 across the replicates with the 10-30cm varying from 3 to 4. PredictaB tests rated crown rot infection below detectable levels. The cooperating farmers’ were asked to provide a presowing yield estimate for the trial site if there was no financial risk to them in purchasing nitrogen fertiliser, their estimate was 3t/ha.

RESULTS No significant interaction between presowing fallow stubble management and timing of nitrogen application was observed. Similarly as shown in the table below during this trial no significant interaction was observed between timing of nitrogen application and grain yield or quality.

SOWING (KGN/HA)

Z 21 (KGN/HA)

Z 30 (KGN/HA)

YIELD(T/HA)

PROTEIN (%)

SCREENINGS(%)

TEST WEIGHT

60 0 0 1.19 16.7 37.3 73.330 30 0 1.16 16.7 38.3 73.820 20 20 1.15 16.4 36.6 74.2Lsd (0.5%) n.s. n.s. n.s. n.s.

TRIAL SITE Weethalle

CO-OPERATOR Luelf family “Malonga Park

PADDOCK HISTORY Rotation is fallow with one cultivation, followed by wheat, followed by barley no till, then back to fallow. 2014 crop wheat


GSR 243mm


March 2015

SOWING DATE Seeding rate 40 kg/ha, 63 kg/ha MAP fertiliser into moist seedbed


SPECIAL NOTES Cultivation treatment imposed with offset discs. Stubble at sowing about 300mm high with an average load of 2 t/ha, ranging from 1.5 to 3 t/ha. The area between last years’ rows was generally bare. Available N to 120cm across the replicates varied from 113 to 145 kg/ha. 0-10 cm Cowell P values varied from 26 to 31 across the replicates with the 10-30cm varying from 6 to 7. PredictaB tests rated crown rot infection below detectable levels. The cooperating farmers’ were asked to provide a presowing yield estimate for the trial site if there was no financial risk to them in purchasing nitrogen fertiliser: their estimate was 3t/ha.

RESULTS No significant interaction between presowing fallow stubble management and timing of nitrogen application was observed. Similarly, as shown in the table below, during this trial no significant interaction was observed between timing of nitrogen application and grain yield. The small differences in grain protein most likely would not change the commercial return to the grower.

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SOWING (KGN/HA)

Z 21 (KGN/HA)

Z 30 (KGN/HA)

YIELD(T/HA)

PROTEIN (%)

SCREENINGS(%)

TEST WEIGHT

60 0 0 2.4 12.6 10.9 80.130 30 0 2.4 12.4 9.9 80.420 20 20 2.4 12 9.7 80.4Lsd (0.5%) n.s. 0.4 n.s. n.s.

TRIAL SITE Tottenham

CO-OPERATOR Paul Adam

PADDOCK HISTORY 2012 lupins, 2013 wheat, 2014 wheat


GSR 148 mm


March 2015



SPECIAL NOTES Cultivation treatment imposed with offset discs. Stubble at sowing about 300mm high with an average load of 3 t/ha, ranging from 1.5 to 4 t/ha. Stubble cover over the ground was generally 100% and the standing stubble represented about half the total load. Available N to 120cm across the replicates varied from 50 to 75 kg/ha. 0-10 cm Cowell P values varied from 15 to 16 across the replicates with the 10-30cm varying from 4 to 5. PredictaB tests rated crown rot infection below detectable levels. The cooperating farmers’ were asked to provide a presowing yield estimate for the trial site if there was no financial risk to them in purchasing nitrogen fertiliser, their estimate was 3t/ha.

RESULTS No significant interaction between presowing fallow stubble management and timing of nitrogen application was observed. Similarly, as shown in the table below, during this trial no significant interaction was observed between timing of nitrogen application and grain yield or quality.

SOWING (KGN/HA)

Z 21 (KGN/HA)

Z 30 (KGN/HA)

YIELD(T/HA)

PROTEIN (%)

SCREENINGS(%)

TEST WEIGHT

60 0 0 1.66 13.9 24.2 78.630 30 0 1.64 14 23.2 78.320 20 20 1.50 14.4 23.5 78.3Lsd (0.5%) n.s. n.s. n.s. n.s.

DISCUSSIONThe seasonal conditions experienced during these trials had a profound impact on the trial results. Heavily edited producer comments summarise the season as a “good start”, “good winter rain” then a “disappointing dry Spring”. “The disappointing spring” started with lower than expected rainfall in September, high daytime temperatures in the mid to high thirties followed by hot strong winds during the first week in October. A rainfall event during September would more than likely resulted in very different results both for the trials and the district crops generally. This combination of seasonal events resulted in significant grower optimism up to the start of spring and then an extremely hard and unexpected finish for all sites. It was one of those seasons in Central West NSW where growers had no options to limit financial risk targeting any yield because the late and sudden change in seasonal weather conditions meant all crop inputs would have already been applied.


With the hindsight of the season and harvest data, it is observed that there was no risk management option available with split applications; as by the time the season collapsed the third time for topdressing had passed. The most profitable option this year was to put all fertiliser on upfront at sowing since this eliminated the cost and time of incrop spreading. As an aside, the appearance of the crops and soil moisture profile in late July and early August may have provide some growers with the incentive to apply even more fertiliser.

ACKNOWLEDGMENTSCWFS would like to acknowledge the support provided by the co-operating farmers, without their in-kind support the trials would not have been possible. The author also thanks Dr Neil Fettell for his support in compiling this report.

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GOOD STUBBLE, BAD STUBBLE MORE PROFIT, LESS PROFIT


GRDC project CWF00018 – Maintaining profitable farming systems with retained stubble in Central West NSW.

Keywords: stubble, management, retention, measurement.

KEY MESSAGES • CWFS regional site trials during 2013 and 2014 suggest stubble

loads greater than 3 t/ha can limit yield.• “No till with no stubble is no good” on hard setting red brown

soil types. The delimma is that the annual incorporation of stubble just prior to sowing by cultivation or removal by burning would result in the loss of signifigant long term benefits to soil health.

• “If you do not measure it you cannot manage it!” Field measurements of stubble are the starting point for deciding what to do.

• Options to manage stubble loads above 3t/ha need to be made seasonally. Good planning may allow other agronomic and farm efficiency outcomes to be achieved at the same time.

BACKGROUNDStubble retention research is not new. The publication Scott et al “Stubble Retention in Cropping Systems in Southern Australia: Benefits and Challenges” (2010) cites research back to 1978. The focus of recent research is concentrating on maintaining profitable retained stubble systems rather than investigating agronomic and economic benefits of stubble retention. The herbicide “glyphosate” was patented by Monsanto in the early 1970s as the active ingredient in the herbicide Roundup®. Roundup® was introduced to the consumer market in 1974 as a broad-spectrum herbicide and since 1980 has quickly become one of the best selling herbicides in Australia and worldwide. When its patent expired in 2000 the number of glyphosate based products grew dramatically and the

GOOD STUBBLE, BAD STUBBLE


cost of the product fell dramatically. The development and adopation of stubble retained farming systems has been and continues to be reliant on the development of glyphosate and different formulations of glyphosate based chemistery.Major agronomic drivers for the adoption of stubble retained farming systems has beeen minimising soil erosion risk and within season benefits of soil moisture, particularly at sowing. Economic drivers for stubble retention have been lower input costs for machinery (less horsepower per hectare), improved efficiencies and timeliness of operations. Most research cited by Scott reports that the presence of stubble in-crop has a negative impact on yield as opposed to stubble removed farming systems. Cameron et al reports similar findings.Looking to the future and based on a quick review of papers delivered at GRDC updates in recent years, it is reasonable to suggest that the decision to retain stubbles in a cropping business will continue to be driven by limiting soil erosion and degradation, maximising sowing soil moisture and improved machinery efficiencies and timeliness of operations. These overarching benefits may be tempered, however, as seasonally tactical stubble management approaches are required for managing herbicide resistance, lowering input costs or production risk and reliably improving yield under certain conditions.

STUBBLE RETENTION REDUCES YIELD BUT NOT PROFITIn a GRDC update paper presented at West Wyalong (29.07.2014) “Lifting productivity in retained stubble farming systems“ by James Hunt, et al, a review of local research demonstrated that most of the benefits of stubble retention (no erosion or run-off) are achieved at stubble loads of 2-3 t/ha. The paper proposed that retaining cereal stubble above 2-3t/ha past sowing is unlikely to provide any yield benefits and in favourable seasons (>250 mm growing season rainfall) can reduce yield (Figure 1). The dilemma is that the annual incorporation of stubble prior to sowing by cultivation or removal by burning would result in the loss of signifigant long term benefits to soil health. Many would question whether this approach to stubble management maintains a stubble retained farming system.

Figure 1: The relationship between growing season rainfall and the yield difference between stubble retained direct drill (RDD) treatments vs. burn and cultivate (BC) treatments form long term sites at Wagga (NSW DPI) and Harden (CSIRO). Figure courtesy of John Kirkegaard, CSIRO.

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The Merrriwagga tillage and rotation trial was established in 1999 and is currently managed by AgGrow Agronomy and Research on behalf of Merriwagga growers and research partners Central West Farming Systems. Since 1999 continuous stubble retention has been more profitable than annual cultivation in all unaltered rotations. Long term stubble loads have not been collected at Merriwagga but given the environment and yields achieved at Merriwagga a 2-3 t/ha stubble load was unlikely to be present at sowing in the great majority of years. Growing season rainfall would also have been less than 250 mm in most years, meaning yield penalties from retaining stubble are unlikely (Figure 1). It cannot be determined whether active stubble management in the high stubble years would have resulted in higher yields or profits. It is observed that in the Merriwagga environment stubble retention is more profitable than the alternate annual tillage system.For further insights into the trial refer to information below. The Merrriwagga tillage and rotation trial established in 1999 aimed to compare five different cropping rotations using no-till farming techniques and conventional farming methods. The trial is situated 10km west of Merriwagga, NSW. Soils are red sandy loams with an underlying calcareous clay with a pH of 5.5-6.5 and have a tendancy to erode with wind and water. Each plot is 1 ha, each treatment is replicated three times and the total trial area is 30 ha. The 2014 Merriwagga trial report highlighted some clear trends after 16 years:• When using contract rates growing crops with no-till techniques has been on average 15% cheaper. In every rotation tested the no-till system has resulted in a higher cumulative gross margin than the conventional rotation. Contract rates are different to the costs a typical farmer would apply but it does allow for a very good comparison of real costs associated with each farming system.• The most profitable rotation has been two cereals followed by a break crop of either peas, lupins or canola under a no-till system (Refer figure 2). Interestingly, a continuous wheat rotation no-till is a close second. It is an interesting discussion and beyond the scope of this paper as to why, despite the agronomic risks, the continuous wheat rotation performs so well in the drier Merriwagga environment.• Generally no-till farming methods compared to cultivation have maintained or increased yields in continuous cropping rotations. The exception is where a fallow exists in the rotation and in this case cultivation has increased yield in most but not all years.

Rotation 1 and rotation 2 are two cereals followed by a break crop such as peas but are not in years. Rotation 1 was in lupins in 2014, rotation 2 is due for a break crop 2015.WFW is wheat-fallow-wheatWLFW has been wheat-fallow-wheat since 2005 but alternates with the wheat-fallow-wheat rotation above. Therefore the years when this rotation is sown to wheat the WFW is fallow.

Figure 2: Cumulative gross margin results from Merriwagga long term trial 1999-2014.


CWFS TRIALS TO DATECWFS has conducted eighteen trials at its regional sites that investigate the impact of different stubble treatments (burning, cultivation or standing stubble) have on the yield of wheat, barley and canola, refer figure 3 for a summary impact of stubble loading on yield. The trials with wheat and barley have also evaluated any varietal responses within crop species to the impact of the different stubble treatments. During 2013 CWFS conducted trials at six locations - Tottenham, Euabalong, Weethalle, Rankins Springs, Wirrinya and Tullamore. During 2014 CWFS again conducted trials at six locations - Nyngan, Alectown, Gunning Gap, Lake Cargelligo, Ungarie and Tullamore. In 2015 similar trials are currently established at Weethalle, Tottenham, Wirrinya, Mumbil Tank and Tullamore; stubble treatments tested are standing, burnt, cultivated and harrowed (knocked over not incorporated into soil). Of the eighteen trials, eight have been established in commercial paddocks with stubble loading of less than 3 t/ha and six have shown no yield response to cultivation or burning stubble late in fallow. Two sites, Tullamore (2013) and Lake Cargelligo (2014) both showed a yield response to cultivation. Both sites suffered compacted soil, at Tullamore due to heavy grazing and Lake Cargelligo due to soil type and lack of ground cover over fallow. A yield response was also observed at Tullamore to burning, most likely related to its effect on the established windmill grass present.Of the 10 trials with stubble loading greater than 3 t/ha an improvement in yield in either the burnt or cultivated treatment has been observed at six trials. It should be noted that a yield improvement in both treatments was only observed at two trials. The four trials where no response to either treatment was observed were the 2014 Alectown and Ungarie cereal trials and the 2014 Rankins Springs and Wirrinya canola trials, all of which suffered moderate to severe frost damage.An important issue highlighted by the cereal trials is that no treatment changed the variety yield ranking. Stubble modification did not improve a poor variety’s performance. The best option in terms of yield was to simply grow the variety with the highest yield potential for the sowing window.

Figure 3: Summary of eighteen CWFS trials investigating late in fallow stubble treatments on yield of wheat, barley and canola.

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HOW CAN STUBBLE LOADS GREATER THAN 3 T/HA BE MANAGED? There are seven options to reduce stubble load between harvest and sowing. The decision will be impacted by many interactive factors that produce a range of potential risks or rewards as shown in figure 4.1. At harvest with the header.2. Left undisturbed during the fallow, the do nothing option. 3. Cultivated into the soil during the fallow.4. Mechanically managed but retained on the surface during the fallow (e.g. flail mulched, slashed, harrowed,

crushed, rolled). 5. Burnt.6. Removed (e.g. baled).7. Grazed during the fallow. CAUTION: Do not place stubble management in front of fallow management i.e. control of summer fallow weeds. Subsoil moisture trumps stubble loading as a driver for future yields!Also important are those paddocks which for some reason end up with no ground cover and are compacted (e.g. end of pasture phase, during drought periods or other natural disasters). Local farmer experience (particularly on red brown earths), CANFA experience and Neville Gould’s summary “No-till with no stubble, no good” (this summary is also supported by Pittelkow et al) show in these instances cultivation is the best option to return the system to production.Golden rules for CWFS districts for fallow stubble:Ground cover minimises soil erosion. Summer rainfall stored as soil moisture during the fallow is a major driver of subsequent crop yield. The presence and architecture of stubble may impact weed germination and spraying results, mice populations, fire risk and in a mixed farming business feed budgets for livestock during the fallow. These impacts need to be actively managed to minimise impact on profit. The seasonal timing and distribution of fallow rainfall will call for different annual management response.The presence and architecture of stubble at the end of fallow will affect sowing conditions. Target and manage what characteristics you desire.

Figure 4: Management considerations in deciding how to manage stubble.


SUMMARISING AVAILABLE OPTIONSAt harvest with the headerGolden rules for CWFS districts at harvest:Ensure harvest is completed ASAP to avoid weather damage. Harvesting costs vary considerably from farm to farm but generally a header at harvest is an expensive option to “groom or mulch” crop residue. “Groom” only for an economic or agronomic outcome that cannot be achieved once harvest is complete such as weed seed management.A/ CWFS harvest height trial at Weethalle 2013, 2014. - A replicated trial concluded that stubble height did not influence fallow efficiency in dry seasons.B/ CWFS windrow burning trial at West Wyalong in 2013 that compared the impact on paddock performance of windrowing and burning to manage rye grass seed bank in comparison to harvesting at a traditional harvest height. Key outcomes of this trial were: • Well managed windrow burning effectively reduces the ryegrass seed bank.• To effectively establish windrows requires forward planning and potentially slows harvest and increases

harvest cost. • Burn as early as conditions allow. Make it a priority job. • Small rainfall events may germinate weeds in burnt areas that require attention before the whole paddock

area. • More work needs to be done over a number of seasons to quantify any impact on fallow efficiency.C/ Farmlink “The cost of harvesting low” data compiled by Paul Breust for wheat cv. Suntop in 2014 at different harvest heights. Values are means of three replicates taken from John Deere 9770 STS yield monitor and all differences are significant (P<0.05).

CUT HEIGHT EFFICIENCY(HA/H)

SPEED(KM/H)

FUEL(L/H)

FUEL (L/HA)

EFFICIENCY(T/H)

YIELD(T/HA)

Short (15 cm) 5.7 6.2 54.3 9.6 14.0 2.05Tall (60 cm) 9.5 10.6 51.2 5.4 28.8 2.19% decrease harvesting short

41% 42% -6% -78% 51% 6%

D/ CWFS stubble trials at Weethalle and West Wyalong 2013. At both sites plots with taller stubble required spraying for weeds prior to plots with shorter stubbles. Effectively this resulted in an extra spray during the fallow in a dry summer.

The do nothing optionTo date this is the business as usual for many farmers and they are balancing the short term loss of potential yield against the long term benefits of organic matter in their farming business. Such decisions are extremely valid despite being extremely difficult to ever accurately quantify long term benefit of short term losses. Every business is different and in the end the decision relates more to the aspirations and attitudes of the individual. From an agronomic viewpoint this option requires careful consideration of how high stubble loads impact on the efficacy of fallow herbicide sprays and pre-emergent in-crop herbicide. Herbicide options will become more limiting and potentially expensive. Higher water rates which add to the expense of spraying should also be considered. The use of “stubble movers” on sowing rigs maybe needed to produce ideal sowing conditions.

Cultivated into the soil during the fallow Advantages of cultivation:• Weed seed burial of difficult to control or herbicide resistant surface germinating weeds e.g.fleabane.• Renovation of tram tracks.• Management of a fallow weed blow out where early summer rain has germinated weeds and subsequent

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hot conditions made herbicide control difficult and expensive, such as in the 2014-2015 summer.• Reduction of fire risk. The wide spread adoption of stubble retention during the summer fallow has

increased the fire risk across the landscape as well as allowing fires that start the opportunity to spread rapidly. During the 2015 CWFS survey of fallow management practice, the cultivation of heavy stubble paddocks along public roadways where fires may start was a consideration. Also on mixed farming operations the cultivation of strategic paddocks to provide a livestock refuge was also practiced.

• Incorporation of lime and other soil ameliorants.• Reduction in some pest and disease populations. Careful consideration to the biology of the specific pest

or disease is required to ensure a positive outcome is achieved.• Accumulation of immobile nutrients such as phosphorus on the surface layers in paddocks with a long

history of no-till has been widely reported. Soil tests from some CWFS regional sites support these reports. During 2015 CWFS is conducting initial trials to investigate if cultivation effectively redistributes immobile nutrients back through the profile for crop use.

Disadvantages of cultivation:• Most likely the most expensive in terms of cash cost, impact of soil structure and potential for wind or

water soil erosion.• Seasonal conditions, either dry or wet, may reduce the number of days with optimum seed bed moisture. • Potential for increasing the spread of weed seeds, soil borne pests and diseases within paddocks and

between paddocks. This is an important consideration when contractors are used for one-off tillage operations. A strict biosecurity plan may reduce the risk.

• Reduction in population of soil based predators such as Carabid beetles, spiders and ants.• Likely to encourage weeds that require burial to trigger germination e.g. black oats. Burial of weed seeds

which reduces natural attrition and efficacy of pre-emergent herbicides such as trifluralin, Sakura and Boxer Gold.

For further information refer to GRDC projects DAN152 and ERM00003.

Mechanically managed but retained on the surface during the fallow (e.g. Flail mulched, slashed, harrowed, crushed and rolled)During the 2015 CWFS survey of fallow management practice the idea of mechanical stubble management with no soil disturbance was observed amongst growers, particularly in the eastern CWFS districts. Advantages:• Potentially the cheapest in terms of cash cost if the motivation is to physically keep the stubble in the

paddock. • Limited impact on soil structure. • Maintain ground cover.• Can easily be adopted in controlled traffic farming systems.• May encourage quicker biological decomposition.Disadvantages:• Laying stubble over may lower the efficacy of pre-emergent herbicides.• Laying stubble over may lead to “hair pinning” issues with disc seeders.• The use of “stubble movers” on sowing rigs maybe needed to produce ideal sowing conditions.• Depending on machinery choice may leave “lumps” of stubble or windrows in the paddock.Bill Long from Ag Consulting Co. (www.agex.org.au/.../innovative-stubble-management-seeding-begins-harvest/) promotes the idea of double cut stubble using the header a second time after harvest is complete, resulting in a greater chaff fraction and less straw and allowing faster breakdown of stubble residues following harvest. The concept is that it is best to keep as much stubble standing rather than laying over to increase herbicide efficacy during crop establishment. Standing stubbles also act as a barrier to soil throw between rows, reducing the chance of crop damage from high herbicide concentrations.


BurningOften seen as the cheap option but the cost of burning stubble needs to be considered both in terms of dollar labour cost and lost nutrients. Costs of compliance with burning regulations, WHS and insurance should not be underestimated. It is also a good last minute option where despite good planning stubble is still interfering with sowing. Burning potentially may lower populations of pests such as mice particularly if a baiting program is used immediately post-burn.

Removal (e.g. baled)Baling straw post harvest can be profitable in some seasons. Unfortunately if drought conditions are driving straw demand the benfits of baling to remove stubble loads above 3 t/ha may not be needed. The impact of machinery used for baling on soil conditions and compaction needs to be carefully considered. Unless carefully planned, opportunistic baling to reduce stubble loads may create as many long term problems as it solves.

Grazed during the fallow In mixed farming operations summer stubble is an important feed resource. CWFS and Farmlink research during both the Water Use Efficiency project and this project confirms that when correctly managed, sheep grazing stubbles during the fallow have no significant impact on subsequent crops.Critical success factors for stubble grazing are:• Sheep’s mouths removing ground cover damage soil rather than soil compaction by feet. • Ensuring at least 2 tonnes per hectare of stubble cover remains (70% cover). The cost and risk of going

below this threshold in periods of drought will be different for each business. Therefore general rules of thumb are unsuitable.

• Do not let grazing compromise summer weed control. Spray weeds before grazing. • Closely monitoring condition of sheep. Once split grain, husks and palatable weeds are eaten the feed

value of standing straw alone maybe not sufficient.

IF YOU DO NOT MEASURE IT YOU CANNOT MANAGE IT!If different stubble loadings, for example above 3 t/ha at sowing and below 3 t/ha at sowing, are going to be managed differently in an attempt to improve yield then stubble loads need to be accurately known at a paddock scale. Growers need to quantify stubble loads to improve seasonal management. The idea is no different to the management of soil nutrients and soil testing, if the amount of soil N or P is not reliably known the most profitable programs cannot be reliably developed. Bowman, 2006, suggests stubble present after harvest is about 1.5 times the grain yield for yields between 0.5 to 4 t/ha in drier areas. This rule of thumb does not account for stubble still present from crops prior to the crop just harvested. Also the amount of stubble decomposition over summer is dependent on seasonal conditions.Mallee Sustainable Farming, Mildura, have produced a series of reference photographs that are useful in estimating ground cover percentage after different stubble management operations. The stubble management guide is available from their website (put the URL here).At the end of the day the most reliable method of monitoring stubble loads is to representatively collect and weigh samples from across the paddock. Same as collecting soil samples, ensure the samples taken represent the paddock by taking multiple samples and avoid unrepresentative areas such as headlands, trees and small areas of distinctly different soil types, all of which will have a greater impact on crop performance than stubble load at sowing. To take samples you will need:• A metre square quadrant.• Rake.• A chaff bag or something similar to put stubble in.• Battery powered digital scales (e.g. for calibrating air-seeder, weighing granular herbicides) or pocket

spring scale (e.g. scales used for checking fish weights when fishing) that can measure in the 0 to 1 kg range.

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Method:1. When stubble in paddock is dry randomly throw quadrant. If stubble is wet samples will need to be dried. 2. Rake up all stubble (standing and lying on ground) inside quadrant, put in bag and weigh. Do not collect soil as it will quickly cause inaccurate weights.3. Every 100 grams of stubble per square metre equals 1 tonne of stubble per hectare. i.e., 200g stubble equates to 2 t/ha, 250g equates to 2.5 t/ha, 300g equates to 3 t/ha.4. It is reasonable to think that after some time the operator will gain an ability to know by feel and volume whether the stubble collected is above or below any pre-determined threshold weight but they should “recalibrate” themselves when conditions change.

CONCLUSIONIn CWFS districts it appears that most of the benefits of stubble retention are achieved by retaining 3 t/ha and more than this can potentially limit yields, particularly in favourable seasons. Options exist to strategically lower stubble loads. Monitoring how much stubble is present is the starting point in deciding if action is required. Seasonal conditions and individual farm business’s aspirations will dictate which option is best. If stubble removal is to be undertaken other non-agronomic advantages such as paddock layout, reduction in business risk and soil improvement opportunities may also be achieved at the same time.

REFERENCESAngus J, Kirkegaard J, (1998) Short term benefits and costs of stubble.Angus J, Poss R, Kirkegaard J, (1998) Long term benefits of stubble.Bowman A, Scott B, (2009) Managing ground cover in the cropping zone of southern NSW.Conyers M, Yash D, (2014) GRDC Strategic Tillage Fact Sheet.Haskins B, McMaster C, Menz I, Muirhead T, (2012) Wheat Fallow efficiency by Nitrogen trial at Rankins Springs.Haskins B, Small J, (2014) Long Term Tillage and Rotation trial, Merriwagga 1999- 2014.Hunt J, Kirkegaard J (2011) Re-evaluating the contribution of summer fallow rainfall to wheat yield in southern Australia.Hunt J, Swan T, Kirkegaard J, Watson L, Rheinheimer B, Peoples M, Fettell N, Small J, Pratt T, Breust P, (2014) Lifting Productivity in retained stubble systems. 2014 West Wyalong GRDC update.Piielkow C, Liang X, Linquist B, Jan van Groenigen K, Lee J, Lundy M,Gestel N, Six J, Venterea R, Kessel C, (2014) Productivity limits and potentials of the principles of conservation agriculture.Scott BJ, Eberbach PL, Evans J, Wade LJ (2010) EH Graham Centre Monograph No 1; Stubble Retention in Cropping Systems in Southern Australia: Benefits and Challenges.Small J, (2013) 2013 Seasonal effects of stubble treatments on canola establishment and grain yield in CWFS districts.Small J, (2013) 2013 Seasonal effects of strategic stubble treatments on wheat, barley and oats in CWFS districts; Year 1 of a 5 year investigation.Small J, Hill N (2015) 2014 Seasonal effects of strategic stubble treatments on wheat and barley in CWFS districts; Year 2 of a 5 year investigation.

CONTACT DETAILSJohn Small Central West Farming Systems PO Box 171, Condobolin 28770488 951 001 [email protected]


LONG TERM TILLAGE AND ROTATION TRIALMERRIWAGGA 1999 - 2015

KEY MESSAGES • No till treatments, for all rotations, were slightly higher yielding than

the conventional tillage treatments for wheat. The yield of peas, in rotation 2, was very low in this trial as a result of the season and Sakura® damage.

• Rotations including a fallow, such as the WFW treatment, had lower weed numbers compared to continuous cropped rotations. The continuous wheat rotation, both conventional and no till treatments, had a large number of ryegrass, even with Sakura®.

• Profit and income for 2015 was highest in the no till wheat/ley/fallow/wheat rotation, and lowest in Rotation 2.

• 17 years of no till wheat on wheat is still second for profitability.

BACKGROUNDEstablished in 1999 and now in its 17th year, the Merriwagga tillage and rotation trial was set up to compare no till farming techniques against conventional farming methods over 5 different cropping rotations.In 2015 the site was managed by Ag Grow Agronomy and Research, on behalf of Merriwagga growers and our research partner Central West Farming Systems Inc.

TRIAL DETAILSSituated 10km west of Merriwagga NSW, the site consists of a total of 30ha. There are 10 treatments in total replicated 3 times, with each plot 1ha in size.The treatments consist of:

LONG TERM TILLAGE & ROTATION

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2 tillage treatments1. No-Till: where all weed control is by eitherherbicides or narrow windrow burning, the plots are sown with a NDF single disc seeder and stubble retained where possible.2. Conventional: where weed control is both by herbicides and cultivation, the plots are sown with aNDF single disc seeder and stubble is incorporated.5 Rotations1. Continuous wheat2. Rotation 1 - Two cereals followed by a break crop such as peas or canola.3. Rotation 2 - Two cereals followed by a break crop such as peas or canola, not in synchronisation with continuous rotation 1.4. Wheat - Fallow - Wheat5. Wheat - Ley - Fallow - Wheat: this rotation has been Wheat - Fallow - Wheat since 2005, and alternates with the above wheat - fallow - wheat rotation.A summary of the treatments and rotations for the past five years are shown in Table 1.

RESULTS AND DISCUSSIONThe wheat used in this trial was Suntop. It was sown 2nd May, with 50 kg/ha MAP and with a NDF disc.The peas in the trial were Sturt and were sown 2nd June with 70 kg/ha MAP/SOA.Total rainfall for 2015 was 273mm, with 222mm falling in the growing season (April to October).This report will focus on the measurements and assessments taken in 2015 as well as the key outcomes of nutrition, weeds and economics.Establishment, weed pressure, grain yield and quality, were all assessed in 2015 and the results are below.EstablishmentPlant counts were taken early July. Establishment was relatively even across the treatments.Plant counts for the wheat plots ranged from 36 plants/m2 for the conventional wheat/fallow/wheat to39 plants/m2 for the no till rotation 1.For peas, as part of rotation 2, plant counts were

Table 1: Treatments and Rotational history for the past five years..


27 plants/m2 for the conventional treatments and 31 plants/m2 for the no till treatments (figure 1).

Figure 1: Establishment counts for each treatment of the long term trial 2015.

WEEDSEach treatment was assessed for the type and density of the main weeds, as shown in table 2.The main weeds observed in the trial were ryegrass, black oats, fumitory, mustard and turnip. Other weeds in the trial included clover, milk thistle, heliotrope, skeleton weed, lupins, brome grass and spiny emex.Differences in weed numbers and weed spectrum have been measured in this trial between rotationsand tillage. As observed in previous seasons, where rotations include a fallow, as in the WFW treatment, weed numbers tended to be lower.The continuous wheat rotation, for both conventional and no till, had a large number of ryegrass, as did the conventional treatment of rotation 2, which was wheat last year. Rotation 1, coming out of lupins last year had a large number of broadleaf weeds in 2015.For all treatments conventional tillage had a higher population of ryegrass than the no-till. This is likely as a result of the pre-emergent herbicides not working as well in a cultivated system. Broadleaf weeds, such as fumitory, were generally higher in no till across the treatments.

Table 2: Weed counts for each treatment of the long term trial, measured before post emergent herbicides were applied in 2015.

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GRAIN YIELD AND GRAIN QUALITYThe average grain yield of wheat in this trial in 2015 was 2.13 t/ha.The lowest yielding treatment was the conventional continuous wheat yielding 1.67 t/ha. The highest yielding treatment was the no till WFW yielding 2.66 t/ha (figure 2).For each of the rotations the no till treatments were slightly higher yielding than the conventional tillage treatments.As a result of the season and herbicide damage, yields of the peas in rotation 2 were very low yielding, yielding less than 0.5 t/ha.Grain protein of the wheat ranged from 9.4% for the conventional continuous wheat rotation to 11.4% for the conventional rotation 1 treatment (figure 2).Protein was higher for all the conventional tillage treatments, with an average of 10.8%, compared to 9.7% for the no till treatments. The average grain protein overall was 10.21%.

Figure 2: Grain Yield for each wheat treatment of the long term trial 2015.

NUTRITIONThe trend in soil P levels at the trial site for the past 13 years is shown in figure 3.Unlike the drought years, where we saw an increase in soil P levels as a result of adding more phosphorous than what was being taken out, the last few years has seen a decrease in soil P levels at the site.The only treatment that remains above 25 mg/kg in 2015 and would be considered adequate is the continuous wheat rotation.


Figure 3: Soil P Curves for each treatment from 2003 to 2015.

ECONOMIC COMPARISONSThe costs, income and profit of each treatment in 2015 is shown in table 3.In 2015 the no till treatments all had a higher income and profit compared to the conventional treatments.Profit and income for 2015 was highest in the no till wheat/ley/fallow/wheat rotation, with an income of $585.20 and a profit of $240.40.Rotation 2, although not having the lowest income had the lowest profit of all the treatments with a loss of $209.70 for the conventional treatment and a loss of $174.70 for the no till treatment.The only other treatment to have a negative profit in 2015 was the wheat/fallow/wheat treatment, which was in fallow in 2015.

Table 3: Costs and profit for each treatment in 2015. Note WFW was in fallow, hence no yield recorded.

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Table 4 shows the individual gross margins for each year the trial has been running as well as the long term gross margins for the past 17 years.It is important to note that all costs are calculated at locally validated contract rates. This is very different to the costs a typical farmer would apply, but it allows a very good comparison of the real costsassociated with each farming system.The standout treatment for both conventional and no till for the past 17 years has been rotation 1, two cereals followed by a break crop. This was closely followed by a continuous wheat system.The average gross margin for the past 17 years is $563.23, with a no till system for rotation 1 having an average gross margin of $1,342.29 and a continuous wheat no till system having an average gross margin of $1,066.60. This is also shown in figure 4. It is important to note that agronomically the continuous wheat rotation has higher risks of crop failure. This is due to the possibilities of higher weed numbers, lower nutrition and subsoil moisture reserves and higher presence of root diseases. This trial however, has proven over the past 17 years that in this environment this rotation has still performed exceptionally well.The only negative gross margin over the past 17 years has been the conventional system for rotation 2, also two cereals followed by a break crop but not in synchronisation with rotation 1, with a gross margin of -$20.99.Table 4: Long Term Gross Margin 1999 to 2015 overpage.


Table 4: Long Term Gross Margin 1999 to 2015 overpage.

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ACKNOWLEDGEMENTSAg Grow Agronomy and Research and Central West Farming Systems would like to acknowledge Ian Barber “Sylvanham” for undertaking various activities such as sowing and harvesting the trial, as well as other local farmers in their efforts to help make this trial what it is.Part of the funding for the 2014 & 2015 activities came from the GRDC project CWF00018 ‘Maintaining profitable farming systems with retained stubble in Central West NSW’

FURTHER CONTACTS Barry Haskins Ag Grow Agronomist [email protected] Whitworth Ag Grow Research Manager [email protected] Small Central West Farming Systems [email protected]

Figure 4: Long Term Gross margins for each treatment 1999 to 2015.


USING SOWING DIRECTION AND ROW SPACING FOR WEED MANAGEMENT IN THE MALLEE

Kelly Angel (BCG) TAKE HOME MESSAGE• Yields were significantly higher under narrow row spacing, but

sowing direction had no influence on yield.• Weeds had a significant effect on yield, but the scale of yield penalty

(t/ha yield loss) did not alter with row spacing or sowing direction in 2015.

• Weeds established faster where row spacings were wider, however by late tillering, all treatments had similar weed numbers and biomass levels.

BACKGROUNDThe reliance of farming systems on agrochemicals, particularly herbicides, has increased over time.As a result, the number of weed populations with some level of resistance to herbicides is increasing.This is motivating growers to seek alternatives to herbicides for weed management.Previous experiments have shown that crop sowing direction and row spacing have an impact on weed growth and seed production. However, these experiments have only been conducted in environments that differ in many ways to that of the Mallee. The reported findings suggest narrow rows and sowing in an east-west direction better suppresses weeds. The aim of this experiment was to determine if this was also true in the Mallee, and is there any benefits from combining the two practices.

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AIMTo determine if sowing direction and row spacing can be used to influence grass weed populations and growth, and their impact on crop performance in the Mallee.

TRIAL DETAILS

LOCATION Jil Jil

SOIL TYPE Sandy clay loam

ANNUAL RAINFALL 191mm

GSR (APR-OCT) 129mm

CROP TYPE Mace wheat

SOWING DATE 23 May

SEEDING EQUIPMENT Knife points and press wheels set at 22.5cm (9 inch), 30.5cm (12 inch) and 38cm (15 inch) row spacings.

TARGET PLANT DENSITY 150 plants/m²


TRIAL AVERAGE YIELD 0.9t/ha

TRIAL INPUTS

FERTILISER Granulock Supreme Z @ 50kg/ha at sowing

HERBICIDE Dual Gold @ 500ml/ha + Diuron @ 500g/ha (PSPE)

Pests and diseases were controlled to best management practice.

METHODOne replicated trial was sown as a split plot design with sowing direction as the main plot and row spacing by weeds as the sub plot. A weed treatment was applied as tame oats broadcast prior to sowing, targeting a weed density of 75 plants/m2.The trial was located within a grower’s paddock of Mace wheat sown at the same time so that overall management could be carried out easily. The previous crop was brown manure peas, grazed over summer, and topdressing in 2015 was not required given the seasonal outlook and background nitrogen status.Assessments carried out in crop included emergence counts of crop and weeds 40 days after sowing, bio Hmass cuts at GS30 (end of tillering) and GS65 (flowering) and maturity crop head and weed panicle numbers. Plots were harvested and processed for standard yield and grain quality assessments.

RESULTS AND INTERPRETATIONGrowing season rainfall in 2015 was decile 1 which resulted in a reasonably low yielding trial. Rainfall just before and after sowing resulted in good crop and weed establishment in all treatments, however by the end of the season, many wheat plants had failed to tiller, and around 30-50 per cent of the oats sown as weeds had also died while the remaining oats were short and only produced one to two panicles at best.

SOWING DIRECTIONSowing direction in the Jil Jil trial had no influence on crop yield, quality, weed biomass production or weed seed set. Given the seasonal conditions, and the observation that wheat plants largely did not tiller, this can most likely be attributed to the fact that the crop did not offer more significant competition for light and nutrients in one direction than the other that may otherwise occur in a more substantial canopy.

ROW SPACINGRow spacing did influence crop establishment. In plots sown on 22.5cm and 30.5cm (9 and 12 inch) rows, 10 and 12 more plants/m2 established than in plots sown at 38 cm (15 inch) respectively (p=0.03, LSD=9.3, CV=11.3).


The narrower spaced treatments also achieved a lower within-row (plants/m of row) density, suggesting there was less competition between neighboring plants.As row spacing widens, the competition between crop plants increases as there are more seeds per meter of row. This can result in reduced plant stands. However, it was found that by maturity, this did not affect the number of heads/m2 in any of the treatments, suggesting plants grown at a wider row spacing did compensate with greater tiller production. The tillers that did form were very small, so although they did increase the head count, they did not increase yield proportionately to having more plants established to begin with.Crops sown on narrow row spacings produced more biomass by anthesis, and resulted in higher yields in a weed free situation, with 38cm (15 inch) row spacing yielding 0.13t/ha less than the other two spacings which were not significantly different from each other (Figure 1).It has long been known that narrower row spacing increases yield, however this was believed to be less important in low yielding environments. The more uniform pattern of crop present in 22.5cm and 30.5cm results in greater radiation interception, reducing evaporative losses and increasing dry matter production which leads to higher yields.

Figure 1: Biomass at flowering and yield as influenced by row spacing (weed free plots). Stats: Biomass P<0.001, LSD = 0.15, CV = 18.7%; Yield P = 0.01, LSD = 0.09, CV = 7.9%.

Figure 1: Biomass at flowering and yield as influenced by row spacing (weed free plots). Stats: Biomass P<0.001, LSD = 0.15, CV = 18.7%; Yield P = 0.01, LSD = 0.09, CV = 7.9%.

One of the arguments in favour of wider row spacing is that it can potentially increase grain yield in low yielding situations (Blackwell et al. 2006; Jones and O’Halloran 2006). This is believed to be because it takes time for the roots to grow and access the reserves in the inter-row area, meaning water is ‘rationed’ to crops at wider row spacings. The resulting reduced biomass production earlier in the season allows water to be conserved for use by the crop after anthesis, potentially increasing harvest index (Scott et. al., 2013). Given the limited stored moisture and in-crop rainfall in 2015, the ability of wide row spacing to do this was restricted.Although there were differences in biomass production by anthesis, the work in 2015 showed no difference in greenness as measured by NDVI at mid-late grain fill, and there were no significant differences in screenings or protein at any row spacing. Grain weight (GW) was also measured and revealed that 38cm spacings actually produced significantly smaller grain (GW=33mg) than 22.5cm (GW=34.1mg) or 30.5cm (GW=33.9mg) (P = 0.016, LSD 0.9, CV = 4.5%). To put this in perspective, at these grain sizes, one milligram difference in GW equates to approximately 26kg/ha difference in yield.Given this result, differences in yield were attributed to a combination of grain size and grain number.

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PRESENCE OF WEEDS IN A DRY SEASON – WHAT IS THE COST?Row spacing influenced early weed emergence with wider row spacings having higher weed density when measured 40 days after sowing (Table 1). However by mid tillering weed populations and biomass production was similar in all treatments (data not shown).Harvest assessments revealed that all row spacings and sowing directions produced a similar number of panicles/m2, and oat grain yield in weedy plots was not significantly different regardless of row spacing or sowing direction.Differences at emergence could be attributed to higher levels of soil throw into the inter-row which may have seen weeds buried a little deeper and taking a bit longer to emerge (in narrower rows). If this is repeatable it could be seen as an advantage in terms of the crop getting a head-start on the weeds.The reasons behind the weed populations leveling out between treatments by harvest, as measured by panicle numbers, could be attributed to the dry conditions and compensation of lower density weeds producing more panicles.

ROW SPACING WEEDS/M2 PANICLES/M222.5cm 34.8 41.730.5cm 43.5 40.938cm 48.4 38.3Sig. diff.LSDCV%

0.0077.716.7

NS

Although the aim was to try and establish 75 weed plants/m2, average weed establishment was only 42/m2, however this was enough to have significant impacts on the growth of the crop right through the growing season. Crop biomass production was lower at the end of tillering in weedy plots and this followed on to impact yield and some quality parameters. The severity of this impact late in the season however was not influenced by sowing direction or row spacing, but just whether or not the weeds were present, with all row spacings being equally affected by weeds.The presence of weeds in 2015 resulted in a 0.23t/ha yield penalty, and also impacted on test weight due to oat seeds being present in the sample. Screenings were also 3.6 per cent higher than nonweedy plots (Table 2).

YIELD (T/HA) CROP HEADS(M2)

TEST WEIGHT(KG/HL)

PROTEIN(%)

SCREENINGS(%)

GRAIN WEIGHT(MG)

No weeds 1.02 167.4 79.3 13.4 3.4 33.62Weeds 0.79 155.8 74.2 13.5 7.01 32.80Sig. diff.LSDCV%

<0.0010.059.6

0.0310.310.6

<0.0012.45.2

NS <0.0010.928

0.0330.62.8

Table 2: Influence of weeds on yield and quality parameters.

The yield reduction in the case of weed presence could be attributed to both a reduction in grain number as a result of lower head numbers produced, as well as a reduction in grain weight (Table 2).This illustrates well that competition for light and nutrient resources, particularly in a poor season, can have dramatic effects on crop yields, not to mention the carryover effects of weed seeds leading into the next crop.

Table 1: Weed density measured 40 days after sowing and panicle number at maturity as impacted by row spacing.


COMMERCIAL PRACTICEThis trial was intended to find out whether growers can use sowing direction or row spacing to manage weed populations, however the low yields in 2015 meant that differences between treatments, where significant, are small.In 2015 crops did not achieve good canopy cover, something that can be considered a key driver to the success of row spacing or sowing direction for weed management. Results from more seasons are required before growers could base management decisions on these data, and this trial will be repeated in 2016.Things that can be taken from this trial are that even relatively low weed populations can have a large impact on yields, with 0.23t/ha yield loss from populations of around 40 plants/m2. So the tolerance to weeds in the farming systems still needs to remain low, and if paddocks are getting out of hand, rotations of crops or herbicides, or the use of alternative weed management tactics such as using competitive crops or harvest weed seed management needs to be considered.In terms of yield, even in a poor year, there are penalties from very wide row spacing, with 38cm being lower yielding than 22.5 or 30.5cm row spacing. When choosing or adjusting row spacing, potentially through the purchase of new machinery, growers should weigh up the reasons they are looking to go wider (ie. trash management or inter-row spraying, timeliness of operations etc.) and determine whether the benefits outweigh the costs.

ON-FARM PROFITABILITYLooking at the profitability aspects of the trial there are a few things to consider. Firstly, narrow row spacings produced more yield and in most cases of slightly better quality. On top of this, adding weeds to the mix, further reduced income through either lower yields or downgrading due to quality issues.When analysed it was found that narrow row spacing with good weed management offered the best returns, and that management of weeds was more critical than management of row spacing with a $80/ha better return from weed management (Table 3).

ROW SPACING WEEDS AVERAGEWeeds No weeds

22.5cm $212.80 $284.60 $248.7030.5cm $185.50 $279.30 $232.4038cm $170.30 $245.30 $207.80Average $189.5 $269.7

Sig. diff.Row spacingWeedsRow spacing x weedsLSD (P=0.05)Row spacingWeedsRow spacing x weedsCV%

P<0.001P<0.001NS$16.85$17.54-12.3

Table 3: Income $/ha for different row spacing and weed scenarios in 2015 (yields used from trial with prices allocated depending on grade achieved from grain prices table on pp.19).

Income from the crop however is only one aspect to consider. Wider row spacings have lower machinery costs due to fewer components, improved timeliness of operations due to faster travel speeds and better trash handling with potentially reduced fuel usage as a result of lower draught.Given the reduction in plant establishment there may also be opportunity to lower seeding rates to reduce seedling losses. But what are the potential risks associated with these benefits? In the Mallee there have been an increasing number of conversations around wider rows not offering a competitive advantage against weeds,

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resulting in increased herbicide use and costs, and higher risks of resistance due to greater reliance on herbicides.When deciding the best system in terms of profitability it is necessary to weigh up the pros and cons of all these elements, identifying the biggest threats to production, and minimising the risk associated with these factors. Herbicide resistance is on the increase, and the development of new chemistries is a slow process. Can we really afford to negate cultural weed management practices like row spacing and sowing direction?

REFERENCESBlackwell P, Pottier S, Bowden B, 2006, Agribusiness Crop Updates. Perth, Western Australia, ‘Response to winter drought by wheat on shallow soil with low seeding rate and wide row spacing, pp. 57-62.French RJ, Schultz JE, 1984, Australian Journal of Agricultural Research, ‘Water use efficiency of wheat in a Mediterranean-type environment. I. The relationship between yield, water use and climate’, 35, pp. 743-764.Jones B, O’Halloran N, 2006, Farming the Mallee with GPS guidance, ‘Wide rows and crop yield’, pp. 1-23.Scott BJ, Martin M, Reithmuller, GP, 2013, Graham Centre Monograph No. 3. Edited by Toni Nugent &Catriona Nicholls, ‘Row spacing of winter crops in broad scale agriculture in southern Australia’.

ACKNOWLEDGEMENTSThis research was funded by the GRDC as part of the ‘Overdependence upon agrochemicals’ project (CWF00020).Agrochemicals project (CWF00020), which is led by CWFS.


ROW ORIENTATION AND WEED COMPETITION.

Amanda Cook Wade Shepperd Ian Richter Nigel Wilhelm

SARDI Minnipa Agricultural Centre

KEY MESSAGES • An east-west (E-W) sowing direction increased yield over north-

south (N-S) sowing direction in an average season. • The results showed a decline in yield due to weed competition, but

no effect on weed competition due to row direction. So sowing in an E-W direction may give a yield benefit with no difference in weed seed set.

• The wider row spacing of 30 cm resulted in a yield reduction and greater weed biomass at harvest.

• There were no differences in yield with ribbon seeding with either 18 or 30 cm row spacings, but ribbon seeding reduced ‘weed’ biomass.

WHY DO THE TRIAL? Controlling barley grass in upper EP farming systems is becoming a major issue for growers, due to the development of herbicide resistance and delayed emergence. Management options other than herbicides need to be considered to address the issue for longer term sustainability. One of the best bets for cultural control of barley grass in-crop is increased crop competition. The Australian Herbicide Resistance Initiative (ARHI) based at University of Western Australia has shown an increase in grain yield with wheat and barley sown in an east–west (E-W) orientation over crops sown in a north-south (N-S) orientation due to a decrease in ryegrass competition. Lower light interception by the weed due to the crop row orientation resulting in a decrease in weed seed set is the cause behind this effect (Borger, 2015).

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A trial was established at Minnipa Agricultural Centre to investigate the impact of row direction and row spacing on grass weed competition and cereal performance over three years.

HOW WAS IT DONE?In 2014 paddock N7/8 on the Minnipa Agricultural Centre was sown with Wyalkatchem wheat on 16 May. It was sown on 30 cm row spacing and yielded 2.4 t/ha with 9.6% protein. A paddock demonstration with crop and stubble aligned in the differing directions was located in this paddock. In 2015 a replicated plot trial was sown with two row orientations; E-W and N-S into the 2014 standing stubble. Treatments within row orientations included two row spacings, 18 cm (7”) and 30 cm (12”), sown with two different seeding boots (a Harrington knife point and an Atom-Jet spread row ribbon seeding boot). Plots were direct drilled with press wheels. Oats were spread as a surrogate weed through hoses at the front of the seeder during the seeder pass. Additional “control” plots were sown near each trial block but in the opposite row orientation to that in each block.The trial was sown on 21-22 May under minimal moisture with Mace wheat and 18:20:0:0 (DAP) fertiliser, both at 60 kg/ha. The oats ‘weeds’ were spread at a rate estimated to achieve 70 plants/m2. The trial was sprayed with a knockdown of 1 L/ha of Roundup Powermax on 21 May and also a post-sowing pre-emergent spray of 1.5 L/ha of Sprayseed to control emerging self-sown cereal on 1 June. The trial was sprayed with 750 ml/ha Tigrex and 100 ml/ha of Lontrel on 27 July.Trial measurements taken during the season included soil moisture (pre-seeding and harvest), PreDicta B root disease test, soil nutrition, weed establishment, weed seed bank germination, crop establishment, crop and weed biomass (early and late), light interception in crop rows, grain yield and quality.Soil samples for moisture and nutrient analysis were taken on 21 April. Initial paddock weed counts were done on 20 May. Soil samples containing weed seeds from the trial site were grown out in germination trays, with monthly assessments on weed emergence. The weed seed bank trays were watered as required in 2015. Crop establishment and weed counts taken on 26 June. Leaf Area Index (LAI) was measured on 18 September using an AccuPAR/LAI Ceptometer (model LP-80), taking the average of 5 readings per plot placed at an angle across the crop rows as per the operator’s instruction manual. The measurements were taken at Zadoks growth stage (GS) 49-51, aiming for maximum crop canopy. The trial was harvested on 12 November. Harvest soil moisture samples of selected treatments were taken on 27 November.Design and analysis of this trial was undertaken by SARDI statistician Chris Dyson using GENSTAT 16.

WHAT HAPPENED?In the 2014 season in the broad acre strips the yields were 2.64 t/ha and 2.95 t/ha for the N-S and E-W orientations respectively. In 2015, crop establishment was similar in both sowing orientations, averaging 130 plants/m2. There were more wheat plants/m2 in the 30 cm row spacing treatment than in the 18 cm (Table 1). Seeding point design had no impact on wheat establishment. An oat-only treatment (no wheat sown) resulted in only 26 plants/m2 which was well below the targeted density of 70 plants/m2, but still provided some weed pressure.Late crop dry matter was greater in the narrow row spacing than in the wider row spacing. The ribbon seeding boot had the highest dry matter compared to knife point and the added weed treatments (Table 1). Wheat yield was greater in the E-W direction than the N-S this season with no difference between seeding boots (Table 1 and 3). The wider row spacing resulted in lower yields compared to narrow (Table 1). The protein level was lower with the higher yield in 18 cm compared to the 30 cm row spacing. There were no differences in protein with the different seeding boots (Table 1). Oats as a surrogate grass weed decreased wheat yields by 12% regardless of row orientation. The weed levels were very low (Table 2). Dry matter taken at harvest shows greater weed mass in the wider row spacing of 30 cm. The knife point system also had a greater weed biomass compared to the ribbon seeding boot. Other weeds within the trial area, such as ryegrass and wild oat were very low in numbers and did not affect the trial results (data not presented).


Crop establishment (plants/m2)

LAI (umols)

Late DM (t/ha)

Yield (t/ha)

Protein (%)

Screenings (%)

Row spacing (cm)

18 104 51.6 5.71 2.99 9.76 6.9

30 156 45.9 4.64 2.33 9.93 6.3LSD (P=0.05)

9 2.8 0.3 0.10 0.15 0.5

Seeding system

Knife points 124 48.7 5.81 2.82 9.9 6.4

Knife points plus weed

131 50.4 5.74 2.53 9.8 7.0

Ribbon 132 48.9 6.06 2.77 9.9 6.0Ribbon plus weed

133 51.3 5.73 2.52 9.8 6.9

LSD (P=0.05)

ns ns 0.45 0.14 ns 0.7

Table 1: Mace wheat growth, light interception (LAI), yield and grain quality with different sowing direction, row spacing and seeding systems at Minnipa 2015.

OAT ‘WEED’ DRY MATTER (T/HA)

BARLEY GRASS DRY MATTER (T/HA)

Row spacing (cm) 18 0.06 0.0230 0.12 0.01

Seeding system Knife points 0.14 0Knife points plus weed 0.10 0.01Ribbon 0.04 0.01Ribbon plus weed 0.08 0.04

Table 2: Average weed dry matter at harvest with different sowing direction, row spacing and seeding systems at Minnipa 2015.

ROW DIRECTION ROW SPACING (CM)

KNIFE POINTS

KNIFE POINTS PLUS WEED

RIBBON SPREAD

RIBBON PLUS WEED

EXTRA CONTROL DI-RECTIONAL PLOTS

North South 30 2.32 1.95 2.29 1.87 2.23East West 30 2.69 2.38 2.66 2.45 2.38

CV 8.4%Table 3: Mace wheat yield (t/ha) sown on 30 cm row spacing with different sowing orientation and seeding boots at Minnipa 2015. Because the orientation blocks were not replicated formal yield comparison is not possible, but values are believed to be indicative. Note the Extra control directional plots were placed alongside the other orientation block.

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WHAT DOES THIS MEAN?These results support previous trial work at Minnipa Agricultural Centre (Cook, 2009) which showed that sowing in an E-W direction increased yield over N-S sowing direction in an average season. Research from Western Australia also showed an increase in grain yield with wheat and barley sown in an E-W orientation due to a decrease in grass weed competition with high ryegrass populations. The extra directional control plots have not fully supported the sowing direction yield increase as the E-W control in the N-S block were not better than the 30 cm N-S treatments (Table 3) which may be due to light interception by the crop.The trial reported here showed a decline in wheat yield from oats as a surrogate grassy weed, but this competition was similar in both row orientations. The wider row spacing resulted in an increase in ‘weed’ biomass as did the knife point system compared to the ribbon seeding boots.The wider row spacing of 30 cm resulted in a large yield reduction regardless of the seeding boots used.While this trial was sown into stubble with the same orientation as the cropping direction in the previous year, factors such as distribution of nutrients/weeds/diseases or soil constraints prior to the previous crop may also have affected our row orientation blocks differently. This trial will continue for another two seasons.

REFERENCESBorger C, Hashem A, Powles S (2015) Manipulating crop row orientation and crop density to suppress Lolium rigidum. Weed Research 56, 22-30.Cook, A., Shepperd, W., and Hancock, J., Row Direction and Stubble Cover. EPFS Summary 2009, p114-115.

ACKNOWLEDGEMENTS Thank you to Sue Budarick for processing the weed counts and managing the weed germination trays. Funded by the GRDC Overdependence on Agrochemicals project (CWF00020).Agrochemicals project (CWF00020), which is led by CWFS.

LOCATION: MINNIPA AGRICULTURAL CENTRE PADDOCK N7/8Rainfall Av. Annual: 325 mm Av. GSR: 241 mm 2015 Total: 333 mm 2015 GSR: 258 mmYield Potential: (W) 3.0 t/ha Actual: 2.7 t/ha Paddock history 2015: Mace wheat 2014: Wyalkatchem wheat 2013: Medic pastureSoil type Red loamPlot size 20 m x 2 m x 4 reps


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