Avoiding stubble trouble

Key points

  • Project examines stubble management options
  • Higher ‘in-crop’ rainfall means higher stubble loads
  • Trials established on commercial scale to better relate to on-farm practices

No-till cropping has become commonplace in the Riverine Plains region of southern New South Wales and northern Victoria.

However, increased rainfall in recent years means stubble loads are becoming more difficult to manage. This has forced some growers to back away from no-till and reintroduce stubble burning or cultivation to manage stubble volumes and disease threats.

Consequently, a new research project conducted by farming systems group Riverine Plains Inc. (RPI) is looking at the options available to growers for overcoming heavy stubble loads.

Image of two people in a paddock of stubble

Damien McKinley (left), Riverine Plains Inc. committee member and grower at Dookie, Victoria, with Michael Straight, FAR Australia, at the Yarrawonga trial site where both groups are researching the best method of dealing with high stubble loads..

‘Maintaining profitable farming systems with retained stubble in the Riverine Plains region’ is a GRDC-funded project running from 2014 to 2018. The project builds on findings from a previous project investigating water use efficiency in no-till and stubble-retained systems.

RPI extension officer Dr Cassandra Schefe says higher rainfall in recent years has caused heavy stubble to become more of an issue.

“The sheer volume of stubble remaining in paddocks at sowing time is causing problems with machinery and is increasing disease loadings. This has left growers with a whole raft of different management options to consider.”

Dr Schefe says the aim of this project is to produce regional guidelines for the Riverine Plains to increase the sustainability and adoption of no-till stubble-retained (NTSR) systems and to advance the agronomic frontier of NTSR systems in the hope of increasing yield potential.

“The different management strategies we are evaluating include the use of cultivation, the use of nitrogen, maintaining full stubble loads, changing the height of stubbles and stubble burning, and overlaying each of these with nitrogen treatments as well.”

Four large trial sites encompassing each geographical point have been established at focus farms across RPI’s region. They are located at Henty and Coreen, in NSW, and Dookie and Yarrawonga, in Victoria.

“Having multiple sites means we are able to look at how different climatic conditions and soil types affect stubble management and also means we are spreading the risk within the project,” Dr Schefe says. “That way, even in a marginal year, the trials are still likely to generate good information.”

Each focus farm site is looking at a different stubble management strategy program (see Table 1).

Table 1 Different stubble-management strategies for RPI focus farms as part of the 'Maintaining profitable farming systems with retained stubble in the Riverine Plains region' project'

Henty

• Control – no-till stubble management
• No-till stubble management plus 40kg N/ha at sowing
• Short stubble mulched – no-till stubble management
• Short stubble mulched plus 40kg N/ha at sowing
• Short stubble mulched – top work to consolidate stubbles to create seedbed prior to sowing
• Short stubble mulched – top work plus 40kg N/ha at sowing 

Dookie

• Control – no-till stubble management
• Short stubble – top work to consolidate stubbles to create a seedbed prior to sowing
• Short stubble – remove straw with baling (raking off in trial)
• Long stubble – no-till full stubble management
• Long stubble burnt – no-till 

Yarrawonga

• Control – no-till stubble management
• Top work to consolidate stubbles to create a seedbed prior to sowing
• Top work plus 40kg N/ha prior to sowing
• Remove straw with baling (raking off in trial)
• Control – no-till stubble management plus 40kg N/ha at sowing
• Stubble burnt 

Coreen

• Control – no-till stubble management
• Top work to consolidate stubbles to create a seedbed prior to sowing
• Top work plus 40kg N/ha prior to sowing
• Faba beans sown – taken as forage
• Faba beans sown – taken as grain
• Stubble burnt 

Alongside the large stubble-retention trials, RPI is also running smaller plot trials looking at:

  • the interaction between plant growth regulators and nitrogen application in early-sown wheat;
  • the effect of row spacing and cultivar in early-sown wheat in full stubble retention;
  • the effect of fungicide timing and nitrogen application on yellow leaf spot in wheat sown into wheat stubbles; and
  • the effect of nitrogen rate and timing on wheat yield and quality in full-stubble-retention systems.

The project is also evaluating the sensitivity of crop-sensing technology in determining crop nitrogen status, both in a small plot trial and at paddock scale. Crop reflectance measurements will be conducted on nitrogen trials with different nitrogen rates and timings to compare green biomass and greenness of that biomass.

As part of the project, RPI will be setting up focus groups at each of the four focus farms to better coordinate extension with growers.

“Those groups will meet three to four times a year at the trial sites,” Dr Schefe says. “We’re hoping to attract growers and agronomists to talk about their different experiences in stubble-retained systems and what they have learnt from it. It is a chance for growers to nut out issues they’ve had and what options are available based on the trials we’ve done. It is a five-year project and we envisage these groups will be maintained throughout that time.”

The project is being run in partnership with the Foundation for Arable Research (FAR) Australia and the University of Sydney’s Precision Agriculture Laboratory. 

More information:

Dr Cassandra Schefe,
03 5744 1713,
extension@riverineplains.com.au

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Cutting high can improve harvest yields

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Trials assess N application timing

GRDC Project Code RPI00009

Region South, North