Help for growers in managing repellence
A range of management options is available to overcome water repellent soils as a result of new techniques developed in recent years.
An assessment of options by the Department of Agriculture and Food WA (DAFWA) will be presented at this month's Agribusiness Crop Updates, supported by the Grains Research and Development Corporation (GRDC), to help growers select the most appropriate strategies to suit their needs.
Nearly 3.3 million hectares of agricultural soils are at high risk of water repellence and a further 6.8 million hectares are at moderate risk. The cost of water repellence resulting in reduced production is estimated at $250 million a year.
Department research officer Stephen Davies said the options could be divided into two categories - mitigation or short-term strategies that would help crop establishment but needed to be repeated each year and amelioration, or more expensive long-term options, which are done once but have a more sustained impact.
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Mitigation options include improved furrow sowing, the use of banded wetting agent, incorporating a blanket wetting agent or water absorber and full stubble retention with low disturbance seeding.
Amelioration encompasses rotary spading, soil inversion through the use of a mouldboard plough and clay spreading or delving.
"We now have research from the 1990s and the last three years of comprehensive trials with growers that provides an opportunity for us to assess the range of options and their application," Dr Davies said.
"Any decision on an individual or combination of strategies should be underpinned by growers' knowledge of their soil types, the area of repellent soils and the ability to finance the management changes."
Dr Davies said more productive soils might be progressively ameliorated first. These were soils with good yield potential once water repellence had been overcome, while mitigation strategies might be used for the balance of the program.
"The best approach may be to use improved furrow sowing and/or banded wetting agents as mitigation tools, which work across a range of soil types over the whole seeding program at low cost," he said.
"The higher cost of amelioration strategies can then be applied to smaller areas of strong water repellence or where there can be big productivity grains.
"Growers may even consider alternative land uses, like perennial pastures or planting trees, for areas affected by severe water repellence that may be too costly to ameliorate or where repellence returns quickly."
The analysis, funded by the department and GRDC, summarises the options, providing approximate costs, the longevity of the treatment, what mechanism is addressed and where each management option is most suited.
Improved furrow sowing will be a focus of research in 2012 by investigating the use of winged points or seeding boosts and press wheel types that prevent the flow of water repellent soil into furrows and produce more stable furrows.
More details of the research findings will be presented at the Department of Agriculture and Food's Agribusiness Crop Updates, supported by the GRDC, on February 28 and 29 in Perth. Regional Updates will follow in March.
For more details or to register, visit <a rel="nofollow" href="http://www.agric.wa.gov.au/2012">www.agric.wa.gov.au/2012 </a>
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