A Department of Agriculture and Food survey of Western Australian grain growers has revealed water repellence ranks as one of their most important soil constraints.
The survey findings, along with research into strategies to mitigate water repellent soils, were delivered on day two of the Agribusiness Crop Updates at Crown Perth.
The department research, funded by the Grains Research and Development Corporation, used a combination of surveys and grower case studies to assess whole farm implementation of water repellence management strategies.
Department research officer Stephen Davies said water repellent soils were less productive because they resulted in reduced crop establishment, weed control and nutrient use.
“More than 100 growers who have water repellent soils were surveyed about their current and intended strategies to manage the problem,” Dr Davies said.
“The farm businesses surveyed were members of grower groups including the Northern Agri-Group, West Midlands Group, Calingiri LCDC and Darkan Farm Management Advisory Service.
“Soil water repellence was ranked by growers as either the most or second most important soil constraint, followed by low soil water holding capacity and acidity, which are often found in combination with water repellence on poorer sandplain soils.
“Growers perceive the problem of water repellence to be increasing, however factors such as increased dry and early seeding, drier starts to the season and less soil mixing may be contributing to their take on the situation.”
Dr Davies said all farm businesses surveyed had conducted on-farm testing of a number of management options to assess the likely productivity, economic and system benefits.
“Survey results indicated there were varying barriers to adoption of different strategies, including the cost for mouldboard ploughing, rotary spading and claying; the risk of wind erosion after deep tillage; and the risk of haying off and inconsistent results for claying,” he said.
“Growers cited cost and inconsistent results as the principal barriers for using wetting agents, while the adoption of zero-till, full stubble retention systems is hampered by concerns about effectiveness, cost, weed and root disease control and suitability of soils hamper.”
Dr Davies said whole farm income could be improved through soil water repellence mitigation options such as wetting agents and paired-row seeding because while the yield benefits might be small, they often resulted in considerable overall income benefits that were realised over the entire seeding program.
“In one of the case studies, we were able to demonstrate that whole farm income was improved by $77,000 using a highly conservative grain yield benefit of just 100 kg/ha, through the use of a more effective seeder for water repellent soils,” Dr Davies said.
“A department research trial compared standard knife-points with banded wetting agents or winged paired-row seeding systems, demonstrating yield benefits in excess of 500 kg/ha for early sown wheat.
“This trial result, and the outcome of case studies, confirms the potential benefit of combined strategies to improve the efficacy of seeding water repellent soils.
“Amelioration options such as spading or mouldboard ploughing are also profitable and often give greater and longer-lasting yield increases, but they are slow and costly to implement.”
Dr Davies said the department’s case study assessment indicated growers were increasingly adopting a combination of short-term mitigation and long-term amelioration management options for water repellent soils.
“Research indicates this is the most cost-effective approach to whole-farm management of water repellent soils,” he said.
The 2013 Agribusiness Crop Updates is supported by the department and the Grains Research and Development Corporation.
Media contacts: Jodie Thomson, media liaison +61 8 9368 3937