Research findings into crop rotations to help grain growers increase profit, manage risk and reduce greenhouse gas emissions will be delivered at Western Australia’s leading annual grains research conference this month.
Department of Primary Industries and Regional Development (DPIRD) research scientist Martin Harries will detail work under the Western Australian Farming Systems project at the Grains Research and Development Corporation (GRDC) Grains Research Updates in Perth.
“The aim of these systems trials is to investigate strategies to increase profit across the rotation while managing production constraints and risk,” Dr Harries said.
“This includes a focus on opportunities and risks of changing the timing of seeding, identifying system break options that deliver improved profit and acceptable risk, and an analysis of management options for maintaining profitability under lower greenhouse gas emission scenarios.”
The WA Farming Systems project is a five-year co-investment by DPIRD and the GRDC, targeting the medium and low rainfall regions of WA.
Dr Harries said rotations are the fundamental tool for managing farming systems.
“In recent years, changes to broadacre farming systems include reductions in the area of pasture and grain legumes, increased canola production and more frequent cereal plantings,” Dr Harries said.
“In addition, the use of farm inputs including fertiliser have increased. One way to better understand the implications of these changes on production constraints across the rotation is through multi-year trials.”
Trials at three sites, Northampton, Merredin and Lake Grace, compared various rotations of legumes and cereals, at different nitrogen fertiliser application rates.
For each trial there is an advisory group of local farmers, agronomists and researchers who identify the rotations to test and agronomy to apply.
“Following three years of trials, our research to date has shown that it is possible to achieve high productivity and gross margins while lowering emissions,” Dr Harries said.
“Gross margin varied substantially between rotations at each site. High nitrogen increased gross margin in most rotations at Northampton and Lake Grace and tended to reduce gross margin at Merredin.
“Large increases in cereal productivity were observed in 2025 due to rotation and nitrogen. This was more pronounced in the higher productivity environments.
“In many instances rotations with legumes were less responsive to fertiliser nitrogen. Some rotations with legumes were able to maintain productivity and profitability with lower greenhouse gas emissions due to the nitrogen provided by the legumes.”
The 2026 GRDC Grains Research Update will be held in Perth on 16 and 17 February.
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