Doubts raised on summer rain value

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New CSIRO research reveals that in some parts of Western Australia growers could more productively use water and optimise profits by redirecting the crop-input focus from stored subsoil moisture to growing season rainfall.

Led by CSIRO researcher Dr Steve Milroy, the study in WA’s northern agricultural region shows adjusting inputs based on stored moisture from summer rainfall at seeding might have a limited effect on wheat yields.

On-farm trials conducted on a range of soil types, including deep sandy soils and red loams, indicated stored water contributed between 9 and 19 per cent of the water used by wheat crops.

Dr Milroy says the results of the project, investigating the effects of different inputs and treatments on crop yields, contrasted with research findings in south-east Australia, but were consistent with previous WA research.

“While further work is needed to quantify these early on-farm trials, it appears it is most important for WA growers to match inputs to in-season rainfall because out-of-season rainfall may not contribute much to wheat yields,” he says.
“In very dry years like 2010, subsoil moisture becomes more valuable, but nevertheless growers should not significantly change inputs at seeding time based on summer rainfall.”

Dr Milroy attributes the findings to the limited water-holding capacity of WA soils.

CSIRO worked with the Liebe Group, the Mingenew-Irwin Group and the North East Farming Futures Group to conduct the on-farm trials on grower properties at Buntine, Mingenew and Morawa in WA.

GRDC Research Code CSP00109
More information: www.grdc.com.au/CSP00109

GRDC Project Code CSP00109

Region West