Consecutive cereal crops can reduce yields
A new model to evaluate crop sequencing shows yield losses caused by consecutive cereal crops are becoming more prevalent in the western grain-growing region.
Dr Roger Lawes from CSIRO and Associate Professor Michael Renton from the University of Western Australia (UWA) developed the model as part of a project funded by the GRDC and the Department of Agriculture and Food, WA (DAFWA).
The Land Use Systems Optimiser (LUSO) model aims to help growers and advisers determine which crops to grow in sequence based on paddock management history.
It draws on commodity prices, nutrient requirements and pressure from weeds and diseases to assess the productivity of different crop rotations.
Dr Lawes says LUSO indicates that growing two consecutive cereal crops without a break crop can cause yield losses of between 10 and 20 per cent, while three or more such crops result in even higher yield penalties.
“LUSO demonstrates that where weeds are controlled, all break crops provide better yields in the following cereal crop,” Dr Lawes says.
As a consequence of these findings, he urges growers to resist price-driven temptations to grow another cereal crop instead of a break crop.
He says the model shows that growing consecutive cereal crops also tends to exacerbate the effects of seasonal conditions on yields.
For example, in a dry season, wheat following wheat might yield 0.75 tonnes per hectare, while wheat following a break crop might yield 1t/ha. Whereas in a season with good rainfall, a typical result for these two scenarios might be 2t/ha, compared with 2.5t/ha.
Dr Roger Lawes
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GRDC Project Code CSA00029