Journal of the Department of Agriculture, Western Australia, Series 4


Phosphorus fertilizers, Application rates, Mathematical models, Western Australia

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* A 400 per cent increase in ihe price of superphosphate has reduced the economic optimum rates of super for crops and pastures in 1975.

* Many factors, both biological and economic, must be taken into account in determining the rate of superphosphate to apply.

• DECIDE, a model developed by CSIRO and the Department of Agriculture, provides a formal system in which all these factors can be considered.

• DECIDE is based on the results of all research on superphosphate carried out in Western Australia. However, each farmer's own knowledge of his farm, the soils, crops and animals is used to adapt the experimental results to get the best, easily available estimate of how much super should be applied to give maximum returns on superphosphate expenditure.

Information about DECIDE is available from all District Offices of the Department of Agriculture.