Soil type and seasonal rainfall were the major factors influencing the differences in optimum wheat seed rate, in research carried out by the WA Department of Agriculture. The research led by Raffaele Del Cima and Wal Anderson found that clay loam soils, especially those at sites with rainfall of more than 325 mm, had a higher optimum seed rate. In 325-450 mm rainfall areas, optimum seed rate was 75 kg/ha and where rainfall was less than 325 mm, optimum seed rate was 61 kg/ha. In sandy soils, the optimum seed rate was greater, with higher seasonal rainfall, but lower than that of clay loam soils. In rainfall areas less than 325 mm, optimum seed rate was 41 kg/ha and where rainfall was more than 450 mm, optimum seed rate was 67 kg/ha. Higher optimum seed rates were only associated with high yields on clay soils.
Contact : Dr Wal Anderson 08 9892 8444