Calcined rock phosphate as fertilizer for pasture and cereal production in Western Australia

Abstract

Calcined rock phosphate is prepared by low temperature (500�F) calcination of 'C' grade Christmas Island rock phosphate that is unsuitable for superphosphate production. It was compared with superphosphate and with mixtures of superphosphate and calcined rock phosphate for pasture and cereal production at two sites in the 12-18 in. annual rainfall zone of the Western Australian wheat belt. At equivalent levels of applied phosphorus, superphosphate was a better fertilizer than calcined rock phosphate over the two years of the trials. There was evidence that the phosphorus in superphosphate was less available when mixtures of superphosphate and calcined rock phosphate were applied, than when superphosphate was applied alone. A pasture response to sulphur occurred at Chapman Research Station on a red-brown sandy loam. There was no response to sulphur by cereals.