Response to superphosphate by rice in an annual rice-cropping system in southern New South Wales

Abstract

In New South Wales, symptoms typical of phosphorus (P) deficiency have occurred in rice where the crop has been grown annually for 9 years without phosphorus fertiliser. Field experiments were conducted to determine the requirements for superphosphate, the residual value of applied P, and rice varietal tolerance to low soil P. As the rate of application of superphosphate increased from 0 to 40 kg/ha P, rice growth and grain yield increased significantly up to 20 kg/ha P. Applications of 20 and 40 kg/ha P (but not 10 kg/ha P) had significant residual values for rice in the second year. The variety Pelde was more sensitive to low phosphorus during early vegetative growth than either M7 or Calrose. The 3 varieties showed similar responses in grain yield to superphosphate.