Effect of flooding and cropping on the changes in the inorganic phosphate fractions in some rice soils

Abstract

Greenhouse experiments were conducted to evaluate the significance to flooded rice of the various forms of inorganic soil phosphate on Aborlan, Luisiana and Pili soils with and without phosphate. Changes in the various inorganic soil phosphate fractions with time under cropped and uncropped conditions were measured. Results showed that the iron phosphate fraction was the most important source of phosphate to the rice plant. It was also evident that phosphate added to the soils was slowly converted into the iron phosphate form. Transformation of soil phosphate seemed to be greatly affected by the presence of plant roots. Changes in the phosphate fractions were marked in the cropped soils.