Controlling phosphorus fixation in calcareous soils by using coated diammonium phosphate

Abstract

In this paper, phosphorus fixation in calcareous soils is controlled by means of rosin-coated diammonium phosphate pellets, with several rates of phosphorus release. Four soils from arid regions in the Spanish south-east were chosen and separately treated with one of the following fertilizers: superphosphate (SP) or diammonium phosphate (DAP) coated with 0, 10 or 22% rosin with a dosage of 1000 Kg P/ha. After treatment, the soils were incubated for 8 months, in the course of which samples were taken to evaluate the evolution of P availability by means of the electroultrafiltration (EUF) technique. The results obtained show that the use of DAP with a 22% coating enables phosphorus fixation in calcareous soils to be controlled. The coating was sufficiently stable to last for the time it takes the crop to grow.