MULTIFACTOR KINETICS OF PHOSPHATE REACTIONS WITH MINERALS IN ACID SOILS .2. EXPERIMENTAL CURVE FITTING

A kinetic model of phosphate reactions with minerals in acidic soils was used to simulate experimental results obtained under a variety of conditions based on three factors—solution pH, solution concentration, and mineral specific surface area. Three minerals with different reactivity (kaolinite, gibbsite, goethite) were studied to check the adaptability of the model and show the effect of mineral properties on reaction with phosphate. The experimental data as well as the kinetic models showed that high pH values, low concentrations of the phosphorus in the reacting solution, and small specific surface area will reduce retention of phosphate. Any other change of the three factors increases the retention capability. The model shows its flexibility in simulating phosphate reactions with different minerals. The results show promise for the miltifactor approximation of phosphate reactions with soil minerals in acid to neutral soils. © 1983 Soil Science Society of America.