Change in Phosphates Solubility Isotherm in Some Calcareous and Gypsiferous Calcareous Soils.

Abstract

Four calcareous soil samples and two gypsiferous calcareous soil samples were selected from certain areas in Saudi Arabia. Dilute phosphoric acid was added to the soil in order to give a concentration equivalent to 0, 20, 200 and 2000 mgP/kg soil. It was found that water soluble P continued to increase with phosphorous application and decrease in pH and solubility product values were noticed. The ability of these soils to saturate with dicalcium phosphate depends on the sorption P-capacity of each soil under study.