Solubility measurements as a means of studying the reaction of phosphorus compounds with soils at different ph levels

In the face of the intricacies involved in the problem, it is difficult to study phosphate reactions in soils with a high degree of definiteness. But the present study was made for obtaining more specific information on the following points:

The reactions taking place between the products of the initial reaction of monocalcium phosphate with water, i.e., (1) metastable triple-point solution (MIPS), which is in metastable equilibrium with monocalcium phosphate monohydrate and dicalcium phosphate dihydrate, (2) triple-point solution (TPS), which is in stable equilibrium with monocalcium phosphate monohydrate and anhydrous dicalcium phosphate and (3) anhydrous dicalcium phosphate, and three different soils, with different pH levels, with various periods of reaction in the air-dry and wet conditions;

The various forms into which applied soluble phosphate is converted over different periods of time under different pH conditions, as indicated by the use of various extractants;

Relationships, if any, between the various forms of phosphate formed, either among themselves or with extractable iron, aluminum and calcium; and the

Relative availability of the different forms of phosphate under the various conditions of study.