Phosphate Sorption by Soils: III. The P Diffusion‐Precipitation Model Tested for Three Acid Sandy Soils

A recently developed diffusion‐precipitation model was tested for three acid sandy soils: two topsoils and one subsoil. It is shown that experimental data fit the model when constant P concentrations are used. As the model predicts no particular curve, third degree polynomials were used to describe the data. For further testing, increasing and decreasing P concentrations were used. Comparison of experimental and computer simulation data show that the model is also valid for varying concentrations. The concentration at the metal‐oxide/metal‐phosphate interface (indicated as C 4 ) is relatively high: 0.1 to 0.25 mmol/L. The diffusion‐precipitation model is useful in modeling P behavior in soils.