Elucidation of phosphorous sorption by calcareous soils using principal component analysis

This study was conducted to understand the mechanisms governing P-sorption and desorption by calcareous soils (up to 48% CaCO (3)). Batch experiments with KCl as background were carried out by adding varying amount of P up to 100 mgP.L-1. The desorption percentage (%DES) results show that little P was released from the adsorbed phase. Principal component analysis was applied to evaluate the combined influence of soil components on P sorption. The complex P sorption process can be related to specific soil components by the following equation: P- sorption=-2.20 (CaCO (3)% )-0.04 (Fe- oxide)+0.04 (pHe)+11.02 (sand % )+3.35 (silt)-10.73 (clay)-1.24 (EC)-0.22 (OM)-0.81 (CEC)-1.93 (P- Olsen) (R-2=0.9941, SSE=380). Sand% and clay% are the most significant variables for modelling P sorption data. The derived equation could be applied to predict P sorption in other soils that have similar compositions to those investigated herein. The degree of P saturation (DPS) threshold level for all soils was less than 3% except in the soil with the lowest iron oxide. All of the studied soils have exceeded the environmentally unacceptable P concentration except the soil with the lowest iron oxide content.