Remaining phosphorus estimate through multiple regression analysis

The remaining phosphorus (P-rem), P concentration that remains in solution after shaking soil with 0.01 mol L-1 CaCl2 containing 60 mu g mL(-1) P, is a very useful index for studies related to the chemistry of variable charge soils. Although the P-rem determination is a simple procedure, the possibility of estimating accurate values of this index from easily and/or routinely determined soil properties can be very useful for practical purposes. The present research evaluated the P-rem estimation through multiple regression analysis in which routinely determined soil chemical data, soil clay content and soil pH measured in 1 mol L-1 NaF (pH(NaF)) figured as P-rem predictor variables. The P-rem can be estimated with acceptable accuracy using the above-mentioned approach, and pHNaF not only substitutes for clay content as a predictor variable but also confers more accuracy to the P-rem estimates.