Widely popular Mehlich-3 phosphorus (P) was not used in the estimation of the intrinsic status of soil P. The objectives of this study were to develop the state-space model to determine the intrinsic soil P pools, a weakly adsorbed P pool, and a tightly adsorbed P pool, from the Mehlich-3 P. A linear relationship between Mehlich-3 P and the intrinsic soil P pools was derived from theoretical analysis of the extraction process of adsorbed P as competitive exchange by aqueous fluoride. Adsorption experiments of soil P were carried out to determin...
