A LITERATURE REVIEW AND EVALUATION OF THE HEDLEY FRACTIONATION - APPLICATIONS TO THE BIOGEOCHEMICAL CYCLE OF SOIL PHOSPHORUS IN NATURAL ECOSYSTEMS [Review]

摘要

The Hedley fractionation recognizes plant-available forms (Resin Pi, Bicarb Pi, and Bicarb Po) and refractory forms (NaOH Pi, NaOH Po, Sonic Pi, Sonic Po, HCl Pi, Residual P) of soil phosphorus. This updated survey of the recent literature shows that the sequential fractionation proposed by Hedley et al. can also be used to separate forms of organically bound soil phosphorus from the geochemically bound fractions. We consider that biological P includes all the extracted organic fractions (Bicarb Po, NaOH Po, Sonic Po) and geochemical P includes the remaining fractions (Resin Pi, Bicarb Pi, NaOH Pi, Sonic Pi, HCl Pi) and the Po and Pi in the Residual fraction.