POTENTIAL MOBILITY OF ACCUMULATED PHOSPHORUS IN SOIL AS ESTIMATED BY THE INDICES OF Q/I PLOTS AND BY EXTRACTANT

Publisher Website
Google Scholar
Abstract
Phosphorus desorption indices determined from Q/I plots, their relation to the inorganic P fractions of Chang and Jackson, and water and acid NH4OAc test values were investigated using samples of soils cultivated for 7 years without P fertilization or amended annually with 30 or 60 kg of P ha-1. Fertilization markedly increased fractionable inorganic P, and it decreased the equilibrium P buffering capacity in three of five soils, though the decrease was statistically significant in only one soil. As would have been expected, fertilization considerably raised the equilibrium P concentration, i.e., the zero point of P exchange at which no net desorption from or adsorption to soil occurs and the quantity of water soluble P that could be desorbed under experimental conditions. In most soils, previous P additions increased the quantity of P available for desorption, determined from the Q/I plot at a given reference equilibrium P solution, more than the P extractable by water or acidic NH4OAc. A desorption-sorption procedure was proposed as a method for quantifying the effect of P fertilization in terms of the amount of P required to be removed from the fertilized samples in order to reduce their equilibrium P concentration to that prevailing in the unfertilized samples. © Williams & Wilkins 1991. All Rights Reserved.

This publication has 0 references indexed in Scilit: