ESTUDIO DEL REGIMEN FOSFORICO DE DOS SUELOS UTILIZADOS EN EL CULTIVO DE LOS PASTOS. I. CINETICA DE SORCION

Abstract

In a Red hydrated Ferralitic and in a yellow-lixiviated Quartzitic Ferralitic soils dedicated to pasture explotation was studied the sorption kinetic in time function. Soil samples in KH2PO4 solution marked with 32P free of bearer were agitated at variable times among 1 and 72 h. Sorption kinetic was characterized by the presence of a fast chemiosorption process, followed by a slow and long interchange reaction and balance was reached after 48 h. Maximum sorption values were of 1 120 and 300 µg of P/g of soil in the Red and Quartzitic soils respectively. P fixation was greater in the Red soil. It is concluded that the selection of grass variety and species should be in accordance with the sorption rate of each soil in order to make a better use of P fertilizer.