Retardation factors and dispersion-diffusion coefficients of phosphate, potassium and ammonium in soils of Minas Gerais - Brazil

摘要

> face="Verdana" size="2">The objective of this study was to compare the retardation factors (R), and dispersion-diffusion coefficients (D) of phosphate, potassium and ammonium, determined in five Brazilian soils from Minas Gerais State (Orthic Quartzarenic Neosoil, RQo; three distrophic Red Latosols, LVd1, LVd2 and LVd3; and a distrophic Yellow-Red Latosol, LVAd). The experiment used percolation columns, applying one of the eight possible solutions resulting from the mixture of two phosphate, potassium and ammonium concentrations (15 and 60 mg L-1 P, 75 and 300 mg L-1 K, and 15 and 60 mgL-1 N). Lower values of R were observed for potassium and ammonium compared to phosphate. The value of R for phosphate was the lowest in the most sandy soil (RQo) and highest in the most oxidic soil (LVd2). The highest Latosol values of R, calculated for potassium and ammonium, were positively related to clay content with no defined relationship for the ion concentration or the accompanying ion under study. No clear relationship was observed for the concentration of these ions in the soils studied and dispension - diffusion coefficients.