Sorption of phosphate ion by alluvial sod soil

The article discusses the adsorption of phosphorus by alluvial sod soil of Western Transbaikalia (the Republic of Buryatia). We have determined the parameters of phosphate ion sorption by soil in a laboratory environment (Qmax - the maxima of phosphorus adsorption and KL - the adsorption constant). Soil samples were selected according to the genetic horizons of each profile. We have developed the phosphate ion adsorption isotherm for each of the soil samples by balancing 3 g of air-dry soil with 30 ml of KN2PO4 solution (its concentration is from 0.25 to 5 mM P2O5/l). We have calculated the parameters of the phosphate ion sorption using the Langmuir and Freundlich equations, which isotherms satisfactorily describe the process of phosphorus adsorption. Humus horizons are characterized by relatively high phosphate ion uptake, and mineral horizons - by smaller uptake. However, mineral horizons bind the phosphate ion more strongly than humus ones. In comparison with virgin soil, cultivated soil is characterized by a high sorption capacity toward phosphate ion.