Comparison Of Langmuir

A laboratory experiment was conducted to evaluate the phosphate sorption potential of some representative soils of Southern Guinea savanna of Nigeria using the Langmuir, Freundlich and Temkin models. Soil samples (0 - 20 cm) of different Land use types were collected from five different locations exhibiting a wide range of physico-chemical characteristics. The soils were equilibrated for six days in a solution of 30 ml of 0.01M CaCl2 containing various amounts of P (0, 25, 50, 100, 200, 400, 800 and 1000µg L-1 P) as KH2PO4 at room temperature and thereafter the amount of phosphate sorbed was determined. Results obtained revealed that, phosphate sorption was positively correlated with pH, (0.925 ), clay contents (0.823 ), exchangeable acidity (0.802 ) of the soils when phosphate was applied at the rate of 100 µg P mL-1. The sorption curves showed more or less similar pattern of changes. Langmuir model showed best fit to the sorption data at higher P concentrations followed by the Freundlich and Temkin. Phosphate sorption was highly correlated with pH, exchangeable acidity and clay content of the soil.