Phosphate sorption isotherms for some Sierra Leone soils

Abstract Phosphate sorption isotherms were obtained for three acid highly weathered soils of Sierra Leone, by equilibrating air dry samples for 24 h with 0.01 M KH 2 PO 4 solution at 25 °C. The Langmuir and Temkin equations were used to evaluate the sorption capacities for phosphate. Phosphate sorption maxima of 2439, 2137 and 1429 mg/kg soil and x /log c of 774, 718 and 610 were calculated; where x =phosphate sorbed (mg/kg soil) and c =equilibrium phosphate concentration (μmol dm −3 ). Qualitative relationships between these sorption parameters and other soil variables are shown.