Phosphorus Adsorption Characteristics of Some Acid and Alkaline Soils

Acid soils adsorbed more P as compared with the alkaline ones irrespective of concentration of P in the equilibrium solution. The P adsorption showing a straight line Langmuir relationship was limited to a known solution concentration which varied with the soil. The treatment of citrate dithionite resulted in maximum reduction of P adsorption in acid soils and similar effect was found with ammonium acetate treatment in alkaline soils. In the former group of soils, more than 90% of the adsorbed P was as Fe and Al phosphate and in alkaline ones, about 40% was saloid bound. Phosphorus was adsorbed at two energy levels, the values of which varied with the nature of the soil.