PHOSPHORUS SORPTION-DESORPTION CHARACTERISTICS OF TWO INCEPTISOLS AND AN ENTISOL OF UTTAR PRADESH

Two inceptisols and an entisol of betwa catchment area of Uttar Pradesh comprising several gradients in physical and chemical properties were studied to relate phosphate sorption and desorption to soil properties From the P isotherm curve, the standard P requirement (SPR) of the soils was determined. Phosphate sorption data were also fitted both to the Langmuir and Freundlich equations. Mean sorption maximum values for different soil series may be arranged as: Mahoba II > Mahoba I > Rath. The fraction of added phosphate sorbed followed the same trend of standard P requirement, phosphate sorption maximum, the Freundlich constant K' and 1/n but not the phosphate affinity constant, maximum phosphate buffering capacity (K. P-max) estimated by the Langmuir isotherm. Inverse relationship existed between phosphate sorption maximum versus the phosphate desorption as well as maximum recovery per cent. Correlation coefficients among sorption parameters of P and soil factors were examined.