Abstract
Two Alfisols and an Entisol with different physical and chemical properties were studied to relate P 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 fitted both to the Langmuir and Freundlich equations. Mean sorption maximum values for the different soil series were Kanchanpur > Lachimpur > Ghoradanga. The fraction of added P sorbed followed the same trend of the SPR, P sorption maximum (Pmax), phosphate affinity constant (K), maximum phosphate buffering capacity (MPBC) (K Pmax), and Freundlich constant K') but not the phosphate desorption and maximum recovery per cent. The P sorption maximum correlated with K, MPBC, Freundlich K', clay, and different forms of Fe and Al. The value of K (bonding energy) was correlated significantly with MPBC, Freundlich K', SPR, clay, pyrophosphate, oxalate, and dithionite extractable Al. The MPBC was significantly correlated with Freundlich K', SPR, clay, pyrophosphate, oxalate, and dithionite extractable and crystalline form of Al. Freundlich K' was significantly influenced by SPR, clay, and different forms of Fe and Al. The SPR of the soils correlated significantly with pH (H2O), clay, and different forms of Fe and Al.
