Phosphate sorption capacity of some tropical soils on basement complex of South Western Nigeria

Phosphate sorption isotherm is a valuable tool for the management of P fertility in soils. This study was conducted to examine how P sorption characteristics were influenced and could be predicted from selected properties of tropical soils. Langmuir and Freundlich equation were adopted in the evaluation and estimation of P sorption parameters in nine soils types of South Western Nigeria developed on basement complex. Two profile pits were dug per soil type where they were dominant (predetermined by Smyth and Montgomery, 1962). The morphological attributes of the soil profile were described and soil samples were taken from pedological horizons for laboratory analysis. Same soil types were bulked and P sorption were determined using 11 concentrations of P and three replicates.. The P sorption data for these soils were slightly better fitted to Freundlich equation than the Langmuir equation. Oxalate extractable Al (Alox) and Clay particles were the properties that were best correlated with sorbed P. This suggest that oxalate Al oxide with silicate clay play a significant role in P sorption.