PHOSPHATE SORPTION CHARACTERISTICS OF SOME BENCH-MARK SOILS OF WEST AFRICA

Abstract

Phosphate sorption characteristics of soil material from selected soil profiles of West Africa were studied. These soils represent a wide range of parent materials and agroclimatic conditions. Phosphate concentration in soil solutions was almost invariably low in comparison with the requirements for most crops. In comparison with many soils of the humid tropics, the surface horizons have low to medium standard P requirements (or the amounts of P required to attain 0.2 ppm P in solution). Phosphorus sorption capacity is mainly related to soil mineralogy, which in turn is related to soil parent materials, BET-surface area, and free Fe oxide content of the soils. Of the profiles studied, Alfisols and Ultisols derived from basalts have the highest standard P requirement. Ultisols have higher standard P requirements than Alfisols. © Williams & Wilkins 1977. All Rights Reserved.