author(s)
Miheretu Bedassa

abstract
Phosphorus (P) availability is commonly\r\nassumed to limit productivity in many tropical soils, yet there is relatively\r\nlittle information on the phosphorus chemical forms, distribution, and\r\ntransformations that P acid soil. The best way to obtain of separate fractions\r\nof phosphorus in soil using a series of solvents of different strengths is\r\nsequential analysis. The method used was Chang and Jackson sequential analysis.\r\nFormation of the forms of soil phosphorus and their binding largely depends on\r\nsoil pH. In neutral and alkali soils the main phosphate compounds are calcium\r\nphosphates, and their solubility depends mainly on the ratio Ca/PO₄.\r\nIn such soils, the activity of Ca ions increased resulting in reduced\r\nsolubility of phosphate while in neutral and acidic soil the adsorption and\r\ndesorption of phosphate mainly occurs at Al and Fe oxide surfaces.