Abstract: Phosphorus (p) adsorption characteristics of 5 soil samples were studied in soils of Southeastern Iran during 2009/2010 cropping season. Some soil properties as well as selected P-adoption characteristics were studied in these soils, Results show for this study Freundlich adsorption isotherm has good match with phosphorus adsorbed data and has good R-square. Freundlich sorption isotherms were used to evaluate the P requirement of 5 soils in a lab study. The soils were medium to heavy textured, acidic in reaction and were highly calcareous. Amount of P sorbed by the soils increased with increasing P in equilibrium solution. Quantities of P retained on sod solid phase were significantly correlated (p<0.05) with clay content of the soils. Maximum P was sorbed by a soil that had the maximum (64%) Clay content. there were negative relationship between P adsorption capacity and SOC and Ca content of soils.