stationary experiment was conducted for 12 years at Hunan Agricultural University to investigate the effects of rice-based cropping system, organic manure groundwater level on phosphate sorption by paddy soils developed on red earth, in treatments of 3 types of rice-based cropping systems, 3 application rates of organic manure and 2 levels of groundwater table. Results showed that the phosphate adsorption isotherms for soils in all the treatments are quite similar in shape, belonging to curve in the shape of "L" with high affinity. The adsorption data all fit in well with the three adsorption equations at a very significant Langmuir equation is better than Freundlich and level of 1.0%, but the One-surface Temkin equations in this respect.