Abstract:In present paper the direct effect of organic manure on phosphorus adsorption-desorption in two paddy soils was studied by a specially designed method to separate the phosphorus coming from minerialization of the organic manure during desorption period. The results showed that both pig feces and cow feces could significantly reduce P-adsorption and increase P-desorption in the soils while cellulose could only play those effects in higher P level soils, especially in the ultisol. On the same type soil, the effect was much more pronounced in the higher P-level soils. The soluble organic substances of organic manure played a main role in the direct effect of organic manure on phosphorus adsorption-desorption in the soils.