The effects of different amount of organic manure on soil phosphorus availability and different forms of inorganic phosphorus content were investigated in this study.The results showed that the total phosphorus and available phosphorus content were increased by fertilization in calcic kastanozems soil in Eastern Gansu,especially for the manure treatments.The contents of high active P such as Ca2P,Ca8P,A1P and PFe were decreased in no P fertilizer area,but the contents of OP and Ca10P was increased;the contents of Ca2P,Ca10P,A1P were increased with the increasing amount of manure,while Ca8P,FeP,OP were on the contrary.Ca2P was significantly positively correlated with organic matter,available P and was significantly negatively correlated with pH.Combining both the content of effective form of Ca2P and the undissolved Ca10P,it was suggested that the application of 60 000 kg·hm2 manure was the most effective to active soil P,reduce P adsorption,and improve the phosphorus availability.