Abstract: By using a radioactive ³²P-labeled technique,this paper studied the effects of P-dissolving Penicillium oxalicum P8 inoculum on the transformation,fixation and efficiency of fertilizer P.The results showed that the inoculum could prevent available P from fixation by soil,and promoted the uptake of applied P by maize and peanut.Additionally,it reduced the amount of Ca₁₀ -P fraction derived from available P,increased the pool of available P,and maintained more ³²P in forms of Ca₂-P and Ca₈-P.With time extending,the ratio of Ca₁₀ -P fraction in soil was gradually increased,and the treatment with P.oxalicum P8 showed the lowest ratio of Ca₁₀-P form,compared with treatment without P.oxalicum P8.The inoculum not only prevented available ³²P from turning into Ca₁₀ -P form,but also had a longer effective period.

Key words: ³²P isotopic technique, P-dissolving fungi, Phosphate fertilizer, Availability