Abstract: The effect of organic manure on microbial numbers, enzyme activities and available phosphate content in rice rhizosphere was studied on red soil by using the rhizobox proposed by Youseff and Chino. The results showed that application of organic manure considerably increased the numbers of fungi, actinomyces and bacteria, and avaiable P concentration both in rhizosphere and in non rhizosphere soil of rice. The larger numbers of microbes were observed in rhizosphere than those in non rhizosphere. The difference of microbial numbers between rhizosphere and non rhizosphere was enlarged by application of organic manure. Organic manure affected bacteria most followed by actionmyces and fungi, and stimulated the great augment of inorganic phosphate solubilizing bacteria and organic phosphorus decomposing bacteria, hence the releasing of P from inorganic and organic phosphorus, and increased the activity of urease and phosphatase in both rhizosphere and non rhizosphere.