Abstract:To investigate mineralization of organic carbon and microbial activity and their relationship under different fertilization in red soil, five kinds of samples from long-term fertilized soil (manure, M; nitrogen plus phosphorus plus Potassium, NPK; manure plus NPK, NPKM; NPK plus straw, NPKS; without any fertilization, CK) were incubated, and the CO2 production rate, the number of and metabolic diversity of microbes of samples were evaluated. The result shows that: soil CO2 production amoung samples is significantly different, the order of potential CO2-C production of five samples, which derived from the first-order kinetic model, is as follows: M(180.3 mg/kg) > NPKM(88.5 mg/kg ) > NPK(47.6 mg/kg) ≈NPKS(43.4 mg/kg )> CK (34.5 mg/kg ). The increasing number of bacteria, fungi and Actinomycete which is later than their mineralization rate of organic carbon, however, is significantly different between the samples under different fertilization at the 14th,35th,69th day of incubation. Their following pattern: M > NPKM > NPK≈NPKS≈ CK, is significantly correlatived with those of CO2 production. The microbial communities of the samples under different fertilizations are obviously different, which is similar to their mineralization of organic carbon. The result shows that long-term fertilization, especially the use of manure, has significant effect on microbial communities, enhances activity of microbe, and then increases the microbial mineralization of organic carbon.