Abstract:The active C pool and CPMI (C pool management index)of soils in different agricultural ecosystems were discussed.The results indicated that CPMI was significantly affected by fertilization,climate,soil utilization patterns and cultivated age. The active C measured by KMnO 4 oxidation of soils varied from 0.49 to 4.99mg/g, CPMI from 51.6 to 165.The CPMI order of red soil in tropics influenced by different fertilization was GM(green manure)>FYM(farmyard manure)>FYM+NPK>PEF(reference)>NPK>CK.In...