【Objective】 Soil microorganisms are important active components in the soil. To understand impacts of farming practices on agro-ecosystems, it is of utmost importance to unfold researches on soil microbial metabolic activity in the farmland. The technique of BIOLOG Eco micro-plate assay is a conventional tool to evaluate soil microorganisms’ ability of utilizing carbon of one sole source, and though having some limitations, could provide clues to source of the carbon utilized by soil microbes relative to farming practice, while microcalorimetric technique is another means to characterize soil microbial activity by measuring heat dissipation and one of high precision. However, being a non-specific technique, it could, only with the support of specific techniques like BIOLOG, provide more explicit information about functions of soil microbe. Previous studies done by this group of researchers reported that BIOLOG could be used in couple with microcalorimetry to detect the factors of carbon source influencing metabolic activity of the soil microbes in the acid and neutral soils. However, little information has so far been reported about this issue in acidic soils. 【Method】 In this study, samples of red soil, a typical type of acid soil, were collected for exploration of ability of the soil microbes to utilize carbon substrates and microcalorimetric dynamics with the technique of BIOLOG coupled with microcalorimetric means in soils applied with chemical fertilizers and organic manure in combination (Treatment OM). Based on the information of carbon source preference of the soil microbes in the red soil obtained via principle component analysis (PCA) of the BIOLOG assay, evaluation was further performed of effects of those carbon substrates on thermometabolism of the soil microbes in Treatment OM and Treatment CK (no fertilization). 【Result】 Results show that Treatment OM significantly increased AWCD (average well color development) on the BIOLOG microplate as compared to Treatment CK. PCA indicates that Treatment OM sat far apart from the other treatments along the first principle component axis. Carbon substrates, like L-arginine, L-threonine, D-mannitol, glycogen and D-cellobiose, were positively related to the first principle component with high correlation coefficient (r>0.5). Microcalorimetric analysis demonstrates that soil microbes in Treatment OM were quite high in thermometabolic activity, which peaked pretty soon, suggesting that Treatment OM stimulated the soil microbes in activity in the red soil. When the carbon substrates found significant in correlation in Treatment OM were spiked into other corresponding Treatments OM and CK, some of them, like D-cellobiose and D-mannitol, did not show any of the effect and instead possibly delayed the appearance of peaks and suppressed metabolic activity of the soil microbes. All these findings suggest that the technique of BIOLOG has its own limitations. However, it was also found that some other carbon substrates, like L-arginine and glycogen did promote metabolism of the soil microbe in Treatments, which might be explained as that these substrates play important roles in stimulating N and P recycling in the soil. 【Conclusion】 Although both the BIOLOG technique and the microcalorimetric technique have their own limitations, coupling of the two makes it feasible to determine key carbon substrates responsible for stimulating the soil microbes in activity in acid soil. This study also demonstrates that L-arginine and glycogen might be the carbon sources of preference to microorganisms in red soil, which further implies that the application of organic manure rich in such kinds of carbon substrates is of great significance to building up soil fertility in the red soil regions.