Abstract:Effects of long-term fertilization on SOC pools and their turnover rates of a red soil were studied using soil organic carbon (SOC) physical fractionation and chemical analysis methods. Results showed that balanced fertilization (NPK, 2NPK) and organic fertilizer application (NPKOM, OM) significantly enhanced maize yield and reduced the temporal variation of yields, and increased the contents of SOC and labile organic carbon (LOC) as compared with control (CK). Based on the five physically fractionated SOC pools, s+c_mM and s+c_M associated C accounted for 31%~53% and 28%~38% of SOC,followed by fPOM (8%~15%) and iPOM_mM (7%~21%),and then by cPOM (5%~12%)。Organic fertilizer application (NPKOM, OM) significantly increased POM associated C pools (cPOM、fPOM and iPOM_mM), but had no significant effect on mineral associated C pools (s+c_M and s+c_mM). As a result, the turnover rates of SOC were the fastest in the two treatments. The turnover rate was positively related with the ratio of LOC to SOC (r=0.66﹡), but not with SOC. We can conclude that the balanced fertilization and organic fertilizer application can improve soil fertility but also benefit SOC accumulation.