3.4 Relationships among organic C fractions
The fractions of SOC showed significant or not significant correlations between each other (Table 3). MBC, contributed to microbial activities in formation of aggregate, was positively correlated with WSOC (r = 0.79, P < 0.01), KMnO4-C (P< 0.001), BR (r = -0.50, P < 0.01) and MWD (r = 0.40, P < 0.05). The EOC was positively correlated with WSOC (r = 0.44, P < 0.05) and MWD (r = 0.63,P < 0.01). Positively correlation between WSOC and KMnO4-C was observed, and WSOC was correlated with MWD (r = 0.72, P < 0.01). Additionally, the MWD was also positively correlated with KMnO4-C content.