[Effects of different land management practices on black soil microbial biomass C and enzyme activities].

In a long-term experimental plot at the Hailun Agricultural Ecology Station of Chinese Academy of Sciences in Heilongjiang Province, Northeast China, the effects of three land management practices including natural restoration, fallowing and cropping on black soil microbial biomass C and enzyme activities at the depths of 0-10, 20-30 and 40-50 cm were investigated. The results showed that at 0-10 cm, soil microbial biomass C and soil urease, phosphatase, catalase and invertase activities were in the sequence of natural restoration > cropping > fallowing, while at 20-30 cm and 40-50 cm, they had less significant differences as those at 0-10 cm. Under natural restoration and cropping, soil microbial biomass C and soil urease, phosphatase and catalase activities decreased with increasing soil depth, while under fallowing, they were higher at 20-30 cm. Correlation analysis showed that there existed significant positive correlations between soil total C and total N, soil total C and microbial biomass C, and soil microbial biomass C and test enzyme activities. The indices soil microbial biomass C and soil enzyme activities showed that black soil under long-term natural restoration had better soil quality.