The Changes Of Soil Microbial Biomass And Enzyme Activities And Their Relations With Soil Fertility In Sheltered Planting

The research explored the changes of soil microbial biomass and enzyme activities and their relations with soil fertility in tomato sheltered planting of Fei Cheng city Shan Dong province. The main results are as follows:1 The averages of soil microbial biomass C and metabolic quotient in sheltered planting were higher than them of open ground, the soil microbial quotient was reverse. With the time prolonging, the soil metabolic quotient in sheltered planting was first decreasing and then increasing, the soil microbial biomass C and microbial quotient were reverse.2 The averages of soil microbial biomass N, microbial biomass P and microbial biomass N/T.N in sheltered planting were higher than them of open ground, the average of soil microbial biomass P/T.P was closed to it of open ground. With the time prolonging, the soil microbial biomass N, microbial biomass P, microbial biomass N/T.N and microbial biomass P/T.P were first increasing and then decreasing.3 Soil microbial biomass C/N and microbial biomass C/P in sheltered planting were lower than them of open ground, and they were all first increasing and then decreasing. Soil microbial biomass C/P in 3 years sheltered planting was the highest.4 Soil invertase, urease, phosphatase and catalase activities in sheltered planting were much higher than them of open ground. With the time prolonging, soil invertase activity had no orderliness, urease and phosphatase activities were first increasing and then decreasing, catalase activity had reverse orderliness.5 The correlation relationships between soil microbial biomass C, N, P, and organic C, Tot.N reached positive significant or extremely significant level, and the path analysis shew that soil O.C had strong positive direct effect on soil microbial biomass C, N, P. The correlation relationships between metabolic quotient and organic C, Tot.N and pH reached negative significant or extremely significant level, soil O.C and Tot.N had negative effect on metabolic quotient.6 Soil C/N had the strongest positive direct effect on soil microbial biomass C and microbial quotient, strong positive effect on microbial biomass P and negative effect on metabolic quotient. Soil Tot.N had the strongest direct effect on microbial biomass N, strong positive effect on microbial biomass C and negative effect on metabolic quotient. Soil teMBPerature, water content, pH, et al. had indirect effect on soil microbial biomass, microbial quotient and metabolic quotient.7 The relationship between soil invertase activity and soil fertility did not reach significant level, the relationship between soil urease and phosphatase activity and organic C, Tot. N and Avail.N reached positive extremely significant level. The relationship between soil catalase activity and organic C and C/N reached negative extremely significant level, the path analysis shew that soil C/N had strong positive effect on invertase, urease, phosphatase.8 The relationships between microbial biomass C and N reached positive extremely significant level, microbial biomass N and P had the same relationship. The relationships between microbial biomass C, N, P and urease and phosphatase activities reached positive extremely significant level, and catalase reached negative extremely significant or significant level. The relationships between soil invertase, urease, phosphatase and catalase reached negative extremely significant or significant level.