Effects Of Carbendazim On The Soil Enzymes And Microorganisms

Object:The carbendazim is a broaden spectrum fungicide used for protection fruit, vagetable and crop from diseases. The object of this study is (1) the residue dynamic of carbendazim in grey desert soil of Xinjiang; (2) the effect of carbendazim on soil enzymes and microorganism..Methods:A field experiment was carried out for investigating the residue dynamic of carbendazim in grey desert soil. The concentrition of carbendazim were set as 0,5,10,20,50, and 100 mg-kg"'dry soil. The residue of carbendazim in soil was analyzed by using HPLC. Effects of carbendazim on soil enzymes and microorganism were studied with a greenhouse experiment and a field experiment. Soil enzymes, microbial biomass and diversities were tested with traditional methods and PCR-DGGE method.Results:(1) The residues of carbendazi in soil of processing tomato field were increased with carbendazim concentration increasing. The half-lives of carbendazim in grey desert soil were from 6.48 to 10.27 d in this study.(2) The cellulase activity and urease activity of soil were increased and sucrase activity was decreased by carbendazim added under greenhouse conditions. The protease activity was decreased initially and then increased subsequently. Catalase activity and alkaline phosphatase activity were inhibited significently after carbendazim application 26 day and 40 day, respctively. Catalase activity and alkaline phosphatase activity can be considered as the indicating index for carbendazim pollution in soil. The EC25 of carbendazim for soil catalase and alkaline phosphatase activity were 6.8 mg·kg-1 and 5.94 mg·kg-1, respectively. Under field condition, sucrase activity and urease activity of soil were increased initially and decreased subsequently in carbendazim trestments. Protase activity, catalase activiy and alkline phosphatase activity were inhibited significantly by carbendazim during the experiment earlier stage (0-28 d), but there are no significant difference among different treatments after carbendazim application 35 day. Those results suggest that protase activity, catalase activiy and alkline phosphatase activity can be used for indicatind the carbendazim pollution in soil at earlier stage. The EC25 of carbendazim for soil protase activity, catalase activiy and alkline phosphatase activity was 8.74,66.06 and 60 mg1kg-1, respectively.(3) The microorganism biomass carbon and biomass nitrogen of soil were decreased significently after treated with carbendazim, and the inhibited effect of carbendazim on microorganism biomass carbon and biomass nitrogen increased with the carbendazim concerntration increasing in soil under greenhouse and field conditions. The microorganism biomass carbon and biomass nitrogen used as the biological index to indicate carbendazim pollution of soil with EC25 11.39 and 10.44 mg·kg-1 for greenhouse condition and with EC2534.79 and 25.13 mg·kg-1 for field condition, respectively.(4) The amount of bacteria was increased by the lower carbendazim concerntration (2.5,5, 10 and 20 mg-kg-1)and decreased by the higher concerntration(50 and 100 mg·kg-1.The amount of fungi were decreased significantly with the carbendazim congcerntration increasing. The EC50 of carbendazim for soil fungi quantity were 7.73 mg·kg-1 for greenhouse condition and 62.32 mg·kg-1 for field condition, respectively.(5) With carbendazim concerntration increasing, Shannon-Wiener index and abundance index of bacteria were increased at 14th day, but decreased at 28th day. Shannon-Wiener index and abundance index of fungi were reduced by 13.40-25.43%,8.10-14.17%,3.31-22.73% and 40-56%, 13.33-26.67%,5.89-52.94% at 7th,14th and 28th days, respectively.Conclusion:In this study, the microbial biomass carbon, biomass nitrogen and the amount of fungi were sensitive to carbendazim residues in soil, so these can be used as diagnose indicators for indicating soil carbendazim pollution. The catalase activity, alkaline activity and protase activity could be considered as assossiate indicators for indicating carbendazim residue in soil. Effects of carbendazim on soil enzymes and microbial were more sensitive under field coditon. The EC25 or EC50 of carbendazim for soil enzymes and microbial were higher in field experiment than that of in greenhouse experiment.