Effect of Pesticides on soil microbial and enzyme activity

Objective Pesticides has gain an increasing awareness because of it is becoming a serious environmental problem and come to threaten the health of humanbeing.The effect of five pesticides(zineb,copforce,the mixture of carbendazim and mancozeb,hymexazol)on soil bacteria,fungi,actinomyces,and Five specific enzymes were chosen for investigation(urease,dehydrogenase,invertase,acid phosphates and protease).Methods The enumeration of the soil micro flora was done by the dilution plate method;The enzyme activity was determined by traditional methods.Shannon-Wiener index as well as 16S rRNA-PCR amplification and DGGE fingerprinting was used for detection of shift in microbial community diversity in pesticides contaminated agricultural soil.Results The outcome showed that the microbial diversity was significantly changed after the application of pesticides,the effect of pesticides on microbe had a order from top to bottom:bacteria-actinomyces-fungi.Conclusions Our results indicate that the use of the pesticides hymexazol resulted in an altered soil community structure,in particular for the actinomyces.Invertase was markedly inhibited by hymexazol,zineb,carbendazim and mancozeb and the inhibiting rates were varied between 30.30% and 21.21%;Urease activity was also inhibited significantly by hymexazol,the inhibiting rate was 37.67%;Protease activity was markedly inhibited by zineb and hymexazol,the inhibiting rates were 27.27% and 18.18% respectively;Phosphates activity was inhibited significantly by hymexazol,zineb,carbendazim and mancozeb,the inhibiting rates were range from 22.12%-3.54%;Dehydrogenase activity was not significantly affected by pesticides.Meanwhile,the correlation of all indexes were analyzed,the data suggested that all indexes existed certain correlation.