Responses of soil enzymes to different heavy metals

Presence of heavy metals (HM) in agricultural soil is a major hazard to the soil-plant system. In the present study, soil samples (0-5 cm depth) were taken in order to determine the effects of heavy metal pollution on soil enzymes like dehydrogenase, alkaline phosphatase (APA), urease (UA) protease, cellulose, invertase, beta glucosidase and amylase. Results showed that Cadmium (Cd) significantly inhibited the four enzyme activities and Zinc (Zn) inhibited urease and calatase activities. Lead (Pb) was not significantly inhibitory than the other heavy metals for the four enzyme activities and was shown to have a protective role on calatase activity in the combined presence of Cd, Zn and Pb. Overall, all the heavy metals were found to have an inhibitory effect on the soil enzymatic activities. Hence our results suggested that enzymatic activities may be used as a sensitive indicator for assessing changes in soil environment quality.