Effects of heavy metals on soil microbial biomass carbon

This study was aimed at evaluating the effect of heavy metals on soil microbial processes. The effects of Lead (Pb) and Cadmium (Cd) at different concentrations were investigated over a period of eight weeks. Chloride salts of Pb and Cd were added singly and in combination to soil samples at room temperature (270C) in different polythene bags. Samples were taken from the bags at two weeks interval and measurements were taken of the microbial biomass carbon (MBC). The results showed that there was a significant decrease in the microbial biomass carbon for all treated soils from the second week to the sixth week. But there was an observed increase in microbial biomass carbon on the eight week. At the sixth week, 2000mgkg-1Pb and 40mgkg-1Cd gave the most significant decrease (P < 0.05) in microbial biomass carbon of 98%.