Heavy metal Impact on Soil Microbial Biomass , Soil dehydrogenase activity and Soil Respiration rate

The contamination of agricultural soils by heavy metals is a global problem. Soil texture as a biotic factor represents one of the most important factors that influences the distribution of organic matter and ultimately play decisive role in retention of heavy metals in soil ecosystem. The effects of heavy metals on soil microbial processes were investigated. Analytical grade sulphate and chloride salts of Copper, Iron, Zinc, Cadmium, and Cobalt were added individually to soil samples and incubated in different plastic pots. Samples were then analysed for microbial biomass carbon, respiration rate and soil dehydrogenase activity. Soil microbial biomass carbon declined in samples treated with Copper and Zinc. The rate of respiration of the soil microbial populations was equally inhibited by the metals in the Iron and Cadmium treated soils by the end of the experiment. Our results also revealed that soil dehydrogenase activity was strongly inhibited by Copper and Zinc.