ABSTRACT
The potential toxicity of xenobiotics to bacteria in agricultural soils has implications for land management and farm production. Metabolic processes which are utilized in toxicity measurements include nutrient cycling, enzyme activities, sulfur oxidation, and quantifications of adenosine triphosphate and biomass. The use of endogenous soil microbes as biological instruments in toxicant assessment has been discussed. The undisturbed cycling of carbon in the soil milieu is a major factor in the maintenance of soil productivity, but the use of this cycle as a measurement of soil microbial activity is still a controversial issue. The movement of nitrogen through the environment is mediated by the metabolic activities of microorganisms. Four processes within the nitrogen cycle are paramount in their dependence on microorganisms: ammonification, nitrification, denitrification, and nitrogen fixation. The validity of the bioassay to produce a fingerprint of the metals which are present in the soil in elevated concentrations was assessed using various metal extractants.
