Testing and evaluating some methods to investigate side effects of environmental chemicals on soil microorganisms.

Some methods of measuring soil biological activities (dehydrogenase activity, short- and long-term respiration, ATP content, nitrogen transformation, and straw decomposition) were used to assess their suitability for testing side effects of environmental chemicals on microbial activities. Reproducibility and, especially, the sensitivity of the methods (and activities) were important. In these investigations, the chemicals Aretit (herbicidal ingredient dinoseb acetate), pentachlorophenol, and sodium dodecyl sulfonate (LAS) were applied at different dosages. The trials were run under laboratory and field conditions to examine agreement between the results. The activities tested varied in their sensitivity to the chemicals. Dehydrogenase activity, short-term respiration, ATP content, and, in some cases, nitrogen transformation were the most sensitive, whereas straw decomposition and long-term respiration needed higher dosages for inhibitory effects. Dinoseb acetate was particularly effective. The effects of all chemicals were strongly modified by the soil type, while temperature and moisture had fewer effects. Inhibitory effects lasted several months under laboratory conditions. Agreement between laboratory and field trials was best with dehydrogenase activity.