The use of integrated soil microcosms to predict effects of pesticides on soil ecosystems

Most studies that aim at assessing the effects of pesticides on soil organisms or soil ecosystem processes are related to a single species of organism or soil process. Such individual studies are usually performed according to standard test guidelines, prepared by national or international authorities or approved test organizations and used in risk assessment. Over the last four years, with scientists from Germany and Russia, we have tested integrated soil microcosms, as model terrestrial ecosystems, to assess simultaneously the overall effects of a single pesticide, on a range of representative soil organisms, ecosystem processes, and environmental fate. This integrated approach takes account of interactions between organisms and processes which may influence the overall environmental impact and fate of a pesticide. Results from a detailed study of the environmental impact of the fungicide carbendazim are presented and some results on the impact of copper on soil systems are also reviewed. Some ecosystem structural parameters that were affected include: microbial activity, nematode communities, earthworm numbers and masses and plant growth. Some of the ecosystem processes affected include: nitrogen mineralization, and nutrient transformations.