Abstract
The paper discusses the impact of pesticides on the biological activity of soils, as well as an environmental assessment of the state of light chestnut soils by the Kazakh Research Institute of Agriculture and Crop Production with the aim to es-tablish diagnostic indicators that reduce biological activity. The study covers physical, chemical and biological properties of soils under crops of winter wheat in the light chestnut soil in the South-East of the Republic of Kazakhstan. The content of pesticides in soil samples was determined using the gas chromatography mass-spectrometric method. The paper shows results of the chromatographic analysis of soil samples regarding the content of pesticides. The study of changes of light chestnut soil biological activity was conducted to determine their relative resistance to pesticide contamination. Data ob-tained revealed the degree of light chestnut soil resistance to pesticide contamination. The study also identified species of soil invertebrates, as well as soil enzymes that should be used as bioindicators for the monitoring of the contamination with pesticides. Results obtained expand knowledge about changes in the biological activity of light chestnut soils due to pesti-cide contamination in the ecosystems of South-East Kazakhstan. In contrast to abundance indicators, the results suggest that the species composition of soil organisms can be used as a criterion for a qualitative assessment of the soil exposure to pesticides.