Nutritional regime and biological activity of soil depending on copper contamination and the role of diatomite as a detoxifier

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Relevance. Modern agricultural production is characterized by an increase in anthropogenic impact on agrocenoses, which poses a threat to obtaining environmentally safe crop production. Among the toxicants, heavy metals are particularly dangerous, along with pesticides. Metals, including copper, which play a dual role in the “soil — plant” system, are absolutely necessary for plants and at the same time highly toxic when received in excess quantities, deserve special influence in this regard.Methods. The study of the amounts of copper was carried out in microfield experiments with artificial soil contamination with copper sulfate (CuSO4 · 5H2O) at the level of 2 MPC, 4 MPC and 10 MPC. The soil of the experimental field is medium-loamy leached chernozem, high-siliceous rock diatomite was used as a copper detoxifier at the rate of 5 t/ha. The experimental crop was spring wheat of the Margarita variety selected by the Ulyanovsk Research Institute of Agricultural Sciences. The repetition of the experiment is fourfold, the location of the plots is randomized, the accounting area of the plots is 1 m2.Results. The threshold value of copper, beyond which the biological activity of chernozems significantly decreases in the conditions of the Middle Volga region, is the level of pollution in the amount of more than 4 MPC. The introduction of diatomite into the soil in its pure form was accompanied by an increase in the activity of soil microorganisms, when combined with copper sulfate — a relative decrease. Artificial contamination with copper did not cause significant changes in the content of humus , phosphorus and potassium compounds in the arable layer. It is shown that the copper content in the soil at the level of 10 MPC led to a significant suppression of the activity of soil biota and a decrease in the yield of spring wheat by 0.58 t/ha, or by 29%.