The Effect of Chemicals of Plant Protection Products on Soil Microbiocenoses

Abstract

With the emergence of agriculture, humankind faced numerous difficult tasks. For example, how to use the potential of the soil while saving its quality and functional properties, how to apply agricultural technologies effectively and environmentally friendly, how to make them safe for human health and biota, and many others. There are several informative and reliable recording criteria and indicator systems that fully and comprehensively describe changes in the ecological condition of the soil and agrocenoses. However, all these systems have one defect – the time from the impact of the factor to the “reaction” of the indicator. Early diagnosis of changes in the agrocenosis is possible due to the biological component of the soil, namely the microbiocenosis. Notably, that microorganisms have a large contact surface with the environment, high rates of reproduction in space and time, sensitivity to changing living conditions. The reaction of soil microbiocenosis and its activity (number of microorganisms of ecologicaltrophic and taxonomic groups, respiration intensity, microbial biomass content, and soil phytotoxicity) under the action of chemicals that are the basis of plant protection products (PPP) was studied in the laboratory. It was found that the number of microorganisms of different ecological-trophic and taxonomic groups under the action of a composition of cymoxanil with dimetomorph decreased by 1.5-4.5 times relative to control, chlorperifosmethyl in 1.1-2 times, and prometryn – not more than 1.5. The content of microbial biomass and the intensity of carbon dioxide emissions when using cymoxanil with dimethomorph compared to the control variant decreased by 44% and 51.4-64.8%, respectively; prometryn – by 10-13% and by 8-12%. The highest level of soil phytotoxicity was observed for variants using prometryn (20-24%), the lowest for a composition of cymoxanil with dimetomorph (7-12%). It was shown, that the high level of inhibition of test culture development with the use of prometryn associated with the class of PPP and the mechanism of its effect on the plant organism. Low indicators of soil phytotoxicity and microbiocenosis activity when using cymoxanil with dimetomorph are explained by the influence of the studied composition not only on phytopathogenic micromycetes, but also on all groups of soil micromycetes (cellulose-destroying, saprophytic) that dominate. Therefore, the influence of PPP chemicals on the microbiocenosis can be shown as follows: PROMETRYN (the lowest level of influence) → CHLORPYRIFOS-METHYL → CYMOXANIL + DIMETOMORF (the highest level of influence)