TAXONOMIC COMPOSITION AND ORGANIZATION OF THE MICROBIAL COMMUNITY OF SODDY-PODZOLIC SOILS AFTER APPLICATION OF STRAW OF CEREAL CROPS AND USING OF THE BARKON BIOPREPARATION

Abstract

The modern concept of the reproduction of soil organic matter (SOM) requires the sequestration of the carbon of plant residues in the soil by the formation of stable organic compounds. In this regard. the role of microbial preparations, accelerating the decomposition of straw are important. Learning the taxonomic structure of the microbial community in these processes is of great importance and not well understood. Microbial communities of arable soddy-podzolic soils decomposing straw of grain crops were studied in field and laboratory experiments. Straw (rye, wheat and oat) were crushed and inoculated with the Barkon preparation (complex association of microorganisms developed at the FGBNU ARRIAM). The functioning of the microbial community was assessed by the number and activity of microorganisms, the agrochemical properties of the soil. The composition of bacterial community of soils was determined by high-performance sequencing of 16s rRNA gene libraries. The rate of decomposition of straw was controlled by the ratio C:N in it: rye straw < wheat < oat. Barkon increased rate of decomposition of straw by 18-42% compared to soil microflora by 3 months of composting. Biopreparation is more effective when straw is incorporation in the 0-5 cm layer than by 9-12 cm. The effect of the Barkon on the number, biomass of microorganisms, and their respiration was not noticeable as compared with the growth of these parameters when introducing straw. The absence of an increase in carbon dioxide emissions with an increase in the rate of straw decomposition when Barkon is introduced, indicates an intensification of the processes of carbon sequestration in soil. The treatment with a biological preparation promotes the formation of microbial destructive communities with the highest efficiency of straw conversion and its conversion into labile organic compounds, and then into soil humus substances. Therefore, the use of Barkon, compared to the uninoculated straw, increased the content of total carbons in the soil by 4.8 to 8.4%. All studied factors (soil, straw, biological preparation, depth and time of decomposition) influence on the composition of microbial communities leading decomposition, the most significant of which is the type of soil. This confirms the high response of the composition of the microbial community to various factors while maintaining the crustal component of the microbiome characteristic of this soil. In the more acid soddy-podzolic soils, at the same humus content, in the taxon Acidobacteria, group 1 and group 2 prevailed, while in the soils with a neutral pH, group 6 predominated. The indicator of straw