Influence of perennial agrophytocenosis based on soil microbial parameters

Study objective. Using high-throughput profiling of soil microbial communities based on the 16S rRNA gene, to investigate the effect of perennial agrophytocenoses based on alfalfa (Medicago sativa var. Varia) as a monoculture or a mixture with cereals on soil microbial diversity under different mowing regimes. Materials and methods. The study was conducted at the Field Experimental Station of the Timiryazev Russian State Agrarian University — Moscow Agricultural Academy in a field trial established in 1996. DNA was isolated from soil samples from the upper organomineral horizon using the Qiagen PowerSoil Pro DNA Kit (Qiagen, Germany) according to the manufacturer’s standard protocol on a QiaCube automated station (Qiagen, Germany). Primers with target regions matching the 515F/Pro-mod-805R primers were used for amplification. The technical sequences included a heterogeneity spacer, a 6-nucleotide index, and a standard Illumina adapter. Primary filtering of low-quality reads was performed using the reformat.sh program in the BBTools package. Results. An increase in the abundance of nitrogen-fixing microorganisms of the genus Bradyrhizobium was detected in experimental plots sown with alfalfa or alfalfa-cereal mixtures compared to arable land. Two-fold mowing was associated with a higher level of variation in alpha diversity metrics compared to three-fold mowing. Furthermore, the advantage of using two-cut grass stands in terms of the accumulation of fixed nitrogen in the soil compared to three-cut grass stands was demonstrated due to the more efficient formation of a branched root system and, consequently, increased intensity of metabolic flows in the rhizosphere. Conclusion. The results demonstrate the possibility of maintaining the productivity of agrocenoses by managing the composition of soil microbiota through optimization of the botanical composition of grass stands and agronomic practices.