Evaluation of the long -term effects of the permanent cropping on soil microbial communities

Abstract

The study of soil microbial communities under different agricultural crops (flax, clover, barley, potato, winter rye) grown in permanent cropping and crop rotation was carried out. The effect of permanent cropping and crop rotation on the taxonomic profile of the prokaryotic and fungal components of the soil microbiome was studied. The effect of permanent cropping and crop rotation on the metabolic intensity and stability of soil biota in the absence of mineral and organic fertilisers was assessed. The subject of the research was the long-term experience established in 1912 by Professor A.G. Doyarenko at the Russian State Agrarian University – Moscow Timiryazev Agricultural Academy, founded in 1912 by Professor A.G. Doyarenko. It was shown that the highest OUT (operational taxonomic units) values for fungi were found in soils under fallow and crop rotation. For prokaryotes, however, the crop rotation variant had the lowest number of OTUs. Ascomycetes were found to be the dominant fungal taxon in all samples studied. Prokaryotes were dominated by Proteobacteria and Acidobacteriota, followed by Actinobacteriota and Firmicutes, and Chloroflexi were represented to a lesser extent. Among the archaea, the Crenarcheota phylum was dominant. It was shown that continuous cultivation of crops generally has a negative effect on the functioning of the microbial community. With an optimal metabolic coefficient of 0.2 in monoculture, they reached 0.6. The sustainability of the soil microbial community is reduced by the continuous cultivation of potatoes, flax and clover without organic and mineral fertilizers, as well as by the “perpetual fallow” option. Particularly unfavorable conditions were found in potato monoculture. Continuous cultivation of cereals, especially winter rye, does not lead to a significant decrease in the activity of soil biota and the stability of soil microbial communities. Crop rotation makes it possible to optimize microbiological processes in the soil and to increase the stability of the soil microbial community.