Abstract <p>Field and laboratory studies were conducted in 2023 to assess changes in the composition of microbial communities in sod-podzolic heavy loamy soil upon growing various crops in the following crop rotation: mustard - winter wheat - barley. This pattern was chosen for the basic assessment of dynamic changes in the structure of soil microbiological communities caused by the cultivation of various agricultural crops. Microbial community in soil samples taken 1, 2, and 3 years after plowdown of green manure was analyzed by amplicon sequencing of 16S rRNA gene of bacteria and archaea. Pairwise comparison of microbial communities in the soil after different crops showed the largest number of reliably changing taxonomically significant groups of microorganisms (55) in the soil after winter wheat and mustard. In the soil after barley and mustard, the number of specific taxa decreased two times (and came to 24). The soils under wheat and barley were almost identical by the composition of predominant bacterial taxa. The most pronounced changes were observed among representatives of archaea from the phylum Crenarchaeota belonging to the class Nitrososphaeria. Individual taxa from this class showed a high specificity in relation to agroecological conditions of cereals’ and mustard cultivation. Green manure was shown to have a marginal effect on the composition of microbial community primarily at the level of changes in the number of individual bacterial taxa.</p>