## 3 Results and Discussion
### Dominant Phyla of Soil Bacteria Under Horse Beans Cultivated in Different Systems
[35] proposed a concept of bacterial classification in which _Proteobacteria_ phyla were described as fast-growing copiotrophs, i.e., microorganisms developing in environments with a high supply of carbon. Their numbers were closely correlated with the degree of carbon mineralization in the soil. Our study also showed that _Firmicutes, Plancomyetes, Chloroflexi, Acidobacteria, Bacteroidetes, Bacteroidetes, and Verucomicobia_ were dominant in all soil treatments (1-5). _Gemmatimonadates_ was also a dominant phylum but only in the soil under horse beans in various cultivation systems. Its number of OTUs was the greatest in the direct drilling system--3.29% (Figure 1). The Firmicutes, Plancomyetes, Chloroflexi, Acidobacteria, Bacteroidetes, and Verrucomicobia phyla were isolated less frequently (Figure 1). _Chloroflexi_ is a phylum of anaerobic or microaerophilic nitriifying bacteria, which can survive in extreme and intensively changing conditions. _Chloroflexi_ occurred more frequently in treatment 1 in sample \"0\" (fallow). This can be explained by the fact that these bacterial communities develop by using cellular compounds from dead microorganisms and their metabolites, which is characteristic of uncultivated (fallow) or exhausted soils. [PERSON] et al. [37] observed a similar dominance of this group of microorganisms. The researchers used rice straw and biochar to effectively improve the soil quality and, thus, reduce the numbers of this bacterial phylum. Figure 2: Relative OTU numbers of dominant phyla of bacteria. The classifications with less than 1% numbers are gathered into the category “Other” (FA—plantless, fallow buffer zone of the field experiment—sample “0”; CT—conventional tillage; RT—reduced tillage; ST—strip tillage; NT—no tillage; “red” means negative difference; “green” means positive difference). \({}^{*}p<0.05\); ns—not significant. The _Frimicutes_ phylum includes bacteria of the _Bacillus_ and _Clostridium_ genera, which produce spores in unfavorable environmental conditions. The phylum was dominant in treatment 1; whereas, in the treatments with horse beans grown in different cultivation systems, the percentage of its OTUs was on average 1-2% lower (Figure 1). Bacteria of the _Verrucomicobia_ phylum are cosmopolitans in the rhizosphere. Their adaptations and functions are enigmatic, because so far, a low percentage of members of the phylum have been cultured. However, research has shown that _Verrucomicobia_ plays a key role in environmental carbon cycling and (poly)saccharide degradation, because they have a high capacity to encode glycoside hydrolase genes [38]. The occurrence of the _Gemmatimonadates_ phylum in the soil samples of the four cultivation systems collected from the horse bean plantation was higher than in the fallow soil sample \"0\" (Figure 1). According to the data in reference publications, _Gemmatimonadota_ is the eighth most abundant phylum of soil bacteria, with a share of about 1-2% worldwide [39]. [PERSON] et al. [40] proved that, although _Gemmatimonadota_ can be found in various environments, the maximum number of their sequences comes from soils used in different ways, including grassland soils, agricultural soils, forest soils, and contaminated soils. The cosmopolitan distribution of _Gemmatimonadota_ in different soils suggests that they are generalist species with a versatile metabolism, and they can adapt to a wide range of nutrients. [PERSON] et al. [41] and [PERSON] et al. [42] found that _Gemmatimonadota_ are a bacterial phylum whose numbers in soil increase with the presence of vegetation in the field. The relative OTU numbers within the phylum then increase strongly and exceeds 2%. Moreover, the bacteria are positively correlated with plant species richness and soil nutrients, mainly carbon. _Gemmatimonadota_ are one of the seven more dominant bacterial phyla, with numbers above 1%. The bacteria are positively correlated with total carbon, nitrogen, and phosphorus in the soil. Studies by [PERSON] et al. [43] and [PERSON] et al.