## 4 Discussion
It is worth noting that in our study, in 2019, when the rainfall was low, there were high counts of heterotrophic bacteria in the variants where the microbial consortium had been applied alone or in combination with the undersown crops. In our experiment, the count of actinobacteria also dropped in the variants with undersown catch crops and PGPR in 2019, as well as, in some cases, after the application of catch crops only in 2020. However, researchers are divided in their opinions on the effect of catch crops on the soil moisture level. They found that catch crops had different effects on water relations in the soil. The effects depended on abiotic environmental factors (mainly soil and rainfall), cereal species, the type of catch crop, and the plants sown in it [29]. Many authors say that catch crops generally cause the soil to dry out when the rainfall is low, whereas in wet seasons they have no effect, or only slightly improve the soil moisture [30]. This situation was also observed in our study. [PERSON] et al. [31] showed that the cultivation of cover crops affects soil microorganism environments that are critically important for maintaining soil functions and ecosystem sustainability as they are involved in the cycling of nutrients and the turn-over of organic matter. It has been reported that cover crops can alter the dynamics of soil bacterial and fungal communities [32], stimulate beneficial microorganisms [33], and suppress soil borne pathogens [34]. The cover-plants produce phytoncides that affect soil microorganisms and limit the occurrence of the pathogen. The literature data indicate [32; 33; 34] that the catch crops used in the cultivation stimulate the development of antagonistic, autochthonic bacteria _Pseudomonas_ spp. and _Bacillus_ spp. as well as saprotrophic fungi, which have an antagonistic effect on, for example, Trichoderma spp. They have a positive effect on the healthiness of root plants by considerably decreasing the infection of roots of the seedlings and later older plants by _Alternaria alternate, Fusarium oxysporum, F. culmorum, Thantephorus cucumeris_, and _Sclerotinia scleroorum_. PGPR play a similar role. The stimulation of the development of microorganisms is accompanied by the stimulation of the biochemical activity of the soil. The diversified methods of cover crop cultivation and PGPR use caused noticeable changes in the activity of soil enzymes, which reflected environmental disturbances affecting both the soil and plants [35]. Dehydrogenase (DHA), catalase (CAT), and acid phosphatase (PAC) are the soil enzymes whose activities are most often studied. Each habitat is characterized by a specific system of microbiological transformation. Soil bioactivity, which is an inseparable element of this structure, is determined by the transformations of compounds and energy occurring in this habitat. It is most visibly manifested by enzyme activity, which is determined by various factors, such as: soil type, vegetation cover, depth of soil profile, soil pH and temperature, weather conditions, organic matter content and agricultural technology [36]. Soil enzymes are the first to respond to changes occurring in the soil environment. The level of their expression is closely related to the content of organic matter in the soil, its physical properties, and the activity of microorganisms [37]. Among various soil enzymes, dehydrogenases, which are classified as oxidoreductases, play an important role in the oxidation of organic matter [38]. The activity of these enzymes is influenced not only by the content of organic matter in soil but also by its physicochemical properties, such as moisture, temperature, and pH. Research has shown that a change in soil oxygenation significantly modifies the activity of dehydrogenases. In our experiment, in 2019 and 2021, when the rainfall was lower than the long-term average, the highest dehydrogenase activity was noted after the application of PGPR and the use of catch crops together with the prepared consortium. [PERSON] et al.