## 2 Materials and Methods
### Soil Sample Collection  
The composition of the soil microbiome under the horse bean plantation was analyzed in 2019, i.e., in the twentieth year of the field experiment. Our study only included the analyses of OTU (operational taxonomic unit) composition, and indicators such as microbial biomass or sequencing read count were not considered. Soil samples were collected from the topsoil (0-20 cm) once, immediately after the harvesting of horse beans in 2019. An Egner probe was used for sampling. Because there were no spaces between the plots, soil samples for microbiological analyses and soil physicochemical properties were collected from the central part of the plot (width 2 m, ten samples per plot). For each experimental \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Period**} & \multicolumn{8}{c}{**Month**} \\ \cline{2-7}  & **Apr** & **May** & **June** & **July** & **Aug** & **Sep** \\ \hline
1 st ten days & 0.00 & 1.73 & 0.03 & 0.32 & 0.65 & 1.75 \\ \hline
2 nd ten days & 0.96 & 1.71 & 0.06 & 1.39 & 0.50 & 0.62 \\ \hline
3 rd ten days & 0.52 & 1.67 & 0.28 & 1.32 & 0.22 & 1.94 \\ \hline month & 0.45 & 2.56 & 0.13 & 1.05 & 0.44 & 1.47 \\ \hline
3 rd & 2.6-3.0 & 2.1-2.6 & 1.7-2.1 & 1.4-1.7 & 1.1-1.4 & 0.8-1.1 & 0.4-0.8 & \textless{}0.4 \\ \hline Extremely humid & Very humid & Humid & Quite humid & Optimum & Quite dry & Dry & Very dry & Extremely dry \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The monthly and ten-day values of the HTC in the growing season. treatment, forty primary samples were collected from random points of all plots (ten samples from each plot \(\times\) four replicates, blocks). They were merged into composite soil samples, each weighing about 1 kg. Apart from that, a protective strip (a fallow field, 2 m wide) was used around the entire experiment, which was not exposed to the tillage system, and from this zone, 40 primary samples were taken for the composite sample \"0\", a plantless, fallow buffer zone of the field experiment. As a result, five treatments of the soil samples were distinguished (one treatment for sample \"0\" and four treatments representing tillage systems). They were used in microbiological analyses, where they were marked in the following way:  
1. Plantless, fallow buffer zone of the field experiment--sample \"0\" (FA);
2. Conventional tillage (CT);
3. Reduced tillage (RT);
4. Strip tillage (ST);
5. No tillage (NT). Both containers and tools for collecting soil samples were washed with water and ethanol (70% solution) before taking the next samples. Soil samples intended for soil microbiome analyses were stored in the dark at 4 \({}^{\circ}\)C for no longer than 24 h. Before laboratory analyses, roots were removed from soil samples, and the soil was sieved through a 2 mm sieve. The regular soil samples before soil chemical analysis were air-dried and crushed in a mortar to obtain homogenized material and sieved through the sieve of 2 mm mesh. The undisturbed soil samples of known volume (100 cm\({}^{3}\)) were collected by using steel rings for bulk density and water properties determination. Soil chemical and physical analyses were performed for each soil sample collected in different cultivation systems (CT, RT, ST, NT). Total carbon (TC) and total nitrogen (TN) content were determined using a VarioMax elemental analyzer. If inorganic carbon (in the form of carbonates) was present, TC values were corrected (inorganic carbon content is subtracted from TC content) and expressed as the soil organic carbon (SOC) content. The content of plant-available phosphorus and potassium was determined with the Egner-Riehm method; whereas, the content of plant-available magnesium was determined with the Schachtschabel method [20] (Table 2). In addition to the chemical properties of the soil, physical properties were determined, including capillary water capacity, bulk density (BD), and soil moisture (Table 3). The capillary water capacity was determined using the Richards pressure chamber method [21].