Distribution and drivers of soil bacterial communities across different soil management practices and soil diagnostic units in agricultural ecosystems

Soil bacterial communities play an important role in soil health, carbon (C), and nutrient cycling, as well as in soil-plant relationships in agroecosystems. However, our understanding of the drivers and distribution of soil bacterial communities across landscapes is limited. For example, it is not clear how changes in soil management practices (i.e. Till vs No-till vs cover crop), soil diagnostic units, and their associated physical-chemical properties interact to influence the composition and abundance of soil bacterial communities at a larger scale. Here, using samples collected in a countrywide soil survey in Hungary, we combined soil metagenomic sequencing, soil management practices, and soil geochemical data to develop a mechanistic understanding of the drivers of bacterial communities in contrasting agroecosystems. We found that bacterial community composition and distribution significantly differed between soil management practices. Furthermore, we found that soil geochemical properties influenced soil bacterial composition and abundance under similar soil diagnostic units, suggesting that the effects of soil management practices on bacterial communities outweighed the ones of pedogenic processes. Together, these results suggest that soil management practices influence soil geochemical properties that drive the composition and spatial distribution of soil bacterial communities. Consequently, effects and types of soil management should be taken into account when developing soil health indicators for agroecosystems.