Evaluation of the microbial community in various saline alkaline-soils driven by soil factors of the Hetao Plain, Inner Mongolia

Soil microbial communities play a crucial role in maintaining diverse ecosystem functions within the saline-alkali soil ecosystems. Therefore, in this study, we collected various saline-alkaline soils from across the Inner Mongolia Hetao irrigation area. The soil chemical properties were analyzed, and the microbial diversity of bacteria and fungi was measured using 16 S rRNA and ITS rRNA amplicon sequencing. The dynamic relationship between the soil microbial community and soil factors was analyzed using the ABT (Aggregate Enhanced tree) model, the co-occurrence network, and the structural equation model. The results indicated that electrical conductivity (EC) was the biggest driving force of various saline-alkaline soils, affecting the community structure of bacteria (22.80%) and fungi (21.30%). The soil samples were categorized into three treatment levels based on their EC values: the low-salinity group (L, EC: 0–1 ms/cm, n = 10), the medium-salinity group (M, EC: 1–2 ms/cm, n = 8), and the high-salinity group (H, EC > 2 ms/cm, n = 6). The results demonstrated a negative correlation between microbial abundance and salinity-alkalinity, while revealing an enhanced interrelationship among species. The alterations in bacterial (12.36%) and fungal (22.92%) communities in various saline-alkali soils were primarily driven by saline-alkali ions, which served as the principal direct factors. The negative correlation between EC and SOM exhibited the highest magnitude, whereas the positive correlation between soil organic carbon and EC demonstrated the greatest strength. Therefore, it was further substantiated that EC played a pivotal role in shaping the distinct microbial communities in saline-alkali soils.