Tillage-Driven Shifts in Rhizosphere Microbial Communities and Their Associations with Soil Chemical Properties in Dryland Maize of Western Liaoning

Tillage is an important agronomic practice that regulates soil quality and microbial ecology. Nevertheless, in-depth evidence on how tillage shapes rhizosphere microbial diversity remains limited. To evaluate the long-term effects of tillage on microbial community structure and diversity in the spring maize rhizosphere four treatments with three replicates have been set up since 2009—rotary tillage (RT), subsoiling (ST), deep ploughing (DT), and no-tillage (NT). Rhizosphere soil samples were collected at the maize harvest stage in 2025 after 17 years of long-term experiment. High-throughput sequencing and soil chemical analyses were used to compare bacterial and fungal diversity and to identify the principal drivers of community differentiation. Compared with the other treatments, NT decreased soil pH by 4.78–7.90%, available phosphorus (AP) by 8.03–22.53%, and available potassium (AK) by 20.43–48.61%, while increasing total carbon (TC) by 8.15–13.29%. Compared with RT, DT increased AP and AK concentrations by 18.72% and 54.84%, respectively. NT significantly decreased the Chao1 and Shannon indices of both bacteria and fungi relative to RT, ST, and DT. For bacteria, the Chao1 index under NT was 18.86–40.18% lower, and the Shannon index was 5.36–8.58% lower than the other three tillage treatments. For fungi, the reduction was more pronounced: the Chao1 index decreased by 35.88–51.32%, and the Shannon index decreased by 15.43–30.70%. ST and DT increased rhizosphere microbial richness and diversity, with similar diversity levels between ST and DT. Redundancy analysis further revealed that soil pH, TC, AP, AK and AN were key factors driving rhizosphere microbial community distribution. Overall, compared with NT, ST and DT improved rhizosphere nutrient status and enhanced microbial richness and diversity.