Contrasting One-Season Responses of Soybean Yield and Rhizosphere Bacterial Communities to Tillage and Straw Management in a Salt-Affected Farmland in Southern Xinjiang

In salt-affected soil, different agronomic practices can alter crop productivity and rhizosphere microbial dynamics, yet whether their short-term responses are consistent remains unclear. A single-site, one-season field experiment was conducted in 2025 in Zepu County, southern Xinjiang, China. Three tillage treatments, conventional tillage (CT), no-tillage (NT), and no-tillage with straw mulching (NT&SM), were compared for soybean yield, rhizosphere soil properties, and bacterial communities. The results showed that the soybean yield under CT was significantly higher than that under NT&SM. Contrary to the yield trend, the NT&SM treatment exhibited the highest mean values for the Chao1 and Shannon indices (the overall treatment effect was significant). PERMANOVA based on Bray–Curtis distance indicated that short-term tillage significantly altered the rhizosphere bacterial community structure, explaining 34.6% of the variation in composition. Tillage practices produced different rhizosphere bacterial community profiles. However, these short-term shifts in bacterial diversity and composition did not parallel the yield response. This suggests that both crop productivity and rhizosphere ecological responses should be considered simultaneously when evaluating conservation tillage practices. These findings represent short-term responses under the conditions of a single site and growing season and require validation through multi-year, multi-site experiments.