Abstract:

The study aims to clarify the regulatory mechanisms of different tillage practices on soil physicochemical properties, rhizosphere microbial communities, and wheat yield in wheat fields under a wheat-maize rotation system, thereby providing a scientific basis for the regionalized and precision-oriented optimization of wheat field tillage regimes. Field experiments were conducted in Gaoling and Yanliang Districts of Xi'an, with three tillage treatments: no deep ploughing, deep ploughing combined with straw removal and deep ploughing combined with straw return. Soil physicochemical properties were determined, rhizosphere microbial community composition was analyzed via high-throughput sequencing, and wheat growth traits and yield parameters were measured. Statistical analyses were further performed to elucidate the correlations among the aforementioned variables. The results demonstrated that the no-deep-ploughing treatment significantly increased soil organic matter (Gaoling: 40.22% increase; Yanliang: 35.57% increase), total nitrogen (Gaoling: 56.70% increase; Yanliang: 32.29% increase), and available phosphorus contents in both experimental areas. In contrast, deep ploughing treatments were more conducive to elevating soil electrical conductivity and available potassium contents, with the most pronounced effect being observed in the deep-ploughing+straw-removal group in Yanliang (188.83% increase in available potassium). The impact of straw return on soil alkali-hydrolyzable nitrogen content exhibited distinct regional variations. At the phylum level, Pseudomonadota dominated the bacterial communities across all treatments, accounting for 28.78%-38.95% of the total bacterial sequences. Specifically, deep ploughing combined with straw removal enhanced bacterial richness in Gaoling (21.84% increase in the ACE index), whereas no deep ploughing maintained relatively high fungal diversity in both regions. As for the fungal communities, Ascomycota was the dominant phylum, with a relative abundance exceeding 48.99%, and the composition of dominant fungal genera showed significant regional specificity. Redundancy analysis revealed that available potassium and total nitrogen were the core edaphic factors driving the differentiation of rhizosphere microbial communities, collectively explaining 48.23% of the variation in fungal community structure. Correlation analysis indicated that soil electrical conductivity and pH were positively correlated with the relative abundance of plant-growth-promoting bacterial taxa, while soil organic matter and total nitrogen contents were positively associated with that of plant-growth-promoting fungal taxa. Moreover, deep ploughing combined with straw removal significantly improved wheat yield in both areas (Gaoling: 15.64% increase; Yanliang: 15.22% increase) and optimized key plant architecture traits. Tillage practices modulate rhizosphere microbial community structure by altering soil physicochemical properties, with available potassium and total nitrogen serving as the pivotal regulatory factors. The deep-ploughing+straw-removal treatment achieves a synergistic “soil-microbe-crop” interaction in both study regions, representing the optimal tillage regime for wheat production under the local wheat-maize rotation system. Although no deep ploughing helps retain soil nutrient reserves, it compromises wheat yield by reducing the abundance of functional microbial taxa that facilitate crop growth.

Key words: tillage measures, soil physicochemical properties, rhizosphere microbial community, wheat yield