Coupling no-tillage with bio-organic fertilizer strategies to regulate soil quality and microbial communities, without compromising crop yield under rainfed conditions on the Loess Plateau, China

Background: The Loess Plateau faces dual challenges of soil degradation and unstable crop yields. No-tillage combined with bio-organic fertilizer synergistically enhances soil health and crop yield in dryland farming; however, their integrated effects on yield, soil quality index (SQI), and microbial communities remain poorly understood. Methods: A three-year field experiment conducted on China’s Loess Plateau was performed with two tillage methods, conventional tillage (T) and no-tillage (N), and two fertilization strategies, chemical fertilizer (C) and bio-organic fertilizer (F), yielding four treatments: TC, TF, NC, and NF. We examined the effects of tillage and fertilization on crop yield, SQI, soil microbial communities and their relationships. Results: Tillage and fertilization significantly influenced winter wheat yield, SQI, and the fungal Shannon index, but had no significant effect on bacterial diversity. The dominant bacterial phyla were Actinobacteria (24.95–28.93%), Proteobacteria (24.50–27.63%), and Chloroflexi (15.53–16.50%), and the predominant fungal phyla were Ascomycota (82.48–90.23%) and Basidiomycota (3.98–10.28%). Linear regression analysis revealed a significant positive correlation between SQI and crop yield. Partial least squares path modeling showed that the NF treatment indirectly increased SQI by enhancing soil structure, increasing nutrient availability, and stimulating microbial community activity. This management strategy directly increased crop yield by optimizing soil physicochemical properties. Conclusions: In the rain-fed agricultural region of the Loess Plateau, the no-tillage system combined with bio-organic fertilizer effectively enhanced wheat yield by reshaping soil microbial communities and improving soil quality and fertility. This integrated approach offers both a foundations and practical strategies for promoting sustainable agriculture on the Loess Plateau.