Straw incorporation combined with double ridge-furrow plastic film mulching enhances soil organic carbon and rhizosphere soil bacterial dynamics on the Loess Plateau.

Abstract

<h4>Background</h4>Straw and plastic film mulching are widely used conservation agriculture practices in dryland farming. However, long-term plastic film mulching can accelerate soil organic carbon (SOC) depletion, while straw mulching can cause planting and crop emergence challenges in arid and semi-arid regions.<h4>Methods</h4>To address these limitations, a two-year field experiment was conducted on the Loess Plateau with four treatments: no straw incorporation or film mulching (CK), straw incorporation (SI), double ridge-furrow plastic film mulching (FM), and SI+FM. The study investigated the effects of the treatments on SOC, microbial biomass carbon (MBC), enzyme activity, and rhizosphere soil bacterial community composition.<h4>Results</h4>Across the two growing seasons, the rhizosphere SOC content increased by an average of 37.85% under SI+FM, 10.45% under SI, and 34.06% under FM, compared with CK. In 2023, non-rhizosphere SOC content was 19.97% and 16.01% higher under SI+FM and SI than that under CK, respectively, whereas no significant difference was observed between FM and CK. SI+FM significantly enhanced rhizosphere soil MBC content and invertase activity, both of which were significantly and positively correlated with rhizosphere SOC content. Shifts in bacterial community composition were also observed, with the relative abundances of <i>Proteobacteria</i> and <i>Actinobacteria</i> being higher under SI+FM and SI than under CK. Co-occurrence network analysis revealed that SI+FM produced the highest number of nodes (697) and modularity value (0.66), suggesting stronger microbial interactions in the rhizosphere.<h4>Conclusion</h4>SI+FM enhanced rhizosphere SOC accumulation on the Loess Plateau, primarily by improving microbial activity and promoting bacterial community assembly.