Film-straw dual mulching improves soil fertility and maize yield in dryland farming by increasing straw-degrading bacterial abundance and their positive cooperation

Film-straw dual mulching (FMSS) has been utilized successfully for corn production in dryland farming. However, the mechanisms by which FMSS improves soil fertility and maize yields remain obscure. Therefore, a three-year field trial with four treatments, including conventional tillage (blank, BL), FM with standard fertilization (FMSF), and with straw incorporation (FMSS), was conducted between 2018 and 2020. The results demonstrated that FMSS significantly increased the concentrations of soil organic carbon (SOC, 17.48%) and total and available nitrogen and phosphorus (TN, 34.48%; TP, 16.90%; AN, 23.34% and AP, 40.95%) in the 040 cm soil profile, resulting in a 31.0% increase in maize yield. FMSS had no significant effect on soil bacterial diversity; however, it selectively increased the relative abundances of Firmicutes, Gemmatimonadetes, and Acidobacteria but decreased those of Proteobacteria, Actinobacteria, Bacteroidetes, and Nitrospirae, and dynamically regulated bacterial life strategies (mainly from k-strategies to r-strategies), thereby forming an efficient straw-degrading functional community. These three straw-degrading bacteria demonstrated a cooperative relationship, and increased labile and recalcitrant straw carbon (C) and nitrogen (N) decomposition rate, nutrient release, and soil fertility. FMSS improved the straw-degrading bacteria abundance, regulated their life strategies, promoted positive cooperation that increases straw decomposition, and increased SOC, TN, TP, AN, and AP, thereby significantly improving soil fertility and maize yield. Therefore, FMSS is an efficient management practice that can replace FM and increase maize yields in dryland farming.