Straw mulch improves soil carbon and nitrogen cycle by mediating soil microbial community structure in maize field

Aims: This study was conducted to investigate the capability of the microbial community networks and soil variables to promote carbon and nitrogen cycles in maize fields under straw mulch. Methods: We covered the surface soil of the maize field with different amounts of wheat straw (0 kg/ha, 2250 kg/ha, and 4500 kg/ha), then used High-throughput sequencing, Biology ECO-plate, traditional enzymology, TOC analyzer, and HPLC to measure soil microbial community composition and functions, characteristics of microbial carbon source metabolism, carbon and nitrogen fraction, enzyme activity, and organic acid content in maize rhizosphere and non-rhizosphere. Results: Our studies indicated that short-term straw mulch significantly influenced microbial β-diversity. The function predicts results revealed that straw mulch significantly increased the relative abundances of bacteria belonging to chemoheterotrophy, aerobic chemoheterotrophy, ureolysis, and nitrogen fixation while inhibiting fermentation and nitrate reduction in maize rhizosphere soil. The Biology ECO-plate results illustrated that straw mulch weakened the metabolism capacity of microbial labile carbon resources, resulting the soil labile C and N fractions raised. Straw mulch primarily regulated the community structure of Firmicutes , Ascomycota , and Basidiomycota . Those microbial communities direct effected on readily oxidizable organic carbon, microbial biomass carbon, available nitrogen, ammonium nitrogen, nitrate nitrogen, and dissolved organic carbon, and indirect effected on these C and N fractions by directly influencing malic acid content and activity of cellulase, protease, and amylase. Conclusions: Our findings imply that straw mulch accelerate soil C and N cycle in maize field by mediating microbial community structuresto boost labile C and N components.