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This study was conducted to investigate the capability of the microbial community characteristics and soil variables to promote carbon and nitrogen cycles in maize fields under straw mulch. We covered the surface soil of the maize field with different amounts of wheat straw (0 kg/ha, 2,250 kg/ha, and 4,500 kg/ha) and used 16S rRNA and ITS sequencing, Biology ECO-plate, traditional enzymology, TOC analyzer, and HPLC to measure bacterial and fungal community composition and functions, characteristics of microbial carbon source metabolism, carbon and nitrogen fraction, enzyme activity, and organic acid content in the maize rhizosphere and non-rhizosphere. The results indicated that short-term straw mulch insignificantly affected the alpha diversity of bacterial and fungal communities whereas significantly influenced their beta diversity. The results of functional prediction revealed that straw mulch considerably boosted the relative abundances of bacteria belonging to chemoheterotrophy, aerobic chemoheterotrophy, ureolysis, and nitrogen fixation and inhibited fermentation and nitrate reduction in maize rhizosphere soil. These processes primarily drove the C and N cycles in soil. Straw mulch also improved fungal saprotrophs by raising the proportion of Chaetomiaceae and Chaetosphaeriaceae. The Biology ECO-plate results illustrated that straw mulch weakened the metabolism capacity of microbial labile carbon resources. As a result, the labile C and N fractions were raised under straw mulch. Our results also showed that straw mulch primarily regulated the microbial community structure in rhizosphere soil by significantly decreasing Firmicutes and Ascomycota relative abundance while increasing Basidiomycota. The fungal community structure is more than bacterial for affecting soil microbial biomass carbon, readily oxidizable organic carbon, dissolved organic carbon, available nitrogen, ammonium, and nitrate directly and indirectly through malic acid content and cellulase, protease, and amylase activity. Overall, our findings imply that straw mulch might influence the bacterial and fungal community structures, thereby boosting the production of labile C and N components and accelerating the C and N cycle in maize fields.

Soil disturbance by tillage practices promotes soil respiration which is a main source of carbon dioxide emission into the atmosphere. The present study was conducted to investigate the effect of different tillage practices on soil respiration and the carbon source/sink characteristics of maize farmland ecosystems in the wheat–maize–soybean cropping system. Six tillage treatments, namely, traditional tillage (T), ridge tillage (R), traditional tillage + straw mulching (TS), ridge tillage + straw mulching (RS), traditional tillage + straw mulching + decomposing inoculants (TSD), and ridge tillage + straw mulching + decomposing inoculants (RSD), were used to measure the soil respiration and its hydrothermal factors. The results showed that the intensity of soil respiration increased initially and decreased afterwards throughout the growth period of maize ranging from 1.011 to 5.575 μmol (m2·s)−1. The soil respiration rate under different treatments varied remarkably presenting a trend of RSD > TSD > TS > RS > T > R. Ridge tillage reduced the soil respiration rate of maize farmland while straw mulching improved it. Meanwhile, ridge tillage and straw mulching increased the soil temperature sensitivity index of soil respiration, but the addition of decomposing inoculants reduced this trend. The soil moisture response threshold under ridge tillage was lower, while the straw mulching was found to increase it, compared with the control. Moreover, there was a positive correlation between trapped soil fauna and soil respiration. Compared with the control, ridge tillage and straw mulching were beneficial to the carbon sink of the farmland ecosystem as shown by the maize field for the entire growing season.

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.