Long‐term ground cover affects soil bacterial community and carbon metabolism in the Loess Plateau, China

Farmland mulching can maintain soil nutrients, which plays a positive role in agricultural planting in the arid area. However, the composition of the soil microbial community and the C cycle involved is unclear under farmland mulching. Based on the Changwu Agro-Ecological Experiment Station, this study set up a long-term positioning experiment to explore the effect on soil bacterial community structure and C metabolism capacity. In this study, we include five treatments: control uncovered (CK), plastic film mulching (PF), high amount of straw mulching carried out in July, August, and September every year (St(90)), low amount of straw mulch throughout the growth period (S-45), and high amount of straw cover throughout the growth period (S-90). We combined Illumina MiSeq sequencing and Biolog-ECO technology to analyze the functional characterization of soil bacterial community composition in terms of C source metabolism. The results indicated that the soil bacteria showed a high degree of epistatic clustering, and the operational taxonomic unit numbers of soil bacteria decrease as St(90), S-45, PF, CK, and S-90. Redundancy analysis showed that soil available P, NH4+-N, soil moisture content were the main environmental factors affecting bacterial community composition. Proteobacteria, Acidobacteria, and Actinobacteria are the main dominant flora in this area. Soil bacterial C metabolism was highest under PF treatment. Structural equation modeling (SEM) shows that surface cover has direct and indirect effects on bacterial C metabolism capacity and diversity through soil physicochemical properties. Reasonable mulching methods have a positive effect on the sustainable development of agro-ecosystems in arid areas.