Long-term ground cover affects soil bacterial community and carbon
metabolism in the Loess Plateau, China
Farmland mulching can maintain soil temperature and moisture, increase
crop yields, which plays a positive role in agricultural planting in the
arid area. However, the composition of the soil microbial community and
the carbon cycle involved is not well understood under the ground cover
scenario. Based on the Changwu Agro-Ecological Experiment Station, this
study set up a long-term positioning Experiment to explore the impact of
long-term land cover pattern on soil bacterial community structure and
carbon metabolism capacity. In this study, we include five treatments:
control uncovered (CK), plastic film mulching (F), high amount of straw
mulching is carried out in July, August and September every year (St90),
low amount of straw mulch throughout the growth period (S45), high
amount of straw cover throughout the growth period (S90). We combined
Illumina MiSeq sequencing and Biolog-ECO technology to analyze the
functional characterization of soil bacterial community composition in
terms of carbon source metabolism. The results indicated that the soil
bacteria showed high degree of epistatic clustering after mulching
treatments, and the operational taxonomic units (OTU) numbers of soil
bacteria under different treatments decrease as St90, S45, F, CK, S90.
Redundancy analysis (RDA) showed that AP, NH4+-N, MC were the main
environmental factors affecting bacterial community composition.
Proteobacteria, Acidobacteria and Actinobacteria are the main dominant
flora in this area. Long-term surface cover resulted in significant
differences in soil bacterial carbon metabolism, which was highest in
the F treatment. Structural equation modeling (SEM) shows that surface
cover has direct and indirect effects on bacterial carbon metabolism
capacity and diversity through soil physicochemical properties.
Reasonable mulching patterns can greatly change the community structure
and carbon metabolism of soil bacteria, and play a positive role in the
sustainable development of agro-ecosystems in arid area.