The succession of microbial communities after residue returning in a Solonchak

Aims Residue returning is a practical agricultural management to combat global warming. However, the role of the microbial community and the metabolic functions during residue decomposition is vague, especially in saline soils. We aimed to clarify these roles during residue decomposition in saline soils. Methods Gas chromatography and high-throughput sequencing techniques were used to measure soil CO2 efflux and microbial community composition on soil and residue surfaces, respectively. Results The CO2 release rate (mg C kg(-1) dry soil per day) decreased from 188.5 to 28.4 from 1 to 15 days, and to 2.6 on the 90th day. The model showed that it took 15 days for the decomposition of the residue labile component and 462 days for a recalcitrant component. The changed dominant leaf surface bacteria class were the Bacilli 39-51% (0-4 days), then Alphaproteobacteria 5-40% (4-15 days), afterward Bacteroidia 20-19% (15-90 days). The changed dominant leaf surface fungal class was Mucoromycetes 24-40% (0-4 days), Eurotiomycetes 28-48% and 22-44% (0-90 days). The major bacterial (>60%) and fungal (>50%) groups that decompose maize residue were present before the residue enter into soil. Compared with soil bacterial community, soil fungi community showed more differences after adding residue. The bacterial genes of Membrane transport and Carbohydrate metabolism on the maize residue surface were stronger than soil with residues during 90 days by function prediction analysis. Conclusions Bacilli, Alphaproteobacteria and Mucoromycota were the most important microorganisms for maize leaf decomposition. The residues are mainly decomposed by the microorganisms derived from the residue surface after entering soils.