Effects of Biogas Slurry Application on Soil Microbial Communities Structure and Function During Wheat-rice Stubble Period

Abstract

To reveal the effects of biogas slurry application on soil microbial community structure and function, a soil column experiment was constructed with three treatments[(no N addition, CM; conventional fertilization, SN; biogas slurry addition, SZ)]. The differences in composition, diversity, and structure of bacterial and fungal communities on day 1 and day 21 after soil flooding were evaluated, and their functions were predicted using Illumina high-throughput sequencing technology. The results of the analysis of α diversity showed that the fungal α-diversity indexes of CM, SN, and SZ treatments on day 1 were significantly higher than those on day 21, and there was no significant difference among the three treatments. However, the bacterial Simpson index differed among the three treatments on day 21, with SZ-21 showing a higher Simpson index but lower Chao1 index compared with those of SZ-21. The analysis of bacterial community structure showed that Firmicutes, Chloroflexi, and Actinobacteria in the SN-1 treatment were different from those in the other treatments on day 1, whereas the relative abundance of bacterial phyla in the SZ and SN treatments were similar on day 21. The analysis of fungal community structure showed that the relative abundance of Ascomycota and Zygomycota in the SZ-1 treatment were higher than those in the SN-1 and CM-1 treatments on day 1. The relative abundance of Ascomycota in the SN-21 and SZ-21 treatments were lower, whereas that of Zygomycota were higher compared with that in CM-21. The analysis of NMDS showed that the composition of bacterial and fungal communities in the SN and SZ treatments showed a gradually similar trend. The PICRUSt analysis showed that the function of the soil bacterial community was similar in the CM, SN, and SZ treatments. The FUNGuild function prediction reflected that the main differences in trophic type between the SN-21 and SZ-21 treatments occurred in saprotroph and pathotroph forms. Therefore, biogas slurry addition in the wheat-rice stubble stage could contribute to balancing soil nutrients and maintaining soil ecological function to a certain extent, but there may still be a risk of fungal disease.