Dynamics of methane emission and archaeal microbial community in paddy soil amended with different types of biochar

Biochar, as a valuable and eco-friendly material generated from greenwaste, has a potential to mitigate CH4 emission in rice paddy soil. However, the response of methanogenesis and associated archaeal community in paddy soil to biochar amendment remains controversial. In this study, we explored the effect of three different biochars (derived from rice straw, orange peel or bamboo powder, respectively) on CH4 emission and associated archaeal microbial community in paddy soil of southern China within 90 days of anaerobic incubation. Results showed that biochar amendment overall inhibited CH4 emission in paddy soil. Significant decrease of alpha-diversity of archaeal community was observed in all samples in the end of incubation as revealed by 16S rRNA gene sequencing, and the addition of biochars mitigated the loss of archaeal biodiversity in paddy soil. Incubation time was found to be the major driver for the succession of archaeal community. Besides, Methanosaeta, Methanocella, Methanobacterium and Methanosarcina were mainly responsible for CH4 production. In addition, biochars had no significant effect on altering relative abundance of methanogens. Overall, our study demonstrated that the addition of three different types of biochar reduced methane emission and total archaeal diversity, while caused no significant change in methanogenic communities in paddy soil.