Livestock dung rather than biochar enhances the anaerobic methane oxidation in grassland soils

The terrestrial anaerobic methane oxidation (AOM) coupled with denitrification is considered to be an important link in the “cryptic cycle of methane”. However, it remains uncertain how land use activity such as biochar and livestock dung amendments regulate the AOM in grassland. Here, we incubated soils with biochar and dung amendments in microcosms to monitor the AOM activity and quantified the maker genes of anaerobic methanotrophs and their potential syntrophs. Dung enhanced the AOM mediated by Candidatus Methylomirabilis oxyfera and stimulated denitrifying bacteria and anammox growths as well. The biochar amendment inhibited AOM due to the trapping of NO3− and NO2−. Our study raised the possibility that anthropogenic activity can regulate AOM through porosity alteration and substrate limitation. [Display omitted] •Dung amendment accelerated the anaerobic methane oxidation mediated by M. oxyfera.•Biochar hindered the growth of anaerobic methanotrophs through substrate limitation.•Biochar amendment might convert the AOM to acetate production.