How does biochar amendment affect soil methane oxidation? A review

Purpose Soil is the crucial biological sink of methane, which is an important and potent greenhouse gas. The extensive biochar application in soil has also aroused interests in its influence on soil methane emissions. However, although numerous studies have paid attention to the methane flux from the biochar amended soil, the research efforts of biochar effects on methanotrophs mediating the methane consumption in soil still lag behind and need to be re-examined. Especially, studies of the nonconventional methanotrophs for atmospheric and anaerobic methane oxidation, which have rapidly developed in recent years, deserve much attention. Results and discussion Here, we literately reviewed the proceedings about the biochar effects on conventional, atmospheric, and anaerobic methanotrophs in soil, respectively. Biochar plays a great role in methanotroph communities through soil characteristics controlling and redox reactions. Key physical soil characteristics such as porosity, aggregation, and moisture and chemical parameters such as soil pH, nitrogen, and metal oxides are confirmed to be altered by the biochar amendment for the regulation of methanotrophs. Conclusion Soil methane oxidation is thereby regulated by biochar amendment. This review improved our understanding of the biochar function in greenhouse gas regulation and provided a scientific basis for better soil management with biochar application.