Biochar effects on methane emissions from soils: A meta-analysis

This study shows that biochar has the potential to mitigate CH4 emissions from soils, particularly from flooded (i.e. paddy) fields (Hedge's d = −0.87) and/or acidic soils (Hedge's d = −1.56) where periods of flooding are part of the management regime. Conversely, addition of biochar to soils that do not have periods of flooding (Hedge's d = 0.65), in particular when neutral or alkaline (Hedge's d = 1.17 and 0.44, respectively), may have the potential to decrease the CH4 sink strength of those soils. Global methane fluxes are net positive as rice cultivation is a much larger source of CH4 than the sink contribution of upland soils. Therefore, this meta-study reveals that biochar use may have the potential to reduce atmospheric CH4 emissions from agricultural flooded soils on a global scale.