Scarce carbon dioxide (CO2) emission data, soil organic carbon (C-org) and labile C-org pool index for croplands in sub-Saharan Africa (SSA) limits our ability to define regional CO2 flux and mitigation prospects provided by biochar amendment. Hence, we conducted a two-year field scale study quantifying effects of biochar (12 t ha(-1)), biochar (12 t ha(-1)) and N fertilizer (90 kg N ha(-1)), N fertilizer (90 kg N ha(-1)) alone and control (no amendment) on C-org, C-org pools, lability index (LI) and CO2 emissions of a humid tropical alfisol under rainfed rice cultivation. Results clearly demonstrate that biochar amendment combined with N fertilizer significantly increased C-org, particulate organic carbon, and particulate organic carbon to organic carbon proportion. Furthermore, this combination decreased dissolved organic carbon, dissolved organic carbon to organic carbon proportion, easily oxidizable carbon, easily oxidizable carbon to organic carbon proportion, microbial biomass carbon, microbial biomass carbon to organic carbon proportion, LI, and CO2 emission when compared to other treatments. Our findings established relationship between labile C-org pools and CO2 emission. Overall, our study suggest that application of biochar and N fertilizer addition can decrease CO(2 )emission from SSA croplands under rainfed rice cultivation, increase essential labile C-org pools, protect labile C-org pools sensitive to losses and sequester C-org with positive implication for global change mitigation and soil quality improvement. (C) 2020 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press. Production and Hosting by Elsevier B.V.