Agro-residue biochar and N fertilizer addition mitigates CO2-C emission and stabilized soil organic carbon pools in a rain-fed agricultural cropland

Scarce carbon dioxide(CO_(2))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 CO_(2) flux and mitigation prospects provided by biochar amendment.Hence,we conducted a two-year field scale study quanti-fying effects of biochar(12t ha^(-1)),biochar(12t 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 CO_(2) 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 CO_(2) emission when compared to other treatments.Our findings established relationship between labile C_(org) pools and CO_(2) 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.