Biochar amendment mitigates greenhouse gases emission and global warming potential in dairy manure based silage corn in boreal climate

About 11% of the global anthropogenic greenhouse gases (GHGs) emissions result from agricultural practices. Dairy manure (DM) application to soil is regarded as a best management practice due to C sequestration and improvement of soil physiochemical properties. However, GHGs emissions from the soil following the DM application could offset its advantages. Biochar (BC) is known to affect N transformation and GHGs emissions from soil. There had been considerably less focus on the BC amendment and its effects on GHGs emissions following DM application under field conditions. The objectives of this study were; i) to determine the temporal patterns and cumulative GHGs fluxes following DM and inorganic nitrogen (IN) application and, ii) to investigate BC amendment impact on DMY, GWP, direct N2O emission factor (EFd) and the response of CH4 emissions (RC) in DM based silage corn. To achieve these objectives a two-year field experiment was conducted with these treatments: 1) DM with high N conc. (DM1: 0.37% N); 2) DM with low N conc. (DM2: 0.13% N); 3) IN; 4) DM1+BC; 5) DM2+BC; 6) IN + BC; and 7) Control (N0); and were laid out in randomized complete block design with four replications. BC amendment to DM1, DM2 and IN significantly reduced cumulative CO2 emission by 16, 25.5 and 26.5%, CH4 emission by 184, 200 and 293% and N2O emission by 95, 86 and 93% respectively. It also reduced area-scaled and yield-scaled GWP, EFd, RC and enhanced DMY. Thus, BC application showed great potential to offset the negative effects of DM application i.e GHGs emissions from the silage corn cropping system. Further research is needed to evaluate soil organic carbon and nitrogen dynamics (substrates for GHG emissions) after DM and BC application on various soil types and cropping systems under field conditions.