Effects of Biochar and Manure Applications on Soil Carbon Dioxide, Methane, and Nitrous Oxide Fluxes from Two Different Soils

Although past research suggested that biochar has the potential to mitigate the emission of greenhouse gases (GHGs), studies investigating how biochar affects GHG emissions from different soil types under field conditions are limited. Furthermore, limited knowledge exists on how interactions between biochar and manure affect GHG emissions from different soils. This field study, conducted in Brookings, SD, in 2013, 2014, and 2015, measured the soil surface GHG emissions (CO2, CH4, and N2O) from sandy loam (SLsoil) and clay loam (CLsoil) soils. Six treatments-three biochar materials (produced from corn [Zea mays L.] stover, pinewood [Pinus ponderosa Lawson and C. Lawson], and switchgrass [Panicum virgatum L.]), manure, a mixture of manure and biochar, and the control (no amendment)-were applied to both soils at 10 Mg ha(-1). The GHG fluxes were measured over the 2013, 2014, and 2015 growing seasons using static chamber. Biochars reduced cumulative CO2 flux compared with the control in the SLsoil in 2014 and 2015. For the CLsoil, biochars increased the cumulative CO2 flux in 2013, but emitted similar cumulative CO2 flux as the control in 2014 and 2015. Biochars reduced cumulative N2O fluxes compared with the control in all years from the SLsoil only. Combining biochar with manure decreased cumulative CO2 and N2O fluxes compared with manure alone in the SLsoil only. Biochar and manure did not affect cumulative CH4 flux in either soils. Overall, the use of biochar can mitigate CO2 and N2O emissions from the sandy loam soil, but not from the clay loam soil. However, higher rates of biochar (>10 Mg ha(-1)) application and long-term monitoring are required to evaluate the effect of biochar on soil surface GHG emissions.