Influence of Biochar on Soil Greenhouse Gas Emissions, Soil Chemical Properties, and Growth of Legume and Non-Legume Crops

Biochar is a carbon-rich material used as a soil amendment in sustainable agricultural practices. This study evaluated the effects of rice husk biochar (RHB) on soil properties, plant growth, and greenhouse gas (GHG) emissions, particularly CH4 and N2O, during the cultivation of a legume (black bean) and a non-legume (chili) crop. A pot experiment was conducted with RHB applied at 0% (control), 2%, 4%, and 6%. Vegetative growth, yield, and soil chemical properties were assessed. Soil CH4 and N2O emissions were measured using a Li-COR gas analyzer. RHB significantly enhanced vegetative growth (p < .05), increasing root length, stem diameter, and yield in black bean, as well as leaf area, root length, and stem diameter in chili. Soil chemical properties improved significantly (p < .05), with increases in pH, total nitrogen (N), soil organic carbon (SOC), and the carbon-to-nitrogen (C/N) ratio in soils under both crops. In black bean soil, RHB reduced CH4 fluxes by 462% and 216% at the 4% and 6% application rates, respectively, due to a transition from net CH4 emission to net CH4 uptake. In chili soil, 6% RHB reduced CH4 fluxes and cumulative emissions by 287% and 222%, respectively. Consequently, global warming potential (GWP) declined substantially in black bean soil, while greenhouse gas intensity (GHGI) declined in the soil of both crops. Overall, the dose-dependent RHB application improved crop performance and soil quality and contributed to effective GHG mitigation.