Biochar carbon-based amendment rather than straw contributes to the mitigation of greenhouse gas emissions while increasing crop yield: Insights from a field experiment and density functional theory calculation

Soil greenhouse gas (GHG) emissions from anthropogenic activities, particularly agriculture, pose a considerable challenge to ecological security. Recently, applying biochar and straw has been recognized as a potential measure to enhance soil carbon sequestration and combat climate change. However, the mechanisms underlying the differences in surface properties of biochar and straw on soil GHG emissions remain unclear. Therefore, this study evaluated the soil GHG emissions reduction potential of biochar- and straw-amended fields based on long-term experimental plots. Additionally, we employed density functional theory calculations to investigate how the distinct surface properties of biochar and straw influence soil GHG emissions at the molecular level. The findings indicated that biochar-amended fields increased CH 4 uptake by 320.7% and reduced N 2 O emissions by 63.1% compared to conventional fertilized (CK) fields, resulting in a net reduction of 538.4 kg ha –1 in CO 2 equivalent (CO 2 eq) emissions, with an increase in crop yield by 10.9%. The straw-amended field increased CO 2 emissions by 31.4%, resulting in a net increase of 1261.2 kg CO 2 eq ha –1 compared to CK. The enhanced resistance to biochemical decomposition and stronger adsorption interactions, facilitated by the aromatized stabilized structure and functional biochar groups, are key factors enabling biochar-amended soils to exhibit lower GHG emissions intensities than straw. These findings could represent a breakthrough in understanding how biochar balances soil carbon sequestration with GHG emissions while aiding in optimizing crop residue management practices to sustain soil health and promote sustainable agricultural and ecological development. • Biochar reduces GHG emissions mainly through CH 4 uptake and N 2 O emission reductions. • Aromatization of biochar enhances its stability, reducing soil carbonaceous GHG emissions. • The differential impacts of biochar and straw on soil GHG emissions were calculated using DFT.