The Role of Crop Straw and Biochar Amendments in Mitigating Greenhouse Gas Emissions from Clay Loam Soils: Insights from a Two-Year Study

Agricultural activities are significant contributors to greenhouse gas (GHG) emissions, posing substantial risks for global warming. Amendments such as crop straw and biochar have emerged as potential practices for sustainable agriculture. However, their specific effects on GHG emissions and global warming potential (GWP) remain underexplored. This study conducted a two-year field-scale experiment to evaluate the emissions of carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄) in agricultural soils under a wheat-maize cropping system. Four treatments were implemented: control (CK, no amendment); synthetic nitrogen fertilizer (NPK); crop straw plus synthetic nitrogen fertilizer (CSNPK); and crop straw biochar plus synthetic nitrogen fertilizer (BCSNPK). GHG fluxes were measured using the static chamber gas chromatography method. Results showed that average annual cumulative CO₂ emissions ranged from 1180 to 2520 kg C ha⁻¹, N₂O emissions from 0.44 to 1.80 kg N ha⁻¹, and CH₄ fluxes from -2.60 to -2.93 kg C ha⁻¹. The average annual GWP of CH₄ and N₂O emissions ranged from 0.08 to 0.64 Mg CO₂ eq ha⁻¹ across treatments. While biochar amendments enhanced CH₄ absorption and improved crop productivity, they also led to increased CO₂ and N₂O emissions compared to crop straw. These findings highlight the dual role of biochar in mitigating GHG emissions and improving soil health, while emphasizing the need for further research on optimizing trade-offs. The study offers valuable insights for sustainable soil management practices aimed at reducing GHG emissions and supporting climate change mitigation.