Biochar mitigates greenhouse gas emissions from bulk soil in wheat-corn rotation system by inhibiting biochemical decomposition

Abstract

Excessive greenhouse gas (GHG) emissions contribute to global climate deterioration and disrupt ecosystems. Although biochar and straw can enhance soil C sequestration, their effects on soil GHG emissions and the underlying mechanisms are unclear. Therefore, exploring the differences in physicochemical properties of biochar and straw and their mechanisms affecting soil GHG emissions from different perspectives is crucial for optimizing crop residue utilization strategies to balance soil C sequestration and soil GHG emissions. Herein, soil GHG emissions (CO₂, CH_4, and N₂O emissions) from bulk soils of wheat-corn rotational systems under different treatments of biochar and straw were continuously monitored for 7 years. The differences in properties between biochar and straw and their interactions with soil enzymes were analyzed via molecular simulation computational techniques to investigate the mechanisms by which biochar and straw affect soil GHG emissions. The results indicated that biochar reduced CO₂eq emission by 14028.1 kg ha⁻¹ (equivalent to 31.5 % of emissions from the control) compared to the control in a 7-year wheat-corn rotation system through the reduced interaction with soil active enzymes and the improvement of soil physicochemical properties. The active surface properties facilitated the interactions of straw with soil active enzymes and its biochemical decomposition, thus increasing CO₂eq emissions by 19242.0 kg ha⁻¹ compared the control. These findings enhance the understanding of the mechanisms by which biochar and straw affect soil GHG emissions and may improve the development of sustainable agricultural practices that balance soil C sequestration and GHG emission reductions.