Biochar as a long-term N2O mitigation strategy

Anthropogenic activities have significantly increased atmospheric greenhouse gas (GHG) concentrations, mainly nitrous oxide (N₂O) emissions. Biochar has emerged as a promising strategy for GHG mitigation in agriculture. However, when applied in soils, the long-term environmental interactions may alter its physicochemical properties, a process known as biochar aging. Therefore, to understand biochar’s behavior over time is crucial to assessing its effectiveness in mitigating N₂O emissions. To this end, we conducted a 44-day greenhouse experiment using maize cultivation under a completely randomized design with four treatments: i) soil control (CNTL); ii) soil + nitrogen fertilizer (NF); iii) NF with biochar (NF + BC); iv) NF with aged biochar (NF + BCE). Biochar was produced using sugarcane straw as feedstock. To simulate the biochar aging process, sugarcane straw biochar was subjected to oxidative aging with 5% hydrogen peroxide. The main results revealed 36% lower carbon content in BCE compared to BC and a 18% reduction in carbon bonds. This modifications in the chemical properties of biochar affects its capacity to mitigate N₂O emissions. Then, daily N₂O emissions were significantly lower with NF+BC. Cumulative N₂O emissions were reduced by 48% with NF+BC and by 30% with NF+BCE compared to NF. These results highlight sugarcane straw biochar as an effective strategy for N₂O mitigation, demonstrating its potential to reduce emissions even after aging, thus supporting its long-term role in sustainable agriculture. These findings can also be correlated with Sustainable Development Goals (SDGs) 13 and 15, Climate Action and Life on Land, respectively, in accordance with the importance of studies and strategies for combat climate change.