Monitoring, characterization, and mitigation of nitrous oxide emissions from Chinese orchards

Abstract

Chinese orchards have emerged as emission hotspots of nitrous oxide (N₂O) due to their high nitrogen (N) inputs. However, unique fertilizer application methods may lead to inaccuracies in monitoring and calculating N₂O emissions, potentially resulting in overestimations or underestimations. The emission variation among different orchards and the dominant influencing factors also need further clarification. This study summarizes the methods used to monitor and estimate soil N₂O emissions from orchards in China. It underscores the critical importance of appropriately arranging sampling boxes by considering fertilized and unfertilized areas and the range of irrigation radiation. Accurately scaling up chamber measurements to the landscape level requires precise calculations of these areas. Corrections must account for the spatial distribution of water, N, and N₂O emissions in irrigated orchards. Random forest and structural equation modeling results indicate that N input is the primary factor influencing N₂O emissions, while climate, soil characteristics, and other field management also play significant roles. Significant variations in emissions among different orchard types were observed, primarily attributed to differences in N input and fertilization methods. Average N₂O emissions from peach and grape orchards (7.21 vs. 8.98 kg N ha⁻¹) are significantly greater than those from other orchards (3.02–4.87 kg N ha⁻¹). Furthermore, N fertilization exacerbated the disparity in N₂O emissions between evergreen and deciduous orchards (4.02 vs. 6.06 kg N ha⁻¹). Three climate-smart strategies have been identified to mitigate the hotspot issue of N₂O emissions from Chinese orchards and promote sustainable orchard development. In conclusion, with policy guidance and improved field management, China is well-positioned to lead in climate-smart orchard management practices and contribute to global climate change mitigation. Further research and innovation in orchard systems management will be crucial in achieving carbon neutrality and ensuring the long-term sustainability of orchard systems.