关键词: 农田土壤, 活性氮损失, N₂O排放, NO^-3-N淋失, 生物炭, 土壤改良

Abstract: N₂O emission and NO^-3-N leaching from cropland are major pathways of reactive N losses in soils, and important sources of global reactive N pollution, resulting in a serious threat to global climate and water environment security. The producing process of cropland reactive N losses is closely related to soil nitrification and denitrification. There exists significant difference regarding to soil nitrification and denitrification under different cultivation systems. Particularly, in our country, long-term and high input of nitrogen fertilization is widespread in continuous cropping farmland of economic crops (e.g., sugarcane), leading to accelerate large-scale soil acidification, and enhance the soil nitrification significantly, which directly affect the change trend and controlling strategy of agriculture-derived reactive N losses. In recent years, as a kind of multi-functional and char-based soil conditioner, biochar has great potential in application for regulating reactive N transformation processes, improving farmland soil, as well as increasing or maintaining crop yield. In this paper, research progress on the status of agricultural soil reactive N losses was reviewed, followed by its main influencing factors and key microbial processes. Furthermore, the potential pathways of biochar amendment to regulate reactive N transformation and nitrogen recycling utilization in cropland were explored, and then the future research direction was also prospected correspondingly, aiming to provide new ideas for the research on the control of reactive N pollution in farmland, efficient utilization of N fertilizers, as well as the development of high-efficiency, green and sustainable agriculture in China

Key words: cropland soil, reactive N losses, N2O emission, NO-3-N leaching, biochar, soil improvement