Mineral nitrogen (N) fertilizer use is essential to maintain high-yielding cropping systems that presently provide food for nearly half of humanity. Simultaneously, it causes a range of detrimental impacts such as greenhouse gas emissions, eutrophication, and contamination of drinking water. There is growing recognition of the need to balance crop production with the impacts of fertilizer use. Here we provide a global assessment of the potential to reduce mineral fertilizer use through four interventions: capping surpluses, enhancing manure cycling to cropland, cultivation of off-season green manures, and cycling of human excreted N to cropland. We find that the combined potential of these interventions is a reduction in global N fertilizer use by 21%–52%. The availability of interventions is spatially heterogeneous with most cropland having three to four interventions available with alternative N sources tending to be more abundant on cropland already receiving fertilizer. Our assessment highlights that these locally in part already practiced interventions bear great opportunities to mitigate synthetic N use and dependency globally. Yet, their limited adoption underpins the need for cross-sectoral policies to overcome barriers to their implementation and agronomic research on their robust scaling.

中文翻译：

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探索通过一系列管理干预措施减少氮肥使用的潜力

矿质氮 (N) 肥料的使用对于维持目前为近一半人类提供食物的高产耕作系统至关重要。同时，它还会造成一系列有害影响，例如温室气体排放、富营养化和饮用水污染。人们越来越认识到需要平衡作物生产与化肥使用的影响。在这里，我们对通过四项干预措施减少矿物肥料使用的潜力进行了全球评估：限制剩余量、加强粪便循环到农田、种植反季节绿肥以及将人类排泄的氮循环到农田。我们发现，这些干预措施的综合潜力是使全球氮肥使用量减少 21%–52%。干预措施的可用性在空间上存在异质性，大多数农田都有三到四种可用的干预措施，而替代氮源往往在已经接受肥料的农田上更为丰富。我们的评估强调，这些在当地部分已经实施的干预措施为减轻全球合成氮的使用和依赖提供了巨大的机会。然而，它们的采用有限，需要制定跨部门政策来克服其实施和农艺研究的障碍，以实现其强劲的规模化。