A Hierarchical Framework for Unpacking the Nitrogen Challenge
A Hierarchical Framework for Unpacking the Nitrogen Challenge
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DOI：
10.1029/2022ef002870
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发表时间：
2019-11
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影响因子：
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通讯作者：
Tingyu Li;Xin Zhang;E. Davidson;Z. Dou;Weifeng Zhang;Fusuo Zhang
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作者：
Tingyu Li;Xin Zhang;E. Davidson;Z. Dou;Weifeng Zhang;Fusuo Zhang
为了在养活世界人口的同时缓解紧迫的氮污染问题，人们已经投入了巨大的努力来开发和实施作物或牲畜生产中的氮高效技术，但取得的进展有限。由于自然系统和人类系统的复杂反应以及利益相关者之间缺乏协调，农场氮素管理的改善并不一定转化为更大范围的氮素污染减少。因此，必须制定一个氮素管理框架，既要涵盖跨系统和空间尺度的复杂氮素动态，又要足够简单，以指导各种利益相关者的政策和行动。在此，我们提出了一个新的框架CAFE，该框架以分层方式定义了四种氮素管理系统（作物、动物作物、食品和生态系统），并将其应用于13个代表性国家，以简单一致的方式将氮素盈余分配到系统之间，从而促进了基于系统的干预策略的识别和优先排序。令人惊讶的是，对大多数国家来说，种植系统对其生态系统内总氮盈余的贡献不到一半，这突出了农田以外氮管理的重要性。该框架揭示了各国加强氮素管理的相关优先事项和关键利益相关者各不相同，例如中国提高种植系统效率，荷兰调整动物-作物组合，美国减少粮食浪费，非洲国家降低作物储存损失并提高整体生产能力。随着氮盈余沿CAFE层级增加，揭示了基于系统的干预策略：(a)通过保持肥料和生物固氮的一半氮来将化学肥料与其他氮源耦合；(b)通过将动物密度降低到每公顷1.2只牲畜以下，并将动物饲料的自给率提高到50%以上，实现动物与作物生产的耦合；(c)将粮食贸易与国内需求和生产结合起来；(d)将人口对经济机会的需求与该地区的环境容量相结合。这个新颖的框架可以帮助解开跨系统的“邪恶”氮管理挑战，为改善农场内外的氮管理提供新的见解和工具。
To feed the world population while mitigating pressing nitrogen (N) pollution problems, tremendous efforts have been devoted to developing and implementing N‐efficient technologies in crop or livestock production, but limited progress has been made. The N management improvement on a farm does not necessarily translate to N pollution reduction on a broader scale due to complex responses of natural and human systems and lack of coordination among stakeholders. Consequently, it is imperative to develop an N management framework that encompasses the complex N dynamics across systems and spatial scales, yet simple enough to guide policies and actions of various stakeholders. Here, we propose a new framework, CAFE, that defines four N management systems (Cropping, Animal‐crop, Food, and Ecosystem) in a hierarchical manner, and apply it to 13 representative countries to partition N surpluses across systems in a simple and consistent manner, thereby facilitating the identification and prioritization of systems‐based intervention strategies. Surprisingly, the Cropping system contributes less than half of the total N surplus within its Ecosystem for most countries, highlighting the importance of N management beyond croplands. This framework reveals that the relevant priorities and key stakeholders for enhanced N management vary among countries, such as improving the Cropping‐system efficiencies in China, adjusting the animal‐crop portfolio in the Netherlands, reducing food wastage in the U.S., and lowering crop storage losses and increasing overall production capacities in African countries. As N surplus increases along the CAFE hierarchy, systems‐based intervention strategies are revealed: (a) coupling chemical fertilizers with other N sources by maintaining half of the N from manure and biological N fixation; (b) coupling animal‐crop production by reducing animal density to lower than 1.2 livestock units per hectare, and increasing self‐sufficiency of animal feed to above 50%; (c) coupling food trade with domestic demand and production; and (d) coupling population needs for economic opportunities with environmental capacity of the region. This novel framework can help unpack the “wicked” N management challenges across systems to provide new insights and tools for improving N management on and beyond farms.