Effective policy measures are required to control environmental problems caused by nitrogen (N) fertilizer use in intensive crop production systems in China. However, simply reducing the use of N fertilizer in all regions may be detrimental to food security. Here we reviewed N management policies and indicators, with a particular focus on European Union (EU), and designed an N index system for cereal crops in China. We suggest to use N surplus as an (environmental) evaluation index and N input as a guide to meet the dual challenge of food security and environmental sustainability, and propose crop and region-specific standards for these indexes. We inferred a mean critical N surplus of 75 kg N ha⁻¹ for maize, 40 kg N ha⁻¹ for wheat and 70 kg N ha⁻¹ for rice. For N input, Maximum N (Max. N) and Minimum N (Min. N) input indices are proposed, to guide farming practices effectively. Max. N was based on the N demand of crops achieving their potential yield, in different regions, Min. N was based on the N demand of crops at their target yield, while associated N surpluses do not exceed the set critical values. To meet the dual challenge of food security and environmental sustainability, China needs to increase maize and wheat yields by 20%–40% (rice has achieved target yield) while reducing N input by 10%–20%. This requires an enormous increase in N use efficiency. The N management indexes proposed here can be used as benchmarks to monitor the progress at regional level. Max. N and Min. N may have to be updated regularly when potential and target yields, and thereby crop N demand, change. Also, critical N surpluses may have to change when insights in the impacts of these N surpluses change.

Agriculture in China, which is dominated by millions of smallholders, consumes 30% of global nitrogen (N) fertilizers and results in a high surplus and vast spatial variability of N. Identifying the N-management practices of smallholder farmers is critical to pursuing sustainable agricultural productivity. However, at the national scale, N budgets and spatial distribution based on first-hand data from smallholder farmers are not well characterized. Here, using data collected from a national survey involving 7.3 million farmers from 2005 to 2014, we quantified N budgets, evaluated their spatial variation, and revealed “hotspots” of low N removal and high N surplus for wheat, maize, and rice systems at the county level. The N surplus for cereal crops was 122–140 kg N ha⁻¹, which is equivalent to an annual N surplus of 11.3 megaton (Mt). Chemical N was the most important contributor to the N surplus, while farmers used manure N less than 10% of the total N input. N budgets exhibited vast spatial variation at the county level, and the hotspots contributed to 56% of the total N surplus in China. Targeted efforts for eliminating hotspots could increase N removal by 13–21%, increase N use efficiency to 0.55–0.70, and significantly reduce the N surplus for all counties and crops, by 42%. Based on farmer survey data, our results provide updated estimates of N budgets and highlight hotspots of N surplus for cereal crop systems in China. They provide a benchmark for the development of new agricultural N management policies and technologies in the country.

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 ( C ropping, A nimal‐crop, F ood, and E cosystem) 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 C ropping system contributes less than half of the total N surplus within its E cosystem 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 C ropping‐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.