Can China reach the win-win goals for food security and pollution control from the perspective of nitrogen flow analysis?

Producing enough food to simultaneously address food shortage and agro-environmental pollution problems attracts attention globally. To quantify the risks of nutrition crisis to food security and the agro-environment under current agricultural policies in China, this study evaluates and predict the spatiotemporal patterns of nitrogen (N) flows during 1949-2050 through material flow analysis (MFA) and spatial analysis methods. The results show that (1) the crop harvest (including grains, fruits and vegetables) in China increased by a factor of 8.12 from 1949 to 2019, accompanied by a large amount of N loss to the environment. Compared to 1949, N runoff increased 1.23 times in 1979 and 3.43 times in 1999 after which time agricultural pollution control policy achieved initial results, and the crop harvest increased steadily. (2) At the national average level, crop production will increase by 58.60% in 2050, which is higher than the food security threshold while N loss to the envi-ronment will be lower than the agro-environmental risk threshold. Under the current agricultural policy, the win-win goals of crop production increase and pollution control can be realized in China. (3) China has obvious temporal and spatial differences in N flows, for which four regions has been divided. Region II, mainly located in Yangtze River Economic Belt, is a high-risk area for N loss. By 2050, environmental pollution can be controlled under the current agricultural policies. However, crop production will only increase by 10% compared with its historical high value, lower than food security threshold. It is necessary to implement more targeted management of high-risk areas by adopting methods such as fallowing or construction of pollution buffer zones while improving N fertilizer use efficiency. For region III, the impact of N loss on the environment has always been at a low level, so there is still great room for increasing future crop production in this region. On average, China will be able to achieve green and sustainable development for agriculture nationally, but there are remaining food security risks in high N loss areas. More targeted N management strategies should be applied to achieve better goals in the future.