Optimizing nitrogen input to control health and environmental risks in Chinese vegetable production

Given the health and environmental risks of excessive nitrogen (N) use, optimizing N input is crucial for sustainable vegetable production in China. We compiled a comprehensive database to examine the relationship between N input, vegetable yield, nitrate content, and reactive N (Nr) loss, and estimated these variables at the county level. The results revealed a linear-plus-plateau relationship between N input and yield, and an exponential relationship between N input and nitrate content. The optimal N input was determined as 245.57 kg N ha −1 season −1 for leafy and 236.45 kg N ha −1 season −1 for fruit vegetable. While current N input substantially exceed these levels, leading to approximately 23 % of 660 counties growing leafy vegetable and 4 % of 860 counties growing fruit vegetable exceeded safe nitrate limits (1268.85 mg kg −1 FW). Optimizing N input could reduce N input and Nr loss by 37 %–45 %, and nitrate content by 29 %–53 %, with a few yield penalty (2 % – 7 %). It could improve the averaged net profit by 905.91 $ ha −1 . Overall, optimizing N input not only mitigates health and environmental risks but also enhances economic returns, providing a sustainable pathway for improving Chinese vegetable production.