Spatiotemporal Dynamics and Influencing Factors of Food Nitrogen Footprint in Urban and Rural China

Food nitrogen footprint (FNF) reflects nitrogen (N) losses associated with food consumption and production, and is an important indicator for evaluating food-system-related environmental pressure. Understanding the spatiotemporal dynamics and driving factors of FNF is essential for improving N management in rapidly developing regions. This study calculated food nitrogen footprint in urban areas (FNFu) and rural areas (FNFr) across 31 provincial-level administrative units in China from 2015 to 2023 using an FNF accounting framework based on provincial virtual nitrogen factor values. On this basis, the spatiotemporal dynamics of FNFu and FNFr were analyzed, and the spatial Durbin model was employed to identify their influencing factors. The relationship between FNF and the Human Development Index (HDI) was further examined in a global context, and energy nitrogen footprint (ENF) was estimated from 2015 to 2022 to compare the relative contributions of food- and energy-related N losses to China’s nitrogen footprint (NF). The results showed that FNFu increased from 15.77 to 19.33 kg N/(cap·yr), while FNFr increased from 13.94 to 19.69 kg N/(cap·yr). FNFr gradually approached FNFu and surpassed it since 2022, indicating that rural food systems have become an increasingly important source of food-related N losses. Spatially, FNFu showed increasing localized concentration of high values, whereas high FNFr became more concentrated in southeastern and southern coastal provinces. Socioeconomic and production-related factors showed differentiated effects on FNFu and FNFr. The Engel coefficient (EC) had significant positive direct effects on both FNFu and FNFr (P < 0.001), whereas its indirect effect was significantly negative for FNFu (P < 0.001) but significantly positive for FNFr (P < 0.01). The proportion of animal-based food consumption (PAFC) was the dominant driver of FNFu, with significant positive direct, indirect, and total effects (P < 0.001). Average household size (AHS) had a significant negative indirect effect on FNFu (P < 0.001) and a significant positive indirect effect on FNFr (P < 0.01). The FNF-HDI fitting results showed an inverted U-shaped relationship, and China’s FNF remained on the rising stage of the fitted FNF-HDI curve. The FNF-ENF comparison indicated that FNF remained the dominant component of China’s NF, while ENF showed a general decline after 2018. These findings suggest that future N management in China should prioritize food-system interventions, especially rural dietary transition, agricultural N input control, and waste treatment improvement, while continuing energy-related N mitigation.