Food-driven transformation of nitrogen fluxes with urbanization in China

Urbanization shifts populations from rural to urban areas, altering food consumption and production patterns, which impacts nitrogen cycles. However, the contributions of urbanization to nitrogen flux dynamics remain insufficiently understood. This study analyzes nitrogen flux changes in China from 1990 to 2020 using data from the National Bureau of Statistics and Agricultural Pollution Censuses, alongside CHANS models. Results show that rising food demand has driven a 75 % increase in fertilizer use and a 132 % rise in nitrogen pollution, with urbanization adding 1.4 million tonnes of nitrogen emissions. By 2050, urban food consumption is projected to rise by 48 %, driving a 45 % increase in nitrogen pollution. Applying multiple measures can reduce nitrogen consumption and losses, with rural areas offering greater reduction potential than urban areas, highlighting the need for targeted nitrogen management to address urbanization's environmental impacts effectively.