Nitrogen and phosphorus trajectories (1998-2030) under regional development strategy of mainland China.

A good understanding of the nutrient cycle under a regional development strategy is crucial for nutrient management decision-making. Quantitatively assessment of nutrient flow under the regional coordinated development strategy in mainland China can provide scientific reference for achieving global high-quality coordinated economic and agricultural development. In this study, the characteristics of nitrogen (N) and phosphorus (P) flows of agricultural systems in mainland China from 1998 to 2030 were quantified using nutrient flows in food chain environment and resource (NUFER) model. The results revealed that national N and P surplus intensity were 50.3 and 18.6 kg·hm in 2018, respectively, and there is still space for soil nutrient retention. The national input and output of N and P showed a continuous upward trend over the last two decades. Chemical fertilizer application and livestock rearing are the key points for nutrient management in China's agricultural systems. Under the regional development strategy, considerable geographical variation in N and P surplus intensity was observed across the country. From 1998 to 2013, the regional distribution of N and P surplus intensity was in accordance with regional economic characteristics. Areas with higher N and P surplus intensities were mainly in the eastern and central regions. From 2014 to 2018, equal emphasis on ecology and economy in the Yangtze River Economic Belt allowed development without aggravating the deterioration of the N and P surplus in the region. Over the next 10 years, our simulation predicts that future nutrient footprints tend to decrease, and coordinated governance of regional development and agricultural environment protection are the key to regional sustainable development.