Phosphorus use efficiency has crossed the turning point of the environmental kuznets curve: Opportunities and challenges for crop production in China.

The overuse of phosphate fertilizer causes waste of resources and is detrimental to the sustainability of agriculture and aquatic systems. Effective management of phosphorus (P) in agricultural systems is important. Lack of understanding on the temporal and spatial variations of P utilization in farmland systems would constrain the development of more precise and effective policies as well as management practices. Here, we used two indicators, P use efficiency (PUE) and P surplus (P), to evaluate changes in P utilization in crop production on both national and regional scale in China during 2005-2018. Great heterogeneity of PUE and P were found across different regions, with Northeast of China showing the highest PUE (0.67) and lowest P (11.0 kg/ha). For temporal trends, our study showed that China crossed the turning point of the environmental Kuznets curve in 2007, which indicates that China has reached a new development stage of P use that is resource-saving and environmentally friendly. Along with the processes of industrialization and urbanization in China, the development of agricultural mechanization has further resulted in an increase of PUE and decrease of P. Although great efforts were made, China still has a relative low PUE and high P compared to developed countries. Our results suggest a regionalized perspective for developing policies for the sustainable use of P resources.