Spatial variation in actual and required nitrogen use efficiency and the potential to close the gap by management practices

Summary

To boost crop production, China uses almost a third of the world's nitrogen (N) fertilizer. However, N losses due to enhanced application of N fertilizers has led to surface water and groundwater pollution. A reduction in N losses without reducing crop yields is possible by increasing nitrogen use efficiency (NUE), which is important for the effective management of local crop production and water quality. This study used two representative agricultural counties in China (Quzhou and Qiyang) to assess if it is possible to achieve N loss thresholds in surface and groundwater by optimizing N management measures while maintaining actual crop production. We used a spatially explicit N balance model to assess the spatial variation in actual N inputs to soil and N losses to water, and in critical