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

Luncheng You; Gerard H Ros; Yongliang Chen; Xuejun Liu; Minggang Xu; Yifei Zhang; Wim de Vries

doi:10.1016/j.scitotenv.2023.166657

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

Sci Total Environ. 2023 Dec 10:903:166657. doi: 10.1016/j.scitotenv.2023.166657. Epub 2023 Sep 1.

Authors

Luncheng You¹, Gerard H Ros², Yongliang Chen³, Xuejun Liu¹, Minggang Xu⁴, Yifei Zhang⁵, Wim de Vries²

Affiliations

¹ State Key Laboratory of Nutrient Use and Management, College of Resources and Environmental Sciences; National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, 100193 Beijing, China.
² Wageningen University and Research, Environmental Systems Analysis Group, P.O. Box 47, 6700AA Wageningen, the Netherlands.
³ State Key Laboratory of Nutrient Use and Management, College of Resources and Environmental Sciences; National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, 100193 Beijing, China. Electronic address: ylchen@cau.edu.cn.
⁴ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
⁵ Integrated Systems Engineering, The Ohio State University, 1971 Neil Avenue, 210 Baker Systems, Columbus, OH 43210, USA.

PMID: 37659538
DOI: 10.1016/j.scitotenv.2023.166657

Abstract

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 N losses and associated agricultural N inputs. We also used this model to calculate the spatial variation in actual NUEs and the required NUE to align actual crop production with N thresholds. We then assessed the feasibility of achieving the necessary NUE changes through optimizing agricultural N management strategies. It was found that actual N input exceeded critical N input in 95 and 83 % of the agricultural area in Quzhou and Qiyang, respectively. To meet actual crop production without exceeding N loss thresholds, the NUE needs to increase with 11 to 15 % whereas the total N input needs to be reduced by 37 %. NUE gaps can be closed by reducing N rates, enhancing organic manure recycling, and using efficiency-enhancing fertilizers, with optimal combinations being dependent on site conditions.

Keywords: Critical nitrogen; Nitrate leaching; Nitrogen runoff; Nitrogen threshold; Nitrogen use efficiency.