Spatiotemporal evolution of crop grey water footprint and associated water pollution levels in arid regions of western China

• Published in: Agricultural water management 2023-04, Vol.280, p.108224, Article 108224
• Main Authors: Zhao, Danyue, Liu, Wenxin, Gao, Rong, Zhang, Ping, Li, Meng, Wu, Pute, Zhuo, La
• Format: Article
• Language: English
• Subjects: Chinese prefectures; Crop production; Leaching-runoff rate; Nitrogen fertiliser; Phosphors fertiliser
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2023.108224

The widespread use of agricultural fertilisers threatens freshwater ecosystems hugely. Grey water footprint (GWF) assessment can be used to evaluate the freshwater pollution level. However, the national fertiliser leaching-runoff rates have been assumed constant while analysing GWF, and this omission could compromise their spatial variations at intra-national levels. This study quantified the GWFs for 12 crops and their related water pollution levels (WPLs) by taking into account the spatial variability of fertiliser leaching-runoff rates in 51 prefectures across five provinces in West China from 2001 to 2017. Considering the main crops and all the provinces, results showed that GWF of unit mass of crops (in m3 t−1) decreased due to increasing crop yields. The total annual GWF (in m3 y−1) increased by 45% during 2001–2017. Although a reduction in the crop fertilisation rates was observed, on average, the expansion of the intensively cultivated areas outperformed the former, thus, worsening the general pollution level. Although declining, the resulting WPLs were always greater than 1 during the study period, pointing out persistent conditions of water pollution. It can be concluded that adjusting crop allocation to land in water-shortened areas was more effective in reducing GWF than simply lowering the fertilisation amount. •Large-scale crop grey water footprints are evaluated in prefecture levels.•Spatial differences in fertiliser leaching rate are non-negligible.•Limited relief of water pollution levels by less fertiliser at unit cropland.•Planting structure adjustment is more efficient for water quality in arid region.