Long-term global water pollution stress from crops production considering different driving forces

Abstract

Increasingly intensive crop farming has been aggravating global water pollution. It is significant to retrospectively investigate world's crop production induced water pollution stress, facilitating sustainable agriculture in the future. In this study, nearly 60-yr grey water footprint (GWF) dynamics of global crop farming are examined at multi-scales covering 146 crops in 162 countries, based on a framework coupling GWF assessment with an advanced dynamic decomposition analysis (DDA). Results show that global crop GWF has increased by 1224.1 % in 1961–2018, presenting three stages of GWF growth: an accelerated period of 1961–1980 (P1), a linear period of 1980–1999 (P2), and a decelerated period of 1999–2018 (P3). The spatial and crop-wise patterns of GWF vary for the stages. Crop GWF generally shifts from developed (North America and Europe) to developing (Asia and South America) regions during P1-P2, with crop-wise GWF showing increased proportions in cash crops (Fruits, Vegetables, Oil crops, etc.) for P2-P3 and decreased in food crops (mainly Cereals). China, America, and India exhibit top three national crop GWF amounts and increases (in total 60.3 % of world's GWF growth). Overall, production efficiency and population scale are determinants of growing global crop GWF, with different drivers recognized for the stages. Fertilization level principally drives up world's crop GWF for P1 (50.7 %) while offsets GWF growth in P3 (−8.61 %). Proportion of rural population becomes the main contributor offsetting crop GWF growth especially in P3. Driving pattern of crop GWF evolution varies among continents, countries, and crop categories, as well. Based on these, we recommend optimizing regional/national crop activities expecting to enhance sustainability of global agriculture.