Impact of urbanization and planting structure on water footprint of food, cash, and feed crops in China's northern agro-pastoral ecotone

China, especially the northern agro-pastoral ecotone, is facing severe water scarcity, which presents a significant challenge for the agriculture sector, the largest consumer of water. This study selected Yanchi County as a typical area. First, the water footprint method is used to evaluate the water usage of food, cash, and feed crops in the region from 1990 to 2020. Then, the vector error correction model (VECM) is used to analyze the short-term effects and long-term effects of urbanization and planting structure on the water consumption of these three types of crops. The results show: 1) The total agricultural water footprint (WF) in Yanchi County, as well as the WFs of the predominantly grown food and feed crops, show an upward trend. Additionally, the proportion of blue WF is relatively high across all crop types. 2) Reducing the proportion of food crops will increase the WF of cash and feed crops, but it will not necessarily decrease the WF of food crops. 3) An increase in the level of urbanization may reduce the agricultural WF in the short term, but ultimately, it will lead to an increase in the WF. Overall, this study reveals the growing pressure on agricultural water use faced by the agro-pastoral ecotone during the processes of urbanization and planting structure transformation. It highlights the importance of developing rain-fed agriculture, seizing the technological development opportunities brought by urbanization, and reasonably adjusting the cropping structure for the sustainable use of water resources.