The value of water in agriculture over the past 30 years on the north slope of the Tianshan Mountains

• The water value of agriculture on NSTM has increased over the last 30 years. • The water value of irrigation is sensitive to irrigation water use efficiency. • Climatic conditions drive the variations in irrigation water value. • Wheat should be geographically reallocated based on its water value. Water is an indispensable resource for agricultural production. However, its value in agriculture remains largely unknown. The oversight results in agriculture water value being seldom integrated into water pricing, restricting the information involved in water allocations. In this study, we estimated irrigation water value over the last 30 years on the north slope of the Tianshan Mountains, where agriculture is largely dependent on irrigation water supply. Using a data-parsimonious biophysical framework with a function of crop growth and water-demanding dynamics, we estimate the additional net economic benefit of irrigated agriculture relative to rainfed conditions for three major crops at the county level. Our results reveal that mean irrigation water values were 0.27, 0.32, and 0.16 USD m –3 for cotton, maize, and wheat, respectively, which were 2.0−3.2 times higher than global estimates. The value of irrigation water significantly increased over time, primarily driven by rising crop prices and improved water use efficiency. Our findings indicate that farmers in arid regions with water limitations may favor crops with high irrigation water use efficiency. Wheat is suggested to be spatially reallocated in light of the economic benefit, given its relatively low output price and water use efficiency. Irrigation water value was more sensitive to precipitation than air temperature by lowering crop prices and narrowing the gap between rain-fed and irrigated yields. The inclusion of irrigation water value in planning could lead to more efficient use of water resources and support decisions regarding irrigation investments, water use rights, and, ultimately, food sustainability.