Coupling irrigation technology upgrades with targeted expansion enables water-efficient and climate-resilient cereal production in China.

Irrigation expansion and water-saving technologies are essential for future water and food security, yet approaches that jointly improve resource conservation, yield stability and investment efficiency remain elusive. Here we integrate 42,190 county-level agricultural records, a nationally representative farmer survey comprising 3,576 observations and 2,230 controlled field experiments on maize, wheat and rice. We show that China's shift towards more efficient irrigation reduced water use by 6.6-13.4% since 2010, but the continuation of historical trends is insufficient to meet national targets or protect yields under future climate change. We identify an optimized investment pathway that combines upgrades in existing irrigated areas with targeted expansion. This crop- and region-specific approach could raise yields by 0.1-10.9% while reducing water use by at least 25.5%, with rice offering the greatest savings potential. This framework provides actionable guidance for strategic irrigation investment in China to support sustainable agricultural intensification.