Closing irrigation-limited maize yield gaps in China under climate change

Abstract

Climate change poses increasingly severe challenges to crop production, yet the status and future trajectory of the irrigation-limited yield gap (IYG) remain poorly understood. This study comprehensively assessed the spatial-temporal patterns and future responses of IYG using a bottom-up framework. We categorized the IYG into closed and unclosed components based on the yield at current limited irrigation levels (Ycir). Our results showed the IYG remains 32% unclosed, accounting for approximately one-tenth (about 26 million tons) of China’s total maize production. Regionally, pronounced disparities in yield sensitivity to irrigation were observed, with the Northwest exhibiting the highest and the Southwest the lowest. Both historical and future simulations revealed a significant declining trend in Ycir and IYG across most northern provinces (e.g., Inner Mongolia, Heilongjiang, Hebei, and Xinjiang). Increasing irrigation levels can offset most of these declines without diminishing marginal benefits. In the Northwest, more than 70% of the projected yield changes are identified as a mitigatable decrease, equivalent to 18% of historical yields. Conversely, the Northeast has nearly reached a climate-limited yield plateau with decreasing marginal benefits. Roughly 20% of the yield change in the North China Plain and Northeast is non-mitigatable. These findings inform region-specific irrigation strategies to sustain maize production in China.