Adaptation strategies for deficit irrigation management under extreme climate conditions

Crop production in arid and semi-arid regions faces increasing threats from severe weather conditions during the growing season. Irrigation, while critical for mitigating the negative impacts of these conditions, requires data-driven scheduling approaches to optimize productivity and curb excessive withdrawal of limited groundwater resources. This study utilizes the Decision Support System for Agrotechnology Transfer (DSSAT) - Crop Environment Resource Synthesis (CERES) Maize model to evaluate maize yield, water savings, and irrigation water productivity under two irrigation scheduling methods: a conventional soil-moisture-based method and a crop evapotranspiration-based (ET c -based) method in Finney County, Southwestern Kansas, United States. Heat and water stress scenarios were induced by increasing the growing season maximum temperatures by 1 °C, 2 °C, and 4 °C, and extending the duration of dry periods by one day during critical growth stages. Twelve ET c -based treatments, comprising of varying ET c requirement thresholds needed to trigger irrigation (15 mm, 20 mm, 25 mm, and 30 mm), and ET c replacement levels (50 %, 75 %, and 100 %), were simulated over 30 years (1991–2020). The ET c -based treatments were compared to a soil moisture-based strategy which automatically applied a fixed irrigation amount whenever the plant available water in the soil dropped to 50 %. Results indicate that applying 75 % of the required ET c at a 30 mm threshold is the most effective strategy. This approach limited yield losses to 10 %, enhanced water savings by 25 %, and irrigation water productivity by 12 % (mean growing season ET c = 736 mm) when compared to the conventional soil-moisture-based method (mean-growing season ET c = 838 mm) under normal and extreme weather conditions. These findings highlight the potential of ET c -based irrigation to conserve water resources, ensuring more sustainable, climate-resilient agriculture. • DSSAT-CERES maize model was used to evaluate soil-moisture and ET-based irrigation scenarios. • Maize yield, water use and productivity were assessed under high temperatures and dry spells. • Prolonged dry spells showed more pronounced maize yield impacts than high temperatures. • ET-based irrigation proved most effective, showing enhanced resilience to severe weather conditions. • 75 % of ET applied when ET threshold reached 30 mm limited yield loss to 10 % and saved 25 % water.