Quantifying water-deficit and heat stress dynamics for corn and soybean in the Mid-Atlantic region of U.S. across historical and projected climates

ABSTRACT Understanding water deficit and water stress is crucial, as these factors directly influence irrigation needs, crop productivity, and long-term agricultural sustainability in regions prone to drought and uneven precipitation. This study quantifies historical and future water-deficit and heat-stress dynamics for corn and soybean in the Mid-Atlantic region of the U.S. under three emission scenarios (SSP126, SSP245, and SSP585). Water deficits were assessed using a multi-temporal cumulative deficit framework that captures the effects of precipitation timing and short-term soil moisture carryover on crop water availability. Heat stress was evaluated using crop-specific temperature thresholds during sensitive growth stages, with metrics including total heat-stress days, maximum consecutive hot days, and cumulative thermal excess. Results show consistent increases in ET0 and ETc across all scenarios, with the greatest rises under SSP585, particularly in southern and central Maryland. Water deficits intensify over time, and although multi-day precipitation accumulation reduces apparent deficits, even the lowest-emission scenario projects water-deficit values above historical baselines. Heat-stress exposure also increases, with higher-emission scenarios producing more frequent, prolonged, and intense hot periods, especially in the late century. The combined trends in water deficit and heat stress indicate that, without adaptation, climate change will significantly increase irrigation demand and crop stress risk.