UMD Research Shows Increase in Water Demands by End of Century Will Require Changes to Irrigation Systems and Strategies
As climate continues to change, shifting rainfall patterns, more heat, and evaporation will mean soybeans require more irrigation to meet yields.
Image Credit: Edwin Remsberg
A new study from the University of Maryland found that even moderate climate change will severely stress underground water supplies on the Eastern Shore during the summer months, and by 2100, soybean crops will need 3 to 4 times more water in July and August than rainfall will provide.
“Maryland's Eastern Shore is heading toward essential irrigation, not just supplemental irrigation anymore. By mid-century, Maryland's Eastern Shore soybean fields will need 37-38 inches of irrigation per season just to meet crop demand,” said Hemendra Kumar, precision agriculture specialist and Extension agent at UMD, and co-author of the paper which was published May 31, 2026, in the journal Agricultural Water Management.
Using climate models and crop water calculations, Kumar and his colleagues estimated how much supplemental irrigation soybeans may require in Maryland under several future greenhouse gas emission scenarios.
The researchers found that soybean irrigation needs are already high in Maryland during the growing season, especially in the hotter summer months, and especially on the Eastern Shore where the flat terrain, sandy soil and other conditions lead to shallow roots and low moisture-holding characteristics.
One of their most important findings was that overall irrigation demand may not rise dramatically by the end of the century, but water stress during the peak summer months of July and August will become much more severe. In addition to a tripling, or quadrupling of water needs for soybean crops during those months, the overall number of “deficit days,” meaning days when crops do not receive enough water from rainfall alone could increase by 10–20%.
The researchers also found that lack of rainfall will not be the primary driver of this projected water stress, but rather it will come from rising evaporation, in which the atmosphere “pulls” more moisture from soil and plants because of hotter and drier conditions. This factor explained most of the increase in crop water demand.
Such a concentrated need for more water during the growing season will increase pressure on groundwater supplies and irrigation systems. Kumar and his team suggest that to adapt to these future conditions local managers must change water permits, build bigger irrigation systems for summer peaks, and schedule watering based on daily evaporation rates.
“Our Farmers must plan carefully for these peak demands,” Kumar said, “and the state must help them manage water through permitting reform, infrastructure support, and science-based scheduling, so Maryland can sustain yields, protect its Coastal Plain Aquifer, and secure its food supply.”
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Kumar’s research is conducted at UMD’s Central Maryland Research and Education Center, Upper Marlboro, Maryland. Kumar’s co-author on this research is Iolanda Borzì, a visiting scientist at the UMD Digital and Precision Agriculture Lab from University of Messina, Italy.
