With climate change, irrigating more crops in the United States will be critical to sustaining future yields, as drought conditions are likely to increase due to warmer temperatures and shifting precipitation patterns. Yet less than 20% of croplands are equipped for irrigation.
To conduct the cost-benefit analysis of irrigating corn and soybeans, the researchers ran a series of crop model simulations. They applied several global climate projections that span the range of potential future climates -- hot and dry, hot and wet, cool and dry, cool and wet, each relative to the average climate projection -- to simulate future crop growth under fully irrigated or rainfed conditions.
The results show that by mid-century there will likely be enough water to irrigate soybeans in Iowa, Wisconsin, Ohio, and northern Illinois and Indiana, but not corn. Iowa is the largest producer of corn in the U.S. Groundwater resources for irrigation were found to be the most abundant in the southeast U.S., especially in the lower Mississippi Valley where agriculture is less intensive. However, in this region the benefits of irrigation are minimal.
"The increasing benefits of irrigation, could incentivize farmers to use more water, which will place additional stress on key aquifers, including the Ogallala," says senior author Jonathan Winter, an associate professor of geography and lead of the Applied Hydroclimatology Group at Dartmouth. Prior research has shown that water is being extracted from the Ogallala Aquifer faster than it can be replenished.