Under the most optimistic sustainable groundwater use scenario, U.S. irrigated production of corn, soybean, and winter wheat is reduced by 20 percent, 6 percent, and 25 percent, respectively. Under the most pessimistic scenario, corn, soybean, and winter wheat production is reduced by 45 percent, 37 percent, and 36 percent.
“Our findings underscore how corn, soybean, and winter wheat production could be affected if we chose to stop depleting aquifers across the United States,” says co-lead author Jonathan Winter, an associate professor of geography and principal investigator of the Applied Hydroclimatology Group at Dartmouth. “However, future precipitation, which affects groundwater resources, is difficult to predict, and improved irrigation technology, more water-efficient crops, and better agricultural water management could reduce the production losses from a transition to sustainable groundwater use.”
The findings show that Nebraska, Kansas, and Texas, which rely on groundwater from the High Plains Aquifer (also known as the Ogallala Aquifer) to grow these crops, would experience some of the greatest production losses as a result of sustainable groundwater use. This region is particularly vulnerable due to its lack of rainfall, which limits rainfed agriculture and groundwater recharge. Prior research found that the High Plains extracts three times as much groundwater as its aquifer’s recharge rate.
Central California, which relies on the Central Valley Aquifer, would also have large production losses in corn and winter wheat from sustainable groundwater use, but production losses of corn and winter wheat in California are limited due to the dominance of specialty crops, such as almonds, grapes, and lettuce, which limit the amount of land used to grow corn or winter wheat.
In contrast, the Mississippi Valley, a significant corn and soybean region, would experience relatively few production losses, as groundwater extraction is typically less than recharge over the region. The Midwest would also experience minimal corn and soybean production losses because the region is humid and relies mainly on rain-fed rather than irrigated agriculture.
“Sustainable groundwater use is critical to maintaining irrigated agricultural production, especially in a global food system that is already taxed by climate change, population growth, and shifting dietary demands,” says co-lead author Jose R. Lopez, a former postdoctoral researcher in geography at Dartmouth. “We need to expand the implementation of water conservation strategies and technologies we have and develop more tools that can stabilize the nation's groundwater supply while preserving crop yields and farmer livelihoods.”
