Menu

Corn Remains King in USDA Irrigation Survey

By Brooke Barton
Senior Program Director, Water Program, Ceres

It’s no secret that our agricultural industry is very thirsty, gobbling up 80 percent of the freshwater that America consumes each year. It takes a lot of water to feed the nation, and every five years we get an accounting of just how much it takes, for what crops and at what cost, from the U.S. Department of Agriculture’s Farm and Ranch Irrigation Survey. The latest survey, released in November, shows an overall positive trend of irrigation water use declining, even as water use for certain crops, like corn, continues to soar.

Corn used 14 percent more irrigation water in 2013 than in 2008, according to survey results, while water use for all crops combined declined 3.7 percent (and 9 percent since 1998, the highest year on record). Those are remarkable findings considering corn production also used more irrigation water than any other crop.

Figure 1 Total Water Use By Crop 2013
Figure 1 Total Water Use By Crop 2013

American farmers are adopting more efficient irrigation techniques, which helps explain the overall drop in water use, but they are also facing decreased water availability due to a spate of recent droughts in the Midwest, Texas and California. With more extreme droughts expected on a warming planet, it’s only a matter of time before corn’s insatiable thirst bumps up against limited water supplies.

To be fair, there’s a reason why water use for corn production continues to climb. U.S. corn farmers are among the most productive in the world, generating another bin-busting harvest in 2014 of 14.2 billion bushels—enough corn to fill a freight train longer than the circumference of the Earth. This production supports a mammoth agricultural sector comprised not just of farmers, but also major food, feed and energy companies.

Ceres_CornValueChain_020415
Figure 2 Key Industries & Companies in the U.S. Corn Value Chain

Nevertheless, corn guzzles more irrigation water than any other crop—an extraordinary fact considering the vast majority of U.S. corn (79 percent) is rain fed and does not rely on irrigation. Irrigation water applied to corn acres rose from 15.4 million acre-feet in 2008 to 17.9 million acre-feet in 2013, paralleling the dramatic increase in corn production during that same period – from 84.5 million to 93.7 million acres.

A key driver in corn’s growing demand for irrigation water is that the crop is increasingly farmed in arid regions such as Kansas, Colorado, Nebraska, and California. Corn production has been expanding into regions with high water stress and groundwater depletion, in part because of the ethanol mandate for gasoline (in 2013, 35 percent of U.S. corn production was used by the ethanol industry). In fact, 87 percent of irrigated corn is now grown in regions with high or extremely high water stress.

Ceres_Map_Water_IrrigateCornProd
Figure 3 Competition for Water in Areas of Irrigated Corn Production

Moreover, groundwater, which is dwindling rapidly in many agricultural regions, is the major source of irrigation water for corn. The amount of corn acres using groundwater for irrigation grew 11 percent between 2008 and 2013. More than half of that irrigated corn relies on the over-exploited High Plains aquifer that underlies eight states, including Nebraska, Kansas and Texas.

The good news is that corn farmers are becoming more water efficient. In fact, corn was one of the most water-efficient crops in 2013. Corn grain farmers have become 21 percent more water-efficient on a per acre basis between since 1984. That means they’re applying less water per acre to obtain the same level of production.

On a per bushel basis, the efficiency gains were even greater—45 percent between 1984 and 2013. Farmers were able to get more “crop per drop,” due in part to the replacement of flood irrigation with more-efficient center pivot irrigation. Eighty percent of corn grain acres now use center pivot irrigation.

Yet even with these efficiency gains, we have a problem. There is a fundamental mismatch between irrigation demand for corn production and long-term sustainable water supplies in many of the crop’s key growing regions.

As we seek solutions to water shortages from Kansas to California, addressing the water demands of corn will be critical to sustaining our water resources into the future. Some of the hundreds of major companies that rely on corn are waking up to this fact. For instance, Kellogg and Coca-Cola have begun partnering with corn suppliers, agronomic experts and farmers to measure and improve water efficiency at the field level. But many more companies need to do the same, and urgently.

About the Author

Brooke Barton is Director of the water program at Ceres, a nonprofit organization working with Fortune 500 businesses and country’s largest institutional investors on sustainability challenges. She is the author of Water & Climate Risks Facing U.S. Corn Production: How Companies and Investors Can Cultivate Sustainability. For details, visit www.ceres.org/costofcorn or follow Barton on Twitter @brookedbarton