Published in The Des Moine Register  June 11, 2014

U.S. corn production is at risk from climate change, unsustainable water use, and “inefficient and damaging fertilizer practices,” according to a report today that assesses the crop’s environmental impact.

As a result, corn growers in Iowa and elsewhere will be under pressure from retailers, food processing and feed companies to find ways to grow the $67 billion crop more sustainably, said Ceres, a nonprofit network of investors, companies and public interest groups supporting more sustainable business practices.

The group said corn is key to dozens of companies across the U.S. economy. For example, 45 companies with $1.7 trillion in revenue rely on corn production – from Deere & Co. and DuPont Pioneer to Cargill, PepsiCo, General Mills, Tyson, Walmart and McDonalds.

Ceres is asking that more U.S. companies develop sustainability goals and provide incentives to farmers and others to meet them.

But Bruce Babcock, an Iowa State University economics professor, said it’s extremely difficult for corporations to determine if the corn they’re using is grown with the sustainable practices they want.

Here’s why: After leaving a farmer’s field, harvested corn becomes mingled with corn grown around it, the state and nation. “Corn is produced by tens of thousands of individual farmers who sell into a system that blends and co-mingles it and sells it to the highest bidder,” he said.

Among the environmental concerns outlined in the report:

— Unsustainable water usage through irrigation: 87 percent of irrigated corn is grown in regions with high or extremely high water stress, meaning that a large portion of existing water supplies are already spoken for. The most vulnerable regions are Nebraska, Kansas, California, Colorado and Texas, the report says.

“Over half of the country’s irrigated corn production — worth nearly $9 billion annually — depends on groundwater from the over-exploited High Plains aquifer,” the report says.

Nearly all Iowa corn is “rain fed,” meaning there’s little reliance on irrigation to grow the crop.

— High nitrogen use: Corn production used 9.5 million tons of the nutrients — nitrogen, phosphorus and potash — in 2010, the report said.

But “only 34 percent of U.S. corn acres are farmed using best practices for nitrogen fertilizer management, such as not over-applying fertilizer and applying fertilizer at the right time in the growing season,” the report said, citing the U.S. Department of Agriculture.

It estimates that “$420 million in inefficiently applied fertilizer washed off corn acres into the Mississippi River and eventually the Gulf of Mexico.”

But Babcock said U.S. producers are making more efficient use of nitrogen, using the same amount or less to grow more bushels of corn.

And Iowa farmers are beginning to embrace recommendations in the report such as extended crop rotations, cover-cropping, and the development of buffer strips as part of the state’s plan to reduce nutrients entering waterways and contributing to the hypoxia zone in the gulf.