Environmental Impacts of Increasing Corn Production

Environmental Impacts of Increasing Corn Production

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You don’t have to be a farmer, or even pay attention to the news, to notice there’s something different about the agricultural landscape of central Illinois this year. Where in past years you might have seen alternating fields of corn and soybeans, this year you often see corn, corn, and more corn.

This observation is reflected in the Crop Acreage Report released at the end of June by the U.S. Department of Agriculture. Nationwide, corn is being grown on 93 million acres this year, a 19 percent increase over last year and the greatest total number of acres in corn since 1944. In Illinois, the increase in corn acreage from 2006 to 2007 was a bit less dramatic but still substantial at about 11 percent.

Farmers are growing more corn because strong demand—driven largely by the rush to produce ethanol for fuel—has pushed corn prices far above the long-term average. While the boom in corn provides economic benefits to agriculture, it also entails a number of environmental costs.

One potential long-term impact of the current corn boom is pressure to move land out of the federal Conservation Reserve Program, or CRP. Under CRP contracts, farmers receive cost-share assistance with conservation projects and annual rental payments on environmentally sensitive land for a specified period of time. In the best cases, CRP parcels help to mitigate the environmental impact of farming on rivers and streams by controlling soil erosion and reducing nutrient runoff. Taking such land out of CRP can, by eliminating the filtering action of streamside buffer strips, have a negative environmental impact far beyond the small additional crop income.

Conservation Reserve Program contracts contain penalties for withdrawing land early, since the up-front public investment in CRP land is designed to provide environmental benefits over time. But already this past spring, the USDA was facing pressure to allow farmers to withdraw from CRP contracts without penalty.

A more immediate potential impact of planting more corn is increased nutrient pollution in waterways, a problem that stretches from the upper Midwest all the way to the oxygen-starved, “dead zone” that forms in the Gulf of Mexico each summer. At some 7,900 square miles, this year’s dead zone is the third largest since monitoring began in 1985. Of course agriculture isn’t alone in the creation of this problem, which is also fed by discharges from industry and sewage treatment plants, as well as fertilizer in runoff from urban and suburban landscaping. But given conventional regimens for fertilizing corn and soybeans, an increase in corn acres would be expected to exacerbate the nutrient problem.

In computer modeling focused on the Embarras River watershed conducted for the St. Louis Post-Dispatch earlier this summer, University of Illinois researchers Wayland Eheart and Thomas Hu sought to estimate how an increased proportion of corn to soybeans would affect nitrogen runoff. Their study projected that going from half corn and half beans to two-thirds corn would lead to a 29 percent increase in nitrogen runoff. The beans, while they actually produce nitrogen, also act as a sponge to soak up excess nitrogen and store it in the soil more stably for later use by corn. Eliminating the beans disrupts the cycle, causing greater nitrogen runoff.

I suppose the upshot of all of this is to call into question whether public policy that favors expanded production of corn can really be said to benefit the environment.