High corn demand could harm U.S. waters
Scientists predict the biggest dead zone ever in the Gulf of Mexico and more problems for the Chesapeake Bay.
Record corn prices have scientists and federal officials worried about the impacts of a booming corn crop on already-stressed coastal waters. Both the Gulf of Mexico and the Chesapeake Bay are predicted to feel the impacts of fertilizer runoff from corn fields.
This year's dead zone in the Gulf of Mexico could be the biggest ever (PDF size: 110 KB), according to scientists from the U.S. National Oceanic and Atmospheric Administration and Louisiana State University (LSU). The region of low-oxygen water near the mouth of the Mississippi River is predicted to cover as much as 8500 square miles, an area about the size of New Jersey.
The forecast is based on particularly high nitrate loads delivered by the Mississippi and Atchafalaya rivers in May. These levels are an important predictor of the size of the summer dead zone, according to Eugene Turner of LSU. Nutrients from fertilizers flow into coastal waters and stimulate the growth of algae, which later consume oxygen as they decay.
Corn is a particularly fertilizer-intensive crop, and the recent expansion of corn production (up more than 15% this year to 93 million acres) to supply ethanol could be an important reason why nitrogen loads are so high, scientists say. "The relatively high nitrate loading may be due to more intensive farming of more land, including crops used for biofuels, unique weather patterns, or changing farming practices," Turner says. River flow, another important factor, cannot explain the high nitrate levels, he adds.
The Chesapeake Bay Foundation, a nonprofit advocacy group, predicts that the bay will also be threatened by increased corn production. Farmers in the bay's six-state watershed are expected to plant at least half a million more acres of corn in the next few years, according to the foundation's report (PDF size: 308 KB), which summarizes findings presented at the U.S. Department of Agriculture's Biofuels and Water Quality Conference. This could add millions of tons of fertilizer to the bay, authors say.
