WASHINGTON - Last fall, the farm fields of the Midwest yielded record profits and the greatest corn crop in recent history. But there may have been an unintended consequence hundreds of miles to the south: As the corn grew, so did the size of the "dead zone" in the Gulf of Mexico.
The dead zone is a low-oxygen area virtually uninhabitable by marine life. It emerges in the spring and summer, created in large part by high nitrogen levels and other nutrients such as phosphorus. Its size varies: Last year it was about as big as Massachusetts.
Recent studies suggest that a prime driver for the dead zone -- or hypoxia -- is farm-field runoff from the Mississippi River basin, although cities also play a role, contributing municipal, industrial and lawn and garden runoff.
Now, with the growing season underway, Congress late last month passed a major five-year farm bill over President Bush's veto. It includes an increase in funds for conservation, which could keep some additional land out of production and rein in some runoff. Market conditions, however, appear to favor production.
Fueled in part by the growing ethanol industry, more corn was planted in the United States last year -- 94 million acres, including 8.4 million in Minnesota -- than in any year since 1944. While projections indicate those totals will be down this year, they will still be substantial. More soybeans and wheat also will be planted, although they require fewer nutrients.
"The ethanol boom is accelerating an already ongoing nitrogen problem from corn production," said Michelle Perez, senior analyst with the Environmental Working Group, an environmental and public health organization based in Washington.
Eugene Turner, a professor of coastal ecology and oceanography at Louisiana State University, says his research has shown that soil in the Mississippi Delta area accumulates carbon from year to year, which decreases oxygen in the Gulf and ultimately translates into a larger hypoxic zone.
Although Turner has said that he can't yet scientifically prove that the ethanol boom is causing the growing hypoxic zone, his research points in that direction. The zone's increase in size in recent years corresponds with the increase in corn planting and ethanol production, he said.