WEST LAFAYETTE, Ind. -- Modifying tile drainage systems and crop rotations in farmer's fields are the best methods to prevent nitrates from fertilizer from leaking off farms and into nearby streams, say two Purdue University agronomists.
Ron Turco, director of Purdue's Environmental Sciences and Engineering Institute, and Sylvie Brouder, assistant professor of agronomy, say that these alternatives are better than a "one-size-fits-all" approach of limiting nitrogen fertilizer use. Simply limiting fertilizer use probably won't solve the problem and will unfairly penalize some farmers, the agronomists say.
Excess nitrogen moving down the Mississippi River is thought to create a hypoxic zone, also known as a "dead zone," in the Gulf of Mexico. Some experts suspect that a large portion -- but not all -- of the nitrogen that ends up in the Mississippi River comes from fertilizer applications by farmers in the Corn Belt.
"I'm sure that you could travel through the Midwest and find some farmers who are applying more fertilizer than they need," Brouder says. "But that's not everybody. Most farmers are trying to use what they need."
A first step to reduce the amount of nitrate runoff would be to improve tile drainage-water management on farms, Turco says. "I maintain that a good chunk of water that is discharged into the Mississippi River and the Gulf of Mexico starts as tile water from agricultural drainage systems," he says. "I'm more convinced of this every day."
The Gulf of Mexico hypoxic zone is an area that has too little oxygen in the water to sustain fish and other marine creatures. The size of the hypoxic zone fluctuates from year to year, but the cigar-shaped zone can be as large as the state of New Jersey (7,000 square miles), stretching from the mouth of the Mississippi River to the Texas coastline.