“Farmers are not to blame,” says U of I researcher Mark David. “They are using the same amount of N as they were 30 years ago and getting much higher corn yields, but we have created a very leaky agricultural system. This allows nitrate to move quickly from fields into ditches and on to the Gulf of Mexico. We need policies that reward farmers to help correct the problem.”

David is a biogeochemist who has been studying the issue since 1993.  “We’ve had data from smaller watersheds for some time, but this new study includes data from the entire Mississippi Basin. It shows clearly where across the entire basin the sources of nitrate are,” he says.
 
“A lot of people just want to blame fertilizer, but it’s not that simple,” David says. “It’s fertilizer on intensive corn and soybean agricultural rotations in heavily tile-drained areas. There is also an additional source of N from sewage effluent from people, although that is a small contribution. It’s all of these factors together.”