A new analysis prepared for the National Corn Growers Association concludes that some of the assumptions surrounding hypoxia or low oxygen in the northern Gulf of Mexico – including that the phenomenon is permanent and the main cause is nitrogen applied to corn – are not supported by the facts.
“Complex natural phenomena, such as seasonal hypoxia in the Gulf, are seldom the result of a single cause,” according to Dr. James McLaren, who researched the issue for NCGA. “Extensive analysis of the data across several factors indicates that there is no evidence relating modern corn nitrogen use with the occurrence of hypoxia in the Gulf.” McLaren noted that U.S. corn farmers have applied new genetics and cultural technologies in such a way that there is now a net balance between nitrogen fertilizer input and nitrogen removed in the grain.
“If there is any nitrogen fertilizer from corn going down the Mississippi, then it is most likely to be in a barge in the form of grain exports that contribute to the economy of the Midwest and the Gulf ports,” he added.
McLaren’s analysis shows how the hypoxic zone is seasonal and, while localized effects can be severe, there are not “vast dead zones” that have widespread negative effects on the local fishing industry. On the contrary, it is possible that the Mississippi-Atchafalaya River Basin water flow delivers the basic nutrients required for the very existence of the northern Gulf fishing industry. Fishing data from 1985 onwards suggest no negative impact nor any clear relationships between the fish catch, the flow of water through the Mississippi-Atchafalaya River Basin, or the size of the seasonal hypoxic zone.
“We’ve always known there were a lot of misconceptions about the hypoxic zone and its causes, based often on a lack of data,” said David Ward, chairman of NCGA’s production and stewardship action team, which funded the hypoxia report. “It is our hope that this report will help keep the discussion as grounded and data-driven as possible.”
TFI responded that the NCGA report is a welcome step toward clearing up the controversy by focusing on “a number of key factors with which we would agree … namely that the causes of the hypoxic zone are multiple and complex which explains why the hypoxic zone has grown in some years when fertilizer use has either been level or declined. It may not be as neat of an explanation as farm use of fertilizers feeding the zone, but the fact remains that man-made attempts to control flooding on the Mississippi River as well as weather patterns all play a part in the size of the zone.” TFI spokeswoman Kathy Mathers added, “Further, we are pleased to see some effort to quantify the nitrogen that is removed with each year’s corn crop as much of the nitrogen fertilizer used by farmers is not lost to the environment, but used instead as critical nourishment for the food that feeds the world.”
Coincidentally, a team of National Oceanic and Atmospheric Administration (NOAA) supported scientists forecast that the “dead zone” off the coasts of Louisiana and Texas in the Gulf of Mexico this summer could be one of the largest on record. These scientists from the Louisiana University’s marine consortium, Louisiana State University, and the University of Michigan are predicting the area could measure between 7,450 and 8,456 square miles, or an area roughly the size of New Jersey. However, they noted, additional flooding of the Mississippi River since May may result in a larger dead zone. The largest one on record occurred in 2002, measuring 8,484 square miles. The prediction was made, the researchers reported, after they observed large amounts of nitrogen feeding into the Gulf from the Mississippi and Atchafalaya Rivers. The rivers experienced heavy water flows in April and May that were 11 percent above average. “The high water volume flows coupled with nearly triple the nitrogen concentrations in these rivers over the past 50 years from human activities has led to a dramatic increase in the size of the dead zone,” said Dr. Gene Turner, a lead forecast modeler from Louisiana State.