A "dead zone" the size of New Jersey is currently occupying the Gulf of Mexico, posing threats to the fishing industry and wildlife in the area. The event, which occurs annually, is the largest in recorded history.
Each year, fertilizer from farms washes its way down the Mississippi River into the Gulf of Mexico, where the increased supply of nitrogen and phosphorus fuels the growth of algae and phytoplankton. The resulting bloom then decomposes and depletes the ocean of oxygen -- a state called "hypoxia" or "anoxia."
Under normal conditions, oxygen concentrations in the Gulf of Mexico are eight to 10 parts per million. Dead zones have just two parts per billion.
Larry McKinney, the executive director of the Harte Research Institute, told KRIS that fish die at two parts oxygen per million. He said that while dead zones are natural occurrences, corn and soybean farming along the Mississippi River have made the phenomenon more extreme.
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The Des Moines Register reported in June that the National Oceanic and Atmospheric Association had predicted that this year's dead zone would be 50 percent larger than they've been in recent years, possibly as large as 8,200 square miles. According to NBC, the dead zone has not exceeded 5,800 square miles for the past five years.
Scientists measured the dead zone at 8,776 square miles this July, breaking the 2002 record by 3 percent.
"We predicted it would be large, and it is large," said scientist Nancy Rabalais of the Louisiana State University and the Louisiana Universities Marine Consortium.
Rabalais, who has helped catalogue the annual dead zone since 1985, said that the area could actually be slightly larger than recorded since the mapping expedition had to stop before reaching the western edge of the hypoxic area. She notes that the water column had been changing, however, so it might not be significantly larger than reported, The Associated Press reports.
CBS News reports that hypoxic waters pose a big threat to mangrove forests, sea grass beds and coral reefs, which provide an environment for fish and support nearby fisheries. It also puts local economies dependent on the Gulf for fishing and recreational tourism in a tough spot.
To treat the problem for towns along the Gulf, other towns may have to modify their farming practices. KRIS reports that in a study published in 2017 by the National Academy Of Sciences, researchers suggest that planting cover crops on fields on off-seasons could reduce fertilizer runoff into the Mississippi by 59 percent, shrinking the dead zone by two-thirds.
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One fourth-generation farmer in Idaho, Seth Watkins, spoke to the National Marine Sanctuary Foundation about his crop rotation practices at their Capitol Hill Ocean Week event in Washington, D.C, The Des Moines Register reports.
Unlike farmers that have a two-crop system, Watkins rotates his corn crop with oats, alfalfa and cover crops. He says that other farmers have called him "nuts" for not using his land to plant more corn.
"My job as farmer is not to produce; my job is to care for the land. And when I do this properly, this provides for all of us," Watkins said.
Research by the Union of Concerned Scientists and Iowa State University suggests that rotating more than two crops like Watkins can increase corn and soybean yields, reduce herbicide runoff by 81 to 96 percent, and reduce the application of nitrogen fertilizer by 43 to 57 percent. The researchers also claimed that taxpayers could save $196 million to $198 million per year in surface water cleanup.
The two-crop standard was largely influenced by federal farm policy, but is slowly changing to support more diverse crop planting, The Des Moines Register reports.
NBC reports that others have suggested setting a limit on fertilizer use, but that the large-scale implementation of such a policy would not be an easy task.
"If the states don't meet their load reduction targets, EPA can step in and enforce more reduction," said a spokesperson for the EPA. "Imagine doing that with the 25 states that are involved [in the Gulf]. It would be very difficult, but something like that would compel the states and agriculture to do more [than] what they're doing."