Amidst little fanfare, the National Oceanic and Atmospheric Administration (NOAA) announced the largest-ever recorded dead zone in the Gulf of Mexico earlier this month. Currently about the size of New Jersey, the dead zone occurs when excess nutrients, primarily from agriculture, flow into the Gulf of Mexico. These nutrients feed massive algal blooms which in turn create low-oxygen environments, killing fish and other aquatic life as well as fouling drinking water sources.
The news received scant coverage. While it’s dismaying that the dead zone is growing, not shrinking, it’s also not surprising. Farmers and animal agriculture operations in the region are in a bind: any steps taken to reduce nutrient losses have so far been insufficient to address the scale of the problem, and climate change is making the situation worse.
Row Crops, Animal Ag Biggest Contributors
As urban areas and industry have reduced their nutrient pollution, the relative contribution to Gulf hypoxia (reduced oxygen levels) from agriculture has grown. According to the U.S. Geological Survey (USGS), row crops (primarily corn and soy), and animal agriculture (concentrated operations of cows, pigs and chickens) in the Upper Midwest are now the primary contributors to the dead zone.
The increasing global appetite for protein, coupled with rising yields for corn and soy, has meant bumper crops for feed corn and soybeans. The result is more crops and animals than ever before on the same, and in most cases, fewer acres. So while agriculture has become incredibly efficient with nutrient application, the concentration of these nutrients on fewer acres means only a few missteps or heavy rains can wash all good intentions into the Gulf.
While this year’s dead zone is only 3 percent larger than last year's, and the growth is largely attributed to increased precipitation events in the Midwest, it portends an inability through existing mechanisms to deal with water quality. Controlling these sources of pollutants is complicated by the fact that they are considered non-point sources of pollution, and are therefore not regulated by the Clean Water Act.
Climate Change’s Compounding Role
Climate change is causing heavy precipitation events to increase in frequency. According to the National Climate Assessment, heavy downpours in the United States have already increased 30 percent above the 1901 to 1960 average. Scientists predict that globally, dead zones will continue to increase as climate change increases the severity and frequency of precipitation events. A recent study published in Science predicts anywhere from a 5 to 33 percent increase in nitrogen loading in U.S. water sources under a business-as-usual scenario.
Therefore, to simply offset these precipitation increases, deep cuts in nitrogen application will be needed. In the Corn Belt, the study's researchers estimated an average cut of 33 percent in nitrogen application will be required to keep things exactly as they are now.
In 2015, the twelve states participating in the Hypoxia Task Force (AR, IN, IL, IA, KY, LA, MN, MI, MO, MS, OH, TN WI) committed to developing state nutrient reduction strategies to reduce nitrogen pollution to the Gulf by 20 percent, which would require a 32 percent reduction in nitrogen applications. The problem is, with increased precipitation, nitrogen reductions would have to be as high as 62 percent to reach the targets outlined by the Hypoxia Task Force, a tall order for even the most cutting-edge farmer.
Voluntary Measures Still Falling Short
Agriculture is exempt from the Clean Water Act, but farmers are implementing voluntary conservation measures to reduce nitrogen off-flows from fields. Any farmer will tell you that lost nitrogen is lost money, and so there is also a business case in ensuring that nitrogen doesn’t leave the field. U.S. farmers have already addressed the low-hanging fruit of nitrogen use efficiency (NUE), increasing efficiency by 36 percent while simultaneously increasing crop yields.
Unfortunately, the mantra of the “4-Rs” for fertilizer application (right source, right rate, right time, right place), will only get you so far if a deluge occurs shortly after fertilizer application.
Moving forward, more transformative steps will be required to meet the deep reductions necessary in nitrogen use and runoff. Research has shown back-to-basics agricultural practices, including crop rotations, cover crops and buffer strips, can greatly reduce nutrient losses from fields and increase the water and nutrient holding capacity of soils. However, the application of these practices is uneven across regions and among different crops.
On the animal agriculture side, waste from concentrated feeding operations (CAFOs) is dealt with by spraying it on nearby fields, where it can easily find its way into water sources as well as foul local air quality. When there are precipitation events, these open lagoons of waste can flood and flow into nearby creeks and rivers. While some companies have committed to reducing the environmental footprint of meat production, progress has been slow.
In a recent interview, Rebecca Clark, of the Illinois Department of Agriculture, suggested that the growing dead zone should be taken as a call to arms by the region’s farmers, stating, “it should be viewed as an opportunity to show how progressive and innovative the agricultural community has been and continues to be… [and] as a way to demonstrate more mandatory or regulatory approaches are unnecessary.”
Farmers rely on programs in the Farm Bill to support voluntary conservation measures, but money appropriated for those programs has steadily been falling over the past decade. With lawmakers currently debating the 2018 Farm Bill, farmers are understandably concerned about the fate of these programs.
A possible inspiration for Midwest farmers is the effort undertaken to restore the Chesapeake Bay. States in the Chesapeake Bay region asked the EPA to put them on a pollution diet back in 2010. While the effort was opposed in court by agricultural groups and states outside the region that were afraid of seeing similar efforts in their region – the effort stood. Early signs show the plan may be working. In the first five years of the program, nitrogen, phosphorous and sediment levels all dropped, with some signs of recovery in grasses and blue crabs.
Currently, it’s an open question whether or not states in the Mississippi River Basin can work fast enough to stem the tide on water quality, and stave off regulation.
For more information see:
- Eutrophication Will Increase During the 21st Century As A Result of Precipitation Changes, Science
- The CAFO Industry's Impact on the Environment and Public Health, The Sierra Club
- Largest Recorded "Dead Zone" Calls For Nutrient Loss Reduction, Ag Web
- How Climate Change Will Worsen Algae and Dead Zones, Inside Climate News
- Editorial: Huge ‘Dead Zone’ Demands New Approach, The Des Moines Register
- Nutrient Pollution: Voluntary Steps Are Failing to Shrink Algae Blooms and Dead Zones, The Conversation
- The Gulf of Mexico Dead Zone is Larger Than Ever. Here’s What To Do About It., The Washington Post