There's something lurking beneath us. Something deadly. And it's getting more and more dangerous every day. Cue the Jaws theme...nitrogen is coming!
Ok, so this common fertilizer doesn't have razor sharp teeth or a movie franchise, but for endangered aquatic life and our water supply, it's no less horrific.
Nitrogen—the most abundant element in the air—is an essential nutrient for growing plants. It also nourishes algae and other aquatic plants that feed and house fish, shellfish, and other smaller organisms. But in excess, it backfires, bleeding into streams, rivers, lakes, bays and coastal waters, causing a toxic chain reaction.
To encourage plants to grow bigger, better, faster, huge farming operations use more nitrogen-based chemicals than plants and soil can possibly absorb. This runoff has nowhere to go but down waterways and into aquatic environments, where it causes algal blooms—a rapid increase in algae population—which produce natural toxins that kill other plant and marine life. The resulting dead organic matter then feeds bacteria, which not only further contaminates drinking water, but also consumes oxygen from the water, leaving many fish and insects vital to aquatic ecosystems in distress.
Agriculture accounts for about 75 percent of the $210 billion spent to nitrogen pollution damages each year. (Cleaning up water, treating respiratory diseases, and restocking decimated fish populations is expensive.)
Need a scapegoat? Look at corn. This crop uses more nitrogen-based fertilizers than any other, even those that $210 billion price tag for dealing with nitrogen fallout is more than twice the total value of corn produced for grain in the US in 2011.
In the 1970s and 1980s, the federal Clean Water Act facilitated major improvements to nutrient pollution by requiring sewage treatment plants to improve infrastructure. Federal and state governments hoped farmers would volunteer to improve their methods as well, but that didn't happen. By 1995, nutrient pollution was an issue once again.
Now, the solution lies in states mandating sustainable use of fertilizer and holding farmers accountable for the responsibilities associated with land ownership. It’s not a lot to ask of farmers. There are relatively easy ways they can combat nitrogen runoff.
Planting radishes, for one. These root vegetables, particularly daikon, have a deep network of fine roots that can reach seven feet deep, creating a framework to keep topsoil in place. As a cover crop, or along the perimeter of fields, radishes support better water absorption of nitrogen runoff, protecting surrounding creeks from toxicity.
Tall, deeply rooted prairie grasses of the Midwestern plains were once emblematic of the rich soil in the region, but unsustainable farming has been extirpating native grasses. Reintroducing native plants among corn or soil fields will improve soil fertility and can reduce runoff by 40 percent and absorb 84 percent of the nitrogen that would otherwise makes its way into aquatic environments. Another way to avoid problems is just to give water some space. According to the Environmental Working Group, leaving 35 feet between the last row of corn or soy crops and the nearest waterway could reduce nitrogen runoff by 7 percent and phosphorus runoff by 18 percent.
So there are solutions for land-based problems, but what about what's going on in the water? Turns out, oysters might be able to lend a hand. A study on the Virginia coast found that an acre of the filter-feeding bivalves could remove 500 pounds of nitrogen from the water over the course of a year. At that rate, a 1,300-acre oyster bed would match the efficiency of an expensive water-treatment plant. Doesn't sound so appetizing, but these oysters would perform a natural niche in an otherwise decaying ecosystem.
Bottom line? To figure out this problem, we’re going to need to get creative. Because if we don’t get nitrogen pollution under control now, we’re looking at a real-life horror story.
Photo credit: Bobby McKay via Flickr