Earth's growing nitrogen threat
It helps feed a hungry world, but it's worse than CO2.
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Researchers have found major growth in ammonium in air quality data across 15 US National Parks, including Rocky Mountain, Yellowstone, Mount Rainier, and Canyonlands parks, the Associated Press reported last summer. At high altitude, delicate alpine tundra is being replaced by nitrogen-loving grasses, which are fed by growing amounts of ammonium falling as rain.Skip to next paragraph
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“The more nitrogen that we use in agriculture or that comes from various combustion processes – cars or power plants – the more ends up in the world’s ecosystem,” says Lester Brown, president of the Earth Policy Institute in Washington. “By altering concentrations of this key nutrient in the system, we are altering that ecosystem in many, many ways.”
Other researchers have spotted invasive grasses that thrive on nitrogen sprouting up in the Mojave and Sonoran deserts. Beside threatening other plant species, such grasses fuel wildfires.
But the most dramatic impacts can be seen in the growth of coastal dead zones where excessive nutrients in the water – fueled by runoff of fertilizers – has suffocated or driven away ocean animals. In the Gulf of Mexico, fish and shrimp have been eliminated in an 8,000-square-mile dead zone at the mouth of the Mississippi River. More than 400 dead zones with a total area of 245,000 square kilometers were identified worldwide last year.
There is reason for hope, however. If new EPA clean-air standards move ahead, then 90 percent of US NOx emissions from stationary sources could be eliminated. That’s because the two-thirds of US power plants that do not now have nitrogen-removal equipment could get it beginning by 2011, says John Walke, clean air director for the Natural Resources Defense Council in Washington.
Efforts to boost the efficiency of nitrogen use in farming are on the march, too. In Pennsylvania, for example, more than 100 farmers are using new tools to determine precisely how much to apply.
“Getting nitrogen right is critical for getting climate change right, food security right, and a lot of issues associated with poverty that have to do with nutrition depletion,” says Bill Herz, vice president of scientific programs for the Fertilizer Institute, a Washington trade organization that represent North American fertilizer manufacturers.
This spring, a federal science advisory report is expected to recommend a national goal of improving the efficiency of farm nitrogen fertilizer use by 25 percent, Herz and Galloway say.
That’s just fine with Mick Lane, spokesman for the On-Farm Network of the Iowa Soybean Association. In 2000, about 40 farmers across the state learned how to use nitrogen fertilizer more sparingly. Now the number is 500 and growing.“ We’ve seen an overall decrease in the amount of nitrogen with no negative impact on farm income,” he says.
That’s also true for Lindsay, the Iowa farmer. Using sophisticated digital systems to monitor how much grain is produced on which acres, he’s cut the amount of nitrogen he uses from more than 200 pounds per acre a decade ago to about 160 pounds.
“I’m just one of hundreds of farmers doing this, trying to use less nitrogen,” he says. “I want the environment to be good, too. We drink the water out here, and we want everything to be safe.”