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Fertilizer Shows Its Deadly Side

Workers at a cooperative farm near Shanghai scatter fertilizer across fields of winter wheat. Image from the May issue of <em>National Geographic</em> magazine.
© Peter Essick
National Geographic
Workers at a cooperative farm near Shanghai scatter fertilizer across fields of winter wheat. Image from the May issue of National Geographic magazine.

My first reaction when I heard details of this week's deadly fertilizer explosion in Texas was horror.

My second thought was, "Maybe I shouldn't have pushed to change that headline."

National Geographic magazine just published in its May issue my article about how nitrogen fertilizer has shaped our planet. The article, with Peter Essick's beautiful pictures, describes fertilizer's critical role in providing our food, but also its toll on water, air and wildlife.

When the article went up online, the headline read, at first, "The Curse of Fertilizer." I didn't like it. It seemed only half of the story. I complained, and the headline soon changed to "A Mixed Blessing" — just as news broke that the West Fertilizer Co. plant had caught fire and exploded, destroying much of the small town of West, Texas. The blast killed at least a dozen people — including emergency workers who were trying to fight the fire — and injured more than 100 others.

Investigators can't yet say for sure how the fire started or what exactly caused the later explosion. According to initial news reports, the plant mainly sold a kind of fertilizer called anhydrous ammonia. "Anhydrous," as farmers often call it, is the most concentrated form of nitrogen fertilizer; it's stored under pressure as a liquid, and it's nasty stuff, dangerous to touch or breathe, but it doesn't usually explode.

Other local fertilizer dealers contacted by NPR, however, confirmed that West Fertilizer also sold another form of nitrogen: ammonium nitrate. In fact, the company reportedly told the Texas Department of State Health Services earlier this year that it was storing 270 tons of ammonium nitrate on site.

Ammonium nitrate can explode. In fact, it's been used to make bombs. Timothy McVeigh combined it with fuel oil to blow up federal offices in Oklahoma City in 1995. So at the moment, it's the prime suspect in the West disaster.

Some countries, including Germany and Ireland, have banned the use of this fertilizer unless it's mixed with other materials that make it less explosive. But the U.S. has resisted such steps. Farmers still like it: It's cheap, convenient, and in the small quantities that farmers handle, it's actually a lot less hazardous than anhydrous ammonia. And somehow or other, most farmers do need nitrogen.

This is where we get back to the bigger story, the subject of my National Geographic article. Nitrogen, in whatever form, powers most of agriculture, whether it's in China or Iowa (both of which I visited while researching the article.) Through habit or necessity, we've come to depend on it.

Fertilizer runoff causes toxic algal blooms. This one covered a third of Lake Erie in 2011.
/ © Peter Essick/National Geographic
© Peter Essick/National Geographic
Fertilizer runoff causes toxic algal blooms. This one covered a third of Lake Erie in 2011.

But there are costs. In the case of the West Fertilizer explosion, the damage is immediate and dramatic, but local. The of nitrogen, meanwhile, is spread across entire continents and along hundreds of miles of shoreline. To quote the article: "Runaway nitrogen is suffocating wildlife in lakes and estuaries, contaminating groundwater and even warming the globe's climate."

Is there any alternative? There certainly are ways to reduce the damage: applying fertilizer more effectively, planting vegetation that captures the excess, recycling animal manure and simply using less of the stuff.

A long-running at Michigan State University's W.K. Kellogg Biological Research Station, near Kalamazoo, shows how effective some of these measures can be. Researchers have been monitoring fields of corn, soybeans and wheat for 20 years. Even modest changes in management, says Michigan State's Philip Robertson, resulted in about a 30 percent drop in the amount of nitrogen released from these fields into the environment.

Why don't all farmers do this? Many don't change their practices out of habit or because they don't personally pay for the environmental damage downstream. But farmers also don't want to take risks, especially when a wrong choice could mean losing the farm. Applying too much fertilizer often seems less risky than using too little.

"Being a good steward," says Robertson, "currently has economic consequences that are unfair."

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Dan Charles is NPR's food and agriculture correspondent.
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