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Ammonium Nitrate Seen As a Likely Culprit in Blast

A massive explosion at a fertilizer plant here has left up to 15 people dead, a figure that may rise, said local police officials. More than 150 people have been treated for injuries. Miguel Bustillo has the latest.

While the chain of events that triggered the mammoth explosion at a Texas fertilizer plant on Wednesday night remains unclear, the likely culprit is the highly explosive material ammonium nitrate that was stored at the facility.

The facility, run by West Fertilizer Co., stored up to 540,000 pounds of ammonium nitrate and 110,000 pounds of anhydrous ammonia, according to a report filed to state and local officials as required by the U.S. Environment Protection Agency.

Map of Blast Site

A massive explosion at a fertilizer plant at West Fertilizer Co. in the small north-central town of West, Texas, left between five and 15 people dead, a figure that is expected to rise.

Photos: Plant Explosion

Industrial Disasters in the U.S.

Read more about fatal plant explosions and other industrial disasters in the United States since World War II.

Ammonium nitrate—which is easy to spread and often used for specialty crops, fruits and vegetables—is a highly explosive material, though it requires a fuel booster before it can ignite. Because of its explosive properties, ammonium nitrate is also used to make bombs and was the material used in the deadly Oklahoma City bombing of April 19, 1995.

It isn't clear what occurred at the Texas facility. The Texas Department of Public Safety said it could take as long as six months to determine the cause of the fire and explosion.

A less-likely scenario in the explosion is the ignition of anhydrous ammonia, which is also used as a fertilizer. It is a colorless, pungent gas that is kept in liquid form under high pressure in steel containers. But because ammonia is relatively stable and can only ignite at a temperature of 1,562 degrees Fahrenheit, such explosions are said to be rare.

Remains of a fertilizer plant and other buildings and vehicles after the plant exploded in West, Texas, on Wednesday. ENLARGE

It is possible that the fire that preceded the blast could have heated up the storage tanks to a high enough temperature to set off the explosion, said Ford West, president of the Fertilizer Institute, or TFI, a U.S. trade association for the fertilizer industry. For now, "that is still speculation," Mr. West added.

"This is pretty new to us," said Kathy Mathers, a TFI spokeswoman. "It's not something we are familiar with in our business."

When ammonia is heated, it expands. "Traditionally, that's our concern," Mr. West said. "That's why tanks [that store ammonia] have safety release valves" that get triggered if the pressure inside rises past a certain point.

West Fertilizer didn't respond to calls for comment.

Write to Gautam Naik at

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