New Process Eliminates a Fertilizer’s Blast Threat

By MATTHEW L. WALD

Correction Appended

A major chemical company will announce Tuesday that it has found a way to render nitrogen fertilizer useless as an explosive, and improve its value to some crops.

The company, Honeywell, of Morris Township, N.J., has patented a method for combining ammonium nitrate fertilizer with a second type of fertilizer, ammonium sulfate. Ammonium nitrate can be soaked in diesel fuel to produce a powerful bomb and is a favorite of terrorists, but when chemically tied to the ammonium sulfate, its chemical structure is changed so that it is no longer explosive.

Chemists had been looking for ways to render ammonium nitrate nonexplosive since the Alfred P. Murrah Federal Building in Oklahoma City was destroyed by a truck bomb in 1995(correction 1996), killing 168.

In 2006, Canadian authorities arrested 17 people who they said were planning to use such bombs in Ontario.

The Department of Homeland Security has certified the new fertilizer, which Honeywell calls ammonium sulfate nitrate, under a federal program devised to encourage such innovations by offering the manufacturers immunity from liability, according to Honeywell.

The Homeland Security Department has been experimenting with diluting ammonium nitrate with coal dust.

Growmark Inc., a cooperative based in Bloomington, Ill., distributes a fertilizer that blends ammonium nitrate and calcium.

An agriculture expert not affiliated with Honeywell, Jack Rabin, associate director for farm programs at the Rutgers New Jersey Agricultural Experiment Station, said many companies were looking for ways to render ammonium nitrate inert, because the Department of Homeland Security requires that farmers safeguard their stockpiles of the widely used fertilizer and report their inventories to the government.

“We are not going to replace ammonium nitrate fertilizer in the U.S. and around the world,” Mr. Rabin said. “It’s too good, too important and too valuable.”

One problem, Mr. Rabin said, was that if nitrogen is the essential chemical in the fertilizer, then diluting it with other materials raises the number of tons that must be carried to the fields to get the desired amount of nitrogen.

A fertilizer incorporating sulfur, as the Honeywell material does, would be helpful in the western United States, where sulfur is commonly used to lower pH values toward neutral, he said. But, he said, “in much of the world, the soils are too acid already.”

But Mark Murray, director of strategic marketing for Honeywell’s resins and chemical business, said, the market was very broad. “Anywhere where ammonium nitrate is used today, this alternate form could be used effectively,” Mr. Murray said.

Honeywell is already a large producer of ammonium sulfate fertilizer.

The new fertilizer has less sulfur than ammonium sulfate, making it more widely usable, Honeywell said, and includes a mixture of nitrogen that is released promptly and nitrogen that becomes available slowly, making it a superior fertilizer.

This article has been revised to reflect the following correction:

Correction: September 24, 2008
An article on Tuesday about a new compound that eliminates the explosive potential of ammonium nitrate fertilizer misstated, in some editions, the year of the deadly bombing of the federal building in Oklahoma City. It was in 1995, not 1996.