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NMSU Scientists Help Recycle Explosives Into Fertilizer

LAS CRUCES -- The same materials that blast U.S. Navy shells from battleships to distant shores may soon make home gardens thrive. New Mexico State University scientists are working with the Navy and TPL, Inc., an advanced materials technology company, to convert propellant into garden fertilizer.

TPL uses space at Fort Wingate, a former U.S. Army depot near Gallup, to "demilitarize" a variety of surplus munitions by breaking them down into safe, recyclable materials. TPL scientists had the idea of converting nitrogen -- a key ingredient of many explosives -- into a more friendly form.

"Nitrogen is abundant in explosives and propellants, and that same nitrogen is an important plant nutrient," said Franklin Kroh, TPL scientist.

To ensure the new fertilizer would work, TPL contracted with NMSU's Agricultural Experiment Station to test raw and treated propellant in greenhouse and field experiments last summer in Las Cruces. Bob McCaslin, an NMSU agronomist, and Lester Boyse, his research assistant, found that untreated propellant would do little for plant growth.

"It became very obvious, very quickly, that some kind of chemical treatment would be necessary for propellant to become a useful garden treatment," McCaslin said. "TPL looked at several methods of treating the propellants and found some treatments that made the nutrients available to plants."

McCaslin and Boyse found that the treated propellant's nitrogen is just as effective as manure, or urea fertilizer, in soil applications.

"We used sorghum as a test crop, but this mixture would work just as well with other crops," he said.

Tons of propellant have accumulated over decades as more sophisticated weapons replaced older weapons. Adding to the piles of propellant were recent, massive military cutbacks. Converting propellant to fertilizer helps the Navy meet one of its major recycling goals, said Keith Sims of the Ordinance Reclamation Program at the Naval Surface Warfare Center in Crane, Ind.

"Currently, the Department of Defense uses open burning to dispose of propellant," Sims said. "This is purely a destructive means. There's no recovery value whatsoever. More recently, we have placed a greater emphasis on the recovery, reuse and recycling of these materials."

At a remote group of buildings at Fort Wingate, TPL workers pour thousands of the dull green, two-inch propellant grains into an ignition-proof reactor, then add treatment chemicals. It takes most of a day to make a batch of the new fertilizer. The solution is removed from the reactor after curing overnight, then packed in dry or liquid form for sale to gardeners.

Gardeners worried about accidently blowing up the pumpkin patch with the new product can rest easy.

"At that point, the propellant is no longer an energetic material," Kroh said. "It's not flammable, it can't explode, and it's perfectly safe material."

The Navy is funding the conversion project through the Small Business Innovation Research Program.

TPL is planning to test market the product, tentatively called Peaceful Green, this spring in New Mexico, Arizona and California nurseries. The company's marketing angle will be that they've beaten "swords into plowshares" by turning a component from a weapon into one that enhances garden growth.