AUBURN UNIVERSITY – A professor at Auburn University says the likelihood of a fertilizer-related incident similar to the fiery West, Texas, fertilizer plant explosion that killed 14 people and injured some 200 others is extremely remote in Alabama. That is because the two products that have been linked to the blast are either not used in Alabama or are extremely rare.
“I don’t see it happening here in Alabama,” said Charles Mitchell, an Alabama Cooperative Extension System agronomy and soils specialist and Auburn University professor of agronomy and soils. “We use neither anhydrous ammonia nor ammonium nitrate to any significant degree anymore.”
Anhydrous ammonia and ammonium nitrate are the two substances that have been investigated as possible causes of the April 17 explosion of the West Fertilizer plant.
Anhydrous ammonium is not used in Alabama, while the use of ammonium nitrate is becoming increasingly rare, said Mitchell, who has spent his career advising farmers about how to make the most optimal uses of conventional fertilizers as well as fertilizer substitutes, such as poultry litter.
Shortly after the explosion, investigators initially suspected stored anhydrous ammonia, a gas that is one part nitrogen and three parts hydrogen, as the possible cause of the explosion. Anhydrous ammonia is typically combined with different compounds – 022nitric acid, sulfuric acid and, in some cases, atmospheric carbon dioxide – to produce different types of fertilizer.
“When I initially heard anhydrous ammonia being the possible cause, I was surprised and wondered how this could have happened because ammonia tanks typically aren’t linked with fiery explosions,” Mitchell said. “After some close reading, I discovered that under very specific conditions of high temperature and with the right kind of catalyst, something like this is conceivable and could explain the West, Texas, explosion.”
However, anhydrous ammonia-related emergencies are more commonly associated with transportation accidents, such as train derailments or highway incidents involving tanker trucks, in which toxic amounts of ammonia gas are released into the air, sometimes forcing the evacuation of entire sections of a city or town.
Anhydrous ammonia is typically injected into the soil as a gas as a nitrogen source in grain production.
“It’s used widely in the Midwest as well as in central Texas, but I don’t know of anyone in Alabama who uses it,” Mitchell said.
For his part, Mitchell believes the more likely culprit is ammonium nitrate.
Several days after the blast, investigators discovered the plant was storing 1,350 times the amount of ammonium nitrate required for oversight by the U.S. Department of Homeland Security. Fertilizer plants and depots must report to the Department of Homeland Security when their inventory of the substance reaches 400 pounds or more.
“We’ve known since the early 1900s when we first began manufacturing nitrogen fertilizer that ammonium nitrate is, potentially speaking, a very combustible substance, used in the first bombing of the World Trade Center in 1993, the Oklahoma City Bombing in 1995 and in the improvised explosive devices used to kill to many people in Iraq, Afghanistan and other regions of the world,” Mitchell said. “If this is true and the plant stockpiled this much ammonium nitrate, it certainly could account for the huge fireball seen 40 miles away and the earthquake-like jolt that was strong enough to register on the Richter scale.”
However, since the Oklahoma City tragedy, the federal government has undertaken strenuous efforts to limit of availability and use of ammonium nitrate. Consequently, there is little incentive for small farmers, much less home gardeners, to use it.
“Today, small farmers and gardeners would find it difficult, if not impossible to find it,” Mitchell said. “Small fertilizer companies simply don’t carry it because of the security and reporting requirements associated with it.”
On top of that, transporting more than 1,000 pounds of it requires a special permit – and 1,000 pounds is only enough to fertilize two acres of corn.”
“While some farmers think they may be purchasing ammonium nitrate, the vast majority of fertilizer used on Alabama crops is a blend of urea and ammonium sulfate, which can be used just like ammonium nitrate,” Mitchell said. “Unlike ammonium nitrate, though, this is not an oxidizer, meaning it will not explode.”
Mitchell said Alabamians who live near fertilizer dealers should rest comfortably, because no dealer in the state handles anhydrous ammonia and only very few still stock ammonium nitrate, and even then in only small amounts.