A new ingredient is being added to a common fertilizer to prevent it from being used to make methamphetamine, the Des Moines Register reported Oct. 10.

Experts say adding calcium nitrate to anhydrous ammonia renders the nitrogen fertilizer useless for making methamphetamine. Early in the meth epidemic, clandestine lab operators in states like Iowa were frequently stealing the fertilizer from farmers to make the drug; today, however, most of the meth sold in the U.S. comes from labs in Mexico, not smalltime local labs.

Still, local officials said the new ingredient will further hinder the remaining local producers of the drug. "The message to all those who are interested in making meth is, 'don't bother,'" said Iowa Gov. Tom Vilsack said. "This will reduce to zero the meth that is cooked in Iowa."

Researchers discovered that calcium nitrate prevented fertilizer from being used to make meth after a six-year, $1.2-million study. It will cost between $1 and $1.50 per acre for farmers to add the chemical to their fertilizer supplies.