February 14, 2012: The United States is trying to get fertilizer manufacturers to produce less explosive products. That's because terrorists increasingly use ammonium nitrate (a commonly used agricultural fertilizer) for their bombs (by mixing it with fuel oil and setting it off with a detonator). There is now a new form of ammonium nitrate fertilizer that it will not function effectively as an explosive. The Honeywell Corporation found that by adding some modified ammonium sulfate to the ammonium nitrate you actually improve the fertilizing ability of the mix (by making the treated soil less acidic) and also prevent the fertilizer from being used as an explosive. Actually, you can still use the ammonium sulfate nitrate mix as an explosive but it requires some creative chemistry to do so and serves as a technological barrier for most terrorist groups. Although not a fertilizer manufacturer, American conglomerate (it makes a lot of different stuff) Honeywell found this less explosive ammonium nitrate formula while developing fire retardants. New discoveries are often made that way, by accident.
The military has long used ammonium nitrate as an explosive in large bombs (usually five tons or more of ammonium nitrate, fuel oil, and powdered aluminum) and would continue to do so. But plain old ammonium nitrate would be reclassified as "military grade explosives material" and its sale would be restricted. Unfortunately, some terrorists will be able to find chemists with the skills to convert the ammonium sulfate nitrate fertilizer to the more explosive type. It is still a difficult process but not so difficult that some terrorists won't find a way to do it. Meanwhile, the larger problem is getting ammonium nitrate fertilizer manufacturers, in areas where terrorists obtain and use the fertilizer for explosives (Pakistan, in particular), to switch to the non-explosive type.