Why Ammonium Nitrate?

The highly water-soluble salt is the preferred nitrogen source of fertilizers. Most of the produced ammonium nitrate ends therefore in the production of fertilizers. However, the runoff of excess ammonium nitrate is a leading source of environmental waste.

As a strong oxidizing agent, ammonium nitrate makes an explosive mixture when combined with a hydrocarbon, usually diesel fuel (oil), or sometimes kerosene or (fine) coal dust. Ammonium nitrate and fuel oil (ANFO) mixtures have been used for bombs in terrorist acts such as the Oklahoma City Bombing, because ammonium nitrate was readily available in bulk. The 34% ammonium nitrate required to make bombs is now difficult to obtain in bulk. During the troubles in Northern Ireland, ammonium nitrate was illegal as a result of it being used in car bombs by paramilitary groups like the IRA.