Guys... let's hold on a minute and review what we know.
Ammonium nitrate is a fertilizer. It is not in itself explosive. When mixed about six percent with No. 2 fuel oil, the resulting mixture is a low-yield explosive suitable for mining operations. The ammonium nitrate functions as an oxidizer, and the fuel oil functions as, well, fuel.
By itself, ammonium nitrate is no big deal.