[mountainlion]

Fertilizer is what blew up the Murra building in Oklahoma city. The article does say it was the largest non nuclear explosion. Ammonium nitrate is used more than other explosives as it has more bang for the buck.

[taxcontrol]

Oklahoma City explosive was an ANFO (Ammonium nitrate, Fuel Oil) mix of AN, nitromethane and diesel fuel. Technically, AN is not an explosive but is considered an oxidizer. Unless AN is contained or confined (like a cargo hold) it will burn, an not explode.

Here is the DOT warning sign for AN:
http://www.safetysupplywarehouse.com/DOT_PLACARD_1942_AMMONIUM_NITRATE_p/dot-1942.htm

Note the flame with the big O. That is the indication of an oxidizer.