As one who owns a couple of Deere machines- you'd better write your passwords down and secure them. Those things have like 2 or 3 levels of authorized access, they are sophisticated technological marvels.
I have some land near this fertilizer plant at Verdigris, OK. They convert nat gas to ammonia fertilizer.
I don't know if that article is correct, I don't think it is the largest in the US. It's one of the largest.
They apparently produce ammonium nitrate at this site. If they make a granular product it can be used as a fertilizer or as an explosive. What was at one time the largest industrial accident in the US was the accidental detonation of a French ship in Texas City, TX loaded with ammonium nitrate. Over 500 people were killed as a result. More recently Timothy McVey blew up the Federal government building in Oklahoma City using ammonium nitrate. Ammonium Nitrate mixed with oil is as potent as dynamite and is used extensively in the mining industry.
Many years ago I was involved with the manufacture of ammonia, ammonium nitrate and urea and liquid solutions thereof. There were very few accidents with ammonium nitrate, but some were big.