You wrote, "but there aren’t any regulations about how close you can put an ammonium nitrate plant?"
And in answer to you question, there are regulations about where you can put an ammonium nitrate plant. The plant owner was violating them. That's how the first sentence answered your question. To wit: "The West, Texas fertilizer plant where a powerful explosion killed at least 14 and injured dozens on Wednesday failed to disclose a massive ammount of ammonium nitrate ordinarily regulated by federal officials, according to Reuters."
They failed to tell the regulators what they had. Whether they did so because they knew it wasn't allowed in the zone they had the business will be determined in the courts, but in answer to your question, it is regulated. I would hazard a guess if the owner wasn't killed in the blast he's going to wish he had been after they're through with him. He might even end up charged with murder or manslaughter for each person killed. I'd bet he's going to be made example (particularly because they want to be able to track those materials for bomb making concerns).
Rhetorical questions don't require answers.
Yeah, we don’t need to grow crops any more, just have everybody plant their own arugula for their own consumption and just watch us become the breadbasket of the world. /s
The 400 lb threshold is about enough fertilizer for 5-10 acres of hay.
That’s less than a 660ft x 660 ft parcel.
The viral video was taken further away than that of an industrial site which more safely produced the fertilizer from raw components, than shipping it hundreds of miles. Best to produce the more volatile stuff closer to its destination in those quantities.
One can argue about producing it several miles out of town,....but then again, West, Texas isn’t in Waco, is it? It’s several miles down the road from the larger suburban complex.
People can still live nearby. The location of the plant isn’t obscene. It’s fairly normal. We can also discuss the dangers of grain dust in silos nearby farming communities, which in many cases are far larger risks.