Someone finally got through to Trump that Belarus has no potash to spare. All of their production is under contract.
Someone is feeding Trump fake news, and Trump is making very public announcements based on it. The bad intel, one might suspect, is designed to make Trump look foolish, having to backtrack. I wonder if that’ someone’ is Vance, who desperately wants to evict Trump from the White House after the mid-terms?
Air, actually! (Well, nitrogen from air, and hydrogen. Which might come from fossil fuels, but that’s a relatively minor consideration)
It’s just a really energy intensive process, so fuel is the main input in cost terms.
Also, fun fact about phosphorus: it’s expected deposits will be depleted in a few decades. Efforts are already underway to start recovering it from sewage, instead.