[zoogeny]

Even if one were to grant your assumptions (which I would challenge) you still end up positing a false dichotomy/dilemma. You might rightfully say that you cannot think of a third possible outcome of your highly specific and one dimensional constructed situation but that does not mean there are precisely two possible cases.

As the most trivial example off the top of my head, I cannot imagine any situation remotely close to what you are suggesting without war. I don't think the cost of the precursors to fertilizer will stop Western countries from taking it.

At any rate, the idea that the nail in the coffin of our society will be our inability to produce fertilizer seems an unlikely and remote possibility. I'm not saying that there is no path to that outcome (we could probably spend all day making up scenarios where that is a possible outcome), it just seems rather unlikely.