Same for Phosphor https://www.stockholmresilience.org/research/planetary-boundaries.html

I'm sorry, but I didn't see anything about the nitrogen cycle in the link you posted. What do you mean by "exceeding the planetary boundaries significantly"? I'm not very familiar with "planetary boundaries" as an ecological theory, and the site doesn't seem to expand on their methodology to a significant degree, or maybe I'm just not looking at the right pages.

use about half of global agricultural lands for animal feed. So the nitrogen fertilizers are not needed to sustain nutrition. They are needed to sustain the meat overconsumption in wealthy countries.

Right..... But do we actually expect that to happen? You seem to be focused on the physical possibility and the science behind the problem, when my argument has been entirely policy based.

If we had the political will, or if we were motivated as nations to help our fellow man, I wouldn't be worried in the first place. My concern isnt that this is some unsolvable and inevitable problem, but that governments will respond to this problem in the easiest and most profitable way. By ignoring it and allowing big AG to create a natural monopoly over an artificially inflated scarcity.