Crop rotation has been used for most of the history of sedentary civilizations. Monoculture was used mostly in very early civilizations, and recently in the modern times (since oil-based fertilizers have made crop rotation less important in some ways).
Monocrop agriculture is certainly not meaningful here. Agriculture is, maybe.
Which fertilizers are those? I was under the impression that nitrogen fertilizers were by far the most important. We get the nitrogen from the sea of it that we're swimming in -- no need to dig it out of the ground. The Haber process also uses hydrogen, which probably comes from WGSR, is that what you mean? If so, I strongly suspect that fertilizer production necessary for human survival would easily be economical on electrolytic hydrogen.
Hydrogen is for the most part produced from natural gas through steam reforming (only a small fraction is produced through electrolysis). And the Haber-Bosch method requires substantial heating which is also usually supplied by burning oil or gas based fuels.
Crop rotation has been used for most of the history of sedentary civilizations. Monoculture was used mostly in very early civilizations, and recently in the modern times (since oil-based fertilizers have made crop rotation less important in some ways).
Monocrop agriculture is certainly not meaningful here. Agriculture is, maybe.