If we're collecting human and livestock waste, we could just as easily use a bunch of the urine as well, and use manure directly instead of capturing the methane and using the methane to power the Haber-Bosch process + supply the central CH~2~ group.

It's much easier to imagine agriculture without oil than it is to imagine heavy industry without oil. Relying on plant/bacteria nitrogen fixation is something we need to pivot back to anyway. Marg Bar America means no longer flooding the landscape with more synthesized urea than it can handle, it means any given region living within its means, ecologically and biogeochemically.

And I'm saying all this as Hexbear's resident composting toilet proselytizer.