Curious about the fertilizer part. I'm wondering if organics will be able enough to supply farms if those fertilizers based on gas ran out or even outright become unavailable or it would result in a situation like in Sri Lanka where their food production went down after they stopped importing fertilizers. Composting is just basically returning back the leftover nutrients after you harvested your crops, it don't really add anything new to replace what's used for the crops unless you bring nutrients from an outside source (manure from someone else's livestock for example).
I'm curious about this myself.
Manure is grass and plant life that has passed through a cows digestive tract. In theory it might be possible to harvest grass and process it through an acidic decompositional state similar to a cow's digestion to produce unlimited amounts of organic fertilizer. It is very easy to get nitrogen and carbon from compost and decomposing plant life. The more difficult to obtain nutrients are phosphorous and other elements more commonly associated with fertilizers.
I've been experimenting with this for awhile now as a side hustle and don't a good conception of it. Sources I've read claimed things like hair and bone can be good sources of phosphorous for natural fertilizers. I'm not certain how to go about trying that on a larger scale without it being weird.
I was thinking mixing grass and compost with an easy to obtain acid like apple cider vinegar might produce something like cow manure. And I have read that apple cider vinegar added to compost can have positive effects. But I don't know that anyone has tried to artificially produce organic fertilizer in a process resembling the one that produces cow manure.