I'd assume food stores could be made to last long enough to enact some kind of rationing, and thus lack of chemical fertilizers will have a less profound effect. The point isn't that we would have to sustain ourselves as before, but to be able to sustain on some kind of level.

Across the world agriculture is subsidised.. even in poorer countries, because the cost of doing agriculture is very high. Farmers are moving to other jobs, selling their farmlands etc.. this will put huge pressure on food supplies and so the govts figured that there has to be some incentive to keep people in agriculture.

Nations which don't have substantial access to food grown within their borders will place themselves at severe disadvantage when it comes to any sort of global negotiations.

Take the example of Qatar - when it was under sanction by many of the Arab countries, they could not import food.. and they were forced to get into agriculture and now agriculture thrives in Qatar even though the climate is not conducive.

https://thefarmermagazine.com.au/qatars-farmers-have-gone-fr...