But if you don't have enough food it all fails. History has taught us that in every corner.
It has always been my understanding that modern farming is reliant on a large industrial outlay and global trade for things like fertiliser and pesticides. And that it also affects the soil in a way that is hard or impossible to reverse (extraction of certain nutrients that cannot be easily replenished naturally)
Traditional farming is not sustainable because they don't have pesticides and so once in a while your whole crop is destroyed and your whole village starves to death. Some traditional practices slowly destroy the soil over time.
Fertilizers like nitrogen (one of the largest fertilizer uses) are needed for the best yields, but modern farming creates enough as on farm to be sustainable without the addition at lower yield levels.
However when a crop leaves the field it takes away some things like sulfur, potassium, and that needs to be replaced for the next crop. I'm considering this a failure of modern transport to bring those back and not modern farming - but this should feel like a meaningless distinction.
When I say modern farming is sustainable I mean that modern farming is building up soil over the decades. While we need to replace anything actually removed with the crop, the soil is getting better year after year.
I think that is already the population. What the attempt seems to be is to create a green belt that prevents further desertification of semi-arable land that they are already subsistence farming on, because if the desert keeps moving, these people will cease to exist.
Captialistically/economically, there is questions as to whether these people should continue to subsistence farm, but if they want to, and it can help keep the desert at bay, then I say more power to them.