You could feed a person off less then half an acre in regions with a decently long growing season. Even could support a few chickens. The above is true with so

You could feed a person off less then half an acre in regions with a decently long growing season. Even could support a few chickens. The above is true with some qualifications. You will need decent soil and plentiful clean water. And a power source to pump the water. And fertility which you will have to bring in. The compost you make won't do it. A way to control pests, (ya ya muh organic, but we are trying to survive here). So some pesticides. Sprayers. More then one, they break. Maybe some herbicides as well so you don't burn so many calories hoeing. Some mechanical help like a rototiller will make this much more possible. Fuel oil and parts for that. Some fencing and trellising. Bird netting. A way to preserve harvests like canning, drying or freezing. Most importantly (and most people will lack this rendering half an acre vs 5 acres moot for practical purposes) you will need a fair amount of expertise to pull it off. Generally from experience. And it will be a lot of work and mostly unforgiving of mistakes. Source: I mostly made it up, but I am an agronomist and long time gardener. It's probably roughly right though.