I got this question on a forum I read:
"How much land would you need to feed yourself"
And I'm going to answer it in the form of a chicken dinner:
Takes about 2lbs of feed to put a pound of weight on a chicken.
For a chicken you add about 5lbs = 20lbs of feed. which means about 20 pounds of grain per chicken, which means half a bushel or so.
Current grain yields are between 30 and 40 bushels per acre, which means for each chicken you'd need 1/60th of an acre of grain.
Want to eat a chicken a week? you'd need an acre of wheat.
(yes, i'm ignoring the protein component of modern chicken feed; this is a thumnail sketch. if it makes you feel better make part of the acre some sort of protein; field peas or garbanzos or soy beans)
But what would it take to get that acre of grain? With a modern tractor, you could till and prepare the seedbed on an acre in a few minutes; at a cost of $150,000. With a mid-sized tractor it may take you an hour, at a cost of $65,000. With a horse and a plow, maybe a day. By hand, with a hoe, a week or two if you worked 12 hour days.
Seed would cost you $12-14 per 50lbs, and you'd need 150lbs for the acre. Putting the seed in the ground you'd need a grain drill (used, $800) or you could broadcast seed it (broadcaster, $800) and then disc it in (8x10 disc, used, $1200) and then you'd be all set to watch it grow.
To harvest it with a modern combine would take a few minutes ($500,000) or you could buy an older one for any price point you want (499,000 to $3k) depending on the decade you're purchasing it from, and it would take a 10 to 40 minutes. Or you could go out with a scythe and cut shocks of wheat down, and dry them, and hand-thresh them and it might take you two weeks of pretty hard labor, threshing and winnowing and drying the wheat.
And then you could store that wheat somewhere so that rodents didn't get it; maybe a nice grain bin, or metal garbage cans in a pinch.
Then you can feed it to the chickens, and watch them grow, and when they're the size you want, you can process them and eat them.
So how much land for your chicken dinner? an acre.
But the real question is how much would that chicken dinner cost you?