I garden on about 1/2 acre and have had over an acre. I can produce well over 5000 pounds of food on 1/2 acre of ground. This is not a boast, it is a simple fact and easily proven. Potatoes, given appropriate culture, will produce up to 50,000 pounds per acre (average is closer to 34,000 pounds/acre), I worked for a local potato farmer as a teenager and can well remember harvesting an acre of potatoes and watching to see how many trucks (5 tons at a time) we could haul off an acre. Corn will produce 8000 pounds per acre (about 140 bushels) with commercial fertilizer when using hybrid seed. I can produce 5000 pounds/acre of most brassicas such as turnips, cabbage, broccoli, cauliflower, etc. Beans are relatively low producing at about 2000 pounds per acre, but make up for it with a lot of protein. Tomatoes will produce 20,000 pounds/acre though they are a lot of work to stake and train.
Somebody will argue that I’m using commercial seed. I have enough open pollinated seed in my freezer to last 5 years and can grow more seed every year that I garden. I do this as a normal routine, producing seed is part and parcel of my gardening work.
I grow things to eat and to produce seed with a diversity of plants. My typical garden is: beans, lima beans, broccoli, cauliflower, cabbage, feed corn, sweet corn, cantaloupes, carrots, cowpeas, cucumbers, tomatoes, okra, onions, peanuts, peas, radishes, squash, turnips, watermelons, and don’t forget cotton which I grow for seed but also know how to turn it into thread to make clothes.
What about wild foraging? Blueberries, blackberries, pokeweed, dandelions, persimmons, walnuts, hickory nuts, and a bunch of other edibles are part of my diet. I fish and hunt though not as much as when I was younger. Deer, rabbits, squirrel, wild turkeys, geese, ducks, and other game are readily available in this area. I also have chickens and turkeys. I have 3 young roosters in a cage to be slaughtered tomorrow. How would I manage if the economy collapsed and I had to feed myself? I’d have to work at it, but I would have an abundance to eat and could provide food to others. For reference, an average person needs about a pound of food per day. I can grow 365 pounds of high quality edibles. With 1/2 acre garden, I could feed about 5 people at that rate.