system
A chat on subreddit /r/wallstreetbets
human
The rule of thumb for about 100 years has been a maximum of 50 chickens per acre for free range. This limit is not only set by the amount of food they could find in a certain area and ensuring that they won't entirely destroy the grass by scratching, but also by the amount of manure they'll produce. Too much "fertilizer" will kill the grass and the supporting ecosystem for the chickens. Even at 50 chickens, after a few years you may need to plow the soil and plant new grass to aerate it and release the buildup of nitrogen. Just 5-6 good laying hens can produce about a dozen eggs every 2-3 days and would be easily supported by 1/4 acre. 

They'll then need an enclosed coop somewhere that offers protection at night with a minimum of 3-4 square feet of space per chicken. They do most of their pooping at night, so if you plan on using it, put their roosting bar above a tray that you can collect and empty as needed. Also, don't use chicken wire to build the coop. It's fine for temporary housing, but you'll need hardware cloth for a permanent, secure, housing. Most pests and predators can squeeze in through the larger holes of the chicken wire or break it.
gpt
Very informative TY