I live in the northeast US, with relatively cold winters (USDA zone 5, about -15°F ) and a short growing season (about 90 days frost-free; snow possible October through April).
I have a small flock (less than 30) of chickens for eggs, and raise a batch of chickens (less than 30) for meat each summer.
Currently I buy most of their feed in bags from the store. In fall, winter, and early spring they get to run loose and forage, but they're too destructive to gardens to run loose in the summer.
What mix of crops makes an appropriate chicken feed? What's a ballpark estimate of how much space will I need to provide about a year's worth of food for 30 hens?
(Note that I'm open to allowing the girls to help with some of the harvesting. E.g. cleaning up fallen fruit from fruit trees, and I've heard good things about Siberian pea shrub for chickens. But some of the food should be non-perishable / storable for a few months.)