We dig a pit deep into the manure pile behind the barn/coop. We dump them there for a year then dig a new one (backhoe on our tractor) and cover the old with soil/compost from the new hole. In ten years we will have crossed the entire pile and can return to square one. BTW if you have a pit, be very careful what goes in. If you bury a diseased bird's body, it can be dug up by foxes and the virus or other organism spread to wild birds then back to your flocks.
