Until recently I had a 12x18 foot area where they could go scratch if I wasn't around to let them in or out. Over the past 8 years or so I've had as many as 15 birds working it. Last winter I took the fence down and plan to move the henhouse to another spot.Unless you free range or pen them in a decent sized yard they will strip it to bare dirt pretty quick.
Last week my piglets got out and made a beeline for that nice bare ground, tearing it all up. I've got some really nice soil there, waiting to be used.