Help Wanted for some Run ideas...

Hello All!

I have about 150 broilers that I have running free range in a fenced area. They are near a creek so the ground slightly slopes, and for housing they have two mobile chicken "tractors" (9' x 9' roofed pens) that they spend the night sleeping in. I think they have enough space to run (just guessing I'd say about a 20' by 60' area with lots of tall weeds on the creekside).

My dilema is this: They generate quite a good amount of feces, and though the ground is not bad yet, a good rain here will make it quite a mud hole. How can I get my run to be clean, dry, and if possible have something hardy growing in it that is edible? Any thoughts would be appreciated!