I've been searching and searching for what to plant. I too live in a dry area; juniper trees, sage brush, yarrow and jack rabbits all thrive here. I found some pretty helpful information on our county's cooperative extension site and the UC Davis animal science site. Both gave good suggestions for forage for my area. Although it wasn't specifically for chickens, I was able to make some decissions based on info gathered from other sources. I have choosen; alfalfa (medicago sativa), alsike clover (trifolium hybridum) and birds foot trefoil (lotus corniculatus). I still need to find a grass - I am thinking an orchard grass.
I also plan to add a bunch of other 'goodies' such as - sunflower, corn, milo, millet, pumpkin, squash, comfrey and stinging nettle.