We just bought a farm...

.....and we don't know what we're doing.  We bought 2.5 acres that had been organically farmed, but with conventional methods (tilling, monocrops).  Most of the top soil is dead and covered with goatheads.  There's about 23 fruit trees that were in desperate need of pruning.  We'll see if they produce this year after the haircut I just gave them all.  Since we're just getting started, what would you plant for market that could be planted in a permaculture fashion and will restore the soil?

Bonnie

Your climate and mine are so vastly different that I don't know where to begin. I added your thread to the "Southwest" forum (so it shows up there, as well as "Market Garden") in hopes someone more knowledgeable with your area can contribute!

The fastest way to regenerate lifeless soil is to pile on the organic matter.  Mulch, mulch, mulch, mulch, mulch.  If you have access to wood chips from a tree trimmer, I would start by mulching your orchard aggressively.  8 inches of chips at a minimum.  Don't till them into the soil, but let them lay on the surface and work their magic.

Start a large compost pile and then start a second and third.  Dead soil needs microbes.  Compost piles are microbial factories, pumping out good bacteria by the billions.  If you can put down a layer of good fresh compost BEFORE your mulch layer, that's a great way to give your soil a microbial innoculation.

Sun will irradiate soil life.  A heavy mulch layer will block the sun and let the microbial herd grow, as well as hold in moisture and keep roots cool.  If you can plant a cover crop soon before the weather gets too hot, that'll also pump life down into the soil profile.  There are a number of companies that sell cover crop mixes.  Find one recommended for your climate and get it established as soon as possible.

Everything I know of Arizona is that it's hot, dry and windy.  You'll need to address each of those variables if that is your case.  Start searching this site for threads about growing in arid environments.  There are hundreds of great threads about this (water harvesting, establishing shade-providing trees, growing in withering conditions, etc.).

Best of luck.

Better late than never?  Please forgive me, but Thank you both.  Nicole, thank you for adding my post to the southwest section.

Marco, thanks for your advice.  Our county offers free mulch of which we took/are taking advantage.  We mulched a few trees with a small (4") plastic border.  Our free ranged chickens loved the mulch and unfortunately dug most of it out.  We had a pile that sat in one spot over winter and spring waiting to be spread.  When we finally moved it this summer, the ground where it had been was beautiful black soil teaming with worms.  

Thanks again,
Bonnie