You have hard packed clay in Phoenix? I thought the area was sandy.

Dare I ask why no tilling?

There are a lot of areas around Phoenix with clay. I'm just glad I don't have caliche, that's the worst!
I hesitate to till a s it will be me doing the work. I broke my neck in 2001 and that sort of vibration could put me to bed for a week, if not in the hospital. With our new law on llegals, there aren't any mexicans standing on the street corners looking for day work anymore.

If I eat the beans and peas do I still get the soil benefits? I guess I still get the benefits of organic matter and roots breaking up the soil but what about nitrogen fixation?

Tracydr, sorry to hear about your injury. Take care of yourself, you are actually very lucky to still be gardening after that.

Do you have anyone else who could till for you? If not, there is lasagna mulching, using cardboard and mulch to hold water in the soil and soften it. In other areas you could pile on grass clippings and fall leaves but maybe Phoenix does not have alot of sources for that. Can you look up golf courses in Phoenix and ask them for their grass clippings? If they have to pay to dump that, they might dump it at your house for free. Same for parks, any buildings that maintain a lawn or that sweep up fallen leaves but you may get seeds and yard trash that you'd have to screen out of it. There are riding stables there, aren't there? Call them all and ask if they will dump spoiled hay or stable cleanings at your location. Ask at supermarkets for spoiled produce. Pile it all on your clay and let it compost, plant in that. If you use large cardboard, remove any big brass staples first. Check the Frugal Gardening Forum for ideas on free or cheap mass quantities of mulch. If you can't rototill, you can at least pile everything on.

By harvesting the beans you do not deprive the soil of the nitrogen removed from the air by the leaves and fixed by the roots. It's a relatively small amount of nitrogen anyway. If you could get chicken manure to apply, your bean nitrogen would be a drop in the ocean. I usually pull out and burn all bean, tomato and vegetable vines to stop the harboring of viruses, fungi, insects and eggs that feed on those plants specifically, and get organic matter and compost from other sources like the ones mentioned above. Best of luck, hope you can get a good garden going there. Clay in the desert is better than sand, it will hold water, you just need to get mass quantities of organic matter in there.

I used to live in the high desert, once helped a family with horses in a sand paddock who wanted a garden. These smart Arabian horses had been pooing in one location instead of all over. In 2-3 days I wheelbarrowed it all into the garden and made a berm 2.5 feet high by 6 feet wide by 10 feet long. (I was young)You should have seen all the green things that came out of that berm after a light watering. Come to think of it now, the pile must have been sprouting fresh greens all the while it was in the paddock, and the horses kept it nipped down.

There used to be lots of ranches all around Phoenix. I'd suggest putting up notices and calling them all and begging them all to dump any manure on your garden. Take down any fence and put up a sign asking for manure and compost to be dumped here. Make up maps with directions and give them to ranchers and parks workers, also contact the utilities that cut back trees from powerlines, ask for chipped tree cuttings to be dumped. You could even check with water treatment to ask for sewage sludge if you feel brave, that's what Milorganite is made of. Not to mention the many possible sources of industrial organic matter like spoiled food or food byproducts.

One final idea, prickly pear is very easy to cut down with a shovel and pick up with a pitchfork. Its loaded with water. You could ask landscapers to dump their cactus cuttings at your location. I just don't know how long it takes the spines to break down to where they are no longer a hazard. Probably prickly pear breaks down sooner than barrel cactus, for instance. If you did get a barrel or saguaro maybe you could take a propane weed burner to the outside or just pile up dry brush or spray with kerosene and burn off the outside spines. DO NOT use gasoline, you don't want a cactus bomb explosion.

Prickly pear has no internal woody skeleton at all, it's like a big celery with spines instead of strings, and it can get huge and people just want it out of their yards. If you could get landscapers to dump a few dozen cubic yards of prickly pears on the clay then cover it with a couple feet of manure and cover that with cardboard and plastic, I think you could just put your seeds in and step back fast.

PPS, Just Google Jacobs Cattle bean, it's common and for sale everywhere.