Rock Hard Dirt / Ground

First, test your soil. You will need to adjust pH first and foremost. If you have sodium issues, amend with gypsum.

I have been fighting this one in my wilderness garden. It happens when the sand/clay mixture dirt we have gets dried out and compacted. The broad fork will break it, but it takes time and lots of effort. Your best bet would be to let nature do the work. This will take a whole season or more, but you can use deep mulch and either plants or animals to do the work for you.

Plants: If you want to go the edible route, you can plant daikons, cowpeas, sunflowers, or brassicas in a thin layer of added topsoil. These plants will break through the hard compacted ground. as the plants grow, mulch around them until the mulch layer is about a foot thick. When they are done growing, cut them off at ground level and let everything rot. This adds carbon into the soil which keeps it from getting compacted.

Animals: You could raise chickens in tractor style coops, keeping deep mulch in the areas and letting the chickens work the area for a season or more until it's ready.

You could just let earthworms do the work. Layer a few inches of composted manure followed by a foot or so of mulch like hay, leaves, or grass clippings. After a season or two the ground beneath will have loosened up.

Broadfork: I have had success with turning rock solid ground into productive garden in less than a month. You will want to get about an inch of composted manure down in the area you wish to plant. you will want to water the area a few times until the ground beneath starts to soak it up a little bit. After a day or two of watering broad fork the area. It should be significantly easier to work. The manure will add carbon into the soil and keep it from re hardening.

Some other tips for dry gardens desert. Plant windbreaks. Plant some kind of native tree or shrub around the property to block wind and stop your topsoil from being eroded.

Try inverted hugelkulture. Basically bury logs underground to slowly rot and hold moisture.

Carbon: add carbon to the soil carbon holds onto moisture and nutrients to be released when needed to the plants. You can add carbon through mulch or compost, but the best way is with cover crops and perennials. Living plant roots constantly die and regrow. The roots that die are left behind to decay in the soil. Always keep life in the garden, and never pull roots out.

If you have land, the absolute best way to build soil is through ruminate livestock small pasture daily rotation. This style of husbandry mimics the large buffalo herds that once roamed the area. small areas were grazed, trampled, and fertilized by the daily habits of the herd. They would move on and wouldn't come back until the area had time to recover. Modern husbandry practices don't allow for this recovery, and don't concentrate the excrimates enough to mimic this process. Joel Salatin has done great work in this area.