Trenches called swales hold and move water throughout the plantings eventually making the need to add water other than rainfall, unnecessary. Greening a desert has been demonstrated several times, creating an oasis in the middle of nothing in areas of low rainfall and poor soil. This does not happen instantly, but over several years.
The garden I am working on is in the front yard next to the driveway. I am not fond of people driving on the lawn. They do anyhow and park their big, ugly trucks on the lawn too. The closer they are to the door the better it seems. They won't be driving on the garden though. It is raised the width of a hay bale, almost 18 inches in this case.
After scraping the little topsoil off that there was, the next step was to cover the base with composting straw. This is freshly composting material from earlier this spring. It is hot and steaming and smelly, perfect for retaining some heat in the raised beds. Over that layer went a layer of well rotted two year old composted manure and straw and hay. This will retain moisture and provide nutrients to the deeper rooted crops. Then the topsoil and sod that was scraped off went over that as the final and third layer. The next step is to water the beds until they are saturated and cover them with a tarp, left in the hot sun to kill the grass and weeds in the topsoil, or at least, hopefully the grass in the sod clumps.
Then the tarps are removed and the garden is ready to plant. It should have lowered the level about a foot by then and it will continue to do so as the substrate turns to compost. There were no worms or life in the soil scraped off. I am quite sure the previous owners must have used some chemicals on their lawn, all 3 acres of it! There were few weeds in the lawn either, but I have carefully seeded dandelions and hope to improve the soil by having the dandelion roots pull up nutrients from deep down.
In the meantime, tomorrow, if time permits, I will water the beds and cover them with the salvaged hay tarps I scored for free after placing an ad on the local buy and sell site. There may be some tweaking necessary in the plantings, like a canopy layer, a vine layer and ground cover layer, but that will take time, even years. The garden is not for today, but for the future. Hopefully whomever buys the farm will appreciate the free food gardens that I am working to establish. Hopefully they won't destroy them and return the area to lawn. Hopefully….