Your Southwest Sod will be coming soon so it's time to prepare the soil for your new turf. Spray any unwanted plant growth with an appropriate herbicide like Roundup (best found at your local nursery or hardware store.). Clear away the rocks and debris. Next, spread mulch or gypsum on the ground 1 inch thick (about 8 cubic feet of mulch for every 100 square feet). Till to a depth of 4-6 inches and install your sprinkler system. Sprinkler heads should be 1 inch above the grade. Finally, level the area with a rake to a grade of 1 inch below sidewalks, driveways, and sprinkler heads.