Mulching is an integral part of desert gardening. It covers the soil. It reduces evaporation caused by sun and wind exposure. It helps ameliorate temperature extremes, and it prevents erosion.
Additionally, mulch stifles (or at least limits) the growth of weeds, thereby reducing competition for water and nutrients.
There is an almost endless variety of mulch...limited only by our imagination and a few basic principles. You can buy mulch from your local nursery. Or you can scavenge.
Related Article:Miracles of Mulch