Deserts are ideal places to grow most crops. Abundant sunlight and low humidity prevents molds and blight. Few plants outside the watered areas to harbor insects. No excess rainfall to leach away your expensive fertilizers and drown your plants.
I have farmed spring potatoes in Florida. Seed pieces washed out of the ground by heavy rainfall. Seed pieces rotting in water soaked soil. Trying to harvest the crop from a muddy field is akin to being sent to Devil's Island.