This¬†video will show you how to take good care of your trees by feeding the roots with verticle mulching. Drill holes in the soil about 15" deep, and put in compost and nutrient materials. Use an auger to drill several 3" holes around the tree. It works best when you moisten the soil first. Use a spade and trowel to fill the holes with the compost and nutrient mixture. You can also use a spading fork to break the soil, sprinkle the mixture on, and the mixture will fall into the cracks in the soil. This is a good technique to help nourish trees in the soils of the Southwest.