After spending some time in the dry desert in Chile, you start to realize how different a desert is from ordinary land. It´s not just lack of water - though that´s the ultimate cause. It´s also that there´s no ´´soil´´.
At school we did an experiment to discover the organic content of soil, by baking some in the oven to kill the living stuff. After which it´s mass had reduced to about 80 something percent of the original.
The desert has sand, and loose stones and rocks. Different granularities of powder and minerals. But no organic material binding it together.