Photosynthesis, how plants survive. Sunlight is absorbed.
There are two main theories for the lack of organic material in desert soils. Firstly, the organic life in most deserts is so sparse that it cannot produce much organic matter. Secondly when things do die and decompose in the desert the heat and sunlight often bleach nutrients out of the matter before it is decomposes enough to be absorbed into soil
It’s carbon dioxide + water > glucose + oxygen + water and energy produced in the form of ATP