Desert soil characteristics, which generally apply to any type of desert soil, include (but are not limited to) a mostly sandy soil composition, very little moisture, and lack of nutrients. A desert soil’s nutrients, or lack thereof, can contribute to its physical appearance and feel. For instance, nutrient-rich, moist, desert soil will have a thick texture and almost dirt-like appearance, while dry, infertile desert soils can blow away in the wind and are practically all sand. The texture of a type of soil depends on three things – sand, silt, and clay. Some types of soil have mostly clay, while others, such as desert soils, have mostly sand. Typically, a soil that can allow plants to thrive contains equal parts of at least two of those factors. Garden soils often have equal parts of silt and sand or a generous combination of all three. When it comes to deserts, 90-95% of their composition is sand.Deserts are unique because of how it can still maintain life in some regions, even without a load of nutrients and water on standby. The physical texture of desert sand is dry and coarse, with large particles that come from eroded rocky parent materials.Deserts also have a low amount of organic material. Since water is a rare occurrence in deserts, fewer animals are living in them and thus, less decomposing organisms. Soils that are rich in organic material are more life-sustaining. Air is abundant in desert soils. Air in between the sand particles is what allows the desert sand to fall easily between your fingers and be picked up so easily by the wind. Thick, black soil has less air in its composition because it is compacted with a high amount of water and organic matter. Some deserts have red sand, some have white, and some are golden-brown. Desert soil takes on the color of the sand it contains. The color itself comes from its mineral content. Red sand soils have high levels of iron, desert soil from white sand typically has gypsum, and yellow sand soils have quartz. The horizons in a desert soil profile show the different types of sand, rock, and minerals that have formed the soil over time. The horizons in a desert soil usually start with a hard desert pavement as the top layer – most desert soils are dry, and so the surface remains compacted and brittle. Below the thin first layer of humus, the layers of the desert soil usually include thick, dry accumulations of clay, calcium carbonate, and soluble salts, along with rocky parent material. There is an exception for arctic desert soils that have a layer of permafrost deep in the soil.