Dry Desert Soil Types

Coarse Soil

• Deserts are broken down into several types. The Sahara, the Mojave and the Chihuahan are some of the most renowned hot, dry deserts. Summer temperatures reach highs of 120 degrees Fahrenheit. Low humidity means low cloud cover and heat retention so night temperatures can drop to 1 degree Fahrenheit or below. Precipitation is limited. Temperatures and lack of rainfall contribute to the development of coarse soils. Weathering and breaking down of large particles does not occur in these climate conditions. The result is gravel, rock and sand. The limited amount of vegetation is responsible for coarse, sandy desert soil's lack of organic matter. Lack of weathering and disturbance tends to make desert soils high in nutrients and minerals. These nutrients are released when exposed to precipitation.

Fine Soil

• Coastal deserts are another desert type. Coastal deserts, like the Atacoma in Chile, contain fine, textured sand with a higher salt content than soils found farther inland. Coastal desert climates are less extreme than hot, arid deserts. The region receives slightly more rainfall. Daily and nightly temperatures are not widely variant. Due to the milder climate, mineral particles are weathered resulting in a finer soil texture. Plant life is more abundant, which in turn makes the area more hospitable to animal life. Plants and animals contribute to a higher organic matter content.

Calcic Soils

• Cross-sections of earth reveal layers of different soils, each exhibiting different colors and textures. These layers are called horizons. Soil horizons develop over time. Precipitation pushes some materials deeper into the earth while other materials are deposited on the surface. Dry desert soils often form a calcic horizon. Calcic horizons present as hard, white, impenetrable calcium carbonate deposits. The horizon's thickness depends upon its age. Over thousands of years, calcium carbonate deposited by dust, precipitation and wind accumulates forming 3-foot layers. Younger soils, or soils that receive more precipitation than others, may have calcic horizons of 6 inches or less. Calcium carbonate layers are not preset in non-desert soils because precipitation washes the carbonate away before layers form.

Clay Soils

• Young desert soils that develop over calcium carbonate based parent rock, such as limestone, are usually uniform in color and do not exhibit red, orange and taupe layers found in older desert soils. Orange, red and deep colored horizons are formed from clay particles that are not able to penetrate lower-lying calcium carbonate horizons. The calcium carbonate prevents clay particle seepage, essentially trapping clay particles and causing them to form argillic horizons. Clay particles are fine and compacted. When moist, these soils form a sticky muck. When dry, clay soils harden into impenetrable brick. Lack of precipitation allows clay soils to form the red horizons normally associated with desert areas of the southwestern United States. The deeper the color, the higher the clay's iron content. Again, lack of precipitation allows iron deposits to build up in the soil.