Aridisols are a soil order found in arid and semi-arid regions, characterized by a lack of organic matter and the presence of calcium carbonate or gypsum horizons. These soils are important in the study of desert ecosystems and land use, particularly in understanding soil fertility and the challenges of agriculture in dry climates.
Reference: Soil Survey Staff (1999). Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys. USDA Natural Resources Conservation Service.