Major Soils, Properties, and Classification

Abstract

Iran is a large territory with diverse climatic condition, geologyGeologyand vegetation cover which have led to formation of different soils that cover about 58% of the total land surface. The remaining areas are composed of bare mountains, sand dunes, playas/salinas, etc. Four major agro-climatic zones are distinguished: (i) arid region, (ii) semiarid region, (iii) humid and sub-humid region of the southern coasts of the Caspian Sea, and (iv) tropical semiarid regionSemi-arid regionof the South. The AridisolsAridisols(Calcids, Gypsids, Salids, and Cambids)Cambids, Entisols (Orthents and Fluvents), and Inceptisols (Xerepts, Ustepts, Udepts, and Aquepts)Aqueptsconstitute about 97% of the total soil resourcesSoil resourcesof the country, i.e., in the arid and semiarid zones. Other soil orders including MollisolsMollisols, AlfisolsAlfisols, and UltisolsUltisols, which have mainly developed in the Caspian SeaCaspian Searegion, constitute less than 3% of the total soil cover. In this chapter, we define the extent of the soil orders, suborders, and dominant great groups in each region and describe main morphological and physicochemical properties of soils representing various soil great groups and their potentials for agricultural use.