مقایسه سامانه های رده بندی آمریکایی و جهانی در توصیف ویژگی های برخی خاک های مناطق خشک و نیمه خشک ایران مرکزی

One of the main objectives of soil classification systems is to identify the differences of soil properties for management purposes. In this study, the efficiency of American and WRB soil classification systems were compared in order to describe some of soil physical, chemical and mineralogical properties in arid and semiarid regions of central Iran. Khatoon-Abad and Mobarekeh plains as arid regions and Koohrang and Shahrekord plains as semiarid regions were selected. Then, representative pedons of each plain were chosen from 16 excavated pedons and soil samples were taken from the genetic horizons to determine soil classification. Results showed that soil orders of both Koohrang and Khatoon-Abad plains are vertisols according to American soil classification system whereas based on WRB system, these soils are classified as cambisols and calcisols, respectively. On the other hand, both Mobarekeh and Shahrekord soils are classified as calcisols in WRB system whereas these soils are classified as aridisols and inceptisols, respectively, according to American soil taxonomy. None of soil classification systems could show the existence of gypsum in horizons lower than 100 cm of the soil surface for Mobarekeh soil. Clay mineralogy indicates that smectite is the dominant clay mineral in Koohrang soil as explains well at the family level of American soil classification system. Results suggest that WRB has somewhat higher efficiency rather than American soil classification system for the studied soils.