Study of Soil Evolution at Different Geomorphic Surfaces of an Elevation-Climatic Profile in Southeast of Ardabil

Soil evolution is the result of a combination of geomorphological and pedological processes. In this study to investigate the spatial variation of soil characteristics and determine the relationship between soil evolution and different geomorphic surfaces of epandage pediment, erosion pediment, slope surfaces, smooth surfaces, horst, lake deposits, alluvial fan, mountain ridge and circgue in an elevation-climatic profile in the Southeast of Ardabil 12 soil profiles were dug. After digging and field studies, physicochemical and clay mineralogical experiments were performed on the samples. The results showed that variations in weathering intensity and the types of soil forming processes at different geomorphic surfaces, had significant effects on soil properties and evolution and vertisols, mollisols, inceptisols, and entisols orders were identified. Smectite, vermiculite, kaolinite, and illite have formed the composition of evolved soil minerals, respectively and the relative amount of smectite varies from 78.5% at the epandage pediment to 12.3% at the mountain ridge. Also statistical comparison of the mean confidence interval of crystalline iron (Fed-Feo) by Bootstrap method showed that there were significant differences between geomorphic surfaces in terms of soil evolution and the highest amount of crystalline iron with mean of 6.372 g kg-1 was observed in epandage pediment with vertiolsols and the lowest value with average of 0.913 g kg-1 in alluvial fan with entiolsols. According to Spearman correlation test, crystalline iron had a direct relationship with clay percentage, calcium carbonate equivalent, pH and cation exchange capacity, but inversely with sand and organic carbon.