Variations in properties of the loess derived soils as affected by geomorphic positions in two different climatic regions of Golestan Province

In order to study the effects of climate and geomorphology on the development of soils and their physico-chemical peroperties, two transects on the loess parent material were selected in two regions of Golestan Province. The regions were: Huttan (Maraveh Tappeh area) and Gorgan with aridic-thermic and xeric-thermic soil moisture and temperature regimes, respectively. Four pedons in Hutan and five in Gorgan were studied. Results revealed that in Hutan area, Aridisols formed on summit and toeslope positions while on the shoulder and footslopes, Entisols were dominant. In contrast, in Gorgan region, Inceptisols were the major members of the summit, shoulder and footslope and Mollisols were dominant on the toeslopes. There were significant differences in soil physico-chemical properties such as texture, CaCO3 content and its leaching depth, organic matter, saturation percentage, acidity, electrical conductivity, cation exchange capacity and soil solution cations and anions in the two studied regions. There was higher clay in Gorgan area. In Huttan however more silt were observed. Carbonate was leached from the surface horizons and accumulated in the depth of soils of Gorgan area. Considering the organic matter and CEC, soils of Gorgan had more favorable conditions. Depth of leaching of calcium carbonate, its dissolution-precipitation processes, and the accumulation of organic matter were among the most important soil forming processes occurred in Gorgan area.