Effect of Different Geomorphologic Surfaces on Soil Evolution Using Pedogenic Changes and Various Froms of Iron in Marand Region, East Azarbaijan

The soil evolution of a region is function of type and intensity of soil forming factors and processes and can be studied using some soil properties such as pedogenic Iron (Fed) content in A and B horizons and its transformation with time and accumulation index of Iron oxides. In this research work different forms of Iron oxides were studied in nine soil families from eleven soil profiles of Marand region. The dominant geomorphologic units in the study area were rock pediment، mantled pediment، piedmont plain and alluvial plain and according to soil-geomorphology relationships، eight geomorphologic surfaces were diagnosed inside the units. Based on soil morphological and physico-chemical properties and different forms of Iron oxides significant correlation were observed between total Iron (Fet)، pedogenic Iron (Fed) and noncystalline Iron (Feo) as well as Iron forms with each other. The variations of different Iron forms followed the geomorphologic units and increased from mountain to alluvial plain units. But Fet، Fed and Feo changes in each unit depended on stability of geomorphologic surfaces. The highest (11. 24 g/kg) and lowest (1. 53 g/kg) Fed were observed at buried argillic horizon in alluvial plain and mountain، respectively، which showed instability of mountain unit. The soils of stable surface of mantled pediment (Smp) surface were more developed by continuity of soil forming processes and the soils of mountain showed less development due to high slope and limited soil forming processes progressing.