Published in Scientific Papers. Series A. Agronomy, Vol. LXI, Issue 1
Written by Tina JAHAN, Shahram MANAFI
Argillic horizons are subsurface diagnostic horizons and presence and identification of argillic horizons in soils of arid and semiarid regions can be used as an important tool for soil classification, interpretation of soil forming processes and condition of their formation. In this study, argillic horizons were investigated micromorphologically and SEM technique. According to micromorphic studies, accumulations of illuvial clay in these soils are present as coatings on skeletal grains and void faces and their thickness varies from 20 to 30 μm and they comprise about 2-5% of argillic horizons. In some argillic horizons, illuvial clay has filled all of pore spaces and comprises about 10% of horizon. In some soils carbonates have covered clay coatings and in some cases clay coatings have been disappeared. Co-existence of argillic and calcic horizons is indicative of polygenesis. A calcic horizon containing illuvial clay is usually interpreted as indicator of climate change. Thus, the formation of complex argillic-calcic horizon shows that these soils are polygenetic and argillic horizons in these soils have been formed in a more humid past climate.
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