Saturday, 15 July 2006

Physical , Chemical and Morphological Properties of the Soils Developed on 5 Parent Materials in Northface of Elborz Mountain in Iran.

Hassan Ramezanpour and Raheleh Hesami. Guilan Univ, Shahrack Ghodse, Azadeh Avenue, No.23, Rasht, Iran

In most forested areas, fertility of the soil is reliant upon mineral weathering and organic matter decomposition. Five representative soil profiles from 5 forested mountain landforms including granite, andesite, phyllite, basaltic andesite and limestone parent material were selected and sampled. Based on X-Ray Fluorescence (XRF) and atomic absorption analysis, total iron (Fet)was lower in soil of granite than the others. Fed-o(citrate-bicarbonate-dithionite extractable Fe minus ammonium oxalate extractable Fe) and Fed/Fet were higher in surface soil of andesite and granite, however, maxima of Fed-o (crystalline free iron) and Fed were associated with maxima of clay accumulation (Fed/clay was relatively constant) in three others confirming higher age of Bt and comigration of some Fe and clay. Moreover, CEC and CEC/clay was lower in two surface soils derived from granite (CEC/clay=0.25) and phyllite(CEC/clay=0.28) which confirmed XRD data implying chlorite ,illite and HIV in these two soils compared to others with higher ratio(0.51)with more smectitic clay minerals. Total Al (Al2O3 of <2mm soil fraction) was relatively high in depth (low SiO2/Al2O3), whereas TiO2 content were higher or constant (in phyllite) in surface, suggesting that Al mobilization occurred within the soil profile due to low pH (5 to 6 in 1:1 H2O) or through dissolved metal-organic species. Morphological features showed that soils from andesite and granite (Udorthents) had no clay illuviation and no development but the others (Hapludalfs) had more solum thickness with maximum in basaltic andesite. However, crystalline pedogenic iron showed that soils developed on andesite were older than granite and soils derived from phyllite were older than the two others. Key words: mobilization, crystalline, parent material.

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