Hasan Huseyin OZAYTEKIN & Sidika OZCAN
Selcuk University, Agriculture Faculty, Department of Soil Science and Plant Nutrition 42031 Konya, Turkey
e-mail: hhuseyin@selcuk.edu.tr

MASS BALANCE OF SOIL EVOLUTION ON MT. ERENLER VOLCANIC MATERIALS IN CENTRAL ANATOLIA - A CASE STUDY

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Mass-balance analysis was used to quantify elemental losses, gains and transformations for Soil developed on Mt Erenler andesitic rocks. Net losses of the main elements (Ca, Mg, K, Na, Fe, Al, and Si) by means of mass-balance calculations of the soils were examined with, selective dissolution analyses, Xray diffraction and some chemical properties. These soils are characterized as medium- and fine-textured with low organic matter content. Bulk density was greater than 0.90 g cm^–3 in all profiles. Selective extraction yielded the following relationship in all extractions: Fe_d > Fe_o > Fe_p. Additionally, in most horizons: Al_p > Al_o > Al_d. According to selective dissolution analysis results and index values, noncrystalline minerals such as allophane, imogolite, and iron-humus complexes have not formed in these soils. Feldspar, cristobalite, and quartz were the most common primary minerals. Hematite, cummingtonite, and magnetite were also found in some profiles. X-ray diffraction indicated that kaolinite and illite were dominant minerals in the clay fraction; furthermore, a considerable amount of smectite was found in the clay fraction. Bulk density ratios of soils and bedrock as well as elemental concentrations referenced to Zr, were used to estimate strain and open-system mass-transport functions through the soil profiles. Estimated strains of the three soils indicated substantial volumetric changes during C horizon and saprolite formation. Dominant soil-forming processes include 1. desilication and loss of base cations and Al from the solum, 2. transformation of iron and aluminum from sand and silt-size fractions to secondary clay and crystalline Fe minerals. Silica represents the largest mass loss of any element from the system and varies from 27.14 to 107.38 kg m^-2 Base cations represent only a small portion of the soil mass, but up to 34.3 % (5.44 kg m^-2. of the sodium present in the parent material is lost due to weathering and leaching. Our results imply that the rate of elemental mass-balance changes is determined by factors influencing its leaching (altitude, facing sites, topography, elevational gradient, slopes, and temperature) in the studied area.