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Selçuk Üniversitesi (2009)

Physical, chemical, mineralogical properties and formation of the soils developed on volcanic material under semi-arid conditions

ALP Sidika

Titre : Physical, chemical, mineralogical properties and formation of the soils developed on volcanic material under semi-arid conditions

Yarı kurak iklim şartlarında volkanik materyal üzerinde oluşan toprakların fiziksel, kimyasal, mineralojik özellikleri ve oluşumu

Auteur : ALP Sidika

Université de soutenance : Selçuk Üniversitesi

Grade : Master 2009

Soils that are forming on volcanic parent materials have unique physical and chemical properties and in most cases on wet and humid climates are classified as andisols. Weathering processes and neoformation of minerals in volcanic soils have been studied extensively in humid climates but little data are available on these soils in arid and semi arid regions. Also studies on soils developed on volcanic materials are insufficient in Turkey compared to their distribution. The objectives of the present work were to asses the influence of climate and other soil forming factors on physical, chemical and mineralogical characteristics and pedolojical processes responsible for soil genesis and soil classification of five volcanic soil profiles derived andesitic parent material. The main purpose of this study is to examine of the soils that are forming on volcanic materials under semi arid climate in Konya (Turkey) meet the requirements to be classified as andisols. For this purpose samples were taken from the horizons after their macromorphological identifications completed in all profiles and analysis for physical, chemical and mineralogical properties carried out. These soils are characterized a medium and fine texture, low organic matter content, low cation exchange capacity (CEC) and soil moisture retention. The results revealed the amount of sand and coarse silt fractions were higher than 30% in all soils. The bulk density is higher than 0.90 in all profiles. In general phosphate retention is low. It is higher than 25 % in the profile 3 and profile 4. But it is lower than 85% in all profiles. The Al + ½ Fe percentages (by ammonium oxalate) are lower than 2 % in all profiles. pH values in NaF are lower than 9.5 in studied soils. Selective extraction give in all horizons the following relationships Fed>Feo>Fep and in most horizons Alp>Alo>Ald. Extraction with sodium dithionite ? citrate, acid ammonium oxalate and sodium pyrophosphate showed that in contrast to soils usually forming on volcanic material world wide soils lack noncrystalline minerals like allophone, imogolite an iron humus complexes. The only noncrystalline minerals are present and in great quantities Al-humus complexes and in little quantities Ferrihydrite. Crystallized Fe minerals were higher than the other Fe minerals. Some selective dissolution analyses index results showed that traces amount amorphous material should be present in profile 3. Feldspar, cristoballite and quarts were more common primer minerals. Hematite, cummingtonite and maghemite were also found in some profiles. X-ray diffraction indicates kaolinite and illite were dominant minerals in clay fraction. Furthermore considerable amount of chlorite-smectite interstrafied was occur in clay fraction. The local climate which due to its short wet season and extended dry season, lower degree of leaching prevent rapid soil genesis and caused an increase in Si concentrations in the soil solution and favorite neogenesis of crystalline clays such as kaolinite and illite, consuming a large amount of Al and Si derived from the parent material as opposite to poorly crystalline colloidal constituents such as allophone. The major factors determining soil genesis on the Mt. Erenler would appear to be climate, topography and nature of parent material by affected leaching regime and weathering rates


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