Assessment of Biogeochemical–Mineralogical Characteristic and Weathering Indices of Soils Developed on Basaltic Parent Material and Toposequence Under Subhumid Ecosystem

Abstract

Especially in local areas, the formation of different soils on the same parent material is closely related to the topographic position, which has an important effect on the morphological, mineralogical, biological, and weathering processes of soils. Because, topography affects the distancing of water and other materials from the soil or addition of soil. Besides mineralogical and geochemical events occurring due to topographic change in soils with different development levels on basalt parent material under semitemperate ecological conditions, the purpose of this study is to examine the changes in the biological properties of soils with microbial biodiversity that affect these changes. For this purpose, six soil profiles representing high land plateau, high land back slope, low land plateau, low land back slope, toe slope, and foot slope were examined, which show distribution on the section in the South–North direction on basalt parent material of Engiz Çayı Basin, Turkey. Since soils formed on high slope land have poor profile development, they are described as young soils and classified in the Entisolls, and others are classified in Inceptisol and Vertisolls according to their horizon developments. pH values of surface horizons of all profiles range between 6.74 and 8.28, while organic matter values range from 1.54 to 3.53%. Although the dominant clay mineral is Smectite especially in surface soils, kaolinite clay mineral is also available in Entisol soils. Soil weathering rates are generally between very little weathering and moderate weathering, and Base/R2O3 values are determined between 0.5 and 1.3. Besides, it was determined that fungi has the most diversity among microorganisms of soil formed on basalt and actinobacterium varieties have the most diversity according to bacillus groups. Moreover, in this study, it has been determined that the isolated Actinobacteria members have gene regions that synthesize molecules called siderophores. This case has also been proposed as evidence that Actinobacteria members contribute to soil formation processes.