Pseudogleyed loess derivates – The most common soil parent materials in the Pannonian region of Croatia. (20th November 2018) - Rubinić, Vedran
Abstract: Loess-derived sediments represent the most widespread soil parent materials in the Pannonian region of Croatia. Pseudogley, as the most common soil type in this region, developed mainly on such parent materials. Pseudogleys largely correlate with the WRB Reference Soil Group of Stagnosols. On the General Soil Map of Croatia at scale 1: 50 000 (GSM of Croatia), the distinction is made between Pleistocene loams (PL) and loess as Pseudogley parent materials. The initial purpose of this research was to investigate if the criteria for this distinction were clear and consistent and if the terms used for labeling these parent materials were adequate. Hence, we investigated parent materials of 18 Pseudogleys across 6 different locations (three on loess and three on PL) in the Pannonian region of Croatia. We analyzed their morphology (including micromorphology of three representative parent materials), particle size distribution, total porosity, pH, and mineral assemblages (by modal analysis of three representative parent materials). Following these analyses, no systematic differences between the loess parent materials and the PL parent materials were found. Additionally, it was concluded that, due to significant geogenetic and/or pedogenetic alterations of all studied parent materials, none of them should be labeled simply as loess. Hence, parent material at one location was labeled as leached loess derivate, and parent materials at all other locations were labeled as pseudogleyed loess derivates. Both types of parent materials were described in detail and defined. In addition, the terminology and the classification of loess(-derived) parent materials in general was proposed. The analyzed pseudogleyed loess derivates were not completely uniform across the investigated locations. Primarily, this was due to the polygenesis of loess (reflected by differences in particle size distributions and compositions of light and heavy mineral fractions). Secondarily, it was due to the 600–1100 mm MAP gradient along the study region (reflected by differences in pH values and properties of redoximorphic features). Although pedogenesis of the investigated parent materials might have started already during the Late Glacial and have continued throughout the Holocene at varying (and overall decreasing) rates, their morphology indicates that pseudogleization and lessivage are still active processes, which occur simultaneously in the analyzed parent materials and agree with the present climate.