A study of Vertisol genesis in North Eastern Greece

Abstract

Four pedons from the alluvial plain of Drama (NE Greece) were investigated in order to provide detailed information on their morphology, chemical, physical and mineralogical properties, classification and genesis. The clay content of all the samples is relatively high (> 35%). Soil reaction with HCl ranges from slightly alkaline (7.2) to alkaline (pH 8.3). The organic matter content ranges from 0.53 to 1.03% in the surface horizons, while the other horizons contain considerably less. The CaCO3-equivalent content ranges between 0.1% and 18.1%. Due to ploughing, gilgai microrelief is absent, but slickenside was apparent in all of the soils studied. Smectite (montmorillonite) is the dominant clay mineral and was mainly inherited from the parent sediments and by neoformation. High smectite content, in combination with alternating wet–dry periods (xeric soil moisture regime), results in the formation of the morphological characteristics that are typical for Vertisols. The pedons located in the highest points of the alluvial plain were classified as Chromic Haploxererts and those in the lowest landscape were classified as Typic Haploxererts. Free iron oxides range between 1.3 and 1.9% for the Chromic Haploxererts to only 0.4–0.9% for the Typic Haploxererts. The properties of these Vertisols reflect the impact of climate (alternating wet–dry periods), landscape position (alluvial plain; seasonally water saturated), and parent material (clayey, smectite-dominated fluvio-lacustrine, highly calcareous sediments).