Pedogenetic Analysis of Xerometamorphic Horizons of Chestnut Soils of the Northern Caspian Sea Plain

The paper characterizes the profiles of virgin chestnut soils and solonetzes in the north of the Caspian Lowland adjacent to the Dzhanybek Research Station. The aim of the study was to analyze the morphology, physical properties, and chemical and mineralogical composition of the so-called “xerometamorphic horizons” of chestnut soils in the research area. The initial hypothesis consisted in the general genetic similarity of xerometamorphic horizons with solonetzic horizons in the corresponding interrelated soils. Despite the general similarity of the morphological features and mineralogical and chemical composition of these horizons, there was a significant difference in the content of exchangeable sodium and in the presence of evidences of clay illuviation in solonetzic horizons. It is suggested that xerometamorphic horizons reflect the initial stages of formation of alkaline soils, which later underwent divergent pedogenesis. The proposal of a number of specialists on distinguishing the BMK horizon in soils used in agriculture and, accordingly, of the type of agro-chestnut soils is supported.