Pedogenetic analysis of xerometamorphic horizons of chestnut soils of the Northern Caspian Sea plain

The paper characterizes the profiles of virgin chestnut soils and solonetz in the north of the Caspian lowland adjacent to the Djanibek reserve. The objective 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 was the general genetic similarity of xerometamorphic horizons with natric horizons in the corresponding conjugate soils. With the general similarity of morphological features, mineralogical and chemical composition of these horizons, there was a significant difference in the content of exchangeable sodium and in the presence of signs of clay illuviation in the natric horizons. It is suggested that xerometamorphic horizons reflect the initial stages of formation of alkaline soils, further diluted by divergent pedogenesis. The proposal of a number of specialists on the allocation of the BMK horizon in soils used in agriculture and, accordingly, the type of agro-soils is supported.