Soil evolution and climate dynamics in dry steppes of the Privolzhskaya Upland during the last 3500 years

The investigation of paleosols of different ages buried under archaeological monuments of the Bronze (16th–15th centuries BC), Early Iron (2nd–3rd centuries AD), and Medieval (14th century AD) ages demonstrated that the evolution of chestnut soils and solonetzes in the dry steppes of the southern part of the Privolzhskaya Upland during the past 3500 years manifested itself at the level of the genus and species characteristics of the soils, such as the degree of the solonetzicity, the humus content, and the content and composition of the soluble salts. The revealed regularities of the variations of the morphological, chemical, and microbiological soil properties in time allowed reconstructing the secular dynamics of the climatic humidity in the region. It was found that the humidization of the climate with a decrease in the degree of the climatic continentality took place in the middle of the second millennium BC. The Late Sarmatian Time (2nd–3rd centuries AD) was characterized by arid climatic conditions, whereas the Golden Horde time (13th–14th centuries AD) was marked by the general humidization of the climate. A gradual aridization of the climate began in the second half of the 14th century and continued in the 15th century AD.