Transformation of dry-steppe soils under long-term agrogenic impacts in the area of ancient Olbia

Abstract

The results of the study of dark chestnut soils (Kastanozems) differing in the time and intensity of their agricultural use and in the duration of the fallow stage are analyzed. Soil sequences differing in the character of their agrogenic changes were studied in the rural area of ancient Olbia with a centuries-long history of diverse economic activities, including crop growing. The agrophysical, agrochemical, and geochemical characteristics were examined in order to assess the soil transformation processes in a sequence from the initial virgin soil to the cultivated soil of the antique period in the fallow stage, the soil under recent (three-five years) fallow, and modern plowed soils in the area of ancient farming. It was found that the contents of humus, total nitrogen, and carbonates; the water stability of the soil aggregates; and the portion of coprolites in the agronomically valuable aggregate fraction are sensitive indicators of the duration of the agrogenesis in the dark chestnut soils. The manifestation of agrogenic processes at different hierarchical levels of the spatial and temporal organization of the soil system depended on the duration and intensity of the farming practices. Temporal abandonment of intensely cultivated lands in traditional farming practices with periodic initiation of the natural processes of restoration of the soil fertility can be considered a suitable measure to regulate agrogenic loads on the soils with the aim to enhance the self-organization processes in the soil system.