Ancient Irrigated Soils of the Bozok Archaeological District, Northern Kazakhstan (11th to 12th Centuries)

Abstract

Results of an interdisciplinary (archaeological and pedological) study of the ancient soils in the Bozok district (8th to 15th centuries) are presented. Part of the district is a complex irrigation system dating to the 11th to 12th centuries. To detect the traces of ancient irrigation, surface and buried soils were studied. Results of the morphogenetic analysis, as well as the assessment of physical and chemical properties of soils and their microbiomorph composition, suggest that soils relating to various functional parts of the irrigation system within the same catena indicate agricultural use. The multivariate analysis revealed significant differences between irrigated and non-irrigated soils, and a high correlation between the former and the presence of diatom algae, sponge spicules, and phytoliths of Phragmites spp. in the microbiomorph fraction. The observed differences in the microbiomorph concentrations between soils in subordinate catena positions confirm the impact of irrigation on the transformation of the microbiomorph profiles of the ancient irrigated soils in terms of relief. The taxonomy of the buried and anthropogenically transformed surface soils at the type level suggest that over the last 900 years the pedogenic conditions changed from automorphic humus-accumulative to more semihydromorphic solonetzic ones.