Soils of Chalk Polygons of the Sub-Ural Plateau: Morphology, Properties and Classification

The unique soils of the chalky polygons soil complexes in the steppe zone of Common Syrt and the Sub-Ural Plateau have been studied. They are characterized by a combination of different age features formed in contrast environments. Modern features are the result of biogenic-accumulative processes, structuring, salinization and crust formation. The relict features are associated to paleocryogenesis, they include the paleo-permafrost complexes of block-pseudomorph, cryoturbations, paleo-permafrost wedges, accumulations and sorting of coarse fraction, etc. The good conservation of relict cryogenic features and modern cryogenic processes determine the uniqueness of these steppe soils. Such horizons and profile formula are not found in the existing diagnostic scheme for the classification and diagnostics of soils in Russia (CaDSR). In order to represent the features, modern image and genesis of these soils in the terminology of CaDSR, a new diagnostic horizon BCM cryostructural-metamorphic was proposed. The soils were diagnosed as cryostructural-metamorphic on microhighs, protohumic and lighthumus cryostructural-metamorphic on the microslopes, and lighthumus and lighthumus cryometamorphic in microdepressions of the chalky polygons. Relict cryogenic features are proposed to be taken into account in the classification of these soils at the level of soil genus with the prefix paleo. According to the WRB soils were classified as Rendzic Endoleptic Calcaric Phaeozem (Relictiturbic, Tonguic) in microdepressions, Skeletic Calcaric Regosol (Relictiturbic, Ruptic, Nudiyermic) in microhighs and (Relictiturbuc, Raptic, Ochric) in microslopes.