Correlation of Soddy Calcareous Soils on the Soil Map of the Russian Federation (1 : 2.5 M Scale, 1988) and in the Russian Soil Classification System

Abstract

Updating of the Soil Map of the Russian Federation (1 : 2.5 M scale, 1988) is planned on the basis of the new classification system of Russian soils. At the first stage, soil information for each polygon on the map is transformed into this system with due account for new factual data. In this paper, we consider problems in reclassification of legend unit “soddy-calcareous soils, including leached and podzolized soils.” In dependence on the geographical position of particular polygons with these soils and the composition and properties of calcareous rocks, the soils of this legend unit are reclassified into different orders, types, and subtypes of the new classification system. The new soil names are introduced into the updated database to the vectorized version of the map. Thus, according to the thickness of the unconsolidated part of the profile, the former soddy-calcareous soils are specified into the orders of lithozems (<30 cm) and organo-accumulative soils (>30 cm). Within the latter order, the character of organic and humus horizons is taken into account in identification of the types of dark-humus, gray-humus, mucky–humus, raw-humus, and (probably) light-humus soil types with residual carbonates recorded at the subtype level. The types of raw-humus and light-humus carbolithozems are added to the classification system. An increased content of semidecomposed phytodetritus in the soils is reflected at the subtype level (the subtype of raw-humus soils). This level is also used to reflect the development of eluviation (eluviated soils), illuviation (clay-illuvial soils), and pedogenic transformation of middle-profile horizons (metamorphized, cryometamorphized, ferruginated, and gleyic subtypes) and the inheritance of some specific features of the parent material (red-profile soils). At the species level, the degree of leaching of carbonates from the upper part of the profile is indicated. Plowed soddy-calcareous soils are specified as agrohumus and agro-dark-humus soils. Geographical patterns of manifestation of these soil features and their “soil-ecological” logic are also discussed in the paper.