Geochemical Soil Associations
(11): They are corresponding to principal trends of soil
formation.Soil classification in Russia continued the general approach first outlined by Dokuchaev. This includes a strong emphasis , evaluating soil properties and the pedogenic processes in the solum in relation to soil forming factors. Today three main components are used: Soil properties, soil forming factors or pedogenic processes, and the agents or factors of soil formation (ecological-genetic classification approach). In the Russian soil classification they focus on the action of soil forming factors to produce soil properties in kinds of profiles called '(genetic) Soil Types' (Ivanova, 1956).
A somewhat different approach to classification of soils of Russia has more recently been offered by Glazovskaya (1983):
Geochemical Soil Associations
(11): They are corresponding to principal trends of soil
formation.
Soil Generations: They
show similarity in acidic-basic and oxidation-reduction reactions and
in specific products of soil formation.
Soil Families: They have
not only a similar profile structure, with similarity of composition,
but also similar kind and arrangement of the products of soil
formation in these horizons.
Soil Types: They have
qualitative similarity of profile structure and with similarity of
current processes due to thermal conditions. The criteria for
dividing Soil Families into four Soil Types are given as presence of
permafrost, seasonal freezing but with permafrost absent, absence of
seasonal freezing but with periodic temperature drops almost to the
freezing point at the soil surface, and stable and constant
above-freezing temperatures throughout the soil profile.
References
Glazovskaya M.A., 1983. Soils of the World. Vol.1. Soil Families and Soil Types. New Dehli, India: USDA and Nat. Sci. Found., Washington, DC. Transl. from the Russian.
Ivanova E.N., 1956. An Attempt at a General Classification of Soils. Transl. from Russian. Pochvovedenie, 6: 82-102.
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3) Soil Formation