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Molchanov E.N.,Dokuchaev Soil Science Institute
Eurasian Soil Science | Year: 2010

The published and author's data on soil-forming conditions, morphology, substance composition and physicochemical properties, total chemical and mineralogical composition, and micromorphology of mountain-meadow soils of the Western Caucasus Range are analyzed. On the basis of the analytical data obtained, the transformation of minerals and features of chemical element profile patterns developed in the course of soil formation are characterized. The main processes accompanying the transformation of mineral and organic parts of the soil mass and migration of soil-formation products are described. Soil formation is shown to be accompanied by two major elementary soil processes developing with participation of soil biota: humus accumulation and clay formation. Ways to improve the classification of mountain-meadow soils are proposed. © 2010 Pleiades Publishing, Ltd. Source

Rozhkov V.A.,Dokuchaev Soil Science Institute
Eurasian Soil Science | Year: 2014

The dualism of notions is a common form of our perception of the world. Thus, the notion of a classification system actually includes two complementary parts: taxonomy and meronymy. Taxonomy describes the structure of taxonomic units (taxa) and their relationships, whereas meronymy deals with the structure of the archetypes and meronyms (parts of the whole) composing them and linked by associative relations. An archetype can be defined as a generalized image consisting of meronyms that can be definitely described by a set of characteristics. Each archetype in meronymy has a corresponding taxon in taxonomy. The notions of the object of classification and the particular objects (things) representing it are explained. The notions of soil objects are somewhat different and depend on the goals and kinds of classification (conceptual, physical, or imaginable). Substantive (natural) classifications that encompass the entire set of conceivable objects (entirety) can be referred to as intensional classifications. They should be distinguished from extensional classifications dealing with a particular group of objects (data) and aimed at their arrangement in a convenient way. Extensional soil classification systems are those systems that actually arrange the lists of known soils into some order according to the rules formulated by their authors. © 2014 Pleiades Publishing, Ltd. Source

Gerasimova M.I.,Moscow State University | Khitrov N.B.,Dokuchaev Soil Science Institute
Eurasian Soil Science | Year: 2012

Three soil classification systems-the World Reference Base for Soil Resources (WRB), Soil Taxonomy, and the recent Russian system-were used for the identification of 17 soil profiles in southwestern Poland; all the systems put emphasis on the soil properties as diagnostic criteria. Different soils developed on glaciofluvial plains, loessic uplands, and in the Sudetes Mountains were classified. The best correlation between the classification decisions in the different systems was obtained for the most widespread soils owing to the similarity of the diagnostic criteria, which were essentially close although not coinciding. The most prominent divergence between the systems in both the names and the taxonomic categories of the soils was found for the polygenetic soils and for the soils developing from the lithologically discontinuous parent materials. It was also found that the diagnostic elements differ in terms of their taxonomic importance among the classification systems. © 2012 Pleiades Publishing, Ltd. Source

Gunina A.,University of Gottingen | Gunina A.,Dokuchaev Soil Science Institute | Kuzyakov Y.,University of Gottingen
Soil Biology and Biochemistry | Year: 2015

Sugars are the most abundant organic compounds in the biosphere because they are monomers of all polysaccharides. We summarize the results of the last 40 years on the sources, content, composition and fate of sugars in soil and discuss their main functions. We especially focus on sugar uptake, utilization and recycling by microorganisms as this is by far the dominating process of sugar transformation in soil compared to sorption, leaching or plant uptake. Moreover, sugars are the most important carbon (C) and energy source for soil microorganisms.Two databases have been created. The 1st database focused on the contents of cellulose, non-cellulose, hot-water and cold-water extractable sugars in soils (348 data, 32 studies). This enabled determining the primary (plant-derived) and secondary (microbially and soil organic matter (SOM) derived) sources of carbohydrates in soil based on the galactose + mannose/arabinose + xylose (GM/AX) ratio. The 2nd database focused on the fate of sugar C in soils (734 data pairs, 32 studies using 13C or 14C labeled sugars). 13C and 14C dynamics enabled calculating the: 1) initial rate of sugar mineralization, 2) mean residence time (MRT) of C of the applied sugars, and 3) MRT of sugar C incorporated into 3a) microbial biomass and 3b) SOM.The content of hexoses was 3-4 times higher than pentoses, because hexoses originate from plants and microorganisms. The GM/AX ratio of non-cellulose sugars revealed a lower contribution of hexoses in cropland and grassland (ratio 0.7-1) compare to forest (ratio 1.5) soils.13C and 14C studies showed very high initial rate of glucose mineralization (1.1% min-1) and much higher rate of sugars uptake by microorganisms from the soil solution. Considering this rate along with the glucose input from plants and its content in soil solution, we estimate that only about 20% of all sugars in soil originate from the primary source - decomposition of plant litter and rhizodeposits. The remaining 80% originates from the secondary source - microorganisms and their residues. The estimated MRT of sugar C in microbial biomass was about 230 days, showing intense and efficient internal recycling within microorganisms. The assessed MRT of sugar C in SOM was about 360 days, reflecting the considerable accumulation of sugar C in microbial residues and its comparatively slow external recycling.The very rapid uptake of sugars by microorganisms and intensive recycling clearly demonstrate the importance of sugars for microbes in soil. We speculate that the most important functions of sugars in soil are to maintain and stimulate microbial activities in the rhizosphere and detritusphere leading to mobilization of nutrients by accelerated SOM decomposition - priming effects. We conclude that the actual contribution of sugar C (not only whole sugar molecules, which are usually determined) to SOM is much higher than the 10 ± 5% commonly measured based on their content. © 2015 Elsevier Ltd. Source

Data on clayey swelling soils with gilgai microtopography are systematized. Classifications of gilgai microtopography representing regularly alternating microhighs and microlows are discussed, and its geometric parameters under different landscape conditions are considered. Gilgai microtopography is developed within flat or slightly inclined elements of the mesorelief composed of swelling clays of different geneses. These materials are characterized by the high swelling–shrinking capacity upon wetting–drying cycles owing to the predominance of clay minerals of smectitic group. These processes are especially pronounced under conditions of the impeded surface drainage and contrasting of the wet seasons with strong soil moistening by atmospheric precipitation or surface water and the seasons with deep soil drying under the impact of physical evaporation and transpiration. The areas with gilgai microtopography have complex soil cover patterns composed of Vertisols and vertic soils. Their formation is related to lateral movements of solid material in the soil profiles and along the curved soil surface. The morphological types of soil complexes in such area are systematized. © 2016, Pleiades Publishing, Ltd. Source

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