THE FEATURES OF SIMILARITY AND DIFFERENCE IN THE MICROSTRUCTURE OF BOGHARIC AND IRRIGATED SOILS OF KASTANOZEM-SOLONETZ COMPLEXES OF THE PRISTAVROPOLSKAYA SLOPING PLAIN

Abstract

A comparative analysis of microspecificities of agrogenic soils of solonetzic com-plexes of inclined plain was conducted to create trends of elementary soil-forming processes under different types of anthropogenic changes (for plowing and irrigation). The task is solved with the help of Olympus BХ51 polarization microscope equipped with Olympus DP26 digital camera and Stream Basic software, which allows us to visualize the results of modern and/or relict process better. The investiga-tion objects are the soils of kastanozem-solonetz complexes of the Stavropol inclined plains of the bogharic and irrigated area. Common microspecificities for all studied soils are numerous carbon particles, humus-ferruginous micronodules and ring-shaped orientation of fine-silt and fine-sandy silicate particles. The first two microspecificities allow us to propose there a weak manifestation of the quasi-gley process that probably was inherited from the pre-agrogenic development of the investigated soils. The ring-shaped orientation of large fractions speak about the cryogenic textural reconstructions of loess-like loam. The impact of irrigation is more clearly manifested in the micro-structure of the arable horizons of irrigated soils: platy organization of surface layers; increased content of fine-dispersed brown humus; increased activity of soil micro- and mesobiota (well-aggregated lumpy-granular microstructure) in the lower parts of the arable horizon. In the subsoil horizon of the residual solonetsic kastanozem under ir-rigation, a decrease in the amount of clay coatings occurred, which was manifested as a decrease in the intensity of the solonetzic process. There also occurred some decrease in the total content of clayey particles, which was a consequence of the process of their eluviation acceleration. There was also observed the reduction of birefringent effect of finely dispersed material, which was a consequence of the process of clay plasma deferrization occurrence. There was also observed the increase in the number of pe-dotubules, bioaggregates, coprolites, biochannels, which were the consequence of the increased biogenic processing. In the subsoil of meadow-chestnut soils under the impact of irrigation, a change in the structure from angular-block to lumpy-grained is revealed. Which was a result of increasing biogenicity. New formations appear within the calcareous horizons due to irrigation. For example, in the upper parts, clayey coatings occurring along the pore walls are the result of eluvial-illuvial redistribution of silt due to migration from the upper horizons. In the lower parts, there is significant recrystallization of carbonate rock grains, destruction of the white soft spot and the formation of micrital hypocoatings in the near-pore space of the pedal mass.