Oganesyan M. S., Stryzhak O. V., Osadcha O. V.

Oles Honchar Dnipropetrovsk National University

BIOGEOCENOTIC AND MICROMORPHOLOGICAL ORGANIZATION OF CARBONATE COMPOUNDS IN THE FOREST SOIL OF STEPPE

Carbonate neoplasms are the characteristic feature of the black soil profile. The study of morphological and micromorphological characteristics and chemical composition gives an idea of the black soil genesis and serves as the diagnostic feature of classification units of them. The study of migration carbonate in the chernozem are of great scientific and practical interest.

Nowadays the issues of migration carbonates, as well as the extent of the manifestation of this process in the soil profile need further researching, which is important as carbonates play an important role in basic soil processes, in particular, they affect the concentration and activity of calcium ions in the soil solution, the composition of the soil absorbing complex and pH in the soil solution. Carbonate neoplasms contribute to the formation of strong coagulation structures, which increases soil fertility and harvest agricultural crops, provides resistance against the wind, prevents reduction of the upper fertile soil layer, increases mobility of some chemical elements and improves such physical characteristics of soil as density, permeability and porosity.

Carbonate inclusions are a source of important information about the soil conditions (the genesis and the composition of rocks, the quantity of humus in the soil, the chemical composition of surface and groundwater, the dynamics of their levels). Carbonate neoplasms differ in color, shape and chemical composition. The most widespread include: spots vague shape, mold accumulation of very fine crystals, white spots – bright, compact, sharply defined spots, segments in the thin pores in soil, tubes with crystalline masses or mealy lime processions of roots, concretions, meadow marl layers, the thickness of which can reach several tenths of a centimeter.

Carbonate neoplasms are distinguished by effervescence with 10 % HCl solution. They are typical of chernozem, chestnut, brown semiarid, saline and a number of other soils.

Black soil plain is characterized by the greatest diversity of forms of carbonate formations, it combines features of typical and southern chernozems. Incursions into the ordinary black may be thin white crusts on the walls of the large pores and the surface structure. There prevail such impregnating excretion as large patches of irregular shape and various degrees of intensity, confined mainly to the plant roots and moves molehill. Quite a lot of carbonate excretion are observed in coprolites.

The nature of carbonate excretion is determined by a complex combination of factors (concentration of the soil solution, soil CO2 partial pressure, humidity and evaporation in the middle of the soil mass, the nature of the soil draining profile, soil temperature regime), which perform a function of soil forming hydrothermal conditions. These factors primarily determine CaCO3 quantity and its structure. On the other hand, the habitus of carbonate neoplasms no less depends on the structure and preparation of the soil, the size and form of cavities, in which the deposition of calcite crystals occurs. All these factors vary naturally within the soil profile, causing the formation of some form of carbonate neoplasms, which are found in black soil profiles and their migration.