ЗАКОНОМІРНОСТІ ПОШИРЕННЯ ТА ЗАГАЛЬНІ МОРФОЛОГІЧНІ ОСОБЛИВОСТІ СОЛОНЦІВ МЕЖИРІЧЧЯ ДНІПРО-МОЛОЧНА

Abstract

The traditional approach to the separation of the dry steppe’s solonetz in the most common schemes of classification of Ukraine’s soils is dominated by three types: salt-chestnut-meadow, meadow-chestnut and chestnut. However, the specificity of formation and the possible morphological differences of solonetz of lowlands (pody) and similar reductions, which are quite common within the boundaries of the country between the rivers of Dnipro-Molochna haven’t been taken into account in these schemes. The investigated chestnut-meadow solonetz belong to hydromorphous soils. They have been formed on the territory of the country between the rivers within the flat low-lying coastal shores and various relief reductions in the off-shore zone, with a significant degree of salinity of the soil profile. Meadow-chestnut solonetz are semi-hydromorphous soils and, in the region of the study, occupy more sublime areas, in particular the lower parts of the slopes of various forms of relief. The conditions for the formation of meadow-chestnut solonetz cause a greater leaching of their soil profile from easily soluble salts, carbonates and gypsum, which are accumulated mainly in the underneath-salolonetz horizons. Chestnut solonetz of the country between the rivers of Dnipro-Molochna belong to automorphic soils and have been formed within the elevations and in the upper parts of the slopes. The evolution of chestnut solonetz of the country between the rivers occurs mainly through their leaching of easily soluble salts, carbonates and gypsum, which in significant amounts have been accumulated mainly in the soil rock formation and in the horizons of the transition to it. Relatively large rounded closed downlands (pody) are the characteristics for the Black Sea lowlands. Solonetz is an important element of the soil cover of the lowlands (pody) of the country between the rivers of Dnipro-Molochna. The studied lowland’s (pody) solonetz should be divided into slightly salted and salty soils (solonchak) species. Salt species (solonchack) have been formed within the bases and lower parts of the slopes of the lowlands (pody) depression, under conditions of close occurrence of mineralized groundwater. They are distinguished by the high degree of salinity of the whole soil profile, the significant content of carbonates, the glueyness of the lower horizons, the absence or weak manifestation of signs of soliferous salinity of the eluvial horizon. Instead, soliferous species of solonetz are formed on the slopes of the lowlands (pody) with a deep degree of occurrence of groundwater and are characterized by a small amount of water-soluble salts, the number of which gradually increases with depth, a small content of carbonates in the soil profile, partially soluble with the upper-solonetz horizon. In addition to the lowlands (pody), the surface of the coastal zone of the country between the rivers is complicated by shallow and small oblate rounded closed declines, the formation of which is associated with processes of subsidence of rocks, the influence of sea, wind and temporary watercourses. Within such reductions, which were studied in detail on the territory of the Jagorlytskyi Peninsula, solonetz soils were formed mostly on the slopes, whereas the bottom soils were represented mainly by salt marshes (solonchack). The specific morphological feature of such solonetz is the surface eluvial horizon completely or partially eroded by sea waters, and a rather powerful upper-solonetz horizon of slightly sandy or sandy composition, formed by deposits of mainly lichen-marine origin. Based on the results of our own field studies, we have proved that the specific conditions of soil formation and migration of water soluble salts within the limits of lowlands (pody) and similar reductions of the dry steppe of the country between the rivers of Dnipro-Molochna lead to the formation of solonetz soils that differ significantly from those traditionally allocated in the generally accepted classifications of the soils of the region.