Temporal changes in the microfabrics of virgin and reclaimed solonetzes at the Dzhanybek Research Station

Abstract

In the past three decades, a trend of an increase in the climatic humidity has been observed in the southeast of European Russia; it has been accompanied by the rising groundwater level. The study of solonetzes at the Dzhanybek Research Station in the north of the Caspian Lowland indicates that the recent climate changes are reflected in the soil microfabric. A comparative examination of thin sections prepared from the soil samples taken in 1982 and in 2002 from the same points characterizing virgin and reclaimed solonetzes has shown the following changes in the soil microfabric: (a) an increase in the amount and diversity of the mesofauna excrements, (b) the accumulation of fine plant detritus at various stages of decomposition, (c) an increase in the content of the dispersed and flocculated brown-colored microforms of humus and charcoal particles in the surface horizons, and (d) the formation of hydrogenic gypsum in the middle and lower soil horizons. The character of changes in the microfabric of virgin solonchakous solonetzes attests to the enhancement of the eluviation of the silty-clayey-humus substances, solodization, and gleyzation. In the reclaimed solonetzes, the artificially turbated horizons have been subjected to desalination, and the gypsiferous and calcareous pedofeatures inherited from the previous stages of soil formation have been destroyed.