Formation of the Microelement Composition of Ordinary Chernozems in the Central Caucasian Region

Abstract

The article discusses the features of the formation of the microelement composition of various genera of ordinary chernozems in the Central Caucasian Region. Their development takes place in peculiar conditions: mild temperate continental climate, non-leaching water regime, carbonate soil-forming rocks, forb-grass vegetation. Depending on the nature of the soil-forming rocks, ordinary and carbonate chernozems (on loess-like loams), solonetzic (on eluvium-deluvium of Maikop clays), and residual-carbonate chernozems (on eluvium of limestone and sandstone) are formed. The main soil-forming processes that determine the development of a system of soil compounds of microelements are humus formation and humus accumulation, claying, accumulation of Ca carbonates, and very weak ferruginization. The distribution of most of the microelements under consideration (Pb, Cu, Zn) in the soil profile is determined, first of all, by the processes of biogenic accumulation in the composition of low-mobility organic-mineral complexes with humic acids. The severity of the sorption geochemical barrier is weakened due to the uniform distribution of the clay fraction along the soil profile. In addition to the binding of microelements to the organic matter of soils, they are intensively fixed in the composition of carbonates. This leads to a decrease in the migration mobility of microelements in the soil profile and their inaccessibility to plants. The features of the formation of the microelement composition of ordinary chernozems in the Central Caucasian Region vary depending on the specifics of soil-forming deposits. In the case of soil occurrence on salt-bearing clay deposits, the solonetz process plays a decisive role, in the case of occur-rence of dense rocks on the eluvium, the proximity of carbonate deposits, and in the case of occurrence on loess-like loams, their increased porosity and water permeability.