Genetic diversity of solonetzes and their post-meliorative changes
1994
Lyubimova, I.N. | Grachev, V.A.
Solonetzes are widely spread in Russian Federation within the forest-steppe, steppe and desertic zones. With increasing climate aridity the salinization chemism alters from the alkaline (sodic) to sodium sulphate and chloride. Solonetzes are usially ingredients of soil complexes, where zonal soils participate, solonetzes are diverse morphologically, but they always have an illuvial compact (B2t) horizon (solonetzic, or natric horizon). The origin and unfavourable properties of this horizon are caused by the elevated clay peptization, which, in its turn, depends on the exchangeable sodium. The efficient agricultural use of these soils is possible only with special reclamation measures. Reclamation induces a complete or partial destruction of the solonetzic horizon, and reclaimed solonetzes have quite different features, they may even lose the diagnostic solonetzic properties. Virgin solonetzes have their natric horizon as a main diagnostic criterion, and the exchangeable sodium behaviour is of auxiliary importance. With advanced reclamation the importance of the latter criterion increases. However, there are some limitations for sodium as a diagnostic criterion. Thus, clay peptization is indirectly related to exchangeable sodium content in soils with different salinity rate. In the areas with neutral salinization clay may be peptized only in a very thin marginal layer close to saline horizons. For solonetzes diagnostics purposes the soil clay peptization and related parameters (swelling kinetics) are suggested to be applied. The destruction of solonetzic horizon in the course of reclamation enhances seasonal migration of soluble salts. In this case, the difference in weather conditions proves to be more important than the effect of reclamation methods
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