Salt-Affected Soils in Russian, American, and International Soil Classification Systems

The notions of saline and solonetzic soils are compared in two Russian (1977 and 2004), American (Soil Taxonomy 1999), and the International (WRB 2014/2015) classification systems. The diagnostics and lists of soils referred to as solonchaks, solonetzes, and other soils containing soluble salts and exchangeable Na are presented. Some features of similarity and differences were revealed in the approaches to identifying salt-affected soils and their taxonomic position. In the Russian systems, data on soil water extracts (1 : 5) are used for the assessment of soil salinization; in addition, the contents of toxic salts are calculated. In western classifications, soil salinity is assessed on the basis of the analysis of extracts from water-saturated pastes. Solonetzes are estimated according to their morphological features and data on the content of exchangeable Na. In three classifications (except for Soil Taxonomy), solonchaks and solonetzes are distinguished at the high taxonomic level. In addition, in all classification systems, soils (both saline and containing exchangeable Na), whose saline and solonetzic horizons do not completely fit their definitions, are considered at a lower taxonomic level. While improving the classification of soils of Russia, some changes and corrections to the definitions of saline soils are recommended.