ИСТИНА

These reflections were induced by the observations on soil profiles demonstrated during WRB field tours in ultra-continental regions of Eurasia: in Yakutia (2013), and Mongolia (2019): our research experience in cold dry steppes of South Siberia did not completely agree with the attribution of soils in WRB system. This concerns mostly topsoils, and is more raising the problem than proposing solutions. Humus horizons in soils of ultra-continental cold steppes and semi-deserts of South Siberia and Mongolia are specific in terms of morphology due to severe extremely continental climate and specific plant communities; hence, they differ of humus horizons in soils of less continental and warmer steppes. Although the topsoils in ultra-continental steppes often meet the diagnostic criteria in colour for mollic and even for chernic horizons and exceed them in Corg content, they have weak crumb structure. In thin sections, microstructure is clearly shaped by cryogenic processes and partially, by pedofauna. One more particular feature of humus horizons of soils in ultra-continental is the enrichment in with fine root detritus, which defines such specific properties, as “warm” brownish colour, low density, weak structure and water repellence. It is impossible to qualify such horizons neither for mollic, nor for chernic bearing in mind the appearance (image) of Chernozems or Kastanozems with their dark and rich in organic matter horizons occurring in typical or dry steppes, and they received a special name in Russia – cryoaridic soils. Probably, we should look for a due qualifier in the RSG of Kastanozems to specify these soils among Kastanozems, as they differ of them in morphology, genesis, and ecology.