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Diverse chernozemic soils featured by thick mollic horizon, rich in humus, dark-coloured, structural, and saturated with base cations are relatively common in the loess-belt of SW Poland. It is postulated, that most of these soils may have similar initial (chernozemic) history of thick humus horizon, related to climate conditions and vegetation in the Late Pleistocene and the Neolithic periods. However, these soils exist on various bedrocks and under different moisture conditions that led to the development accompanying features and variable classification of soils, both in Polish and international soil classifications. The aim of the paper is to presents the most important variants of loess-derived chernozemic soils of SW Poland, in relation to local conditions, which influenced soil transformation and present spatial diversification. ‘Typical’ chernozems (WRB: Calcic Chernozems), which have a mollic horizon and secondary carbonates, but are free of strong redoximorphic features, are rather uncommon in the region. Whereas, the black earths (WRB: Gleyic/Stagnic Chernozems/Phaeozems), featured by the presence of mollic horizon and strong gleyic or stagnic properties in the middle and bottom parts of the profiles, are predominant loess-derived chernozemic soils in SW Poland. Their most specific forms, developed on the clayey bedrock, are black earths with a vertic horizon (WRB: Vertic Stagnic Phaeozems). The strongly leached chernozemic soils developed over permeable subsoils, lacking carbonates and free of (strongly developed) stagnic/gleyic properties are called grey soils, often featured by the presence of subsurface diagnostic horizons cambic or luvic (WRB: Cambic/Luvic Phaeozems).

The sixth edition of the Polish Soil Classification (SGP6) aims to maintain soil classification in Poland as a modern scientific system that reflects current scientific knowledge, understanding of soil functions and the practical requirements of society. SGP6 continues the tradition of previous editions elaborated upon by the Soil Science Society of Poland in consistent application of quantitatively characterized diagnostic horizons, properties and materials; however, clearly referring to soil genesis. The present need to involve and name the soils created or naturally developed under increasing human impact has led to modernization of the soil definition. Thus, in SGP6, soil is defined as the surface part of the lithosphere or the accumulation of mineral and organic materials permanently connected to the lithosphere (through buildings or permanent constructions), coming from weathering or accumulation processes, originated naturally or anthropogenically, subject to transformation under the influence of soil-forming factors, and able to supply living organisms with water and nutrients. SGP6 distinguishes three hierarchical categories: soil order (nine in total), soil type (basic classification unit; 30 in total) and soil subtype (183 units derived from 62 unique definitions; listed hierarchically, separately in each soil type), supplemented by three non-hierarchical categories: soil variety (additional pedogenic or lithogenic features), soil genus (lithology/parent material) and soil species (soil texture). Non-hierarchical units have universal definitions that allow their application in various orders/types, if all defined requirements are met. The paper explains the principles, classification scheme and rules of SGP6, including the key to soil orders and types, explaining the relationships between diagnostic horizons, materials and properties distinguished in SGP6 and in the recent edition of WRB system as well as discussing the correlation of classification units between SGP6, WRB and Soil Taxonomy.

Vertisols are characterized by high content of clay fraction that affects their specific morphological and physical features. The shrink-swell phenomena of clayey materials under specific moisture regime cause formation of cracks, wedge-shaped structural aggregates and slickensides on aggregate surfaces. It was formerly believed that these soils can be found only in tropical/subtropical zones, thus Vertisols have not been expected to form under temperate climate of Central Europe. As a result, Vertisols are insufficiently recognized and documented on soil maps in Poland, including the Lower Silesia region. The aim of this study was to examine soils developed on clayey parent materials near Strzelin, focusing on their morphology, properties and classification issues. There was confirmed that soils developed from Neogene clays have vertic and mollic horizon, accompanied by stagnic or gleyic properties. However, not all soils fulfil the criteria for Vertisols due to the presence of surface or subsurface coarser-textured (sandyor silty-textured) layers. Native differentiation of parent material and geomorphological processes were found the main factors, which control the spatial mosaic of Vertisols and black earths (Chernozems or Phaeozems).

Taking into account the fact that (a) measurement of the cation exchange capacity and base saturation is practically unavailable in the field, that formally makes impossible the reliable field classification of many soils, (b) base saturation is measured or calculated by various methods those results significantly differ, (c) base saturation and soil pH are highly positively correlated, it is suggested to replace the base saturation with pHw (measured in distilled/deionized water suspension) in the classification criteria for diagnostic horizons and soil units/subunits, both in the Polish Soil Classification and FAO-WRB. Based on statistical analysis of 4500 soil samples, the following pHw values are recommended instead of 50% base saturation: pHw

Wielkoskalowa regulacja, odwodnienia oraz intensywne rolnicze zagospodarowanie doliny Baryczy zainicjowane w XVII wieku uruchomiły transformację pierwotnych gleb aluwialnych i błotno-aluwialnych. Gleby na holoceńskich terasach zale- wowych mają głęboki, kwraśny poziom próchmczny (umbric) i są płytko oglejone, a do głębokości 100 cm nie zaznacza się stratyfi- kacja materiału macierzystego} Mimo położenia na terenach zalewowych, gleb tych me można zaliczyć do mad czamoziemnych posługując się kryteriami Systematyki gleb Polski (2011). Gleby na plejstoceńskich terasach nadzalewowych mają głęboki, wysyco- ny zasadami poziom prócliniczny (mollic) i oglejenie w dolnej części profilu, co przybliża je do czarnych ziem. Dobrze widoczna stratyfikacja materiału macierzystego nie ma w tych glebach znaczenia klasyfikacyjnego ze względu na wiek osadów'. Niemal wszyst- kie poziomy próchmczne spełniają kryteria poziomu anthric, a ponad pokwa badanych gleb może być zaliczona do gleb kulturo- ziemnych - ngosoli, co podkreśla istotną rolę człowieka w transformacji i kształtowaniu cech morfologicznych tych gleb. Brak precyzyjnych kryteriów identyfikacji typów' w rzędzie gleb czamoziemnych w Systematyce gleb Polski (2011) powoduje trudności w klasyfikacji gleb na terasach rzecznych, a wr szczególności rozgraniczanie między madami czamoziemnymi oraz czarnymi ziemiami.