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).
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 aim of work was to characterize the water retention in the silt-textured Luvisols with lamellic illuvial horizon (argic) that occur in the loess covered northern part of the Silesian Lowland. Soil pits were localized on the Trzebnica Hills near the villages: Machnice (profile 1), Skarszyn (profile 2) and Zaprężyn (profile 3 and 4). Profiles Machnice 1 and Skarszyn 2 were situated in the upper parts of the hills covered with beech stands with an admixture of oak, linden and maple. Profiles Zaprężyn 3 and 4 were situated in the central and lower parts of the arable slope. During the field work conducted in April 2011, 29 soil samples were collected for texture, bulk density and water properties analysis. The soils under study were characterized by texture of silt loam with lower clay content in humus horizons (.loamy silt. according to Polish classification), and higher clay content (.clayey silt.) in the illuvial and subsoil horizons. The texture of all examined profiles was dominated by the „loess“ fractions. Variable abundance of the massive lamellae causes variations in water properties of the illuvial (sub-)horizons. It was found that lamellic illuvial horizons in the loess-derived Luvisols have higher field water capacity than the homogenous illuvial horizons, apart of the clay content. There was no apparent effect of the horizon kind (homogeneous versus lamellic) on the soil bulk density. These properties mainly depended on the total clay content in a particular horizon (sub-horizon).
Differentiation of soil organic carbon (SOC) concentrations and pools in topsoil horizons of forest soils in the Karkonosze Mountains was examined in relation to environmental and human-induced factors, with special focus on altitudinal gradient, related climatic conditions, and a zonality of vegetation. The samples were collected from the forest litter and soil layers 0–10 cm and 10–20 cm, in 621 plots arranged in a regular network of monitoring established in the Karkonosze National Park. The concentrations of SOC were determined in laboratory and used for calculation of SOC pools. Four elevation zones were distinguished for analysis: 500–750 m, 750–1000 m, 1000–1250 m, and >1250 m. The concentrations of SOC in forest litter (38.3–44.1%) showed an insignificant increasing trend with altitude. The concentrations of SOC in the layers 0–10 cm and 10–20 cm, were in a very broad range 0.27–47.6%, thus indicating a high differentiation, and also tended to insignificantly increase along with altitude. The largest share of accumulated SOC pools was proved to be present in the layer 0–10 cm, except for the highest zone >1250 m in which forest litter contains slightly larger amounts of SOC. The pools of SOC accumulated in the 20 cm thick topsoil and forest litter turned out to vary considerably (3.6–58.2 kg·m−2), but the mean values and medians in particular elevation zones fall in a narrow range 10.5–11.9 kg·m−2, close to the values reported from the Alps. The lack of statistical significance of reported tendencies was explained by a monitoring sites-oriented random soil sampling, i.e. in forest stands of various age, species-composition and degradation degree.
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.