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.

The objective of the study was to determine role of soil sealing degree as the factor influencing soil contamination with polycyclic aromatic hydrocarbons (PAHs). The study area included four sampling sites located within the administrative boundaries of the Toruń city, Poland. Sampling procedure involved preparing soil pits representing three examples of soil sealing at each site: non-sealed soil as a control one (I) and two degrees of soil sealing: semi-pervious surface (II) and totally impervious surface (III). Together with basic properties defined with standard procedures (particle size distribution, pH, LOI, content of carbonates) content of selected PAHs was determined by dichloromethane extraction using gas chromatography with mass spectrometric detection (GC-MS). Obtained results show that urban soils in the city of Toruń are contaminated with polycyclic aromatic hydrocarbons. Soil sealing degree has a strong influence on the soil contamination with polycyclic aromatic hydrocarbons. Totally sealed soils are better preserved from atmospheric pollution including PAHs. Combustion of grass/wood/coal was the main source of determined PAHs content in examined soils.

The simultaneous impact of climate change and human activities on soil organic carbon content (SOC) in peatlands is insufficiently recognized, especially in relation to peatlands affected by open‐pit lignite mining. Given their importance in climate change feedback loops, long‐term observations of SOC changes in peatlands are essential. The aim of the study was to determine recent changes in the properties and SOC content/stock of agro‐managed fen peatlands located adjacent to open‐pit lignite mines. We studied two soil layers (0–20 and 20–40 cm) within 12 sampling plots in the Grójec Valley (Central Poland). Soil sample collection and field measurements took place in 2005 and again in 2015. The largest negative changes in soil properties (e.g. SOC content drop from 208 to 318 g kg⁻¹ in 2005 to 125–263 g kg⁻¹ in 2015 and SOC stock decrease from 12.1–16.2 kg m⁻² in 2005 to 9.22–14.5 kg m⁻² in 2015), as well as the largest variability of watertable level were recorded in the northern part of the study area, affected by long‐term lignite mining (1982–2009). While such a strong changes were not observed in the plots from central and southern part of the valley (230–439 g kg⁻¹ in 2005 and 228–396 g kg⁻¹ in 2015; 11.5–29,2 kg m⁻² in 2005 and 13.4–36.1 kg m⁻², respectively). Our results showed that depletion of SOC content in lowland peatlands in the temperate climate zone (due to human activity and changeable weather conditions) will proceed unless we implement sustainable management practices or apply restoration plans at these sites.