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.

As a form of environmental degradation, soil degradation directly or indirectly affects many lives through decreased agricultural yields, increased flooding and habitat loss. Soil loss has been increasing in most parts of the world and is most pronounced in tropical developing countries where there is poor or zero soil and water conservation (SWC) planning and management activities. Identifying areas prone to soil erosion has also been inadequate, having not been informed by dedicated scientific studies. This is true of the poorly understood watershed of Welmel in the Oromia region of Ethiopia, where most livelihoods heavily rely upon agriculture. To plan effective SWC management techniques, a solid knowledge of spatial variations across different climate, land use and soil erosion is essential. This study has aimed at identifying potential areas needing SWC practices through conducting a spatial modeling of soil erosion within the Welmel watershed’s Genale Dawa basin using a geographic information system (GIS), remote sensing (RS), multiple factors as land uses and climate. The Welmel catchment is located in southeastern Ethiopia and extends between 5°0′0″ N–7°45′00″ N and 39°0′0″ E–41°15′0″ E. The revised universal soil loss equation (RUSLE), which was previously adapted to Ethiopian conditions, was used to estimate potential soil loss. It used information on interpolated rainfall erosivity (R), soil erodibility (K), vegetation cover (C) and topography (LS) from a digital elevation model (DEM) and that of conservation practices (P) from satellite images. The study demonstrates that the RUSLE using GIS and RS considering different climates and land management practices provides a great advantage in that it allows one to spatially analyze multilayer data in order to identify soil erosion-prone areas and thereby develop the most appropriate watershed management strategy. The mean soil loss was determined to be 31 tons ha−1 year−1 and it varied between 0 and 169 tons ha−1 year−1. About 79% of the watershed lies within the tolerable level of 11 tons ha−1 year−1. However, the remaining 21% has a high soil truncation trait, mainly due to its steeper slope and use as cultivated land. Our study identifies cultivated and deforested areas of the watershed as the potential SWC practice demanding areas. Thus, the application of RUSEL using GIS across different land management practices and climate zones is a potential tool for identifying SWC demanding sites. This remains helpful in efforts towards sustainable land management practices for the sustainable livelihood of the local human population.

Erozja jest jednym z najpowszechniejszych problemów związanych z użytkowaniem gleb. Między innymi prowadzi ona do zmian właściwości poziomów powierzchniowych i co się z tym wiąże – tempa procesów stokowych. Zjawisko to może być szczególnie istotne w obszarach młodoglacjalnych wysoczyzn morenowych gdzie ogłowienie gleb płowych wpływa nie tylko na spadek zawartości próchnicy w poziomach ornych ale także zmienia ich uziarnienie. Wpływ tych przeobrażeń na zmiany tempa procesów stokowych może być mierzona za pomocą szeroko stosowanego w modelach erozyjnych wskaźnika podatności gleb na erozję wodną (K). Celem prezentowanych badań było określenie w jakim stopniu ogławianie gleb płowych prowadzi do zmian ich podatności na erozję wodną. Wskaźnik K (zaadoptowany z modelu EPIC) obliczono dla czterech grup gleb: całkowicie, silnie i umiarkowanie zerodowanych oraz w pełni ukształtowanych nie przekształconych erozyjnie. Uzyskane wyniki ukazały znaczne zróżnicowanie wielkości wskaźnika K od 0.0171-0.0352 t·ha·h/ha·MJ·mm zależne wyraźnie od stopnia zerodowania gleby. Gleby całkowicie zerodowane mają średnio o 6% większą podatność na erozję w porównaniu z glebami silnie zerodowanymi oraz o 12% z glebami słabo zerodowanymi i aż o 48% w porównaniu do gleb płowych nie przekształconych erozyjnie. Głównymi czynnikami wpływającymi na wzrost podatności na erozję były stopniowo zmniejszające się wraz ze stopniem zerodowania zawartości próchnicy i frakcji piasku w poziomach ornych. Równocześnie, lecz w nieco mniejszym stopniu, było to spowodowane wzrostem zawartości frakcji iłu w odsłoniętych na powierzchni poziomach Bt i Ck.