The Polish Soil Classification () is a soil classification system used to describe, classify and organize the knowledge about soils in Poland. Overview Presented below the 5th edition of Polish Soil Classification was published by Soil Science Society of Poland in 2011 and was in use to 2019 when 6th edition of Polish Soil Classification was published. Previous ones were published in 1956, 1959, 1974 and 1989, and they, following Dokuchaiev's ideas, were relied mostly on the natural's criteria (quality) like soil forming processes and soil morphological features (4th edition was transient because diagnostic soil horizons appeared there). 5th edition of classification, where it was possible, was built on quantitative criteria, like quantitative described diagnostic horizons, diagnostic materials and diagnostic properties. Soil forming processes are not a part of classification but the relationship between the processes and their morphological effects was taken into account during creating differentiating criteria of diagnostic horizons, materials and properties. The classification derives much of international systems: USDA soil taxonomy (1999) and World Reference Base for Soil Resources - WRB (2006). Polish soil science intellectual tradition has always maintained a balance between genetical-geographic approach (typical for the Russian scientific school) and substantional-geological-petrographic approach (characteristic for Western Europe). Multilateral look at the soil manifested, in all editions of classification, that each soil was described by three types of characteristics: Genetical genesis described by type of soil – based on diagnostic horizons, materials and properties, Geological origin of bedrock described by what might be literally translated as "kind" or "sort" of soil, Soil texture described of what might be literally translated as "class" or "species" of soil. The Polish Soil Classification has a hierarchical construction. Type of soil is a basic unit of the classification. They are distinguished on a basis of specific layout of main soil genetic or diagnostic horizons, similar chemical, physical and biological properties, type of humus, type of weathering and movement and deposition of results of that weathering. In principle, soil type is a result of main soil forming process. Types of soil are grouped into soil orders. They are identified based on the presence or absence of diagnostic horizons and properties reflecting the effect of specific groups of soil forming processes. Soil types are divided into subtypes. Genetical classification of soils (2011-2019) Order 1. Initial soils (; WRB: Leptosols; ST: Entisols) The order covers all soils where there is thick organic layer or