Background

The World Reference Base for Soil Resources (WRB) aims to establish an international reference base for soil classification. A Working Group of the International Union of Soil Sciences (IUSS) with collaboration of soil scientists from all over the world has worked out and tested proposals for WRB, leading to the publication of the World Reference Base for Soil Resources by FAO in 1998. It was endorsed by the IUSS as the union’s system of soil classification during the 16th World Congress of Soil Science in 1998 in Montpellier, France.

WRB is a two-tier system of soil classification, with 30 Major Soil Groups (the “Reference Base”) and 121 uniquely defined qualifiers for specific soil characteristics (the “WRB Classification System”). A set of prefixes is also established which may be added to the qualifier to indicate the depth of occurrence or the degree of expression of certain soil features.

WRB has come forth from an initiative of the Food and Agriculture Organization of the United Nations (FAO) and the United Nations Educational, Scientific and Cultural Organization (UNESCO), supported by the United Nations Environmental Programme (UNEP) and the International Union of Soil Sciences (IUSS).

 
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