World Reference Base for Soil Resources (WRB)

The World Reference Base for Soil Resources is an international soil classification system for naming soils and creating legends for soil maps

World Reference Base for Soil Resources 2014 book cover.

The World Reference Base for Soil Resources (WRB) is the international standard taxonomic soil classification system endorsed by the International Union of Soil Sciences (IUSS). It was developed by an international collaboration coordinated by ISRIC–World Soil Information and sponsored by the IUSS and the FAO and was designed to cater for any soil in the world.

WRB is a two-tier system of soil classification, with 32 Major Soil Groups (the “Reference Base”) and over 120 uniquely defined qualifiers for specific soil characteristics (the “WRB Classification System”).

The third edition, update 2015, is the currently valid WRB: Download document (pdf, 2.3 MB).

The definitions in the WRB are based on field and laboratory data:

 

 

WRB structure
New Zealand and the WRB