Five tonnes of animal life can live in one hectare of soil.

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The International Union of Soil Sciences (IUSS) is the global union of soil scientists. The objectives of the IUSS are to promote all branches of soil science, and to support all soil scientists across the world in the pursuit of their activities. This website provides information for IUSS members and those interested in soil science.

Working Group World Reference Base for Soil Resources (WRB)


Working Group World Reference Base for Soil Resources (WRB)


The Working Group is the editor of the WRB – International soil classification system for naming soils and creating legends for soil maps. Testing and further developing the WRB is a continuous task. Discussions, meetings and field trips are therefore essential.

When & Where

The third edition of the WRB was published in 2014 as FAO World Soil Resources Report No. 106 and is the currently valid system. It and can be downloaded here (as pdf and as an Android app): .
The first edition of the WRB was published in 1998 and the second in 2006. The WRB is originally based on the Legend (1974) and the Revised Legend (1988) of the Soil Map of the World produced by the FAO and UNESCO (1971 – 1981).
The WRB field trip of 2015 will go to China (Inner Mongolia, Gansu, Qinghai, Tibet – sorry, it’s already full).

Soil message

Our discussions have two major topics:
  • When we discuss a soil profile, we strictly apply the rules and definitions of the WRB and see if this results in an informative and satisfying soil name. If not, we have to discuss changes of the definitions or amendments to the soil name. An informative soil name must inform about the genesis and the functions of the soil. The continuum of the soilscape must be ordered into classes in a logical way.
  • For map legends, generalization and ranking of properties is required. Do our rules allow the creation of informative names for soil map units? If not, we have to discuss changes to the rules for ranking and generalization.