Soil specifiers (WRB)

World Reference Base for soil resources
Key principles of classification Diagnostic horizons Properties Materials Reference soil groups RSG qualifiers RSG specifiers

There are ten specifiers used in the World Reference Base for soil resources. They are used to indicate depth of occurrence, or to express the intensity of soil characteristics.

The WRB specifiers

How are specifiers used ?

Each specifier can be "coded" through a letter, which comes third to the code of the qualifier it completes.

Example :

• the qualifier histic can be noted hi
• the specifier thapto can be noted ..b
• thaptohistic will be coded hib

The specifiers

• Bathy (..d)
• Cumuli (..c)
• Endo (..n)
• Epi (..p)
• Hyper (..h)
• Hypo (..w)
• Ortho (..o)
• Para (..r)
• Proto (..t)
• Thapto (..b)

The meaning of specifiers

• Specifiers indicating depth of occurrence
  • somewhere within 50 cm of the soil surface : Epi
  • somewhere between 50 and 100 cm from the soil surface : Endo
  • somewhere between 100 and 200 cm from the soil surface : Bathy
  • having a buried layer relating to diagnostic horizons, properties or materials starting within 100 cm of the surface : Thapto

• Specifiers indicating the intensity of the characteristic
  • having a repetitive accumulation of material with a cumulative thickness of 50 cm or more at the soil surface : Cumuli
  • having a strong expression of certain features : Hyper
  • having a weak expression of certain features : Hypo
  • having a typical expression of certain features (typical in the sense that no further or meaningful characterization is made) : Ortho
  • having resemblance to certain features : Para
  • indicating a precondition or an early stage of development of certain features : Proto

See also

• The FAO reference text, (2007 version)