The FAO developed a supra-national classification, also called World Soil Classification, which offers useful
generalizations about soils pedogenesis in relation to the interactions with the main soil-forming factors. It was first published in form of the Unesco Soil Map of the World (1974) (scale 1 : 5 M.). Many of the names offered in that classification are known in many countries and do have similar meanings.
The Soil Units (106) are mapped as Soil Associations, designated by the dominant soil unit,
with soil phases (soil properties, such as saline, lithic, stony),
with three textural classes (coarse, medium, and fine)
three slopes classes superimposed (level to gently undulating, rolling to hilly, and steeply dissected to mountainous)
Soil Units form 26 World Classes. The FAO soil map is a very simple
classification system with units very broad) but it is the only truly international system, and most soils can be accommodated on the basis of their field descriptions. The FAO soil map is intended for mapping soils at a continental scale but not at local scale.
