FAO soil classification
The Food and Agriculture Organization of the United Nations (FAO) developed a supra-national classification, also called World Soil Classification, which offers useful generalizations about pedogenesis in relation to the interactions between 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.
Originally developed as a legend to the Soil Map of the World, the classification was applied by United Nations sponsored projects. Many countries modified this system to fit their particular needs.
The Soil Units (106) were 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 was a very simple classification system with units very broad, but was the first truly international system, and most soils could be accommodated on the basis of their field descriptions. The FAO soil map was intended for mapping soils at a continental scale but not at local scale.
In 1998 this system was replaced by the World Reference Base for Soil Resources.
FAO Soil Units
- world map using the FAO legend
- key to the FAO soil units 1974
- A Compendium of On-Line Soil Survey Information: Soil Classification Systems