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| Andisol | |
|---|---|
| Andosol | |
 An andisol profile | |
| Used in | USDA soil taxonomy, World Reference Base for Soil Resources |
| Profile | ABwC |
| Parent material | tephra |
In USDA soil taxonomy, andisols are soils formed in volcanic ash and defined as soils containing high proportions of glass and amorphous colloidal materials, including allophane, imogolite and ferrihydrite.[1] In the World Reference Base for Soil Resources (WRB), andisols are known as Andosols.[2]
Because they are generally quite young, andisols typically are very fertile except in cases where phosphorus is easily fixed (this sometimes occurs in the tropics). They can usually support intensive cropping, with areas used for wet rice in Java supporting some of the densest populations in the world. Other andisol areas support crops of fruit, maize, tea, coffee, or tobacco. In the Pacific Northwest US, andisols support very productive forests.
Andisols occupy about 1% of the global ice-free land area. Most occur around the Pacific Ring of Fire, with the largest areas found in central Chile, Ecuador, Colombia, Mexico, the Pacific Northwest US, Japan, Java and New Zealand's North Island. Other areas occur in the Great Rift Valley, Kenya, Italy, Iceland and Hawaiʻi.
Fossil andisols are known from areas far from present-day volcanic activity and have in some cases been dated as far back as the Mesoproterozoic 1.5 billion years ago.[3][4]
- ^ "Andisols". National Resource Conservation Service. United States Department of Agriculture. Archived from the original on 2006-05-09. Retrieved 2006-05-14.
- ^ IUSS Working Group WRB (2015). "World Reference Base for Soil Resources 2014, Update 2015" (PDF). World Soil Resources Reports 106, FAO, Rome.
- ^ Grunwald, Sabine. "Andisols". Soil & Water Sciences. University of Florida. Archived from the original on 2006-09-16. Retrieved 2006-05-14.
- ^ "Andisols". Soil and Land Sciences Division. University of Idaho. Archived from the original on 2009-03-09. Retrieved 2006-05-14.