Andisols

Characteristics Derived from Japanese ando meaning black soil. Formed in volcanic ash or other volcanic ejecta. Contain high proportions of glass and amorphous colloidal materials such as Allophane, Ferrihydrite, and Imogolite. Resulting Andic properties: chemical and physical properties that include high water-holding capacity and the ability to "fix" (and make unavailable to plants) large quantities of phosphorus. Most soils very productive and fertile.

Ferrihydrite, Imogolite, Allophane

Volcanic eruption! https://www.youtube.com/watch?v=pNTci6qESy0 https://www.youtube.com/watch?v=BUREX8aFbMs

These andic soil properties are in layers either: (1) with a cumulative thickness of 36 cm within 60 cm of the mineral soil surface; or (2) comprising at least 60 percent of the depth between the mineral soil surface and a root- restrictive horizon.

Epipedons - is a horizon that forms at or near the surface and in which most of the rock structure has been destroyed. Melanic epipdeons: Black chroma High OM Volcanic ash > 30 cm thick

Least extensive soil order. They occupy approximately 1.7% of the U.S. land area, including some very productive forests in the Pacific Northwest region.

An Andisol near Quito, Ecuador at an elevation of 3200 meters (9600 feet). Photo: Soil Science 

Aquands Water table at or near surface for the majority of the year. Lower landscape positions and under forest or grass vegetation. Some of the soils have been drained and are used as cropland or pasture.

Cryands (Iceland)

Cryands Cold climates that dominate some areas in Alaska and in the mountains of the Pacific Northwest. Most of the soils formed under coniferous forest vegetation.

Gelands Andisols of very cold climtaes. The mean annual soil temperature is <0◦C.

Torrands Torrands, which have a very dry climate moisture regime and are in very few areas in western Oregon and in Hawaii. Most of the soils formed under grassy or shrub vegetation. They are used as rangeland or as irrigated cropland.

Udands Andisols have a humid climate. and a relatively high content of water held too tightly for plants to use. Dominate mostly in western Washington and Oregon and in Hawaii. Most of the soils formed under forest vegetation.

Ustands A relatively high content of water held too tightly for plants to use. Very small extent in the United States. They are mostly in Hawaii. They formed mostly under forest or savanna vegetation. Ustands are used mostly as forest, cropland, or pasture or for urban development.

Udands (Costa Rica)

Vitrands Relatively young Andisols that are the more or less well drained, coarse textured and dominated by glass. Low content of water that is held too tightly for plants to use, occur mostly in Idaho, Oregon, and Washington. Formed under coniferous forest vegetation.

Vitrands (New Zealand)

Xerands A frigid, mesic, or thermic temperature regime. Formed under coniferous forest vegetation. Those with a thermic temperature regime are formed under grass and shrub vegetation. They are used mostly as forest, but some have been cleared and are used as cropland or pasture.

Xerands (Idaho)

No we did not see these soils on our Field trip. They typically occur in areas with moderate to high rainfall and cool temperatures. They also tend to be highly erodible when on slopes.

Resources: https://www.uidaho.edu/cals/soil-orders/andisols https://www.soils.org/discover-soils/soil-basics/soil-types/andisols https://www.britannica.com/science/Andisol https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/class/maps/?cid=nrcs142p 2_053593