Aridisols
The central concept of Aridisols is that of
soils that are too dry for mesophytic plants to
grow. They have either:
(1) an aridic moisture regime and an ochric
or anthropic epipedon and one or more of
the following with an upper boundry within
100 cm of the soil surface: a calcic, cambic,
gypsic, natric, petrocalcic petrogypsic, or a
salic horizon or a duripan or an argillic
horizon, or
(2)A salic horizon and saturation with water
within 100 cm of the soil surface for one
month or more in normal years.
An aridic moisture regime is one that in
normal years has no water available for
plants for more than half the cumulative
time that the soil temperature at 50 cm
below the surface is >5° C. and has no
period as long as 90 consecutive days when
there is water available for plants while the
soil temperature at 50 cm is continuously
>8° C.
Aridisols are in the Western States. For
long periods, they are too dry for
mesophytic plants to grow. The concept of
Aridisols is based on the limited availability
of soil moisture for sustained plant growth.
The redistribution and accumulation of
soluble materials in some layer of the soils
are common.
Dominant Suborders
Argids
Argids have an argillic or natric horizon, but not a duripan or a gypsic, petrocalcic, petrogypsic,
or salic horizon.. Most Argids are used as rangeland or wildlife habitat. Some are used as
irrigated cropland.
Calcids
Calcids have a calcic or petrocalcic horizon and have calcium carbonate in the layers above. The
parent materials are high in content of carbonates, or carbonates were added as dust, or both.
Precipitation has been insufficient to remove the carbonates or even move them to great depths.
These soils are in the Western States. Most are used as rangeland or wildlife habitat. Some are
used as irrigated cropland.
Cambids
Cambids are characterized by the least degree of soil development. They are mostly in
Washington State. Most are used as rangeland or wildlife habitat. Some are used as irrigated
cropland.
Cryids
Cryids are the Aridisols of cold areas. They have a cryic temperature regime. The growing
season is short. The short growing season and arid conditions severely limit the use of these
soils. The soils are at high elevations in mountain valleys and basins in Idaho. Most of these soils
are used as rangeland or wildlife habitat.
Durids
Durids are the Aridisols that have a duripan. They are in the Western States. The largest extent is
in Nevada and Idaho. Most of the soils are used as rangeland or wildlife habitat. A few are used
as irrigated cropland.
Gypsids
Gypsids are the Aridisols that have a gypsic or petrogypsic horizon. They are mostly in the
Southwestern States. They are on many segments of the landscape. The gypsic horizon limits
many soil uses. A petrogypsic horizon is an even greater limitation. Most of these soils are used
as rangeland or wildlife habitat.
Salids
Salids are the Aridisols that have a salic. They are commonly in depressions (playas). They are
mostly in Utah and Nevada. As a rule, Salids are unsuitable for agricultural uses unless they are
leached of salts. Leaching the salts is an expensive undertaking, particularly if there is no natural
outlet for the drainage water. Most of these soils are used as rangeland or wildlife habitat.