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WALLACE H. FULLER
2. Haplargids
Haplargids are Argids with an argillic horizon but not with a high solium
content, such as natric horizons (Solonetz and solodized-Solonetz). They
do not have a duripan or petrocalcic horizon within 1 meter of the surface.
The clay gradually transists between the A and B horizons or the horizon
has less than 35% clay.
3. Nadurargids
Nadurargids are Argids that have prominent structure and a natric
(sodic) horizon above a duripan that appears within 1 meter of the surface. The hardpan is platy or massive and indurated.
4. Natrargids
Natrargids also have a natric horizon but not a duripan within 1 meter
of the surface. Soil scientists recognize this group in more historic terms
as Solonetz and solodized-Solonetz. Columnar structure is one of their
widely recognized features. These soils are usually dry, pale in color at
the surface and have more organic matter in the B than the A horizon.
They are also known for their bare desert-pavement surfaces, soft vesicular
crusts, and accumulation of lime and other soluble salts at moderate
depths. They are like the soils with which they are associated in most of
their properties. Sodium-affected horizons may develop in almost any soil.
In general, these soils possess horizons having more than 15% of their
cation-exchange capacity saturated with sodium. Magnesium in the exchange positions is quite common in sodic layers. If the exchangeable sodium plus magnesium exceeds that of calcium, the soil is placed in a natric
group.
5. Paleargids
Paleargids are Argids that have either a petrocalcic horizon within 1
meter of the soil surface or that have an argillic horizon that has both
35% or more clay in some part and an abrupt increase in clay content
at the upper boundary of the argillic horizon. These are dry soils that resemble the better known humid zone Planosols in some respects.
B. ORTHIDS
The Orthids are Aridisols with no argillic or natric horizon (U.S. Soil
Conservation Service, 1967). They are believed to have developed since
late Pleistocene time (in the last 25 χ 10
3
years) under an arid climate.
WALLACE H. FULLER
2. Haplargids
Haplargids are Argids with an argillic horizon but not with a high solium
content, such as natric horizons (Solonetz and solodized-Solonetz). They
do not have a duripan or petrocalcic horizon within 1 meter of the surface.
The clay gradually transists between the A and B horizons or the horizon
has less than 35% clay.
3. Nadurargids
Nadurargids are Argids that have prominent structure and a natric
(sodic) horizon above a duripan that appears within 1 meter of the surface. The hardpan is platy or massive and indurated.
4. Natrargids
Natrargids also have a natric horizon but not a duripan within 1 meter
of the surface. Soil scientists recognize this group in more historic terms
as Solonetz and solodized-Solonetz. Columnar structure is one of their
widely recognized features. These soils are usually dry, pale in color at
the surface and have more organic matter in the B than the A horizon.
They are also known for their bare desert-pavement surfaces, soft vesicular
crusts, and accumulation of lime and other soluble salts at moderate
depths. They are like the soils with which they are associated in most of
their properties. Sodium-affected horizons may develop in almost any soil.
In general, these soils possess horizons having more than 15% of their
cation-exchange capacity saturated with sodium. Magnesium in the exchange positions is quite common in sodic layers. If the exchangeable sodium plus magnesium exceeds that of calcium, the soil is placed in a natric
group.
5. Paleargids
Paleargids are Argids that have either a petrocalcic horizon within 1
meter of the soil surface or that have an argillic horizon that has both
35% or more clay in some part and an abrupt increase in clay content
at the upper boundary of the argillic horizon. These are dry soils that resemble the better known humid zone Planosols in some respects.
B. ORTHIDS
The Orthids are Aridisols with no argillic or natric horizon (U.S. Soil
Conservation Service, 1967). They are believed to have developed since
late Pleistocene time (in the last 25 χ 10
3
years) under an arid climate.