Hardsetting Sodosols

These soils display a distinct texture contrast between the surface and subsoil horizons. The surface soil condition is usually hardsetting.

Group 6. Hardsetting Red Sodosols

Group 7. Hardsetting Mottled Red Sodosols

Group 8. Hardsetting Brown Sodosols

Group 9. Hardsetting Mottled Brown Sodosols

Group 10. Hardsetting Yellow Sodosols

Group 11. Hardsetting Mottled Yellow Sodosols


Main Characteristics

Soils included in the six groups above have the following characteristics:

• Strong texture contrast between surface (A) horizons and subsoil (B21) horizon.
• Hardsetting surface soil.
• Commonly, the depth to the clayey subsoil is about 15 cm (range: 3-50 cm).
• Soil pedality is lacking in the surface horizons but is moderate to strong in the subsoils.
• The subsoils are often sodic and contain varying amounts of soluble salts.
• In most subsoils, segregations of carbonates usually occur, and often are associated with color changes. Gypsum may also occur in the deep subsoils.
• Commonly, the soil reaction trend is alkaline. However, in some localities soils with acid or neutral reaction trends are present.

Description of Soil Groups

The soils in these six groups have distinct texture contrast between hardsetting surface horizons and clayey pedal subsoils.

Surface Soil

The total thickness of the A horizons usually varies between 10 to 30 cm.

A1 horizon:

Ranges from dark grey-brown to brown, dark brown, reddish brown or dark reddish brown loamy sand to clay loam. It is massive, hard to very hard (dry), friable to non-friable (moist) and non-plastic and non- to slightly, sticky (wet). Gradual to clear boundary to:

A2 horizon:

This horizon is lacking in many soil profiles. When present though, it is of similar soil material to that of the surface soil layer above, except for the color which is lighter in the A2 horizon. Whitish areas of sporadic bleaching often occur throughout the A2 horizons or at the interface between the surface and subsoils. In some profiles the A2 horizons are prominent and conspicuously bleached. Clear to abrupt boundary to:

Subsoil

Medium to heavy clay, coarse blocky to prismatic or columnar structure, parting into smaller blocky peds with smooth and shiny fabric. Soil consistence is usually hard to very hard (dry), friable to slightly friable (moist), plastic and sticky (wet). Subsoil colors vary markedly and are major distinguishing features, between the various groups included in this category. For each group, the main colors and degree of mottling of its subsoils (particularly with regard to the upper most segment, that is at least 15 cm thick of the B horizons) are as follows:

Group 6. Hardsetting Red Sodosols: Whole-colored, red to red-brown (sometimes dark reddish brown). At depth, colors usually become browner or yellower and may contain prominent mottles.

Group 7. Hardsetting Mottled Red Sodosols: Distinctly mottled red to red-brown or yellowish red. Mottles may include brown, yellow or grey.

Group 8. Hardsetting Brown Sodosols: Whole coloured brown to yellowish brown (sometimes dark brown), often becoming greyer of yellower with depth and may contain distinct mottles.

Group 9. Hardsetting Mottled Brown Sodosols: Distinctly mottled brown to greyish brown. Mottles include reddish, yellowish and/or greyish colors.

Group 10. Hardsetting Yellow Sodosols: Whole colored yellow-brown to grey (sometimes reddish yellow). At depth, colors usually become lighter (commonly yellow-grey) and may contain strong mottles.

Group 11. Hardsetting Mottled Yellow Sodosols: Distinctly mottled, yellow-brown to grey-brown or brownish grey. The mottles vary from red to yellow and/or light grey. In the deep subsoils colors usually become yellower or paler and less prominently mottled.

Soil Inclusions

Segregations of soft and/or hard carbonate (lime) nodules occur in the subsoils often in association with color changes. Gypsum may occur in the deeper subsoils.

Some profiles contain trace to moderate amounts of ironstone gravel and/or rock fragments, particularly, in the A horizons.

Soil Reaction (pH)

For most soils the reaction trend is alkaline, showing an increase in pH value down the profile. Typically, the surface soils are strongly alkaline. In some subsoils maximum pH values do not exceed pH 6.5 (acid reaction trend) or pH 8.0 (neutral reaction trend).


Group 6. Hardsetting Red Sodosols.


This group includes the following soil series:

Charlton Series
Wycheproof Series
Series A
Donald Series
Callawadda Series


Group 7. Hardsetting Mottled-Red Sodosols.

This group includes the following soil series:

Watchem Series
Yeungroon Series


Group 8. Hardsetting Brown Sodosols.

This group includes the following soil series:

Stratford Series


Group 9. Hardsetting Mottled-Brown Sodosols.

This group includes the following soil series:

Series B
Series C


Group 10. Hardsetting Yellow Sodosols.

This group includes the following soil series:

Brim Series


Group 11. Hardsetting Mottled-Yellow Sodosols.

This group includes the following soil series:

Series D
Glenorchy Series
Dadswells Series
Bunguluke Series