Kandosols [KA]

Concept

This order accommodates those soils which lack strong texture contrast, have massive or only weakly structured B horizons, and are not calcareous throughout. The soils of this order range throughout the continent, often occurring locally as very large areas.

Distribution of Kandosols in Australia.
Soil Profile (View type example photo of Yellow Kandosol).

Definition

Soils other than Hydrosols which have all of the following:

1. B2 horizons in which the major part is massive or has only a weak grade of structure.
2. A maximum clay content in some part of the B2 horizon which exceeds 15% (ie. heavy sandy loam, SL+).
3. Do not have a tenic B horizon.
4. Do not have clear or abrupt textural B horizons.
5. Are not calcareous throughout the solum, or below the A1 or Ap horizon or to a depth of 0.2m if the A1 horizon is only weakly developed.

Comment

Because of the lack of clearly defined horizons in some of these soils (particularly the red forms) with thick sola, there can be argument as to how to identify the limits of the B2 horizon.

As noted under Tenosols (see Comment following Definition), there may also be difficulty in deciding whether B horizon development is strong enough for the soil to be classed as a Kandosol, or is only weak and better classed as a tenic B horizon.

Suborders

• The dominant colour class in the major part of the upper 0.5 m of the B2 horizon (or the major part of the entire B2 horizon if it is less than 0.5 m thick) is red.
Red [AA]
• The dominant colour class is brown.
Brown [AB]
• The dominant colour class is yellow.
Yellow [AC]
• The dominant colour class is grey.
Grey [AD]
• The dominant colour class is black.
Black [AE]

Comment

The colour class frequency of the soils classified to date is dominated by Red (58%) and Brown (22%), a result similar to that for the Chromosols and Dermosols.

Great Groups

It is thought that most of the following great group categories will be appropriate for the various suborders. At present the Duric and Mellic great groups are only known to occur in Red or Brown Kandosols, particularly the former. The Duric soils are confined to the arid zone.

• Soils with a red-brown hardpan either within or directly underlying the B horizon.
Duric [BJ]
• Soils with a B horizon either containing or directly underlain by ferricrete, a petroferric horizon, or a petroreticulite horizon.
Petroferric [EA]
• Soils with a B horizon that is not calcareous and which directly overlies a calcrete pan.
Petrocalcic [DZ]
• Soils with a thin ironpan which occurs within or directly underlying the B horizon.
Placic [EC]
• Soils with massive to weakly structured (about 10 mm subangular blocky parting to finer granules) B horizons that are very porous with a weak consistence strength when moist. Bulk density appears to be relatively low. (See Comment below).
Mellic [DO]
• Soils with an exchangeable Ca/Mg ratio of less than 0.1 in the major part of the B2 horizon.
Magnesic [DB]
• Soils in which the major part of the B2 horizon is dystrophic.
Dystrophic [AF]
• Soils in which the major part of the B2 horizon is mesotrophic.
Mesotrophic [AG]
• Soils in which the major part of the B2 horizon is eutrophic but the B and BC horizons are not calcareous.
Eutrophic [AH]
• Soils in which the carbonate is evident only as a slight to moderate effervescence (1M HCl), and/or contain less than 2% soft finely divided carbonate, and have less than 20% hard carbonate nodules or concretions.
Hypocalcic [CV]
• Soils with a calcareous horizon containing more than 50% of hard calcrete fragments and/or carbonate nodules or concretions and/or carbonate-coated gravel.
Lithocalcic [DA]
• Soils with a calcareous horizon containing 20-50% of hard calcrete fragments and/or carbonate nodules or concretions and/or carbonate-coated gravel.
Supracalcic [FB]
• Soils with a calcareous horizon containing more than 20% of mainly soft, finely divided carbonate, and 0-20% of hard calcrete fragments and/or carbonate nodules or concretions, and/or carbonate-coated gravel.
Hypercalcic [CQ]
• Other soils with a calcareous horizon. (See carbonate classes).
Calcic [BD]

Comment

The calcareous classes above approximately correspond to those of Wetherby and Oades (1975) as follows: Hypocalcic - Class IV, Lithocalcic - Class III B and IIIC, Supracalcic - Class III B, Hypercalcic - Class III A, Calcic - Class I and IIIA. In the Lithocalcic and Supracalcic classes the coarse fragments may be >0.2 m in size and soft carbonate may or may not be present.

Of all the Kandosol profiles classified (1572), the Hypercalcic great group only accounted for 6%, but it was found to be most common (45%) in the 187 soils with a calcareous horizon. The most common non-calcareous great group was the Mesotrophic class at 40% of the total Kandosol profiles classified.

The Mellic soils are very common but little-known acid soils in the high rainfall - high altitude forested areas of south eastern mainland Australia and Tasmania. Structure is often difficult to determine because of weak consistence strength and the usual presence of more than 20% of rock fragments throughout the profile. Any peds present do not possess smooth faces.

Subgroups

It is thought that the following subgroups will cater for most situations, although obviously some will not be relevant for particular great groups of particular suborders. As an example, the various acidic subgroups will not be required for the calcareous great groups.

• Soils with a humose horizon and the major part of the B2 horizon is mottled.
Humose-Mottled [CM]
• Soils with a humose horizon and the major part of the B2 horizon is strongly acid.
Humose-Acidic [GY]
• Other soils with a humose horizon.
Humose [CK]
• Soils with a melacic horizon and the major part of the B2 horizon is mottled.
Melacic-Mottled [DI]
• Other soils with a melacic horizon.
Melacic [DG]
• Soils with a melanic horizon and the major part of the B2 horizon is mottled.
Melanic-Mottled [DM]
• Soils with a melanic horizon and the major part of the B2 horizon is strongly acid.
Melanic-Acidic [FV]
• Other soils with a melanic horizon.
Melanic [DK]
• Soils with an argic horizon within the B horizon.
Argic [AP]
• Soils with a bauxitic horizon within the B horizon.
Bauxitic [AS]
• Soils with a ferric horizon within the solum and a B2 horizon in which the major part is strongly acid.
Ferric-Acidic [GW]
• Soils with a ferric horizon within the solum and a B horizon in which at least the lower part is sodic.
Ferric-Sodic [HC]
• Soils with a conspicuously bleached A2 horizon and a ferric horizon within the solum.
Bleached-Ferric [AV]
• Other soils with a ferric horizon within the solum.
Ferric [BU]
• Soils with a manganic horizon within the solum and a B2 horizon in which the major part is strongly acid.
Manganic-Acidic [GX]
• Soils with a conspicuously bleached A2 horizon and a manganic horizon within the solum.
Bleached-Manganic [AY]
• Other soils with a manganic horizon within the solum.
Manganic [DC]
• Soils in which the major part of the B2 horizon is strongly acid and at least the lower part of the B horizon is sodic.
Acidic-Sodic [HO]
• Soils with a conspicuously bleached A2 horizon and a B2 horizon in which the major part is strongly acid.
Bleached-Acidic [AU]
• Soils in which the major part of the B2 horizon is strongly acid and mottled.
Acidic-Mottled [AJ]
• Other soils with a B2 horizon in which the major part is strongly acid.
Acidic [AI]
• Soils with a conspicuously bleached A2 horizon and a B horizon in which at least the lower part is sodic.
Bleached-Sodic [BA]
• Soils in which the major part of the B2 horizon is mottled and at least the lower part of the B horizon is sodic.
Mottled-Sodic [HB]
• Other soils with a B horizon in which at least the lower part is sodic.
Sodic [EO]
• Soils with a conspicuously bleached A2 horizon and the major part of the B2 horizon is mottled.
Bleached-Mottled [AZ]
• Other soils with a conspicuously bleached A2 horizon.
Bleached [AT]
• Soils with a reticulite horizon below the B2 horizon.
Reticulate [EF]
• Other soils in which the major part of the B2 horizon is mottled.
Mottled [DQ]
• Other soils in which the major part of the B2 horizon is whole coloured.
Haplic [CD]

Comment

In some of the Dystrophic Kandosols there may be a future need to modify the definition of sodic subgroups. (See ESP). As in Chromosols, Dermosols and Ferrosols, Haplic is the most common subgroup (47%) of the Kandosol profiles classified. While this could indicate a need for further subdivison, it is difficult to find criteria that could be used.

Family Criteria

A1 horizon thickness

Gravel of the surface and A1 horizon

A1 horizon texture

B horizon maximum texture¹

Soil depth

¹ This refers to the most clayey field texture category.

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