Australian Natural Resources Atlas

Natural Resource Topics

Australian Agriculture Assessment 2001

Australian agriculture assessment 2001
National Land and Water Resources Audit, 2001

Appendix 3 - Dermosols

Dermosols Map

Dermosols are distinguished by their moderate to strong structured B2 (subsoil) horizon and the lack of a strong texture contrast between the A and B horizons. These soils are not high in free iron (<5% Fe), nor are they calcareous throughout the profile. Dermosols are a diverse Order, bringing together a wide range of soils with some common important properties.

Red Dermosols

Red and Brown Dermosols are the most common of the Suborders. A description of a Haplic, Eutrophic, Red Dermosol is given below.

Environment

Distribution: Red Dermosols are most common in the east Australian coastal and subcoastal zones and northern Tasmania. The eutrophic and calcareous forms are uncommon in the higher rainfall areas and dominate the arid and semi-arid occurrences.

Climate: Very broad mean annual rainfall range, 300 mm to 4000 mm in the wetter east coastal zones.

Parent materials or substrate: Acid to intermediate igneous and metamorphic rocks and derived alluvium.

Landform: Undulating plains to high, hilly or mountainous lands with terraced stream valleys.

Native vegetation: Eucalypt forest, rainforest and open woodland.

Land use

The Eutrophic, Red Dermosols are closely associated with Red Chromosols in the wheatbelt of New South Wales and are also common in north-east Victoria and Gippsland where they generally occur on lower river terraces and are widely used for improved pastures. Small areas of Acidic, Dystrophic forms are used for sugar cane in north Queensland where landform is suitable.

Common variants

As would be expected from their wide rainfall range, Red Dermosols vary greatly in base status from very low (dystrophic) and acidic, to forms with calcareous subsoils. Some soils are sodic in their deep subsoils, particularly those low rainfall forms that grade to Vertosols.

Nomenclature

Also known as gradational Red Podzolic soils and erroneously as Krasnozems.

Soil qualities

Water availability: Plant available water capacity is usually greater than 100 mm and may exceed 200 mm in deeper soils.

Drainage: Relatively well drained due to well developed soil structure.

Aeration: No restriction.

Physical root limitations: Effective rooting depths are commonly 1.0 m.

Erosion hazard: Susceptible to surface slaking upon rapid wetting, resulting in hardsetting if organic matter is low.

Nutrient availability: Highly variable. Organic matter declines on cultivation.

Toxicities: Aluminium toxicity may become a problem if pH levels decline to below 5.5.

Workability: Good, however a hardsetting surface will restrict workability in degraded soils.

Acknowledgment

Photo, soil description and laboratory data from Department of Natural Resources and Environment, Victoria. Site NE 25.

Typical profile

Typical profile from Tallangatta Valley, north-east Victoria.
Tallangatta Valley, north-east Victoria.

Soil description of a typical profile

A1 0 - 0.15 m Very dark greyish brown (10YR 3/2) light fine sandy clay loam; moderate medium blocky parting to moderate fine blocky structure; moist, firm consistence; clear boundary to:

A2 0.15 - 0.30 m Strong brown (7.5YR 4/6) fine sandy clay loam with brown worm casts; moderate coarse blocky parting to fine blocky structure; moist, firm consistence; clear boundary to:

B21 0.30 - 0.50 m Yellowish red (5YR 4/6) clay loam; moderate medium blocky parting to strong fine blocky structure; moist, firm consistence; gradual boundary to:

B22 0.50 - 0.70 m Yellowish red (5YR 4/6) fine sandy light clay; moderate medium blocky parting to strong fine blocky structure; moist, firm consistence; gradual boundary to:

B23 0.70 - 0.85 m Yellowish red (5YR 5/8) light clay; moderate medium blocky parting to medium fine blocky structure; moist, soft consistence. At 1.5 m depth a coarse river gravel layer occurs.

Laboratory data for the typical profile

Laboratory data for the typical profile

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