Australian Agriculture Assessment 2001
Australian agriculture assessment 2001
National Land and Water Resources Audit, 2001
Appendix 3 - Podosols
In Australia the majority of these soils are distinguished by a bleached A2 horizon and a coloured B horizon caused by the accumulation of organic compounds, aluminium and/ or iron compounds. These diagnostic horizons may occur singly or in combination.
Semiaquic Podosols
The Suborders of Podosols are separated on soil and site drainage conditions. Semiaquic Podosols have few restrictions to drainage in the B horizon or substrate and experience only short term saturation. The Parapanic, Humosesquic, Semiaquic Podosol described below has a strongly coherent B horizon with consolidated tongues of ‘coffee rock’ in the subsoil.
Environment
Distribution: Virtually confined to coastal and subcoastal zones of Queensland, New South Wales, southern Victoria and South Australia, northern Tasmania and south-west Western Australia. Occurrences elsewhere are of small extent.
Climate: Mean annual rainfall range is very broad, approximately 300 mm to over 3000 mm.
Parent materials or substrate: Coastal soils occur on Quaternary deposits of quartz sands. Less common forms are found on acidic parent rocks such as quartzite, sandstone, granites and gneisses, or within the A horizons of older soil profiles.
Landform: Sand plains and low beach ridges, swales and large dune systems.
Native vegetation: Extremely wide range from shrub heath and mallee shrublands to tall, open eucalypt forests and rainforests.
Land use
Grazing on improved pastures. Other uses include sugar cane in Queensland, irrigated vegetables in Victoria, Pinus plantations and mining for heavy minerals.
Common variants
Weakly coherent B horizons and absence of any restrictive layer of consolidated materials such as ‘coffee rock’.
Nomenclature
Otherwise known as a Humus Podzol.
Soil qualities
Water availability: Low to high depending on soil depth.
Drainage: Very well drained sandy surface horizons and subsoil horizons where pans are not a feature.
Aeration: Well aerated.
Physical root limitations: ‘Coffee rock’ or siliceous pans may restrict rooting depth.
Erosion hazard: The surface soil is prone to wind erosion if vegetation cover is removed.
Nutrient availability: Very low fertility, naturally deficient in nitrogen, phosphorus, sulphur, potassium, calcium and trace elements.
Toxicities: None apparent.
Workability: Good. Can be cultivated throughout most of the year.
Acknowledgment
Photo, soil description and laboratory data from Department of Natural Resources and Environment, Victoria. Site 7 SW Gippsland.
Typical profile
Bald Hills district, south-west Gippsland, Victoria. |
Soil description of a typical profileA1 0 – 0.30 m Dark grey (10YR 4/1) loamy sand; loose surface condition; clear boundary to: A2e 0.30 – 0.75m Light grey (10YR 7/2) sand; single grain structure; clear wavy boundary to: Bhs 0.75m – 1.40 m Strong brown (7.5 YR 5/8) and dark reddish brown (5YR 3/3) sand with tongues of variably cemented ‘coffee rock’; massive structure; firm consistence; diffuse boundary to: C 1.40 m+ Brownish yellow (10YR 6/6) sand; single grain structure. |
Laboratory data for the typical profile
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