MySoil: Deep sandy duplexes (Swan Coastal Plain)

Grey, brown and yellow sands over sandy clay or reticulite (mottled loamy sand) at 30–80 centimetres (cm) depth.

Broad scale map (1:250 000) of the Swan coastal plain Agzone showing the distribution of deep sandy duplexes. Distribution is scattered along the Darling scarp with 50–100% and 25–50%.
A stylised diagram of the soil profile showing the topsoil and subsoil layers for yellow/brown deep sandy duplex.  The soil profile is yellow/brown sand over sandy clay loam to clay at <30cm.
Soil pit showing the profile of yellow/brown deep sandy duplex in the Swan coastal plain region. Yellow sand over clay at <30cm.

Summary

Table 1 Deep sandy duplexes summary
Occurrence Swan Coastal Plain (4%)

Soil Groups of Western Australia (WA)

401 Alkaline Grey Deep Sandy Duplex

403 Grey Deep Sandy Duplex

407 Yellow /Brown Deep Sandy Duplex

409 Reticulite Deep Sandy Duplex

Also known as Sandy duplex

Australian soil classifications

401, 403, 407 - Calcic Grey, Grey, Yellow or Brown Sodosol, Grey, Yellow or Brown Chromosol

409 - Reticulate Kandosol, Reticulate Chromosol, Tenosol

Distinguishing features

Topsoil

  • Pale brown, yellow or white acidic to neutral sands between depths of 30–80 cm.
  • Gravel (<20%) can be present usually at the base of the topsoil (sand) layer.

Subsoil

  • Bleached sand layer commonly occurs above clay layer.
  • Abrupt boundary between sand and clay layers or mottled reticulite.
  • Clays often sodic, mottled and appear as polyhedral columns.
  • Clay pH mildly acidic to neutral (403, 407, 409) through to alkaline (401).

Constraints

The following data has been derived from actual site samples taken. These results are recorded in this Excel spreadsheet.

Table 2 Common management constraints key
Rating Implications

Not applicable (n/a)

No constraints identified

Minor

Minor constraint - reduces crop yields in some years

Major

Major constraint - reduces crop yields in most years

Severe

Severe constraint - will always reduce crop yields

Table 3 Management constraints for deep sandy duplexes

Soil Groups of WA

401 Alkaline grey deep sandy duplex*

401 Alkaline grey deep sandy duplex*

401 Alkaline grey deep sandy duplex*

 

403 Grey deep sandy duplex*

403 Grey deep sandy duplex*

403 Grey deep sandy duplex*

Constraints

Topsoil (0-10cm)

Subsurface (10cm - clay)

Subsoil (clay)

 

Topsoil (0-10cm)

Subsurface (10cm - clay)

Subsoil (clay)

Acidity and aluminium toxicity n/a n/a

n/a

  Major Major

n/a

Salinity

n/a

n/a

n/a

 

n/a

n/a Minor
Sodicity and alkalinity

n/a

n/a Minor  

n/a

n/a Minor
Boron toxicity

n/a

n/a

n/a

 

n/a

n/a

n/a

Poor nutrient retention

Major

Major Minor  

Major

Major

Minor
Aggregate stability

n/a

n/a

n/a

 

n/a

n/a Minor
Compaction and hard layers

n/a

Minor

Major

 

n/a

Minor

Major

Hard setting and crusting

n/a

n/a

n/a

 

n/a

n/a

n/a

Water repellence

Major

n/a

n/a

  Major n/a

n/a

Low plant available water

Major

Major

n/a  

Major

Major

n/a
Water-logging 

(seasonal)

n/a n/a

n/a

 

n/a

n/a

n/a

Wind erosion 

(seasonal)

Major n/a

n/a

  Major n/a

n/a

Water erosion

(seasonal)

n/a

n/a

n/a

 

n/a

n/a

n/a

*Note - Data derived from site identifications (ID's).

  • Soil Group of WA - 401 Alkaline grey deep sandy duplex site ID includes: NCP 0876.
  • Soil Group of WA - 403 Grey deep sandy duplex site ID includes: SWL 0002, GWRDC MR_D_KD, BMA 0352, BMA 0354, SWL 0081, CHT 1111.

Further information

Department of Agriculture and Food (2013) Report card on sustainable natural resource use in agriculture, Department of Agriculture and Food, Western Australia.

McArthur, WM (2004) Reference Soils of South-western Australia (Reprint). Department of Agriculture, Western Australia.

McArthur, WM and Bettenay, E (1960) The Development and Distribution of the Soils of the Swan Coastal Plain, Western Australia. Publication No.16. CSIRO, Melbourne, Vic.

Moore, G (2004) Soil Guide: A Handbook for Understanding and Managing Agricultural Soils. Bulletin 4343. Department of Agriculture, Western Australia.

Schoknecht, N and Pathan, S (2013) Soil Groups of Western Australia. Resource Management Technical Report 380. Department of Agriculture and Food, Western Australia.

Smolinski, HJ and Scholz, G (1997) Soils of the West Gingin Area. Land Resources Series No. 15. Agriculture Western Australia.

Tille, PJ and Lantzke, NC (1990) Busselton Margaret River Augusta Land Capability Study. Land Resources Series No. 5. Department of Agriculture, Western Australia.

Wells, MR (1989) Land Capability Study of the Shires of Mandurah and Murray. Land Resources Series No. 2. Western Australian Department of Agriculture.

 

See also

Further information

Page last updated: Wednesday, 18 November 2015 - 9:18am