MySoil: Shallow sandy duplexes (Southern Wheatbelt)

Grey or yellow/brown sands over neutral to alkaline clay at <30 centimetres (cm) depth.

Broad scale map (1:250 000) of the Southern Wheatbelt Agzone showing the distribution of shallow sandy duplexes. There is a scattered distribution of 25–50% near Cranbrook, while Lake King area 10–25% and Fitzgerald region 3–10%.
Figure 2 Topsoil and subsoil layers for shallow sandy duplex (for example soil group 404) in the Southern Wheatbelt Agzone.
Soil pit showing the profile of grey shallow sandy duplex in the Southern Wheatbelt region. Grey sand over sandy clay loam to clay at <30cm.

Summary

Table 1 Shallow sandy duplexes summary
Occurrence Southern Wheatbelt (10%)

Soil Groups of Western Australia (WA)

404 Grey shallow sandy duplex

408 Yellow/Brown Shallow sandy duplex
Also known as

Duplex (sand over clay)
Australian soil classifications

404 Grey, yellow or brown Sodosol, Grey, yellow or brown Chromosol

408 Yellow or Brown Chromosol, Yellow or Brown Sodosol

Distinguishing features

Topsoil

  • Sand to a maximum depth of 30cm.
  • Acid to neutral pH.
  • Gravel (<20 %) can be present usually at the base of the topsoil (sand) layer.

Subsoil

  • Abrupt boundary between sand and clay layers within 30cm of the surface.
  • Clays often sodic, mottled and appear as polyhedral columns.
  • Clay pH can range from highly acid (pH <4) through to neutral.

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 shallow sandy duplexes

Soil Groups of WA

404 Grey shallow sandy duplex*

404 Grey shallow sandy duplex*

408 Yellow/Brown Shallow sandy duplex*

408 Yellow/Brown Shallow sandy duplex*
Constraints Topsoil Subsoil Topsoil Subsoil
Acidity and aluminium toxicity Major n/a Minor

n/a
Salinity

n/a

 Minor

n/a

n/a
Sodicity and alkalinity

n/a

 Major

n/a

 Minor
Boron toxicity

n/a

n/a

n/a

n/a
Poor nutrient retention

n/a

n/a

n/a

n/a
Aggregate stability

n/a

 Major

n/a

 Major
Compaction and hard layers

n/a

n/a

n/a

n/a
Hard setting and crusting

n/a

n/a

n/a

n/a
Water repellence

Minor

n/a

 Minor

n/a
Low plant available water Minor Minor Minor Minor
Water-logging (seasonal)

n/a

 Major

n/a

 Major
Wind erosion (seasonal) Minor

n/a

 Minor

n/a
Water erosion (seasonal)

n/a

n/a

n/a

n/a

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

  • Soil Group of WA - 404 Grey shallow sandy duplex site ID includes: TBO 0160, TBO 0702, TBO 1383, KLC 0069, NYA 1022, FFC 0145, FFS 0117, COR 1783.
  • Soil Group of WA - 408 Yellow/Brown Shallow sandy duplex site ID includes: FFS 0112, FFS 0113, COR 1638, COR 2002, COR 2004.

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.

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

Overheu, TD (1995) Soil Information Sheets for Ravensthorpe and part of the Jerramungup Agricultural Areas. Department of Agriculture, Western Australia and Landcare Western Australia.

Percy, H (2003) Nyabing-Kukerin Area Land Resource Survey. Land Resources Series No. 18. Department of Agriculture, Western Australia.

Sawkins, D (2010) Landscapes and Soils of the Katanning District. Bulletin 4817. Department of Agriculture and Food, Western Australia.

Sawkins, D (2011) Landscapes and Soils of the Lake Grace. Bulletin 4825. Department of Agriculture and Food, Western Australia.

Stoneman, TC (1990) An Introduction to the Soils of the Lake Grace Advisory District. Bulletin 4178. Western Australian Department of Agriculture.

Stoneman, TC (1991) An Introduction to the Soils of the Narrogin Advisory District. Bulletin 4221. Western Australian Department of Agriculture.

Stoneman, TC (1991) An Introduction to the Soils of the Katanning Advisory District. Bulletin 4202.  Western Australian Department of Agriculture.

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

Stuart-Street, A (2005) Tonebridge-Frankland Area Land Resource Survey. Land Resources Series No. 19. Department of Agriculture, Western Australia.

Verboom, B and Galloway, P (2004) Corrigin Area Land Resource Survey. Land Resources Series No. 20. Department of Agriculture, Western Australia.

See also

MySoil

Further information

Soils

Topics

Page last updated: Wednesday, 18 November 2015 - 9:32am