27. Sodic, red texture contrast soils/Calcareous dunefields: Linear dunes subdominant, Hummocky dunes subdominant and Plains

These soils have developed on Quaternary unconsolidated material, generally of aeolian origin in the North West Dunefields and Plains, in the north of the WCMA. The soils are neutral to alkaline in the surface and alkaline and calcareous in the subsoil.

The surface soil is usually a dark brown sandy loam to sandy clay loam, with weak structure. It occasionally overlies a bleached subsurface horizon. The contact with the subsoil will often have strong consistence (hard). There is a clear change to a dark red to yellowish red (occasionally yellowish brown) medium clay. It has strong structure (with coarse parting to medium sized peds). With depth there is less structure and clay content, grading into lighter textured highly calcareous material, with weak structure. Some soils may have yellow subsoils with red mottling or red deep subsoil. The profile depth is about 120 cm or more with subtle change into unconsolidated regolith or less alkaline clay on less alkaline parent material, with variable depth of the surface horizon, generally 10-15 cm.

Notable features include:

• Texture contrast soil, variable surface friability (generally hardsetting).
• Strong consistence of lower surface and upper subsoil (strength) when dry.
• Occasional sporadic bleached subsurface soil.
• Decreasing pedality of subsoil with depth, with increasing calcium carbonate content.
• Occasional brown or yellow subsoil variants.