28. Sodic, yellow and grey texture contrast soils/Calcareous dunefields: Linear dunes subdominant, Hummocky dunes subdominant

These soils have developed on Quaternary unconsolidated material, generally of aeolian origin in the North West Dunefields and Plains, in the north of the region. The soil has a neutral to alkaline surface over a strongly alkaline subsoil.

The surface soil is a yellowish brown to light yellowish brown loamy sand, with apedal (sandy) to weak structure. It overlies a bleached fine sand subsurface horizon, which is apedal (sandy). There is a sharp/abrupt change to a mottled yellow brown (occasionally brown) sandy clay loam to medium clay, often with a red mottle. This is strongly structured (with coarse parting to medium sized peds). This may grade into a lighter calcareous horizon before grading into a sodic medium clay at depth. Some soils may have yellow subsoils with red mottling or red/brown deep subsoil. The profile depth is about 150 cm or more with slightly variable depths of the surface horizons, generally 10 cm for the surface and 5 cm for the subsurface, often deeper.

Notable features include:

• Texture contrast soil, variable surface friability (generally can be soft or slightly hardsetting).
• Strong consistence of the subsoil (strength) when dry.
• Occasional bleached subsurface soil.