18. Sodic brown and yellow texture contrast soils (sandy surfaces)/Low elevation plateaux: High relief, low drainage density and Low relief, low drainage density

These soils have developed on mainly of Neogene sands (often indurated) and associated colluvial material in the Western Uplands, predominantly on the Dundas Tableland.

The surface soil is usually a dark loamy sand, which is weakly structured and has weak consistence (strength). It clearly overlies a conspicuously bleached pale loamy sand subsurface horizon, which is massive and has weak consistence (strength). There is a clear change to a (brown, brown and red) mottled yellow or yellowish brown medium to heavy clay. This soil has strong structure (with coarse to medium ped size) and some quartz or ironstone fragments. This grades into lighter textured weathered material of clay and ferruginised sandstone. The profile depth is about 120 cm or more with variable depths of the surface horizons, generally 15 cm for the surface and 20 cm for the subsurface, shallower on upper topographic positions.

Notable features include:

• Texture contrast soil, hardsetting or non-hardsetting surface.
• Bleached subsurface soil, often with some ferruginised nodules (buckshot).
• Mottled subsoil has restricted soil drainage, often sodic at depth.with ferruginised material at depth and can have some calcium carbonate at depth.
• The upper soil has low nutrient capacity and depth limited water holding capacity.
• These features make these soils vulnerable to sheet, wind erosion and compaction, given low consistence/coherence and lighter surface materials.