12. Sodic brown, yellow and grey texture contrast soils/Dissected Uplands: Terraces and floodplains

This soil has developed on mainly Quaternary alluvial and colluvial unconsolidated material in the Western Uplands. These soils often have acidic surface horizons becoming alkaline with depth

The surface soil is usually a dark greyish brown, sandy loam to sandy clay loam, which is weakly structured. It generally overlies a yellowish brown silty loam to sandy clay loam subsurface horizon, which is massive and conspicuously bleached. There is a clear change to a mottled (red) yellowish brown, medium to heavy clay, which is often vertic. This soil has weak to moderate structure (medium parting to fine sized peds). Occasionally, calcium carbonate occurs in the mid to lower subsoil. The subsoil grades into lighter textured weathered material (alluvium). The profile depth is about 130 cm or more with variable depths of the surface horizons, generally 10 cm for the surface and 25 cm for the subsurface, often deeper (0–40 cm).

Notable features include:

• Sharp or clear change in clay percentage with depth.
• Vertic properties (including variable topsoil depth).
• Strongly sodic subsoil and associated dispersive characteristics.
• Low nutrient capacity and low water holding capacity of the more acidic, lighter upper soil.