4. Sodic, yellow texture contrast soils /Dissected Uplands:.Palaeozoic granitic plateaux, mountains, hills and plains

This soil has developed on mainly granitic (rock or colluvial material) in the Western Uplands. The soil is strongly acidic at the surface, becoming slightly acidic or neutral with depth.

The surface soil is usually a dark brown coarse clayey sand which is massive to weakly structured. It overlies a conspicuously bleached clayey sand subsurface horizon which is massive (not structured). There is a clear change to a very pale brown (occasionally reddish yellow), often with orange and red mottles medium clay upper subsoil. This is strongly structured (with medium to fine sized peds) and grades into lighter weathered material. The profile depth is generally greater than 80 cm or more with variable depths of the surface horizons, generally 5 -15 cm for the surface and 20-30 cm for the subsurface (often deeper). Topographic position is important for depth and profile development variations.

Notable features include:

• Strong texture contrast and associated structure differences between the surface horizons and subsoil.
• Possible strongly sodic lower subsoil.
• The sandy surface horizons have a low nutrient status, low water holding capacity and are highly permeable. The clayey subsoil will restrict water movement and waterlogging may occur in the surface soil as a result after heavy rains.
• These features make these soils vulnerable to erosion, particularly on sloping terrain given poor drainage characteristics and lighter surface materials.