30 Black calcareous (and sodic) cracking clays on Palaeogene basic volcanics

This soil is found predominantly on a residual older (Palaeogene) basic volcanic outcrop on the Bellarine Peninsula.

The surface is a self-mulching clay loam to light clay which overlies strongly structured heavy clay subsoil, the lower portion of the latter is denser and exhibits strong vertic properties such as lenticular peds and smooth surfaces where swelling and shrinking produce polished surfaces. The profile sits on weathered parent material (basalt) quite abruptly at a depth of about 80 cm to 100 cm in a mid slope topographical position. Topographical position may influence soil depth, and in conjunction with slope and land use, influence the presence or absence of the friable surface material. While structure is strong throughout with evident deep cracks, permeability will be low once the clays have swelled, putting strength strains on plant root systems, particularly when the soil dries. This is a nutrient rich soil, though sodic at depth.

Notable characteristics are the self-mulching surface, strongly structured, cracking (high shrink-swell) clay soil over a weathered regolith with high nutrient and water holding capacity, though not all available to plants.

Soil Sites

Site Code	Soil-landform unit	Component	ASC	FK	1:100 000 mapsheet
CLRA6	80	Mid slope	Endocalcareous - Endohypersodic, Self-mulching, Black Vertosol	Ug5.26	T7821 - Sorrento

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