33 Black and brown strongly acidic and non-sodic texture contrast soils on Quaternary alluvium

These soils are found on Quaternary alluvium, within the basic volcanic plains and sedimentary plains terrain, mainly in low-lying areas such as swamps or terraces.

These soils have texture contrast profiles where there is a very large sudden increase in clay percentage with depth. Those soils on the sedimentary plains have organic fine sandy loam to clay loam surface soils (10–15 cm) over a bleached massive fine sandy clay loam subsurface horizon occasionally with dense (many) ferruginous gravel (to 50 cm). This clearly overlies a dark moderate to fine structured clay loam to medium clay which grades into a lighter coloured mottled lower subsoil which may grade into a reticulated layer (tiger mottles) at 200 cm. These profiles, though on accumulated material, are often similar to profiles found directly on the original parent material. Darker profiles (SW2) reflect different parent material as well as a wetter climate. Some of these soils are sodic in the lower subsoil, even though they have acidic upper soils.

Soil characteristics include strong texture contrast, acidic or neutral relatively deep profiles and mottled often dependant on (source) parent material.

Soil Sites

Site Code	Soil-landform unit	Component	ASC	FK	1:100 000 mapsheet
SW2	-	Lower Terrace	Humose, Hypocalcic, Black Chromosol	Dd1.13	T7421 - Mortlake
SW38	200	Flat	Ferric-Sodic, Mesotrophic, Grey Chromosol	Dy3.42	T7521 - Corangamite
SW67	170	Simple slope	Bleached-Mottled, Eutrophic, Brown Chromosol	Db2.21	T7521 - Corangamite

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