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37 Brown, black and grey non-sodic and sodic texture contrast soils on Quaternary basic volcanics

These soils occur extensively on basic volcanic deposits including ash deposits and moister areas (compared with the strongly sodic soils) and can be moderately acidic to alkaline. These soils have dark organic fine sandy loam to very fine sandy clay loam surface soils (5–15 cm, up to 30 cm) overlying a bleached often very ferruginous (>40%) clay loam subsurface horizon (to 25–50 cm), abruptly overlying a brown medium structured medium clay which may be mottled (orange, yellow, red) and/or sodic with depth. The lower subsoil may well be neutral or alkaline. Variants with sodic upper subsoils (SFS5) may not have an A2 horizon; the generally shallower topsoil (20 cm) will abruptly overly the subsoil, which is another example of the puff component of gilgai microrelief.

Notable characteristics include: texture contrast, structure differences between horizons, presence of bleached A2 (or occasional absence), acidic upper soil, and alkaline/sodic lower subsoil, often with shrink-swell properties (and associated spatial variations).
CLRA Soil Unit 37

Soil Sites

Site Code
Soil-landform unit
1:100 000 mapsheet
Lower slopeVertic, Magnesic, Black ChromosolDd3.13T7621 - Colac
-Eutrophic, Subnatric, Brown SodosolDy2.23T7722 - Bacchus Marsh
-Vertic, Subnatric, Grey SodosolDy3.22T7722 - Bacchus Marsh
-Vertic, Subnatric, Brown SodosolDy3.22T7722 - Bacchus Marsh
CrestEutrophic, Mottled-Subnatric, Black SodosolDd2.33T7621 - Colac
CrestVertic (& Calcic), Subnatric, Black SodosolDd2.33T7622 - Ballarat
Mid slopeBleached-Ferric, Eutrophic, Black ChromosolDd4.32T7521 - Corangamite
Upper slopeMottled-Sodic, Mesotrophic, Brown ChromosolDb2.31T7521 - Corangamite
FlatHaplic, Calcic, Black ChromosolDd1.13T7521 - Corangamite
FlatBleached-Ferric, Eutrophic, Brown ChromosolDb2.41T7521 - Corangamite
FlatMelanic, Mottled-Subnatric, Black SodosolDd2.12T7521 - Corangamite
CrestMelanic, Mottled-Subnatric, Brown SodosolDy3.32T7721 - Geelong
CrestMottled, Eutrophic, Black ChromosolDd1.32T7722 - Bacchus Marsh
Mid slopeVertic (& Sodic), Eutrophic, Brown ChromosolDy3.13T7522 - Skipton
Mid slopeFertic, Eutrophic, Brown ChromosolDb1.22T7521 - Corangamite
Lower slopeBleached-Vertic, (& Ferric), Eutrophic, Grey ChromosolDy3.42T7521 - Corangamite
FlatBleached-Sodic, Eutrophic, Brown ChromosolDb2.42T7521 - Corangamite
Mid slopeBleached-Vertic, Mesotrophic, Brown ChromosolDy3.41T7521 - Corangamite
Lower slopeBleached-Vertic (& Ferric), Eutrophic, Brown ChromosolDb2.41T7421 - Mortlake
FlatVertic (& Calcic), Subnatric, Grey SodosolDy3.43T7621 - Colac
Upper slopeVertic (& Hypercalcic), Subnatric, Black SodosolDd1.13T7721 - Geelong
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