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Soil/Landform Unit 153

Landform Unit Description

Unit 153 image a
Looking orth over swamps, lunettes and plains of this unit
      Area: 16 788 ha
      1.26% of CMA region

      This unit consists of gently undulating plains, swamps and associated minor lunettes that occur between Cressy and Colac. Located within the volcanic Western Plains, the relief of this unit is subdued having a masked affect upon agricultural performance and land versatility. This unit has a number of components, some (such as the low rises and undulating plain) are erosional landforms while others (such as the swamps, flats and lunettes) are depositional. The unit is adjacent to lakes and basaltic (stony) rises and forms a north-south corridor between Cressy and Lake Colac. Remnant vegetation of this unit is Plains Grassy Woodland. The soils are black strongly sodic texture contrast soils on the plains (coarse structure, hardsetting) with black and red cracking self-mulching soils on the lunettes, and black and grey cracking soils in the swamps. Land use is generally grazing, with the capability of the unit varying with component composition. The shallower soils on rock and strongly structured soils on the lunettes provide more use throughout the year than the wetter flats.
Unit 153 geomorphology

Unit 153 image b
Soils are prone to pugging by cattle when saturated
Unit 153 cross section

Unit 153 graph

Unit 153 image c

Dairy farming and feed lots of Friesian heifers on the
plains and swamps

Component
1
2
3
4
5
Proportion of soil-landform unit
2%
3%
10%
60%
25%
CLIMATE
Rainfall (mm)

Annual: 600
Temperature (oC)
Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration
October-March
GEOLOGY
Age and lithology

Quaternary source bordering sand dunes, alluvium and minor basalt
Geomorphology
LANDUSE
Uncleared: Nature conservation; water supply; active and passive recreation
Cleared: Cropping; beef cattle and sheep grazing; dairy; regional development
TOPOGRAPHY
Landscape

Gently undulating plains with swamps, lakes and lunettes
Elevation range (m)
112-139
Local relief (m)
10
Drainage pattern
Centripetal
Drainage density (km/km2)
1.3
Landform
Low rises and hillocks
Lunettes
Plains with minor drainage depressions
Swamps and broad depressions
Landform element
Crests and upper slopes
Mid and lower slopes
Lunettes
Plains
Swamps
Slope and range (%)
3 (1-6)
5 (3-10)
2 (1-5)
1 (0-3)
2 (1-5)
Slope shape
Convex
Concave
Convex
Straight
Concave
NATIVE VEGETATION
Ecological Vegetation Class

Plains Grassy Woodland (1%)
SOIL
Parent material

In situ basalt

In situ basalt

Aeolian deposits

In situ basalt and associated colluvium

Alluvial clay, silt and sand
Description
(Corangamite Soil Group)
Friable red gradational soils (40) and alkaline red self-mulching clays and some black self-mulching clays (39)
Alkaline red self-mulching clays (39) and friable red gradational soils (40)
Alkaline black and grey self-mulching clays (9)
Alkaline mottled black texture contrast soils, some not mottled (35)
Alkaline grey cracking clays (31)
`Soil type sites
SW26, SW102, BD5
SW103, BD5, SW26
Surface texture
Clay loam
Light clay
Medium clay
Fine sandy clay loam
Medium clay
Permeability
Moderate to high
Moderate
Moderate
Low
Very low
Depth (m)
<1.5
<2
>2
<2
>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Friable soils, some expansive clays. Gradational or uniform texture change with depth. Moderate to high permeability, moderately rapid site drainage. Moderate to high nutreient capacity.
Friable but expansive clays and other friable soils. Uniform or gradational texture change with depth. Moderate permeability, moderately rapid site drainage.
Friable but expansive clays, calcareous and often sodic at depth. high nutrient capacity.
Texture contrast, possible waterlogging and compaction.
High seasonal watertable leads to soil compaction. High organic matter content, high clay content and expansive clays.
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