Soil/Landform Unit 50

Cropped and grazed gentle basalt plains with shelter belts of cypress pine and radiata pine

Area:

38 818 ha

2.91% of CMA region

The basaltic plains that occur throughout the Midlands of the Western Uplands as separate fragments are characterised by long gentle slopes with Plains Grassy Woodlands as the major vegetation class. The gently undulating plains in the east are bound by a steep scarp/slopes that define their margin with the valley of the Lal Lal Reservoir and Moorabool River. This dissection has produced steeply dissected terrain highlighting a wide diversity of geologies that are also found in varying quantities across the plains. The dominant soils are mottled texture contrast soils with minor occurrences of sporadic

bleached

subsurface horizons. The dominant soils of this unit also occur on the mounds and in the depression of

gilgai

areas. Other soils often found associated with gilgais are black texture contrast soils, other texture contrast soils with shallow surface horizons and black cracking clays. A few surface stones may occur in these gilgai areas. Land use includes beef cattle and sheep grazing, water supply, softwood plantations and residential development around the smaller communities. Erosion hazards are minimal except at scarps, which have a moderate susceptibility to soil loss. Areas with shallow stony gradational soils are susceptible to leaching of nutrients, and compaction is a problem on the flatter gilgaied areas.

Looking north towards the higher sedimentary country of the Western Uplands
	Gentle grassed plains near Meredith

Component	1	2	3	4
Proportion of soil-landform unit	55%	5%	5%	35%
CLIMATE Rainfall (mm)	Annual: 710
Temperature (^oC)	Minium 7, Maximum 18
Precipitation less than potential evapotranspiration	October-March
GEOLOGY Age and lithology	Quaternary basalt, Orodivician marine sandstone and shale, minor Neogene fluvio-marine sand
Geomorphology	2.1.4 Dissected Western Uplands associated with volcanic landforms
LANDUSE	Uncleared: Nature conservation Cleared: Beef cattle and sheep grazing; water supply; cropping (cereal); hoticulture; residential development
TOPOGRAPHY Landscape	Gently undulating basalt plains
Elevation range (m)	220-575
Local relief (m)	1-3
Drainage pattern	Dendritic
Drainage density (km/km²)	1.2
Landform	Plains			Gentle rises
Landform element	Undulating plain	Drainage line	Depression	Roling hillslopes
Slope and range (%)	2 (0-5)	2 (0-5)	1 (0-2)	5 (3-10)
Slope shape	Straight	Concave	Concave	Convex
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassy Woodland (1.9%)
SOIL Parent material	Basalt	Basaltic colluvium and alluvium	Basaltic colluvium and alluvium	Sandstone and shale
Description (Corangamite Soil Group)	Acidic and neutral mottled brown, grey or yellow texture contrast soils (36)	Acidic mottled black texture contrast soils (31) and grey cracking clay (32)	Acidic mottled black texture contrast soils (32) and acidic and neutral mottled brown, grey or yellow texture contrast soils (31)	Acidic mottled brown, grey or yellow texture contrast soils (26)
Soil type sites	MM173	SW37, CLRA48, SW88	SW88, CLRA48	BD13, BD11, MM204
Surface texture	Fine sandy clay loam	Light medium clay, fine sandy clay	Fine sandy clay loam	Sandy loam
Permeability	Low	Low to very low	Very low	Moderate
Depth (m)	<2	>2	>2	<1.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrast soil, moderate water holding capacity and moderate nutrient holding capacity in surface and subsurface soils, higher in deep subsoil. Low to very low permeability. Some stone. Strongly sodic subsoil. Moderate site drainage. Surface susceptible to compaction.	Texture contrast and uniform expansive clay soil, moderate water holding capacity and moderate nutrient holding capacity in surface and subsurface soils, higher in deep expansive subsoil. Low to very low permeability. Strongly sodic subsoil, possibly surface soil associated with poor drainage. Slow to very slow site drainage.	Texture contrast soil, moderate water holding capacity and moderate nutrient holding capacity in surface and subsurface soils, higher in deep subsoil. Low to very low permeability. Minor stone. Strongly sodic subsoil, possible surface soil associated with poor drainage. Slow to very slow site drainage.	Texture contrast soil, low water holding capacity and nutrient holding capacity in surface and subsurface soils, higher in deep subsoil. Low permeability. Some stone. Occasionally sodic subsoil, generally strongly acidic. Moderately rapid site drainage. Slight susceptibility to sheet and rill erosion.

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