Soil/Landform Unit 127

Gilgai and cracking clays are fond on the plains and depressions. These soils support deep rooted perennial pasutres such as phalaris, cocksfoot and fescue

Area:

17 987 ha

1.35% of CMA region

These gently undulating plains exist along the Corangamite and Glenelg-Hopkins catchment divide. The basalt plains are relatively young and have experienced little

regolith

and drainage development within the Western Plains. The plains have a wide array of land elements and derived soils. The most common soil types are the texture contrast soils on the rises. These soils vary in depth and may have a conspicuously

bleached

subsurface. Stone at the surface and as rock floaters also varies in concentration across the landscape.

Friable

red and black loams are found on crests and upper slopes while black and grey cracking clays are associated with depressions and the

gilgai microrelief

of this unit. Local relief is low with a sparse drainage network. The only significant vegetation class of these plains is the plains grassy woodland at 0.6%. This is a large unit with few outliers and is surrounded by other basaltic areas (including stony rises) to the north and east. This unit provides a western margin for unit

136

. The land use is grazing (mainly sheep) with cropping on rock-free plains, slopes and depressions. Waterlogging is a major land degradation and productivity issue due to the low relief and impermeable nature of most soils.

Drainage is variable in pattern and reflects the diverse array of soils and surfaces of this unit
	Stony rises and soils with many surface stone are common in this unit

Component	1	2	3	4	5	6	7	8
Proportion of soil-landform unit	25%	35%	8%	15%	4%	7%	4%	2%
CLIMATE Rainfall (mm)	Annual: 640
Temperature (^oC)	Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration	October-March
GEOLOGY Age and lithology	Quaternary basalt, minor clay, sand and gravel
Geomorphology	6.1.3 Volcanic Western Plains with poorly developed drainage
LANDUSE	Uncleared: Nature conservation Cleared: Sheep and beef cattle grazing; cropping (cereal) on rock free land
TOPOGRAPHY Landscape	Gently undulating basalt plain
Elevation range (m)	129-261
Local relief (m)	2-3
Drainage pattern	Dendritic-sporadic
Drainage density (km/km²)	0.5
Landform	Undulating plains		Gentle rises (lacking surface stones)		Steeper rises (with surface stones)			Drainage depressions
Landform element	Long gentle slopes	Plains	Crest, upper slopes	Long gentle side	Crestm upper slopes	Lower slopes	Valley flats	Swamps and depressions
Slope and range (%)	2 (1-4)	1 (0-2)	4 (1-8)	3 (2-6)	6 (3-12)	4 (2-6)	0 (0-2)	1 (0-3)
Slope shape	Straight	Straight	Convex	Straight	Convex	Straight	Straight	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassy Woodland (0.6%)
SOIL Parent material	In situ basalt and colluvium	In situ basalt and colluvium	In situ basalt	In situ basalt and colluvium	In situ basalt	In situ basalt and colluvium	Colluvium and alluvium	Colluvium and alluvium
Description (Corangamite Soil Group)	Alkaline mottled brown, grey or yellow texture contrast soils (36)	Alkaline mottled brown, grey or yellow texture contrast soils (36)	Alkaline mottled brown, grey or yellow texture contrast soils (36) and neutral and alkaline mottled black texture contrast soils (35)	Alkaline mottled brown, grey or yellow texture contrast soils (36) and neutral and alkaline mottled black texture contrast soils (35)	Alkaline mottled yellow duplex soils (36) and shallow friable stony loam soils (41)	Alkaline mottled brown, grey or yellow texture contrst soils (36) and neutral and alkaline mottled black texture contrast soils (35)	Grey cracking clay soils (39) and alkaline mottled brown, grey or yellow texture contrast soils (36)	Grey and black cracking clay soils (31)
Soil type sites	SFS6, MM5015, CLRA47	SFS6, MM5015, CLRA47	SFS6, MM5015, SW86	SFS6, MM5015, SW86	SFS6, BD5, SW96	SFS6, MM5015, SW86	SFS2, SW102, SW89	CLRA15, SW37, MM332
Surface texture	Fine sandy clay loam	Fine sandy clay loam	Fine sandy clay loam	Fine sandy clay loam	Sandy loam	Fine sandy clay loam	Light clay	Light clay
Permeability	Low	Low	Low to moderate	Low	Moderate to high	Moderate	Very low	Very low
Depth (m)	<1.5	<2	<1.5	<2	<0.7	<1	>2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrast, moderate water holding capacity and nutrient holding capacity in upper soil. Strongly sodic, low permeability subsoil, occasionally upper soil. Some stone and buckshot gravel.	Texture contrast, moderate water holding capacity and nutrient holding capacity in upper soil. Strongly sodic, low permeability subsoil, occasionally upper soil. Stone common along with some buckshot gravel.	Texture contrast, moderate water holding capacity and nutrient holding capacity in upper soil. Strongly sodic, low permeability subsoil, occasionally upper soil. Stone comon along with buckshot gravel.	Texture contrast, moderate water holding capacity and nutrient holding capacity in upper soil. Strongly sodic, low permeability subsoil, occasionally upper soil. Some stone and buckshot gravel. Slow to moderate site drainage.	Shallow, stony. Texture contrast or loamy. Sodic often strongly. Moderate to high permeability subsoil. Rapid site drainage.	Texture contrast, moderate water holding capacity and nutrient holding capacity in upper soil. Strongly sodic, low permeability subsoil, occasionally upper soil. Some stone and buckshot gravel. Slow to moderate site drainage.	Expansive clays, high water holding capacity and nutrient holding capacity. Strongly sodic, low permeability soil, occasionally upper soil. Minor stone. Slow to very slow site drainage.	Expansive clays, high water holding capacity and nutrient holding capacity. Strongly sodic, low permeability soil, occasionally upper soil. Slow to very slow site drainage.

Page top