Soil/Landform Unit 126

Looking south westerly across gently undulating basalt plain with basalt rocks appearing at the surface. This unit is found near Lara

Area:

840 ha

0.06% of CMA region

The undulating rises extend from Lara to Bacchus Marsh. These broad rises are volcanic in origin with many surface stones and rock floaters found in shallow soil profiles. The thin soils support grazing and minor cropping from a low average annual rainfall (500 mm). Vegetation is limited to Plains Grassland and Plains Grassy Woodland. The broad rises consist of alkaline red texture contrast soils. There are minor occurrences of alkaline

mottled

yellow and black texture contrast soils and alkaline grey cracking clays in the low-lying areas and depressions between rises. Topsoils have a moderate to high water holding capacity where they are deep. The cracking clay soils of lower slopes and depressions are expansive and have very slow site drainage.

Gently undulating basalt plain
	Roadside drainage with prominent soil cracking and soil depression within the subsoil

Component	1	2	3	4
Proportion of soil-landform unit	30%	20%	45%	5%
CLIMATE Rainfall (mm)	Annual: 500
Temperature (^oC)	Minimum 10, Maximum 20
Precipitation less than potential evapotranspiration	September-April
GEOLOGY Age and lithology	Quaternary basalt, Quaternary fluvial clay, sand and gravel
Geomorphology	6.1.3 Volcanic Western Plains with poorly developed drainage
LANDUSE	Uncleared: Nature conservation Cleared: Sheep and cattle grazing; cropping
TOPOGRAPHY Landscape	Undulating rises
Elevation range (m)	10-24
Local relief (m)	18
Drainage pattern	Dendritic
Drainage density (km/km²)	0.5
Landform	Rises			Drainage depressions
Landform element	Broad gentle crests and upper slopes	Mid slopes	Lower slopes
Slope and range (%)	4 (2-8)	5 (2-10)	3 (1-5)	3 (1-5)
Slope shape	Convex	Straight	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassland (0.4%), Plains Grassy Woodland (0.3%)
SOIL Parent material	In situ basalt	In situ basalt and colluvium	In situ basalt and colluvium	In situ basalt colluvium and alluvium
Description (Corangamite Soil Group)	Alkaline red texture contrast soils (38)	Alkaline red texture contrast soils, some alkaline mottled yellow and black texture contrast soils (38)	Alkaline red texture contrast soils (38), alkaline mottled brown and black texture contrast soils (36) and some alkaline grey cracking clays (39)	Alkaline red texture contrast soils (38), alkaline grey cracking clays (39) and alkaline mottled brown and black texture contrast soils (36)
Soil type sites	MM5075, MM5413	MM5075, MM5413	MM5075, SFS6, CLRA47	MM5075, SFS2, SW89
Surface texture	Clay loam, loam	Clay loam, loam	Clay loam, light clay	Clay loam, light clay
Permeability	Moderate	Moderate to low	Low to moderate	Low
Depth (m)	<1.5	<2	<2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrast, moderate nutrient holding capacity in upper soil, high in subsoil. Stone common. Moderate to high water holding capacity, shallow to deep soil. Moderate to high permeability on shallower soils. Strongly sodic in subsoil. Expansive clay soils, moderate rapid site drainage.	Texture contrast, moderate nutrient holding capacity in upper soil, high in subsoil. Some stone. Moderate to high water holding capacity, moderately deep to deep soil and moderately permeable. Strongly sodic in subsoil. Expansive clay soils, moderately rapid site drainage.	Texture contrast, moderate nutrient holding capacity in upper soil, high in subsoil. Moderate to high water holding capacity, moderately deep to deep soil. Very low permeability on cracking soils, low on yellow and black soils. Strongly sodic in subsoil. Expansive clay soils, very slow site drainage.	Texture contrast, moderate nutrient holding capcity in upper soil, high in subsoil. Moderate to high water holding capacity, moderately deep to deep soil. Very low permeability on cracking soils. Strongly sodic in subsoil. Expansive clay soils, very slow site drainage.

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