Soil/Landform Unit 185

Level plains of Lara in the foreground of plains and rises leading to the You Yangs. This area is currently undergoing major land use change as the urban spread of Geelong further expands across this landscape

Area:

4583 ha

0.34% of CMA region

The near-level plains around Lara represent one of the driest areas in the Corangamite region. With an average annual rainfall of 490 mm and relatively high average yearly temperatures (minimum of 10

C and maximum of 20

C), land use may be somewhat limited with respect to higher rainfall regions of the catchment. Grazing and subdivision for residential and industrial development are the major land use practices of these plains. The geology comprises Recent clays, sand and gravel with minor

Quaternary

basalt found in the east. Topographically low (<40 m), this landscape has been vulnerable to marine inundations previously in geologic time. This is reflected in the abundance and occurrence of carbonate fragments at the surface of cultivated land. Native vegetation communities include Plains Grassy Woodland and Creekline Grassy Woodland. The sedimentary plain has black and red

mottled

texture contrast soils, with cracking clays found in lower depressions and sinks. Soils are prone to

compaction

and erosion due to the

sodic

nature of subsoils.

Red texture contrast soils with prominent carbonate fragments. Most likely these fragments have been brought to the surface via cultivation
	Level plains looking towards the You Yangs

Component	1	2	3
Proportion of soil-landform unit	85%	9%	6%
CLIMATE Rainfall (mm)	Annual: 490
Temperature (^oC)	Minimum 10, Maximum 20
Precipitation less than potential evapotranspiration	September–April
GEOLOGY Age and lithology	Recent clay, sand and gravel and minor Quaternary basalt
Geomorphology	6.2.4 Plains, rises and low hills of the Sedimentary Western Plains
LANDUSE	Uncleared: Nature conservation Cleared: Residential development, sheep and cattle grazing
TOPOGRAPHY Landscape	Level plain
Elevation range (m)	8–40
Local relief (m)	13
Drainage pattern	Dendritic
Drainage density (km/km²)	1.1
Landform	Plains	Drainage lines and depressions
Landform element	Plain	Drainage line/stream channel	Depression
Slope and range (%)	0 (0–1)	2 (1–3)	1 (0–1)
Slope shape	Linear	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassy Woodland (1.6%), Creekline Grassy Woodland (0.7%)
SOIL Parent material	Colluvium and alluvium: clay, silt and sand	Colluvium and alluvium: clay, silt and sand	Colluvium and alluvium: clay, silt and sand
Description (Corangamite Soil Group)	Alkaline mottled black texture contrast soils (14)	Alkaline mottled black texture contrast soils (14) and black cracking clays (31)	Alkaline mottled black texture contrast soils (14) and black cracking clays (31)
Soil type sites	SW99, SW93, SW102	SW99, SW37, CLRA48	SW99, SW37, CLRA48
Surface texture	Fine sandy clay loam	Fine sandy clay loam, light clay	Fine sandy clay loam, light clay
Permeability	Low	Low	Very low
Depth (m)	<2	>2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrast, moderate waterholding capacity and nutrient holding capacity in surface soil. Strongly sodic clay subsoil. Poor to moderate site drainage reflected in waterlogging and mottling. High organic matter may alleviate compaction and waterlogging susceptibility in surface soil. Carbonate present at surface and also in subsoil.	Texture contrast, moderate waterholding capacity and nutrient holding capacity in surface soil. Strongly sodic clay subsoil. Poor to moderate site drainage drainage reflected in waterlogging and mottling. High organic matter may alleviate compaction and waterlogging susceptibility in surface soil. Carbonate present at surface and also in subsoil.	Texture contrast, moderate waterholding capacity and nutrient holding capacity in surface soil. Heavier clay soils are prone to cracking. Strongly sodic clay subsoil. Poor to moderate site drainage reflected in mottling and low-lying areas of landscape. High organic matter may alleviate compaction and waterlogging susceptibility in surface soil.

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