Soil/Landform Unit 186

Area:

750 ha

0.06% of CMA region

The near-level to gently undulating sedimentary plains south of Anakie on the Western Plains are derived from long gentle slopes with minor depressions and occasional stony rises. Geology is quite diverse including

Quaternary

basalt, Recent clay, sand and gravel, and minor

Devonian

granite. However the greatest geological source for soils of these plains is the Neogene fluvio-marine sediments. The western margin of this unit abuts a large

alluvial

floor at the base of an erosional steep slope or scarps that lead to an elevated plateau of volcanic and sedimentary origin. Soils of these plains are alkaline red texture contrast, with heavier clay soils found in the minor drainage depressions.

Hardsetting

surfaces of these soils are prone to sheet erosion from the lack of infiltration. Nearly all land has been cleared with very few remnants observed in the landscape. Rainfall generally exceeds evaporation between the months of April and October where the land use is sheep and cattle grazing.

Long gentle slopes looking towards the You Yangs
	Looking south-east over the plains from Pringles Road. A large alluvial depression at the base of an erosional scarp provides the western boundary of this unit

Component	1	2	3
Proportion of soil-landform unit	95%	3%	2%
CLIMATE Rainfall (mm)	Annual: 560
Temperature (^oC)	Minimum 9, Maximum 19
Precipitation less than potential evapotranspiration	October–April
GEOLOGY Age and lithology	Quaternary basalt, Neogene fluvio-marine sediments, Recent clay, sand and gravel and minor Devonian granite
Geomorphology	6.2.4 Plains, rises and low hills of the Sedimentary Western Plains
LANDUSE	Uncleared: Nature conservation Cleared: Sheep and cattle grazing, occasional cropping (cereal)
TOPOGRAPHY Landscape	Near level plains
Elevation range (m)	54–115
Local relief (m)	2
Drainage pattern	Dendritic
Drainage density (km/km²)	2.1
Landform	Depressions
Landform element	Long gentle slopes	Depression	Stony rise
Slope and range (%)	1 (1–3)	1 (1–2)	3 (2–5)
Slope shape	Straight	Straight	Convex
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassy Woodland (0.7%)
Dominant species	E. ovata, E viminalis, E. rubida, E. obliqua	E. ovata, E viminalis, E. rubida, E. obliqua	E. ovata, E viminalis, E. rubida, E. obliqua
SOIL Parent material	Unconsolidated sediments with In situ weathered basalt	Alluvium	In situ weathered rock
Description (Corangamite Soil Group)	Mottled brown, yellow, grey or red sodic texture contrast soil, coarse structure (13/35/38)	Black clay soil, coarse structure (39)	Red shallow, stony gradational soil (40)
Soil type sites	SW67, SW90, MM5143	SW103, SW98, SFS4	BD5, SW96, SW26
Surface texture	Clay loam	Clay	Clay loam
Permeability	Moderate-low	Moderate	High
Depth (m)	1.5	1.5	0.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Hardsetting surfaces allow little infiltration, therefore high surface runoff. Slowly permeable subsoils are also quite sodic and prone to erosion if surface horizons are removed through sheet erosion. Periodic waterlogging common in wet seasons. Compaction of surfaces can benefit from addition of organic matter.	Clay soils beside creeks. Periodic waterlogging common in wet seasons. Streambank undercutting and stream bank erosion common. Slowly permeable subsoils are also quite sodic and prone to gully erosion. Compaction of surfaces can benefit from addition of organic matter.	Overland flow prominent due to shallow soil depth. Leaching of nutrients (nutrient decline) also a limitation of these rises along with sheet erosion. Compaction of surfaces can benefit from addition of organic matter.

Page top