Soil/Landform Unit 131

Plains and low hills north of Cobden

Area:

1594 ha

0.12% of CMA region

This unit of undulating low hills is part of the Western Plains. This single unit occurring in the west of the Corangamite CMA region (north of Cobden) is a ‘window’ of Neogene sediments surrounded by basalt, including a number of eruption points. This area is a major area of dissection of Neogene sediments. Unit components are hill crests, upper, mid and lower slopes on the low hills, and drainage lines. The soils are

acidic

mottled

brown texture contrast soils (

Chromosols

). Susceptibility to waterlogging occurs in the depressions, but given the higher rainfall of the area and light surface soils, susceptibility to nutrient decline is high. Slight to moderate susceptibility to sheet erosion occurs on the slopes. Land use is intensive grazing (dairying) and some cropping.

Cleared land that is mainly used for grazing dairy cattle
	Remnant vegetation near Naroghid

Component	1	2	3	4	5
Proportion of soil-landform unit	5%	15%	30%	40%	10%
CLIMATE Rainfall (mm)	Annual: 830
Temperature (^oC)	Minimum 9, Maximum 18
Precipitation less than potential evapotranspiration	November-March
GEOLOGY Age and lithology	Quaternary basalt and scoria, minor Neogene fluvial-marine clay, sand and gravel
Geomorphology	6.1.4 Volcanic Western Plains with well developed drainage
LANDUSE	Uncleared areas: Water supply, nature conservation Cleared areas: Dairy farming; sheep and beef cattle grazing; cropping
TOPOGRAPHY Landscape	Undulating low hills
Elevation range (m)	135-201
Local relief (m)	40
Drainage pattern	Parallel
Drainage density (km/km²)	1.1
Landform	Low hills				Drainage line
Landform element	Crest	Upper slope	Mid slope	Lower slope	-
Slope and range (%)	4 (1-7)	8 (3-15)	5 (3-10)	3 (2-5)	2 (1-5)
Slope shape	Convex	Convex	Convex	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassy Woodland (6.1%)
SOIL Parent material	Sand, silt and clay	Sand, silt and clay	Sand, silt and clay	Sand, silt and clay	Alluvial sand, silt and clay
Description (Corangamite Soil Group)	Acidic mottled brown texture contrast soils (13)	Acidic mottled brown texture contrast soils (13)	Acidic mottled brown texture contrast soils (13)	Acidic mottled brown texture contrast soils (13)	Acidic mottled brown texture contrast soils (13/33)
Soil type sites	SW67, CLRA3, OTR601	SW67, CLRA3, OTR601	SW67, CLRA3, OTR601	SW67, CLRA3, OTR601	SW67, CLRA3, OTR601
Surface texture	Fine sandy loam	Fine sandy loam	Fine sandy loam	Fine sandy loam	Fine sandy loam
Permeability	Moderate	Moderate	Moderate to low	Low	Very low
Depth (m)	<1.5	<2	<2	<2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Large texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soils, higher in subsoil. Acidic (not quite strongly). Heavy, possible expansive clay subsoil. Rapid site drainage.	Large texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soil, higher in subsoil. Acidic (not quite strongly). Heavy, possible expansive clay subsoil. Moderate rapid site drainage.	Large texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soil, higher in subsoil. Acidic (not quite strongly). Heavy, possible expansive clay subsoil. Slow to moderate site drainage, higher susceptibility to waterlogging and compaction compared with Components 1 & 2.	Large texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soil, higher in subsoil. Acidic (not quite strongly). Heavy, possibly expansive clay subsoi. Slow site drainage, higher susceptibility to waterlogging and compaction with Component 1.	Texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soil, higher in subsoil. Acidic (not quite strongly). Heavy, possibly expansive clay subsoil. Slow site drainage, susceptibility to waterlogging and compaction.

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