Soil/Landform Unit 190

Undulating plains west of Bannockburn

Area:

7563 ha

0.57% of CMA region

This undulating plains and terrace unit within the sedimentary Western Plains. This unit occurs in the Bannockburn, Mount Moriac, Buckley and Paraparap areas and predominantly consists of a Neogene plain (plateau) but includes a terrace complex where dissected. This unit occurs as a ‘window’ amongst various basaltic landforms (mainly plains), with a dominant upper plain component and minor lower plain, drainage line and two terrace components. The soils are

mottled

brown texture contrast soils (

Chromosols

) on the upper plains and similar but

sodic

soils (

Sodosols

) on the lower plains and higher terraces. The lower terrace has dark gradational soils (

Dermosols

). The lighter surface soils are prone to nutrient decline and sheet and rill erosion as well as structure decline especially where soils are sodic. Waterlogging is also a possibility in the depressions, though rainfall decreases northward in terms of this unit. Land use is grazing, cropping, ferruginous gravel extraction on the Neogene plains, grazing on the upper terrace with some market gardening on the lower terrace.

Near-level plain as part of window near Moriac
	Cropping on these soils is a minor land use with grazing dominant

Component	1	2	3	4	5	6
Proportion of soil-landform unit	70%	9%	8%	1%	5%	7%
CLIMATE Rainfall (mm)	Annual: 500–680
Temperature (^oC)	Minimum 9, Maximum 19
Precipitation less than potential evapotranspiration	October–April
GEOLOGY Age and lithology	Neogene fluvio-marine sand, Quaternary basalt and alluvium, minor Ordovician marine sandstone
Geomorphology	6.2.4 Plains, rises and low hills of the Sedimentary Western Plains
LANDUSE	Uncleared: Nature conservation Cleared: Cropping (cereal); sheep and beef cattle grazing; low quality plantations; ironstone gravel extraction; regional development; market gardens (on lower areas)
TOPOGRAPHY Landscape	Undulating plains and terraces
Elevation range (m)	27–293
Local relief (m)	3–8
Drainage pattern	Dendritic				-
Drainage density (km/km²)	0.7				5.7
Landform	Undulating plain				Terrace
Landform element	Upper plain	Drainage line	Lower plain	Sandridge with ferricrete	Higher terrace	Middle terrace
Slope and range (%)	3 (2–5)	1 (1–2)	3 (1–5)	4 (3–5)	2 (1–5)	1 (0–2)
Slope shape	Straight	Concave	Straight	Convex	Straight	Straight
NATIVE VEGETATION Ecological Vegetation Class	Woodland to open forest	Woodland to open forest	Woodland to open forest	Woodland to open forest	Woodland
Dominant species	E. leucoxylon, Acacia pyncnantha, E. melidora, Casurina stricta, E. viminalis	E. camaldulensis	E. leucoxylon, Acacia spp	E. viminalis, A. .pyncnantha	E. viminalis E. radiata
SOIL Parent material	Unconsolidated clay, silt, sand and gravel	Unconsolidated sediments and recent alluvial deposition	Unconsolidated clay, silt, sand and gravel	Unconsolidated sediments and ferricrete	Unconsolidated river deposits	Unconsolidated river deposits
Description (Corangamite Soil Group)	Mottled brown, grey or yellow texture contrast and red texture contrast soils, both finely structured (13)	Mottled brown, grey or yellow texture contrast soils, fine structure (13)	Mottled brown, grey or yellow sodic texture contrast soils, coarse structure (14)	Mottled red texture contrast soils, acidic (15)	Mottled brown, grey or yellow texture contrast soils (32)	Dark clay soils, variable texture-mainly clay loams (34)
Soil type sites	CLRA3, OTR601, SW67	CLRA3, OTR601, SW67	SW99, SW93, MM204	SW63, OTR499, MM5109	SW88, SFS20, CLRA4	SW39, CLRA15, CLRA1
Surface texture	Fine sandy loam	Sandy loam	Sandy loam	Fine sandy loam	Clay loam	Clay loam
Permeability	Moderate	Moderate to low	Low	High	Moderate to low	Moderate to low
Depth (m)	1–2	1.5–2.5	2	0.7–1.8	1.2–2	1.2–2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Hardsetting surfaces with overland flow and minor sheet erosion.	Seasonal high watertables combined with slope position result in periodic waterlogging and minor gully erosion.	Dispersibility of subsoils when exposed leads to moderate gully erosion. Overland flow and subsurface flow occur.	Hardsetting surfaces result in overland flow and minor sheet erosion.	Hardsetting surfaces result in overland flow and minor sheet erosion.	Low-lying areas prone to flooding, overland flow, periodic waterlogging and siltation.

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