Soil/Landform Unit - Broughton undulating plains

WLRA Landform Broughton undulating plain

Gently Undulating Plains with Red Sodosols dominant (note the grey surface soil of Grey Vertosol in foreground. Red Sodosols occur on low rises.

Area: 6894 ha

0.29% of CMA region

Undulating plains near Broughton in the north-west of the Wimmera CMA region form part of the prominent ridges and oriented swales of the

North West Dunefields and Plains

(

5.5.1

). Characterised by gentle slopes and flats, the plains are characterised by

sodic

red texture contrast soils on the slopes where they have

hardsetting

surfaces that are susceptible to sheet and rill erosion, and wind erosion where exposed. Grey to brown cracking soils on the flats (swales) between ridges suffer from periodic inundation and waterlogging but this can be variable due to micro relief (

gilgai

). Soils may be susceptible to

compaction

at critical moisture contents. Land use is primarily dryland cropping with grazing by sheep and cattle less prominent today. The main remnant vegetation communities include Low Rises Woodland, Ridged Plains Mallee, Plains Grassland, Plains Woodland and Plains Savannah.

Gently undualting plain with Buloke (C. leuhmanni)
	Sodic red brown earth

Component	1	2	3
Proportion of soil-landform unit	15%	45%	40%
CLIMATE Rainfall (mm)	Annual: 410
CLIMATE Rainfall (mm)	Annual: 410
Temperature (^oC)	Minimum 8, Maximum 22
Precipitation less than potential evapotranspiration	September–April
GEOLOGY Age and lithology	Neogene marine sand and silt (Parilla Sand); Quaternary paludal silt and clay (Lowan Sand); Quaternary aeolian dune sand
GEOLOGY Age and lithology
Geomorphology	5.5.1 Prominent ridges and oriented swales of the North West Dunefields and Plains
LANDUSE	Uncleared areas: nature conservation Cleared areas: dryland cropping; sheep grazing
LANDUSE
TOPOGRAPHY Landscape	Gently undulating plains
TOPOGRAPHY Landscape	Gently undulating plains
Elevation range (m)	102–172
Local relief (m)	2–3
Drainage pattern	Dendritic
Drainage density (km/km²)	0.4
Landform	Plain
Landform element	Upper mid to moderate slopes	Low gentle slopes	Flat
Slope and range (%)	3 (2-10)	1 (1-4)	0 (0-1)
Slope shape	Concave	Linear	Straight
NATIVE VEGETATION Ecological Vegetation Class	Ridged Plains Mallee (31.5%), Low Rises Woodland (24.8%), Plains Woodland (21.6%), Plains Savannah (12.8%), Other (8.8%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	Aeolian dune sand	Aeolian dune sand	Aeolian sand and silt, swamp deposits
SOIL Parent material	Aeolian dune sand	Aeolian dune sand	Aeolian sand and silt, swamp deposits
Description (Corangamite Soil Group)	Sodic red texture contrast soils (35)	Sodic red texture contrast soils (35)	Grey and brown cracking clay soils (37)
Soil type sites	LS15, LS8, LS23	LS15, LS8, LS23	LS3, LSWW9, LSWW5
Surface texture	Sandy clay loam	Sandy clay loam	Medium clay
Permeability	Moderate	Moderate	Slow
Depth (m)	1.6	1.6	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Weakly structured soil surface (hardsetting) is susceptible to sheet and rill erosion, and wind erosion where exposed. Dispersive and deep subsoils susceptible to gully erosion on steeper slopes. Compaction of soil dependent upon depth of force and moisture content. Subsoils are highly sodic and saline.	Weakly structured soil surface (hardsetting) is susceptible to sheet and rill erosion, and wind erosion where exposed. Dispersive and deep subsoils susceptible to gully erosion on steeper slopes. Compaction of soil dependent upon depth of force and moisture content. Subsoils are highly sodic and saline.	Susceptible to inundation and waterlogging in lower areas, but can be variable due to micro relief (gilgai). Slightly susceptible to surface sheet erosion where soils are exposed. Surface soils are friable and only slightly susceptible to wind erosion. Soils susceptible to compaction at critical moisture contents.

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