Soil/Landform Unit - Lowan salt valley

Looking north-west from near Arkona along the Lowan salt valley gypseous lakes

Area: 34 924

1.49% of CMA region

Running from west of Dimboola to the north-western tip of Lake Hindmarsh is what has historically been referred to as the ‘Lowan salt valley’. Believed to have once been a southern path for the Murray River, the valley is a northern extension of the Douglas Depression to the south, being separated by deposits of

aeolian

sands as part of the Little Desert. The valley, like the Douglas Depression, is relatively gentle in nature with the eastern margin much more pronounced than the subtle graduation into the valley on the west. Landforms including rises and plains are common with soils including

calcareous

gradational soils (

Calcarosols

) and

sodic

red texture contrast soils (

Sodosols

) prominent on rises while sodic yellow and grey texture contrast soils (Sodosols) and seasonally wet soils (

Hydrosols

) common on plains and swamps. Salts within the valley are often found as significant deposits of gypsum in lower topographic positions and are often excavated for agricultural applications. Soils may be prone to wind erosion where ground coverage is poor and areas are prone to seasonal inundation. There are a variety of woodland, heathland and mallee vegetation types present including Shallow Sands Woodland, Lignum Swampy Woodland, Woorinen Mallee, Parilla Mallee, Low Rises Woodland, Sandstone Ridge Shrubland and Ridged Plains Mallee.

Pink Lake, looking south towards the Little Desert

Component	1	2	3	4	5	6
Proportion of soil-landform unit	5%	30%	10%	15%	10%	30%
CLIMATE Rainfall (mm)	Annual: 385
CLIMATE Rainfall (mm)	Annual: 385
Temperature (^oC)	Minimum 9, Maximum 22
Precipitation less than potential evapotranspiration	September–April
GEOLOGY Age and lithology	Quaternary paludal silt and clay; Quaternary aeolianites and evaporites (Yamba Formation); Quaternary aeolian dune sand (Lowan Sand)
GEOLOGY Age and lithology
Geomorphology	5.1.3 Linear dunes sub-dominant of the Calcareous North Western Dunefields and Plains
LANDUSE	Uncleared areas: nature conservation Cleared areas: dryland cropping; sheep grazing; gypsum extraction
LANDUSE
TOPOGRAPHY Landscape	Valley plain
TOPOGRAPHY Landscape	Valley plain
Elevation range (m)	79–127
Local relief (m)	10
Drainage pattern	Dendritic
Drainage density (km/km²)	0.5
Landform	Rises		Plains
Landform element	Low rise crest	Low rise slope	Lunette	Playa	Drainage line	Plain
Slope and range (%)	4 (1-7)	4 (1-7)	5 (2-9)	1 (0-2)	1 (0-2)	2 (1-6)
Slope shape	Straight	Straight	Convex	Straight	Concave	Convex
NATIVE VEGETATION Ecological Vegetation Class	Plains Woodland (24.0%), Low Rises Woodland (21.7%), Ridged Plains Mallee (20.1%), Plains Savannah (11.1%), Other (21.8%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	Marine sand and silt, aeolian sand	Marine sand and silt	Aeolian sand	Paludal silt and clay, evaporites and aeolianites	Fluvial gravel, sand and silt	Marine sand and silt
SOIL Parent material	Marine sand and silt, aeolian sand	Marine sand and silt	Aeolian sand	Paludal silt and clay, evaporites and aeolianites	Fluvial gravel, sand and silt	Marine sand and silt
Description (Corangamite Soil Group)	Calcareous gradational soils (26) and sodic red texture contrast soils (27)	Calcareous gradational soils (26) and sodic red texture contrast soils (27)	Calcareous gradational soils (26)	Seasonally wet soils: sodic yellow and grey texture contrast soils (33)	Sodic yellow and grey texture contrast soils (28) and seasonally wet soils: sodic yellow and grey texture contrast soils (33)	Sodic yellow and grey texture contrast soils (28) and cracking clay soils (29)
Soil type sites	TopCrop4, TopCrop2, LS17	TopCrop4, TopCrop2, LS17	TopCrop4	NA171, NA141, NA178	LS17, WAR33, NA171	LS17, WAR33, WLRA126
Surface texture	Sandy loam to clay loam	Sandy loam to clay loam	Clay loam	Sand	Sand to loamy sand	Loamy sand to sandy clay loam
Permeability	Moderate to high	Moderate	Moderate	Slow	Slow	Slow
Depth (m)	> 2	> 2	> 2	> 1.5	> 2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Moderately well drained soil with dispersive subsoil subject to erosion where exposed. Surfaces can be hardsetting and susceptible to sheet and rill erosion. Surface soil may be susceptible to sheet and wind erosion where apedal. Soils are prone to compaction at critical moisture contents.	Moderately well drained soil with dispersive subsoil subject to erosion where exposed. Surfaces can be hardsetting and susceptible to sheet and rill erosion. Surface soil may be susceptible to sheet and wind erosion where apedal. Soils are prone to compaction at critical moisture contents.	Moderately well drained soil with dispersive subsoil subject to erosion where exposed. Surface soil may be susceptible to sheet and wind erosion where apedal.	Susceptible to seasonal inundation, waterlogging and ultimately soil salinity. Upper soils susceptible to sheet erosion and wind erosion when exposed.	Susceptible to seasonal inundation and waterlogging. Upper soils susceptible to sheet erosion and wind erosion when exposed.	Wind erosion along with sheet and rill erosion occur on hardsetting surfaces with little organic matter. Subsoils are dispersive and susceptible to gully erosion on steeper slopes. Soils compact at critical moisture contents.

Page top