Soil/Landform Unit - Horsham South sand-clay plain

WLRA Landform Horsham South sand-clay plain

Looking north over the alluvial aprons and fans of the Mackenzie River, Burnt Creek and Norton Creek

Area: 31 859 ha

1.36% of CMA region

The sand-clay plains between the Grampians Range in the east and the western Black Range in the west form part of the alluvial fans and aprons landscape (4.3) of the Wimmera CMA region. Comprising a sequence of Neogene to recent sedimentary deposits, the plains are very gentle with numerous sandsheets scattered amongst these sandy clay plains. Swamps also figure prominently with drainage systems of MacKenzie Creek, Burnt Creek and numerous channels that supply lakes and the Wimmera River further north. Soils are quite variable owing to sediment sources and include cracking clays (

Vertosols

), red

sodic

texture contrast soils (

Sodosols

) and deep sands (

Tenosols

and

Podosols

). Seasonal inundation can be an issue where depressions and flats occur during wet seasons. Soil compaction on the texture contrast soils is a management issue also. Land use is mainly cereal cropping along with pasture production and sheep grazing. There are a number of woodland vegetation communities including; Damp Sands Herb-rich Woodland, Heathy Woodland, Plains Grassy Woodland and Creekline Grassy Woodland for example. Other vegetation communities include herblands, wetlands, marshes and scrub.

Plains with Buloke and red gum near Wonwondah South
	Cropped plains south-west of Mockinya

Component	1	2	3	4	5
Proportion of soil-landform unit	5%	30%	5%	10%	50%
CLIMATE Rainfall (mm)	Annual: 590
CLIMATE Rainfall (mm)	Annual: 590
Temperature (^oC)	Minimum 8, Maximum 20
Precipitation less than potential evapotranspiration	October–March
GEOLOGY Age and lithology	Neogene marine sand and silt (Parilla Sand); Quaternary paludal silt and clay; Quaternary alluvium, silt, sand and minor gravel (Shepparton Formation)
GEOLOGY Age and lithology
Geomorphology	4.3 Pediments, alluvial fans and aprons (Glencoe, Yallambee)
LANDUSE	Uncleared areas: nature conservation; water supply Cleared areas: dryland cropping; sheep grazing
LANDUSE
TOPOGRAPHY Landscape	Sand and clay plain
TOPOGRAPHY Landscape	Sand and clay plain
Elevation range (m)	124–323
Local relief (m)	3
Drainage pattern	Dendritic
Drainage density (km/km²)	0.9
Landform	Plains
Landform element	Creek/drainage line	Dune slope/sandsheet	Playa	Gentle rise	Level plain
Slope and range (%)	1 (0-2)	4 (3-10)	0 (0-1)	3 (2-8)	2 (1-5)
Slope shape	Concave	Convex	Concave	Convex	Straight
NATIVE VEGETATION Ecological Vegetation Class	Plains Woodland (40.1%), Creekline Sedgy Woodland (20.4%), Heathy Woodland (7.7%), Riparian Woodland (6.7%), Other (25.1%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	Alluvial gravel, sand and silt	Aeolian dune sand and silt	Paludal silt and clay	Marine sand and silt	Fluvial and marine sand and silt
SOIL Parent material	Alluvial gravel, sand and silt	Aeolian dune sand and silt	Paludal silt and clay	Marine sand and silt	Fluvial and marine sand and silt
Description (Corangamite Soil Group)	Cracking clay soils (23)	Sandy soils with and without pans (31) and sodic yellow and grey texture contrast soils (32)	Cracking clay soils (23)	Sodic red texture contrast soils (25)	Cracking clay soils (23) and sodic red texture contrast soils (25)
Soil type sites	WIA11, WIA12, WIA17, HOR04	WLRA74, WLRA85, LSWW	WIA11, WIA12, WIA17, HOR04	WIA16, WIA14, WLRA105	WIA11, WIA12, WIA16
Surface texture	Light clay	Loamy sand	Light clay	Fine sandy loam	Fine sandy loam - light clay
Permeability	Very slow	High	Very slow	Slow	Slow
Depth (m)	> 2	> 2	> 2	> 2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Drainage areas are susceptible to seasonal inundation and waterlogging, but can be variable locally due to micro relief (gilgai). Surface soils generally not friable and are susceptible to compaction (less structure).	Soils with low organic matter levels can be susceptible to wind and sheet erosion where exposed. Low inherent soil fertility.	Flat areas susceptible to seasonal inundation and waterlogging. Surface soils are generally not friable and are susceptible to compaction (less structure).	Hardsetting soil slightly susceptible to sheet and rill erosion. Soils are prone to compaction at critical moisture contents. Subsoil susceptible to gully erosion when exposed due to dispersive (sodic) nature. Slight susceptibility to acidification of surface soil.	Soils may be slightly susceptible to inundation and waterlogging where surface soil is shallow. Hardsetting soil slightly susceptible to sheet and rill erosion. Soils are prone to compaction at critical moisture contents.

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