Soil/Landform Unit - Morton drainage plains

Morton plains, north-east of Watchem

Area: 1805 ha

0.08% of CMA region

The plains and depressions are part of the hummocky dunes subdominant landscape within the calcareous dunefield of the North West Dunefields and Plains. These plains are also associated with the older

alluvial

plains of the Northern Riverine Plains (4.2) to the east. These low-lying plains/depressions lie between other plains (Kalkee and Charlton) and low hummocky dunefields (Beulah), and are generally orientated NNW/SSE. The plains are dominant with a drainage depression as a minor component that receives drainage from the surrounding units, though the terrain is essentially flat. Soil types are predominantly red sodic texture contrast soils (

Sodosols

), with yellow, brown and grey

sodic

texture contrast soils (Sodosols) and occasional grey and brown cracking clay soils (

Vertosols

) in the depressions. There is little resistance to wind movement due to the cleared flat terrain.

Compaction

is also a potential land degradation susceptibility, as is waterlogging in the depression and to some extent the plain, where topsoil is shallow. Dryland cropping is the major enterprise with some grazing (sheep). The four main vegetation communities found are Low Rises Woodland, Ridged Plains Mallee, Plains Woodland and Plains Savannah.

Plains with clayey roads
	Channel weir

Component	1	2
Proportion of soil-landform unit	70%	30%
CLIMATE Rainfall (mm)	Annual: 370

Temperature (^oC)	Minimum 9, Maximum 22
Precipitation less than potential evapotranspiration	September–April
GEOLOGY Age and lithology	Neogene marine sand and silt (Parilla Sand); Quaternary silt, sand and minor gravel (Shepparton Formation); Quaternary fluvial gravel, sand and silt; Quaternary aeolian lunettes, sand, silt and clay

Geomorphology	5.1.5 Hummock dunes sub-dominant of the Calcareous North West Dunefields and Plains
LANDUSE	Uncleared areas: water supply; nature conservation Cleared areas: sheep grazing; dryland grazing

TOPOGRAPHY Landscape	Gently undulating plains

Elevation range (m)	101–114
Local relief (m)	1–2
Drainage pattern	Dendritic
Drainage density (km/km²)	0.1
Landform	Alluvial plains
Landform element	Plain	Drainage depression/closed depression
Slope and range (%)	1 (0-2)	0 (0-2)
Slope shape	Straight	Straight
NATIVE VEGETATION Ecological Vegetation Class	Plains Savannah (45.0%), Plains Woodland (45.4%), Ridged Plains Mallee (5.4%), Low Rises Woodland (1.5%)

SOIL Parent material	Fluvial gravel, sand and silt	Paludal silt and clay, fluvial sand and silt

Description (Corangamite Soil Group)	Sodic red texture contrast soils (27) and sodic yellow and grey texture contrast soils (28)	Sodic yellow and grey texture contrast soils (28) and cracking clay soils (29)
Soil type sites	TopCrop2, LS17	LS17, WAR33, WLRA126
Surface texture	Sandy loam	Loamy sand to clay loam
Permeability	Moderate	Slow
Depth (m)	> 2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Hardsetting surface susceptible to sheet and rill erosion along with wind erosion. Dispersive and deep subsoils susceptible to gully erosion where exposed. Soils are prone to compaction at critical moisture contents.	Wind erosion along with sheet and rill erosion occur on hardsetting surfaces with little organic matter. Soils can be subject to inundation and waterlogging especially in low-lying areas. Subsoils are dispersive and susceptible to gully erosion on steeper slopes. Soils compact at critical moisture contents.

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