Soil/Landform Unit 136

The gently undulating plains have a geater density and depth of dissection further south near Lismore. Above is an example of the broad drainage depressions undulating across the plains

Area:

58 432 ha

4.38% of CMA region

The gently undulating plains that exist between Lismore and Skipton have well developed

regolith

profiles on

Quaternary

basalt within the Western Plains. These gently undulating plains may have some stone on the surface on the gentle crests and upper slopes. The soils are texture contrast with variable depth surface horizons that are often shallow with sporadically

bleached

subsurfaces over strongly

sodic

medium or heavy clay subsoils. Local relief is low with a sparse drainage network and depressions generally having similar soils to the slopes. This drainage network does become more pronounced further south towards Lismore. The only significant vegetation class of these plains is the Plains Grassland/Plains Grassy Woodland Mosaic (0.9%). This is a large unit with few outliers, surrounded by other basaltic areas (including stony rises) and granite to the north. This unit surrounds a granitic unit (Unit

143

) centred to the north of Lismore. The land use is extensively cropping and grazing (mainly sheep). Land degradation issues include waterlogging and overland due to the low relief and sometimes

hardsetting

sufaces.

Crops are extremely productive on these gentle plains with deeply developed regolith
	uch of these plains are cropped and grazed in rotations

Component	1	2	3	4
Proportion of soil-landform unit	5%	50%	38%	7%
CLIMATE Rainfall (mm)	Annual: 620
Temperature (^oC)	Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration	October-April
GEOLOGY Age and lithology	Quaternary basalt, Neogene fluvio-marine sand, silt and clay
Geomorphology	6.1.4 Volcanic Western Plains with well developed drainage
LANDUSE	Uncleared areas: Nature conservation Cleared areas: Sheep and cattle grazing; cropping (cereal); softwood plantations; water supply
TOPOGRAPHY Landscape	Gently undulating basalt plains
Elevation range (m)	114-329
Local relief (m)	20
Drainage pattern	Dendritic
Drainage density (km/km²)	0.5
Landform	Low rises		Plains	Drainage depressions
Landform element	Broad low crests and stony rises	Long gentle slopes	Broad plains	Drainage lines and depressions
Slope and range (%)	4 (2-8)	2 (1-5)	1 (0-3)	3 (0-5)
Slope shape	Convex	Linear	Straight	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Gassland / Plains Grassy Woodland Mosaic (0.9%)
SOIL Parent material	Basalt	Basalt and colluvium	Basalt	Basalt colluvium and alluvium
Description (Corangamite Soil Group)	Alkaline, mottled brown, grey or yellow texture contrast soils, shallow surface horizons (35)	Alkaline, mottled brown, grey or yellow texture contrast soils, shallow surface horizons (35)	Alkaline, mottled brown, grey or yellow texture contrast soils, shallow surface horizons (35)	Alkaline, mottled brown, grey or yellow texture contrast soils, shallow surface horizons (35)
Soil type sites	MM239, SW86, CLRA49	MM239, SW86, CLRA49	MM239, SW86, CLRA49	MM239
Surface texture	Clay loam	Clay loam	Clay loam	Clay loam
Permeability	Low	Low	Low	Very low
Depth (m)	<1.5	<2	<2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrast soil, moderate water holding capacity and nutrient holding capacity in shallow surface and subsurface soils, higher in deep subsoil. Some stones, but mottled; low permeability. Strongly sodic subsoil, possible surface soil associated with poor drainage. Moderate site drainage.	Texture contrast soil, moderate water holding capacity and nutrient holding in shallow surface and subsurface soils, higher in deep subsoil. Some stones, but mottled; low permeability. Strongly sodic subsoil, possibly surface soil associated with poor drainage. Slow to moderate site drainage.	Texture contrast soil, moderate water holding capacity and nutrient holding capacity in shallow and deeper surface and subsurface soils, higher in deep subsoil. Some stones, mottled, low permeability. Strongly sodic subsoil, possible surface soil associated with poor drainage. Slow site drainage.	Texture contrast soil, moderate water holding capacity and nutrient holding capacity in shallow and deeper surface and subsurface soils, higher in deep subsoil. Very low to low permeabiity. Strongly sodic subsoil, possible surface soil associated with poor drainage. Very slow site drainage.

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