Soil/Landform Unit 23

Broad gentle crests north-east of Rokewood Junction. Soils of these slopes tend to be hardsetting and are vulnerable to erosion

Area:

25 836 ha

1.93% of CMA region

This land unit is situated in the dissected uplands (Midlands) within the Western Uplands and consists of gently undulating plains. The broad rounded topography is in association with a Neogene capping of sands and other unconsolidated sediments. Vegetation communities include Heathy Dry Forests, Grassy Dry Forest, Creekline Herbrich Woodland and Valley Grassy Forest. This unit is predominantly a single mass with a few outliers situated to the south of the exposed

Palaeozoic

sediment terrain, capping more of this terrain with poorly defined coarse drainage falling to the south. This broad crests and plains unit has been divided into components based on drainage (as a result of differing soils and parent material). The basalts form a significant border. The soils generally have a significant sand component, with clay subsoils or a clay base at depth, and are strongly

acidic

in the surface and subsurface soil. These soils have a low nutrient holding capacity with some having

sodic

subsoils, particularly in the poorer drained areas.

Ferricrete of a cutting at Corindhap
	Deep dissection of lower Palaeozoic sediments is common within this landscape

Component	1	2	3	4
Proportion of soil-landform unit	70%	2%	15%	13%
CLIMATE Rainfall (mm)	Annual: 720
Temperature (^oC)	Minimum 7, Maximum 18
Precipitation less than potential evapotranspiration	October-March
GEOLOGY Age and lithology	Ordovician marine sediments with Neogen sediments and minor Quaternary basalt and alluvium
Geomorphology	2.1.3 Dissected Weatern Uplands associated with Cainozoic gravel and sediments
LANDUSE	Uncleared: Nature conservation; sport and recreation; residential development; softwood plantations Cleared: Softwood plantation; residential development; sheep and beef cattle grazing
TOPOGRAPHY Landscape	Undulating plains and rises associated with Ordovician hills
Elevation range (m)	200-560
Local relief (m)	40
Drainage pattern	Dendritic
Drainage density (km/km²)	2.3
Landform	Undulating plains
Landform element	Well drained non-sandy areas	Patches of deep sandy soil	Poorly drained non-sandy areas	Low-lying areas
Slope and range (%)	2 (1-3)	2 (1-3)	0 (0-2)	1 (1-3)
Slope shape	Convex	Convex	Flat	Concave
NATIVE VEGETATION Ecological Vegetation Class	Heathy Dry Forest (26.9%), Grassy Dry Forest (5.7%), Creekline Herb-rich Woodland (2.5%), Valley Grassy Forest (15%)
Dominant species	Callitris columellaris, E. viminalis, E. obliqua, E. radiata, E. rubida, E. ovata, E. pauciflora	Pteridium esculentum, E. viminalis	E. ovata	E. ovata
SOIL Parent material	Unconsolidated gravel, sand and clay	Unconsolidated sand	Unconsolidated gravel, sand and clay	Unconsolidated gravel, sand and clay
Description (Corangamite Soil Group)	Red mottled, brown, grey or yellow texture contrast soil, fine structure (15)	Deep grey or yellow sand soil (8/16)	Bronw, grey or yellow sodic texture contrast soil, coarse structure (14)	Mottled brown, grey or yellow texture contrast soil (13)
Soil type sites	MM5109, OTR499, SW63, MM5308	SW61, SW70, OTR608	SW99, SW93, MM204	SW67, CLRA3, OTR601
Surface texture	Sandy clay loam to loamy sand	Sand	Clay loam	Clay loam, sandy clay loam
Permeability	Moderate	High	Low	Moderate
Depth (m)	2	2	2	2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Hardsetting surfaces and low permeability leads to overland flow. This flow often creates sheet and rill erosion with major rainfall events. Gully erosion and leaching of salts also occur. Surface compaction can benefit from controlled traffic.	Low water and nutrient holding capacities lead to leaching and fertility decline.	Hardsetting surfaces and low permeability leads to overland flow. This flow often creates sheet and rill erosion with major rainfall events. Gully erosion and leaching of salts also occur. Surface compaction can benefit from controlled traffic.	Hardsetting surfaces and low permeability leads to overland flow. This flow often creates sheet and rill erosion with major rainfall events. Gully erosion and leaching of salts also occur.

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