Soil/Landform Unit 88

Rolling plains near Yeodene

Area: 5385ha

0.40% of CMA region

West of Yeodene, a rolling and irregular landscape forms part of a broad ridge extending from the foothills of the Otway Ranges towards Colac. Paleogene sand outcrops on most parts of the landscape, often forming a veneer over exposures of Paleogene silt and clay. The soils have loamy sand or sandy loam surface textures and are prone to nutrient and moisture deficiencies. Hardpans between the sand veneers and clay horizons may result in perched watertables, although only small areas have such poor site drainage that frequent waterlogging occurs. Sand and gravel have been extensively mined in some areas, and pine plantations have been established near Yeodene. However, most of the area remains in a fairly natural state and constitutes a significant area of natural vegetation close to Colac. Its potential for recreation is at present not fully utilised. Only minor areas have been cleared for agriculture, but the establishment of improved pastures is difficult.

The rolling plains have broad crests that support gazing and cropping as the major land uses
	Slopes graduate into broad depressions and drainage lines

Component	1	2	3	4	5
Proportion of soil-landform unit	35%	25%	5%	30%	5%
CLIMATE Rainfall (mm)	Annual: 750-850, lowest January (40), highest August (100)
Temperature (^oC)	Annual: 13, lowest July (8), highest February (19)
Seasonal growth limitations	Temperature: less than 10^oC (av.) June-August Precipitation: less than potential evapotranspiration late October-early April
GEOLOGY Age and lithology	Paleogene marine mudstone, sandstone, silty clay and Cretaceous fluvio-volcanic mudstone, sandstone and conglomerate, Recent sand veneer
Geomorphology	3.3.2 Dissected rolling low hills of the Southern Uplands
LANDUSE	Uncleared areas: Hardwood forestry for posts, poles and fuel; sand and gravel extraction; forest grazing; water supply; passive and active recreation; softwood forestry Minor cleared areas: Sheep and beef cattle grazing; dairy farmins
TOPOGRAPHY Landscape	Rolling plain in the western parts of the Barwon catchment and northern parts of the Gellibrand catchment
Elevation range (m)	120-260
Local relief (m)	40
Drainage pattern	Dendritic
Drainage density (km/km²)	1.3
Landform	Plains
Landform element	Crest and slope	Slope	Broad slightly depressed area	Crest and slope	Drainage line
Slope and range (%)	9 (1-15)	15 (5-20)	2 (0-5)	8 (1-15)	3 (1-5)
Slope shape	Convex	Irregular	Concave	Linear	Concave
NATIVE VEGETATION Ecological Vegetation Class	Woodland	Woodland	Low woodland	Open forest	Low woodland
Dominant species	E. viminalis, E. obliqua, E. radiata	E. radiata, E. ovata, E. viminalis occasionally E. obliqua	E. nitida, E. radiata, occasionally E. viminalis	E. obliqua, E. radiata	E. ovata, Acacia melanoxylon, Leptospermum juniperinum, Melaleuca squarrosa
SOIL Parent material	Quartz sand	Silt and clay with sand veneer	Silt and clay with sand veneer	Clay, sitl and sand	Colluvial and alluvial sand, silt and clay, plant remains
Description (Corangamite Soil Group)	Grey sand soils (29)	Grey sand soils, weakly structured clay underlay (11)	Grey sand soils, weakly structured clay underlay (11)	Brown, grey or yellow gradational soils, weak structure (29/17)	Black sand soils (29)
Soil type sites	OTR742	-	-	OTR497, OTR741	OTR609, OTR739
Surface texture	Loamy sand	Loamy sand	Loamy sand	Sandy loam	Silty loam
Permeability	Very high	Low	Low	High	Moderate
Depth (m)	>2	>2	0.6	>2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Very low inherent fertility and high permeability lead to nutrient decline.	Low inherent fertility and leaching permeable surfaces lead to nutrient decline. Weakly structured surfaces and low permeabilities lead to sheet erosion on steeper slopes.	Low permeability and poor site drainage lead to seasonal waterlogging and soil compaction.	Weakly structured surfaces on steeper slopes are prone to sheet erosion.	High watertables lead to waterlogging and soil compaction. Runoff from adjacent hills leads to siltation and flooding.

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