Soil/Landform Unit 197

Looking south over Swan Bay and the undulating sedimentary plains of this unit

Area:

5206 ha

0.39% of CMA region

This single unit of level and undulating plains is on the east coast of the Bellarine Peninsula, drains into Swan Bay and receives drainage from the Neogene plateau (Unit

) and the Palaeogene basaltic low hills (Unit

) to the west. Some Neogene ferruginised sediments occur on the coast at St Leonards. The soils are strongly

sodic

mottled

brown texture contrast with light surface soils which are susceptible to sheet erosion. Rainfall while relatively low is annually variable. This unit is susceptible to waterlogging where inundation is sufficient. Surface soil nutrient and structure decline and susceptibilities are also concerns. Land use is extensive grazing (beef and sheep) and minor cropping.

Level plain west of St Leonards
	Bleached texture contrast soils are dominant across the unit

Component	1	2
Proportion of soil-landform unit	80%	20%
CLIMATE Rainfall (mm)	Annual: 620
Temperature (^oC)	Minimum 10, Maximum 19
Precipitation less than potential evapotranspiration	October–March
GEOLOGY Age and lithology	Recent clay, sand and gravel and coastal sand dunes, Neogene fluvio-marine sand
Geomorphology	6.2.5 Alluvium, alluvial terraces, floodplains and coastal plains of the Sedimentary Western Plains
LANDUSE	Uncleared: Nature conservation; passive and active recreation Cleared areas: Sheep and beef cattle grazing; regional development
TOPOGRAPHY Landscape	Level and gently undulating plains
Elevation range (m)	4–90
Local relief (m)	2–5
Drainage pattern	Dendritic
Drainage density (km/km²)	1.4
Landform	Plains/Stagnant plains
Landform element	Flat	Depression
Slope and range (%)	1 (0–1)	1(0–2)
Slope shape	Straight	Concave
NATIVE VEGETATION Ecological Vegetation Class	Calcarenite Dune Woodland (1.7%), Plains Grassy Woodland (1.4%), Coastal Saltmarsh (1.0%), Other (0.8%)
SOIL Parent material	Gravel, sand, silt and clay	Sand, silt and clay
Description (Corangamite Soil Group)	Sodic brown often mottled texture contrast soils (32)	Black cracking clays (31) and sodic brown, often mottled texture contrast soils (32)
Soil type sites	CLRA4	CLRA15, CLRA35, CLRA4
Surface texture	Fine sandy loam	Light clay, fine sandy loam
Permeability	Low	Very low
Depth (m)	> 2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrast soil, low water holding capacity and low to moderate nutrient holding capacity in upper lighter soil, higher in subsoil. Strongly sodic subsoil, hardsetting, coarse structure. Low subsoil permeability and slow site drainage is common. Susceptible to compaction and structure decline and waterlogging. Some susceptibility to sheet and wind erosion.	Texture contrast soil and expansive clay soil, low water holding capacity and low to moderate nutrient holding capacity in upper lighter soil, higher in subsoil and cracking clay soils. Strongly sodic subsoil, hardsetting, coarse structure. Soils tend to have a low permeability. Very slow site drainage. Susceptible to waterlogging, compaction and structure decline.

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