Soil/Landform Unit 113

The stony rises of Pombornbeit are a topographically significant landform of the plains that offer little land use potential but high environmental (biodiversity) value

Area:

17 052ha

1.28% of CMA region

This unit consists of gently undulating rises (hummocky stony rises) and associated drainage depressions and flats. This unit occurs within the volcanic Western Plains. Relief is quite subdued on these stony rises, however, relief has a large influence on component performance. This unit has a number of components, some (such as the low rises and undulating plain) are erosional, while others (such as the depressions and flats) are depositional. This relatively young terrain unit in the Pomborneit area is adjacent to basaltic undulating plains near Lake Corangamite in the east, and swamps and sedimentary terrain to the south-west. Native vegetation is scarse with Stony Rises Herb-rich Woodland, Plains Sedgy Wetland and Swamp Scrub the major classes. Within this unit there is an excellent example of remnant vegetation located on the stony rises. The soils are shallow black and red

friable

gradational soils with black cracking

self-mulching

soils on the depressions and flats. Agricultural land use is generally grazing, with the capability of the unit varying with component composition. The undulating plains between the rises are probably the most sought after, agriculturally. Waterlogging and stony soils provide the greatest limitations to cropping.

Stony rise flow of Mount Pomborneit
	Remnant vegetation of the stony rises

Component	1	2	3	4
Proportion of soil-landform unit	55%	30%	13%	2%
CLIMATE Rainfall (mm)	Annual: 790
Temperature (^oC)	Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration	November-March
GEOLOGY Age and lithology	Quaternary basalt and minor scoria, Recent clay, sand and gravel
Geomorphology	6.1.2 Stony rises of the Volcanic Western Plains
LANDUSE	Uncleared: Nature conservation; water supply Cleared: Beef cattle and sheep grazing; minor cropping
TOPOGRAPHY Landscape	Undulating stony rises
Elevation range (m)	107-196
Local relief (m)	5
Drainage pattern	Centripetal-deranged
Drainage density (km/km²)	0.5
Landform	Stony rises		Drainage depressions
Landform element	Stony hummocks and ridges	Undulating plains	Depressions	Drainage lines
Slope and range (%)	4 (1-7)	2 (0-5)	1 (0-2)	1 (0-3)
Slope shape	Convex	Straight	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Stony Rises Herb-rich Woodland (2.2%), Plains Sedgy Wetland (0.6%), Swamp Scrub (0.5%)
SOIL Parent material	In situ basalt	In situ basalt and colluvium	Baslatic alluvium; clay silt and sand	Basaltic alluvium; clay silt and sand
Description (Corangamite Soil Group)	Shallow, red or black loams (40)	Shallow, red or black loams (40) and black cracking clays (39)	Black cracking clays (31)	Black cracking clays (31)
Soil type sites	BD5, SW96, SW26	BD5, SW26, SW101	SW37, CLRA48, CLRA15	SW37, CLRA48, CLRA15
Surface texture	Clay loam or loam	Clay loam, light medium clay	Medium clay	Light medium clay
Permeability	High	Moderate to high	Very low	Low
Depth (m)	<0.7	<1.5	>2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Shallow, stony soils. Friable. Stongly structured. Moderate to high nutrient holding capacity. Well drained but low water holding capacity.	Shallow, stony soils and deeper clay soils. Friable. Strongly structured. Moderate to high nutrient holding capacity. Well drained but low water holding capacity where shallow.	High seasonal watertable leads to soil compaction. High organic matter content, high clay content and expansive clays. May be better drained where lighter soil occurs.	High seasonal watertable leads to soil compaction. High organic matter content, high clay content and expansive clays. May be better drained where lighter soil occurs.

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