Soil/Landform Unit 158

Regional development in the towns of Jan Juc and Torquay is a major land use on slopes on the rolling hills

Area:

1775 ha

0.13% of CMA region

Below the ferruginised plateau to the east of the Otway Range lie a series of rolling hills that have formed by dissection along the valleys of Spring Creek and Jan Juc Creek. Weathering of limestone and marl exposed along these valleys has resulted in

calcareous

soils. Fertility is moderate, and thus contrasts with the surrounding impoverished soils of the ferruginised plateau and acid sands and clays. The red soils, or those deeper profiles transitional to the red soils, are the most favoured for agriculture and are used for cropping as well as dairy farming. Grazing of sheep and beef cattle is also common. Agricultural use is decreasing, however, as the township of Torquay extends its urban limits. Subdivision into small farmlets in other parts of the valleys also tends to decrease agricultural production. Sheet erosion occurs on some of the cropped steeper slopes, while gully erosion and slumping are problems of the dispersible texture contrast soils.

Rolling hill slopes at Jan Juc
	Wide drainage lines and rounded hills typify this landscape, as it rises to the ferruginised plateau in the distance

Component	1	2	3	4
Proportion of soil-landform unit	25%	40%	20%	15%
CLIMATE Rainfall (mm)	Annual: 600-650, lowest January (30), highest August (65)
Temperature (^oC)	Annual: 14, lowest July (10), highest February (18)
Seasonal growth limitations	Temperature: less than 10^oC (av.) July Precipitation: less than potential evapotranspiration early October - early April
GEOLOGY Age and lithology	Paleogene marine marl and limestone; Neogene fluvio-marine sand; minor Quaternary clay, sand and gravel
Geomorphology	6.2.2 Dissected plains, rises and low hills of the Sedimentary Western Plains
LANDUSE	Cleared areas: Dairy farming, beef cattle grazing; residential; cropping Minor uncleared areas: Forest grazing; active and passive recreation; hardwood forestry for fuel, posts and poles
TOPOGRAPHY Landscape	Rolling hills dissected out below the lateritic plateaux
Elevation range (m)	5-70
Local relief (m)	60
Drainage pattern	Dendritic
Drainage density (km/km²)	2.7
Landform	Hills
Landform element	Upper slope	Middle slope	Steeper slope	Lower slope and drainage line
Slope and range (%)	5 (3-9)	11 (5-14)	15 (7-20)	7 (1-9)
Slope shape	Linear	Linear	Convex	Concave
NATIVE VEGETATION Structure	Open forest	Open forest	Open forest	Open forest
Dominent species	E. viminalis, E sideroxylon, E. obliqua	E. leucoxylon, E. sideroxylon, E. viminalis	E. viminalis, E. ovata, Acacia melanoxylon	E. viminalis, E. sideroxylon, E. leucoxylon, E. ovata
SOIL Parent material	Truncated ferricrete remnants	Calcareous clay and deeply weathered limestone	Limestone	Colluvial limestone, clay, ferruginised material
Description (Corangamite Soil Group)	Brown texture contrast soils, coarse structure (27, 13)	Yellow-brown calcareous sodic texture contrast soils, coarse structure (19)	Red calcareous gradational soils (24)	Brown, grey or yellow sodic texture contrast soils (19)
Soil type sites	OTR783, OTR490	OTR490, OTR743	OTR489, OTR784, MM334	OTR743, SW80
Surface texture	Fine sandy loam	Fine sandy loam	Fine sandy clay loam	Loamy sand
Permeability	Low	Moderate	High	Moderate
Depth (m)	>2	>2	0.7	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Dispersible subsoils receiving seepage water are prone to gully erosion, slumping and rilling.	Highly dispersible subsoils are prone to gully erosion and slumping.	Steeper slopes are prone to sheet erosion.	High dispersible subsoils are prone to gully erosion and tunnel erosion.

Page top