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Soil/Landform Unit 20

Landform Unit Description

Unit 20 image a
Gentle undulating sedimentary plains with many forested remants soulth of Lal Lal
      Area: 7855 ha
      0.59% of CMA region

      The gently undulating plains occur near Napoleons, Lal Lal and Durdidwarrah are composed of Neogene fluvio-marine sand overlying Ordovician marine sandstone and shale. These sedimentary plains of the Western Uplands support a wide range of vegetation classes including forests and woodlands. Some of the major classes are plains Grassy Woodland, Heathy Dry Forest, Valley Grassy Forest, Damp Sands Herb-rich Woodland and Grassy Dry Forest. Dominant species are Callitris columellaris, Eucalyptus viminalis, E. obliqua, E. radiata, E. rubidia, E. ovata and E. pauciflora. The low fertility and low water holding capacity of the soils have discouraged further clearing. Soils include an association of bleached sandy mottled texture contrast soils or unbleached equivalents in better drained areas. Heavier surface textured soils may occur in drainage lines. These soils can be prone to gully erosion which is minor to moderate in severity in some cleared areas.
Unit 20 geomorphology

Unit 20 image b
Grazing is the major land use for these plains
Unit 20 cross section
Unit 20 graph

Component
1
2
3
4
5
6
7
8
Proportion of soil-landform unit
50%
7%
6%
2%
20%
5%
5%
5%
CLIMATE
Rainfall (mm)

Annual: 730
Temperature (oC)
Minimum 7, Maximum 18
Precipitation less than potential evapotranspiration
October-March
GEOLOGY
Age and lithology

Neogene fluvial sand,
Quaternary sand, gravel and minor basalt, Orodivician marine sandstone and gravel
Geomorphology
LANDUSE
Uncleared: Nature conservation; hardwood; gravel extraction
Cleared: Sheep and beef cattle grazing; cropping (cereal); gravel extraction
TOPOGRAPHY
Landscape

Gently undulating sedimentary plains
Elevation range (m)
334-502
Local relief (m)
3
Drainage pattern
Dendritic
Drainage density (km/km2)
2.6
Landform
Undulating plains
Flat plains
Drainage lines
Lakeside sandridges associated with Lal Lal swamp
Undulting plains
Minor hill
Landform element
Well drained non-sandy areas
Poorly drained non-sandy areas
Low-lying areas
Long gentle slope
Crest
Dry exposed slope
Crest
Slope and range (%)
2 (1-3)
0 (0-2)
1 (1-3)
3 (2-3)
3 (3-9)
2 (1-3)
15 )10-35)
3 (1-6)
Slope shape
Convex
Flat
Concave
Convex
Straight
Convex
Straight
Convex
NATIVE VEGETATION
Structure

Low open forest-woodland

Low open forest-woodland

Low open forest-woodland

Open forest

Open forest

Open forest

Open forest

Open forest
Dominant species
Callitris columellaris,
E. viminalis, E. obliqua,
E. radiata, E. rubida,
E. ovata, E. pauciflora
E. ovata
E. ovata
E. viminalis, E. radiata
E. viminalis, E. obliqua
E. obliqua, E. radiata
E. obliqua, E. dives,
E. radiata, E. viminalis
E. obliqua, E. dives
E. radiata, E. viminalis
SOIL
Parent material

Unconsolidated gravel, sand and clay

Unconsolidated gravel, sand and clay

Unconsolidated gravel, sand and clay

Unconsolidated sand

In situ weathered sandstone and shale

In situ weathered sandstone and shale

In situ weathered sandstone and shale

In situ weathered sandstone and shale
Description
(Corangamite Soil Group)
Red mottled, bornw, grey or yellow texture contrast soil, fine structure (13)
Brown, grey or yellow sodic texture contrast soil, coarse structure (14)
Mottled brown, grey or yellow texture contrast soil (13)
Yellow sand soils, uniform texture (8)
Mottled red, brown, grey or yellow texture contrast soils (26)
Mottled brown, grey or brown, grey or yellow texture contrast soils (25)
Red mottled brown or yellow gradational or texture contrast soils, fine structure (25/26)
Shallow stony red and brown, grey or yellow gradational soil (25)
Soil type sites
CLRA53, CLRA54, BD10
CLRA54, BD10, CLRA58
CLRA53, CLRA58
Surface texture
Sandy clay loam to
loamy sand
Clay loam
Clay loam, sandy clay loam
Sand
Clay loam
Loam to clay loam
Fine sandy loam
Gravelly loam
Permeability
Moderate
Low
Moderate
High
Moderate to low
High
High
High
Depth (m)
2
2
2
>2
0.8-1.8
0.5-1.0
2
0.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Hardsetting surfaces, dispersible subsoils and overland flow result in leaching of salts, sheet and rill erosion and gully erosion.
Hardsetting surfaces, dispersible subsoils and overland flow result in leaching of salts, sheet and rill erosion and gully erosion.
Hardsetting surfaces, dispersible subsoils and overland flow result in leaching of salts, sheet and rill erosion and gully erosion.
Low water and nutrient hilding capacity lead to leaching and fertility decline.
Harsetting surfaces, dispersible subsoils and overland flow result in leaching of salts, surface compaction, sheet and rill/gully erosion.
Hardsetting surfaces, dispersible subsoils and overland flow result in leaching of salts, surface compaction, sheet and rill/gully erosion.
Steep slopes, hardsetting surfaces and overland flow result in sheet and rill erosion and surface compaction.
Moderate hardsetting surfaces and overland flow result in sheet and rill erosion and surface compaction.
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