Your gateway to a wide range of natural resources information and associated maps

Victorian Resources Online

SG4

Location: Wonthaggi

Australian Soil Classification: Endoacidic, Epipedal, Aquic (Black) VERTOSOL
Northcote Factual Key: Ug 5.1Great Soil Group: black clay
Geology: Recent alluvium derived from South Gippsland Uplands.General Landscape Description: Interdune swale.
Soil Mapping Unit: Tarwin (also minor component of Heath Mounds Unit).Site Description: Bushland reserve on Boundary Road, Wonthaggi.
Native Vegetation: Predominantly Swamp Paperbark (Melaleuca ericifolia).

Photo: West Gippsland Soil Site SG4 Landscape
Site SG4 Landscape


Soil Profile Morphology:

Surface Soil

A10-20 cmBlack (10YR2/1); light clay; strong fine polyhedral structure; weakly self-mulching; surface cracking occurs when dry; weak consistence moist; pH 6.2; clear change to:
Photo: West Gippsland Soil Site SG4 Profile
Site SG4 Profile
Subsoil

B21
20-35 cm
Black (10YR2/1); medium clay; moderate very coarse prismatic, parting to moderate coarse blocky structure; firm consistence moist; pH 6.3; clear and wavy change to:

B2235-70 cmDark grey (10YR4/1) with yellowish brown (10YR5/6) mottles; heavy clay; structure similar to above; firm consistence moist; slickensides present; pH 5.7; gradual change to:

B2370-105 cmLight brownish grey (10YR6/2) with brownish yellow (10YR6/8); heavy clay; moderate very coarse prismatic, parting to strong medium to coarse blocky structure; firm consistence moist; pH 5.1; clear change to:

B31

105+ cmLight grey (10YR7/1) with brownish yellow (10YR6/8) mottles; fine sandy clay; firm consistence moist; pH 5.2.

Key Profile Features:
  • Clay texture throughout profile.
  • Shrink-swell (i.e. vertic) properties resulting in strong cracking when dry.
Soil Profile Characteristics:


Graph: West Gippsland Site SG4, pH levels

Graph: West Gippsland Soil Site SG4, Salinity levels
Graph: West Gippsland Soil Site SG4, Exchangeable Aluminium
The surface soil and top of the subsoil
are slightly acid. The pH decreases
further down the profile and from
70 cm depth the soil is strongly acid.
The level of soluble salts is very low
for most of the soil profile. From
105 cm the salinity rating becomes medium.
As the soil becomes strongly acid from
70 cm depth, the exchangeable aluminium
levels become high.

Horizon Depth
(cm)
pH
(water)
pH
CaCl2
EC 1:5
NaCl
%
Exchangeable Cations
meq/100g
Ex. Al
mg/kg
Ex. Acidity
meq/100g
Field Capacity
pF 2.5
Wilting Point
pF 4.2
Coarse Sand
(0.2-2.0 mm)
Fine Sand
(0.02-0.2 mm)
Silt
(0.002-0.02 mm)
Clay
(<0.002 mm)
Ca
Mg
K
Na
A1
0-20
6.2
5.1
0.06
7.3
7.4
1.0
0.5
38.8
18.9
6
32
21
30
B21
20-35
6.3
4.8
0.06
4.6
9.6
0.7
1.2
12.7
36.9
19.8
5
28
19
41
B22
35-70
5.7
4.4
0.11
2.5
9.7
0.5
2.0
13.2
B23
70-105
5.1
4.3
0.34
0.08
2.0
12
0.4
3.9
280
14
B31
105+
5.2
4.4
0.44
0.12
1.9
12
0.3
6.4
160
11

Management Considerations:

Whole Profile
  • Deep cracking occurs when the soil is dry. This will allow heavy rains to move down to the subsoil. When wet, the soil will swell and further infiltration of water will be relatively slow. Waterlogging will occur in winter as a result. Much of the soil profile will be saturated for a prolonged period (i.e. 2-3 months) of the year.

  • Plant Available Water Capacity (PAWC) is considered to be low (estimated at approximately 85 mm). This is based on available laboratory data and assumes an effective rooting depth of 70 cm.

Surface (A) Horizons
  • Tillage or overstocking of cracking clay soils should be avoided if the soil is wet (i.e. wetter than the plastic limit). At such moisture conditions, tillage and excessive trafficking or over-stocking could result in structural damage (e.g. compaction, smearing) occurring. Ideally, tillage and trafficking should take place when the soil is drier than the plastic limit down to at least the tillage depth.

Subsoil (B) Horizons
  • From approximately 70 cm depth the subsoil becomes strongly acid. As a result, aluminium toxicity may occur. The level of exchangeable aluminium measured in the laboratory is high and likely to restrict the growth of deeper-rooted aluminium sensitive species.

  • In the deeper subsoil, the level of soluble salts increases to levels which may affect deeper-rooted salt sensitive species. The salt problem is below effective rooting depth but could be monitored over time.

  • The subsoil is likely to have strong vertic properties which indicates that significant shrinking and swelling occurs on wetting and drying. This can disrupt the roots of perennial plants and will have implications for engineering applications (e.g. building foundations).
Profile Described By: Mark Imhof, Ian Sargeant and Sonia Thompson (20/6/95).
Page top