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SG1

Location: Leongatha South.

Australian Soil Classification: Humose-Acidic, Dermosolic, Redoxic HYDROSOL
Northcote Factual Key: Gn 4.61Geology: Quaternary alluvium which has originated from the South Gippsland Uplands.
General Landscape Description: Very gently undulating alluvial plain.Soil Mapping Unit: Powlett.
Site Description: Roadside verge near corner of Hillgroves Road and Hudson Road at Leongatha South. This site is seasonally saturated for an average of 3-5 months per year.
Native Vegetation: Includes Swamp Paperbark (Melaleuca ericifolia), Gippsland Mallee (Eucalyptus kitsoniana), Swamp Gum (E. ovata).

Photo: West Gippsland Soil Site SG1 Landscape
Site SG1 Landscape


Soil Profile Morphology:

Surface Soil

A110-20 cmBlack (10YR2/1); very fine sandy loam; firm surface condition; weak very coarse blocky structure; weak consistence dry; pH 5.2; gradual change to:

Photo: West Gippsland Soil Site SG1 Profile
Site SG1 Profile
A1220-30 cmVery dark grey (10YR3/1); very fine sandy loam; firm consistence dry; pH 5.1; gradual change to:

A230-45 cmGreyish brown (10YR5/2) conspicuously bleached (10YR7/2d); very fine sandy loam; firm consistence dry; contains a few "coffee rock" (soft to semi hard) fragments at 40-45 cm depth; pH 4.9; gradual change to:

Subsoil

B2145-70 cmLight brownish grey (10YR6/2) with brownish yellow (10YR6/6) diffuse mottles; light very fine sandy clay loam; strong consistence dry; moderately structured; pH 4.7; gradual change to:

B2270-80 cmLight brownish grey (10YR6/2) with brownish yellow (10YR6/8) diffuse mottles; silty clay; moderate structure; pH 4.7.


Key Profile Features:
  • No clear or abrupt texture change throughout the profile.
  • Humus rich surface horizon.
  • High fine sand and silt content throughout the profile.


Soil Profile Characteristics:


Graph: West Gippsland Soil Site SG1 pH levels

Graph: West Gippsland Soil Site SG1 Salinity levels
Graph: West Gippsland Soil Site SG1, exchangeable aluminium


Graph: West Gippsland Soil Site SG1, Clay %


The soil is strongly acid in the
surface horizon and becomes
very strongly acid from 30 cm.
Total soluble salt levels are very
low throughout the whole profile.
Exchangeable aluminium levels
increase with depth down the profile.
No large increase in clay percentage
throughout the profile.

Horizon
Horizon Depth
(cm)
pH
(water)
pH
(CaCl2)
EC 1:5
Exchangeable Cations
Exchangeable Aluminium
mg/kg
Exchangeable Acidity
meq/100g
Wilting Point
pF4.2
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
meq/100g
A11
0-20
5.2
4.1
0.06
1.5
1.2
0.3
0.1
110
14
7.3
1
50
34
8
A12
20-30
5.1
3.8
<0.05
0.4
0.4
0.1
0.1
180
12.8
4.7
A2
30-45
4.9
4.0
0.05
0.2
0.3
0.2
<0.1
210
9.2
B21
45-70
4.7
4.0
0.09
0.2
0.3
0.2
<0.1
280
9.8
2
46
31
23
B22
70-80
4.7
4.1
0.08
0.1
0.3
0.1
<0.1
230
4.8
2
48
34
19

Management Considerations:

Whole Profile
  • The major limitation with this soil is the poor site drainage - which results in the profile being saturated for prolonged periods (several months or more) in most years.

  • This soil has a very low inherent fertility. This is due in part to the very high fine sand (50%) and silt (34%) content which results in a low cation exchange capacity.
Surface (A) Horizons
  • The surface soil has a high organic matter content. This is important for maintaining soil aggregation on surface soils with high fine sand and silt contents. If organic matter levels are low then structural deterioration (e.g. exacerbated hardsetting, compaction and surface sealing) is more likely to occur. The surface soil organic matter is also important in terms of cation exchange.

  • The surface soil is strongly acid which indicates that aluminium toxicity may occur. The level of exchangeable aluminium measured in the laboratory (110 mg/kg) is high enough to affect aluminium sensitive species. If the test results are representative of this paddock, then there should be long term benefits of incorporating lime into this soil. Raising surface soil pH will help reduce any toxic effects of aluminium.

  • Deficiencies in molybdenum, phosphorus and potassium may occur in the strongly acid surface soil. Lime application may assist in alleviating molybdenum deficiency and will increase phosphorus availability. Plant tissue analysis may give a more accurate assessment of molybdenum deficiency. Phosphorus tends to become "fixed" by high levels of exchangeable aluminium.

  • The level of exchangeable aluminium increases in the A12 and A2 horizons to levels which are likely to affect a number of moderately aluminium sensitive plant species (e.g. sub clover, white clover and cocksfoot) and possibly some more tolerant species (e.g. ryegrass, cocksfoot).

  • Pugging caused by stock will be a problem in wet seasons.
Subsoil (B) Horizons
  • The inherent fertility of the subsoil is very low.

  • The level of exchangeable aluminium increases in the subsoil to very high levels (i.e. 280 mg/kg). Root development of aluminium sensitive species into this zone is likely to be restricted.
Profile Described By: Mark Imhof, Ian Sargeant and Sonia Thompson (20/6/95).
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