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EGC207

Location: Doctors Flat

Australian Soil Classification: Eutrophic, Subnatric, Red SODOSOL

Map Unit: Dargo (Component 1)
Previous Site Name: EG207

General Landscape Description: Rolling low hills
Site description: Mid north-west facing slope (8% slope)
Land Use: Grazing on annual pasture
Native Vegetation: Grassy woodland
Geology: Palaeozoic granite


Soils and landforms of the Omeo/Benambra and Tambo Valley region - soil-landform unit Dargo EG207 landscape


Soil Profile Morphology:

Surface soil

Soils and landforms of the Omeo/Benambra and Tambo Valley region - soil-landform unit Dargo EG207 profile
A10 – 15 cmDark brown (10YR4/3); sandy loam; weak fine (2 – 5 mm) granular structure; weak consistence dry; clear change to:
A215 – 20/25 cmVery pale brown (10YR7/4) conspicuously bleached (10YR8/3d); sandy loam; apedal; very weak consistence dry; many (20 – 50 %) coarse (6 – 20 mm) ferruginous concretions; sharp wavy change to:
Subsoil

B2120/25 – 45 cmYellowish red (5YR5/6); medium clay; moderate medium (10 -20 mm) angular blocky structure; strong consistence dry; diffuse change to:
B2245 – 75 cmReddish brown (10YR5/4); medium clay; weak medium (10 -20 mm) angular blocky structure; strong consistence dry; few (2 – 10 %) manganiferous veins; diffuse change to:
B2375 – 110 cmLight reddish brown (10YR6/4); medium clay with sand; very strong consistence dry; very few (<2 %) manganiferous veins

Key Profile Features:
  • Strong texture contrast between the surface (A) horizons and the subsoil (B) horizons.


Soil Profile Characteristics:

-

pH
Salinity
Surface soil
(A1 horizon)
Strongly Acid
Very Low
Non-sodic
None
Subsoil
(B21 horizon)
Slightly Acid
Very Low
Sodic
Slight
Deeper subsoil
(75-110cm)
Strongly Alkaline
Low
None


Chemical and Physical Analysis:


Horizon
Horizon Depth
(cm)
pH
(water)
EC
dS/m
Organic Carbon
%
Total
Nitrogen
%
Exchangeable Aluminium
ppm
Exchangeable Acididty
meq/100g
Exchangeable Cations
Coarse Sand
(0.2-2.0 mm)
%
Fine Sand
(0.02-0.2 mm)
%
Silt
(0.002-0.02 mm)
%
Clay
(<0.002 mm)
%
Field Capacity
% w/w
Wilting Point
% w/w
Ca
Mg
K
Na
meq/100g
A1
0-15
5.1
0.1
1.6
0.12
16
6.3
1.3
0.52
0.48
0.11
43
37
9
4
11.8
3.6
A2
15-20/25
5.5
<0.05
0.66
<0.05
19
4.6
0.79
0.52
0.24
0.07
41
38
11
6
11.5
2.5
B21
20/25-45
6.5
0.08
0.54
2.5
4.8
9.1
1.1
0.82
12
26
12
47
31.1
18.2
B22
45-75
7.6
0.14
0.41
3.6
11
0.39
1.5
20
28
13
36
26.9
14.8
B23
75-110
8.7
0.33
0.3
21
23
12
40
33.7
17.4


Management Considerations

Whole profile
  • Plant available water content for this profile is considered to be low, as the effective rooting depth is largely limited to the surface horizons due to the dense and coarsely structured nature of the subsoil.
Surface (A) horizons
  • The low wilting points (3.5 and 2.5 %) of the surface soils indicates the plants are able to utilize very light rains when the soil is dry. However, due to the low water storage capacity, plants will soon suffer moisture stress unless further rains occur.
  • The surface soil is strongly acid. However the level of exchangeable aluminium is reasonably low (16 mg/kg) and is unlikely to affect the growth of aluminium sensitive species, except the most sensitive. Lime can be used to increase soil pH but a pH/aluminium test is best performed by taking samples across the paddock and bulked together. The use of test strips to observe lime response could be used as an aid in evaluating its cost/benefit. For this soil a response to lime (about 1-2 tonnes/ha) would be expected.
  • The organic matter content of the soil is low. Such levels result in a poor to moderate structural condition and low to moderate structural stability.
  • Potassium is at a moderate level for pastures and no response to potassium fertilisers would be anticipated.
  • Salinity is not a problem in the surface soil.
  • The nutrient holding capacity of the surface (A1 and A2) horizons is very low (based on the sum of the exchangeable calcium, magnesium, potassium and sodium cations).
Subsoil (B) horizons
  • Root and water movement is likely to be restricted in the dense and coarsely structured subsoil although the red colour of the subsoil indicates the soil is generally well drained.
  • The roots tend to follow cracks between the soil aggregates and can only extract part of the soil water.
  • The subsoil and the deep subsoil are slightly dispersive but slake considerably. If the subsoil is exposed, for example by a gully head, headward erosion is highly likely.


Profile Described By: Heather Adams, Julieanne Sargant and Ian Sargeant, June 2009.
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