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

Victorian Resources Online

GP22

Location: Clyde.Australain Soil Classification: Ferric-Sodic, Eutrophic, Brown CHROMOSOL.
Northcote Factual Key: Dy 3.31 Great Soil Group: soloth/solodic.
Geology: Tertiary sandstone (some areas may be covered with a veneer of Quaternary aeolian deposits). The rock may be in the order of 10-20 million years old and consists mainly of iron oxide cemented clays and sands (pers. comm. Jim Rowan).
General Landscape Description: Gently undulating rises.Site Description: Grassed verge on the edge of a celery cropping paddock.
Soil Mapping Unit: Bittern sandy loam.

PHOTO: Soil Site GP22 Landscape
Site GP22 Landscape


Soil Profile Morphology:

Surface Soil


A10-20 cm Dark brown (10YR3/3); sandy loam; pH 7.0; clear change to:

PHOTO: Soil Site GP22 profile
Site GP22 Profile
A220-35 cmSporadically bleached; light sandy loam; firm consistence dry; contains many (40%) iron-cemented sandstone and ferruginous nodules (mainly in the 30-35 cm zone); pH 5.8; sharp change to:

Subsoil

B2135-80 cmYellowish brown (10YR5/4) with bright yellowish brown (10YR5/6) and red (2.5YR4/6) mottles; light medium clay; moderate medium blocky, parting to strong fine sub-angular blocky structure; strong consistence dry; pH 6.4; gradual change to:

B2280-120 cmLight grey (10YR7/1), yellowish brown (10YR5/8) and red (2.5YR4/6) mottles; light medium clay; strong coarse polyhedral structure; strong consistence dry; contains many (30%) iron cemented sandstone; pH 6.2.

Key Profile Features:
  • Strong texture contrast between surface (A) horizons (16 % clay) and subsoil (B21) horizon (72 % clay).
  • Presence of 'ironstone' nodules and ferruginous sandstone fragments at the A/B horizon interface. These may be lag deposits formed during more tropical Tertiary climatic conditions.
  • Intensively weathered B horizon with kaolinitic clays approximately 2 million years old (pers. comm. Jim Rowan).

Soil Profile Characteristics:

GRAPH: Soil Site GP22 pH

The surface soil is neutral . The rest of the soil profile is slightly acid.

GRAPH: Soil Site GP22 Salinity

The salinity rating is very low throughout the profile.
GRAPH: Soil Site GP22 Clay %

The clay percentage increases sharply at the A/B horizon interface.
GRAPH: Soil Site GP22 Coarse Sand %

The coarse sand content decreases in the clayey B horizons.

Horizon
Horizon Depth
(cm)
pH
(water)
pH
(CaCl2)
EC 1:5
Exchangeable Cations
Ca
Mg
K
Na
meq/100g
A1
0-20
7
6.5
0.14
7.7
2
0.64
0.3
A2
20-30
5.8
4.7
<0.05
0.97
0.85
0.06
0.07
B21
35-80
6.4
5.5
0.07
2.6
7
0.1
0.4
B22
80-120
6.2
5.7
0.1
1.1
7
0.11
0.98

Horizon
Horizon Depth
(cm)
Field Capacity
pF2.5
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)
A1
0-20
13
6
39
37
5
16
A2
20-30
13
4
28
47
10
13
B21
35-80
34
25
9
15
6
72
B22
80-120
31
21
11
20
6
64

Management Considerations:

Note: This pit site occurs on a grassed verge (never cropped) beside a cropping paddock (see landscape photo). All samples were taken from this pit site except for the surface horizon, which was sampled in the cropped paddock. This was done as the grassed verge site showed evidence of surface disturbance. Surface soil results will therefore more closely represent cropped conditions, but may still not be representative of the whole paddock, as the whole paddock was not sampled.

Whole Profile
  • Plant available water capacity (PAWC) is considered to be low (estimated at 85 mm) for the top metre of the soil profile. Rooting depth will vary depending on crop type, so the estimated PAWC should be considered as potential only. PAWC is estimated at approximately 50 mm for the surface horizons (ie. to 35 cm depth).
Surface (A) Horizons
  • The surface (A1) horizon sample was taken from inside the paddock. The neutral pH (ie. pH 7) reflects the use of lime on the surface soil.
  • These soils can be prone to waterlogging as the water ponds on top of the relatively slowly permeable clay subsoil. The presence of a sporadically bleached subsurface (A2) horizon indicates that periodic waterlogging occurs. As a result, the A2 horizon is likely to become 'spewy' when wet and restrict traffickability.
  • The levels of total nitrogen and organic carbon are relatively low as measured for this one point in the paddock. However, these levels are better assessed by sampling across the paddock.
Subsoil (B) Horizons
  • Some initial ponding will occur above the very clayey subsoil. However, the upper subsoil is reasonably well structured (parting to relatively fine sized peds) and is non-sodic. Root and water movement through the subsoil is not likely to be as restricted as Site GP21.
  • The subsoil has a high level of exchangeable magnesium relative to other cations. This may result in some nutrient imbalances (e.g. potassium deficiency). Nutrient deficiencies can be assessed by plant tissue analysis.
Profile Described By: Mark Imhof. Ian Sargeant
Page top