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SW70

SW70 landscape
Trench section at site of SW70 showing deep A2 horizon and underlying mottled clay

    Site Code
SW70
SW70 profile
Humose, Sesquic, Semiaquic PODOSOL

    Location
Irrewillipie road, south of Underwoods road, south of Colac
    Landform
Undulating low hills
    Geology
Neogene Hanson Plain Sand, Palaeogene Dilwyn Formation
    Element
Waxing upper slope
    Slope
5%
    Aspect
West
Horizon
Depth (cm)
Description
Ap
0–20/25 Very dark greyish brown (10YR3/2 moist), greyish brown (10YR5/2 dry); loamy sand; apedal structure; pH 5.3; diffuse boundary to:

A2
30–90/110 Greyish brown (10YR5/2 moist), conspicuously bleached (10YR7/2 dry); sand; sporadic gravel band (>100 mm); with dark very medium to coarse (5-15 mm) nodules with manganiferous centres; very weak to weak consistence; pH 5.4; abrupt boundary to:

B21s
90/110–150 Brown (7.5YR4/4 moist and dry) and brownish yellow (10YR6/8 moist) to yellow (10YR7/8 dry); sandy clay loam; cemented sand, (‘coffee rock’) massive structure; firm to strong consistence; clear boundary to:

B22g
150–200 Yellowish brown (10YR5/8 moist) (50%) and light greenish grey (5GY7/1 moist) (50%); very dark greyish brown (10YR3/2 moist) coatings; sandy light clay; pH 6; clear boundary to:

B23
200 +Mottled yellowish brown (10YR5/8 moist) (30%) and light greenish grey (5GY7/1 moist) (70%); sandy light clay; apedal structure.

Management considerations
This deep sandy soil is very acidic and has poor chemical fertility. The soil lacks peds and is likely to be hard setting when dry and ‘spewy’ and weak when wet. The water holding capacity of this soil is low but the cemented B horizon will tend to hold up water and prevent excessive vertical drainage of the profile. This soil will become compact under animal and vehicular traffic and is vulnerable to wind or water erosion if left bare (e.g. when cultivated).

Analytical data
Site SW70
Sample
depth
pH
EC
NaCl
Ex Ca
Ex Mg
Ex K
Ex Na
Ex Al
Ex acidity
FC
(-10kPa)
PWP
(-150kPa)
KS
FS
Z
C
Horizon
cm
H2O
CaCl2
dS/m
%
cmolc/kg
cmolc/kg
cmolc/kg
cmolc/kg
mg/kg
cmolc/kg
%
%
%
%
%
%
A1
0–10
5.3
4.6
0.25
N/R
2
1.1
0.44
0.72
15
9.9
15.1
6.8
48.9
32.3
9
5
A2
30–50
5.4
4.6
0.07
N/R
0.27
0.13
<0.05
0.18
11
2.1
8.2
1.2
47.8
38.3
8
4.5
B21s
65–85
5.8
4.9
0.08
N/R
1.3
1.9
0.09
0.33
<10
4.1
12
6
45.8
31.8
3.5
17.5

SW70 image 1
SW70 image 2
SW70 image 3
Contrasting soils upslope from SW70 showing deep sandy profile over ferruginised (iron-enriched) sedimentary parent material; profile with thin sodic clay B horizon at 1 metre (left), trench cutting (centre), profile with no clay B horizon and no ironstone gravel (right)
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