Victorian Resources Online (archived)
SW82
Location: Warncoort
Australian Soil Classification: Vertic (& Sodic), Calcic, Black CHROMOSOL
General Landscape Description: Gently undulating plain.
Site Description: Puff of a gilgai.
Geology: Basalt plain.
Soil Profile Morphology:
Surface Soil
| A1 | 0-10 cm | Very dark brown (10YR2/2 moist); loam; pH 5.5; clear change to: |  SW82 Profile. Note: Surface (A1) horizon has been stripped from the soil profile |
| Subsoil | |||
| B21 | 10-40 cm | Very dark grayish brown (10YR3/2 moist); medium heavy clay; medium to fine (5-20 mm) polyhedral structure; strong consistence dry; pH 5.8; gradual change to: | |
| B22 | 40-90 cm | Dark grayish brown (10YR4/2 moist) and brownish yellow (10YR6/6) mottles; heavy clay; some pockets of fine buckshot; coarse prismatic, parting to fine lenticular structure; strong consistence dry; pH 6.8; abrupt change to: | |
| B23ssgk | 90 cm+ | Dark grayish brown (10YR4/2 moist) with brownish yellow (10YR6/6 moist) and very few (<2%) light olive brown (2.5Y5/4 moist) mottles ; medium (20-50 mm) prismatic structure; strong consistence dry; very few (<2%) soft carbonate segregations; strongly vertic; pH 8.5. |
SW82 Profile wider view.
Key Profile Features:
- Strong texture contrast between surface (A) horizons and subsoil (B21) horizon.
- Colour contrast in deeper subsoil.
Soil Profile Characteristics:
pH | Salinity Rating | |||
Surface (A1 horizon) | Strongly Acid | Low | Non-Sodic | None |
Subsoil (B21 horizon) | Moderately Acid | Very Low | Non-Sodic | None1 |
Deeper Subsoil (at 90+ cm) | Moderately Alkaline | Low | Strongly Sodic | Strong - Complete |
| 1 Slight dispersion after remoulding. | ||||
| The surface soil is strongly acid. The subsoil is moderately acid becoming moderately alkaline with depth. | Salinity rating is low in the surface becoming very low in the subsoil. |
| The clay content increases markedly at the A/B boundary. |
Horizon | Sample Depth (cm) | pH (water) | pH (CaCl2) | EC 1:5 | NaCl % | Exchangeable Cations | |||
Ca | Mg | K | Na | ||||||
meq/100g | |||||||||
A1 | 0-10 | 5.5 | 4.9 | 0.21 | 6.2 | 3.2 | 0.61 | 0.37 | |
B21 | 10-40 | 5.8 | 4.8 | 0.1 | <0.01 | 7.2 | 7.9 | 0.4 | 0.5 |
B22 | 40-90 | 6.8 | 5.6 | 0.09 | 7.9 | 13 | 0.41 | 1.8 | |
B23 | 90+ | 8.5 | 7.3 | 0.17 | 6.5 | 12 | 0.27 | 3.2 | |
Horizon | Sample Depth (cm) | Exchangeable Aluminium mg/kg | Exchangeable Acidity meq/100g | Organic Carbon % | Nitrogen % | 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 | 0-10 | <10 | 12 | 3.8 | 0.29 | 25.6 | 10.8 | 23 | 37 | 14 | 21 |
B21 | 10-40 | 18 | 15 | 39.6 | 24.6 | 13 | 21 | 7 | 56 | ||
B22 | 40-90 | 12 | 45.5 | 26.7 | 11 | 16 | 6 | 63 | |||
B23 | 90+ | 18 | 25 | 7 | 48 |
Management Considerations:
Subsoil (B) Horizons
- This profile is the “puff” of a gilgai soil. See GP 83 for a description of the associated “hollow”.
- The subsoil displays vertic features (i.e. slickensides) which indicates that significant shrinking and swelling occurs during wetting and drying cycles. This may have engineering implications and is likely to explain the variability in surface horizon depth across the trench.
- Between Aireys Reserve Rd and Birregurra Creek soil has coarse prismatic subsoil, very gilgaied, some patches of soft calcium carbonate (CaCO3) below 1 m. Abrupt A2/B boundary. Deeper material grey/yellow mottled clay with fine quartz gravel >10 mm, rounded, below 1.5 m (<5% of matrix). Some (occasional) fragments of ferrguniated sandstone (<50 mm) in subsoil, but rare.
Profile Described By: Richard McEwan (March 1999).
