SW17a
Location: Glenormiston College (North Farm).
Australian Soil Classification: Vertic, Mottled-Subnatric, Grey SODOSOL
Northcote Factual Key: Dy3.13
Great Soil Group: solodic
General Landscape Description: Level Plain.
Site Description: Roadside reserve adjacent to grazing paddock.
Geology: Quaternary basalt (Qvn).
 SW17a Landscape |
Soil Profile Morphology:
Surface Soil
| A11 | 0-20 cm | Very dark greyish brown (10YR3/2); fine sandy clay loam; moderate medium polyhedral, parting to strong fine polyhedral structure; weak consistence dry; pH 5.5; clear change to: |  SW17a Profile |
| A12 | 20-30 cm | Very dark greyish brown (10YR3/2); fine sandy clay loam; strong polyhedral, parting down to strong fine polyhedral structure; weak consistence slightly moist; contains a common (10-20%) amount of mainly ferruginous gravel (2-10 mm in size); pH 5.9; abrupt change to: | |
| Subsoil | |||
| B21 | 30-45 cm | Dark greyish brown (10YR4/2) with yellowish brown (10YR5/6) mottles; medium heavy clay; moderate coarse blocky structure, parting to moderate medium polyhedral structure; firm consistence moist; pH 6.4; clear change to: | |
| B22 | 45-70 cm | Pale yellow (2.5Y7/4) with yellow (2.5Y7/6) and light brownish grey (2.5Y6/2) mottles; rusty root channel mottling present; heavy clay; coarse prismatic, parting to coarse blocky structure; very firm consistence slightly moist; slickensides present at 60 cm; pH 7.1; gradual change to: | |
| B23 | 70-110 cm | Pale yellow (2.5Y7/4); very coarse prismatic structure; very firm to strong consistence slightly moist; contains many slickensides; pH 8.1: | |
 | | Note: Deep cracks were observed throughout the subsoil. | |
Key Profile Features:
- Strong texture contrast between surface (A) horizons (26-29% clay) and sodic subsoil (B21) horizon (50% clay).
- Vertic properties i.e. significant shrink-swell characteristics in the subsoil.
| pH | Salinity Rating | ||
Surface (A1 horizon) | Strongly Acid | Very Low | Non-Sodic | None |
Subsoil (B21 horizon) | Slightly Acid | Very Low | Sodic | Slight 1 |
Deeper subsoil (at 90 cm) | Moderately Alkaline | Very Low to Low | Strongly Sodic | Complete |
 |  |  |  |
The surface is strongly acid. The subsoil is slightly acid becoming moderately alkaline at about 90 cm. | The salinity rating is very low throughout the profile. | The subsoil is sodic becoming strongly sodic about 75 cm. | The clay content increases abruptly at 30 cm by 21 %. |
Chemical and Physical Analysis:
Horizon | Horizon Depth (cm) | pH (water) | pH (CaCl2) | EC dS/m | 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) % | Wilting Point % w/w | |||
Ca | Mg | K | Na | ||||||||||
meq/100g | |||||||||||||
A11 | 0-20 | 5.5 | 4.8 | 0.1 | 5.3 | 3.4 | 0.37 | 0.6 | 11 | 33 | 19 | 26 | 17 |
A12 | 20-30 | 5.9 | 5.1 | 0.06 | 5.1 | 4 | 0.3 | 0.52 | 12 | 34 | 19 | 29 | 16 |
B21 | 30-45 | 6.4 | 5.7 | 0.07 | 6.1 | 9 | 0.42 | 1.5 | 10 | 22 | 12 | 50 | 25 |
B22 | 45-70 | 7.1 | 6.2 | 0.1 | 5.6 | 12 | 0.36 | 2.4 | 8 | 20 | 10 | 58 | 28 |
B23 | 70-110 | 8.1 | 7.1 | 0.29 | 7.1 | 16 | 0.37 | 5.2 | 4 | 15 | 10 | 67 | 29 |
Profile Described By: Mark Imhof and David Rees (May 1997).
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