SW82

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Very dark brown (10YR2/2 moist and 10YR4/2 dry); pH 5.5; loam; clear change to:	SW82 Profile - Note: Surface (A1) horizon has been stripped from the soil profile
Subsoil
B21	10-40 cm	Black (10YR3/2 moist); medium heavy clay; medium to fine (5-20 mm) polyhedral structure; strong consistence; pH 5.8; gradual change to:
B22	40-90 cm	Black (10YR2/1 moist); heavy clay; some pockets of fine buckshot; coarse prismatic, parting to fine lenticular structure; strong consistence; pH 6.8; abrupt change to:
B23ssgk	90 cm+	Dark greyish brown (10YR4/2 moist) with brownish yellow (10YR6/6 moist) and minor (<2%), light olive brown (2.5Y5/4 moist) mottles; soft carbonate and strongly vertic; medium (20-50 mm) prismatic structure; strong consistence; pH 8.5.

• Strong texture contrast between surface (A) horizons and subsoil (B21) horizon.
• Colour contrast in deeper subsoil.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Strongly Acid	Low	Non-Sodic	None
Subsoil (B21 horizon)	Moderately Acid	Low	Non-Sodic	None
Deeper subsoil (at 90+ cm)	Moderately Alkaline	Low	Strongly Sodic	Strong - Complete
1 complete dispersion after remoulding

Horizon	Horizon 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	Horizon Depth (cm)	Ex Al mg/kg	Ex Ac meq/100g	Field 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	25.6	10.8	22.9	37	13.5	20.5
B21	10-40	18	15	39.6	24.6	12.5	20.5	7	55.5
B22	40-90			45.5	26.7	10.6	15.7	5.5	63
B23	90+					17.8	24.6	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.