SW86

Soil Profile Morphology:

Surface Soil

Ap	0-8 cm	Very dark brown (10YR2/2 moist), greyish brown (10YR5/2 dry); sandy clay loam; rusty root channel mottling prominent; hard-setting; strong consistence; pH 6.2; clear change to:	SW86 Profile
A2	8-17 cm	Very dark greyish brown (10YR3/2 moist and 10YR5/1 dry); loam; rusty mottling prominent (~5% fine magnetic buckshot); strong consistence; pH 6.9; abrupt change to:
Subsoil
B21tg	17-40 cm	Very dark greyish brown (10YR3/2 moist), dark greyish brown (10YR4/2 dry) with olive grey (5Y5/2 moist) mottles in ped interiors, and prominent yellowish brown (10YR5/8 moist) mottles associated with root channels; light medium clay to medium clay; many (~25%); roughly coarse prismatic (~100 mm), parting to coarse (mostly rough-face) blocky and angular coarse blocky; very strong consistence, pH 8.1; clear change to:
B22ss	40-60 cm	Very dark greyish brown (2.5Y3/2 moist); fine lenticular and polyhedral structure; moderate slickensides; pH 8.6; clear change to:
B23	80-200 cm	Olive to light olive grey (5Y6/2-5/3 moist); fine brownish yellow (10YR6/8 moist) mottles; soft, yellowish white carbonate; calcareous continues to 2 metres; pH 9.2.

Slickensides in B22ss horizon (40-60 cm)
Key Profile Features:

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

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Slightly Acid	Low	Non-Sodic	None1
Subsoil (B21 horizon)	Moderately Alkaline	Medium - High	Strongly Sodic	Strong
Deeper subsoil (at 80 cm)	Very Strongly Alkaline	High - Very High	Strongly Sodic	-
1 Moderate dispersion after remoulding

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl2)	EC 1:5	NaCl %	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-8	6.2	5.7	0.24		7.3	8.9	0.72	1.4
A2	8-17	6.9	6.2	0.15		4	5.2	0.2	1
B21	17-40	8.1	7.3	0.6	0.11	4.4	12	0.7	3.8
B22	40-60	8.6	8.1	1.6	0.4	5.1	18	0.8	7.5
B23	60-80	8.8	8.5	2	0.46	5	19	0.7	8.1
B24kg	80-200	9.2	8.6	1.3	0.25

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	0-8	<10	12	35	17.9	20.2	30.5	14	28
A2	8-17			22.2	8.9	26.1	39.6	15	18
B21	17-40			38.7	18.2	15.1	31.8	12.5	37
B22	40-60			46.6	24.9	11.6	24.4	13	47.5
B23	60-80
B24kg	80-200

Management Considerations:

Subsoil (B) Horizons

• The dense and coarsely structured subsoil is sodic and disperses completely. This will result in significantly restricted root and water movement into the subsoil.
• 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.
• The subsoil has a high level of soluble salts, which will restrict the growth of salt-sensitive species.

• To the west rising out of the depression more rock is present but soil deeper than west of GP 16. Cracking content at the surface which is rough and hard setting. Sea Barley grass and thistles. Heavy prismatic structures greyer than previous site.