SW85

Soil Profile Morphology:

Surface Soil

Ap	0-10 cm	Very dark greyish brown (10YR3/2 moist); fine sandy clay loam, pH 5.7:	SW85 Profile
A2	10-25 cm	Very dark greyish brown (10YR3/2 moist), conspicuously bleached (10YR6/2 dry); fine sandy clay loam; rusty root channels; pH 5.9; abrupt change to:
Subsoil
B21t	25-65 cm	Dark grey (10YR4/1 moist); heavy clay; coarse [15-40 cm], coarse prismatic, parting to irregular moderate blocky structure; mixed rough and smooth faced peds; strong consistence; pH 7.4; gradual change to:
B22ss	65-100 cm	Light olive brown (2.5Y5/3 moist) to greyish brown (2.5Y5/2 moist); strongly vertic; slickensides [10-20 cm]; pH 9.0; gradual change to:
B23ss	100-130 cm	Light olive brown (2.5Y5/4 moist); light medium clay; coarse lenticular, parting to fine lenticular structure; very large slickensides; pH 9.1; sharp change to:
B24k	130 cm+	Light brownish grey (2.5Y6/2 moist); brownish yellow (10YR6/8 moist) mottles; soft carbonate and hard silica rich calcium carbonate nodules; pH 9.3:

• Strong texture contrast between surface (A) horizons and subsoil (B21) horizon.
• Vertic properties in deeper subsoil (i.e. slickensides and lenticular peds).

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Moderately Acid	Very Low	Non-Sodic	None1
Subsoil (B21 horizon)	Slightly Alkaline	Low	Sodic	Complete
Deeper subsoil (at 130+ cm)	Very Strongly Alkaline	Medium	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	0-10	5.7	4.7	0.1	5	2.8	4.8	0.34	0.77
A2	10-25	5.9	4.7	0.09		2.2	4.6	0.24	0.9
B21	25-65	7.4	6.2	0.18		4.4	14	0.72	3.3
B22	65-100	9	8.4	0.86	0.11	5.7	19	0.6	8.6
B23	100-130	9.1	8.5	0.85	0.11
B24	130+	9.3	8.5	0.77	0.1

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	13	10	28.4	11.1	21.4	35.1	15	20.5
A2	10-25	13	10	26.1	9.6	17.2	40.2	19	19
B21	25-65	<10	8.8	35.7	16.4	16	32.6	15.5	30.5
B22	65-100			55.8	26.7	7.2	17.7	13	55.5
B23	100-130
B24	130+

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.