SW85

Location: Warncoort

Australian Soil Classification: Vertic (& Calcic), Subnatric, Grey SODOSOL

General Landscape Description: Gently undulating plain.
Site Description: Alluvial plain.
Geology: Alluvium in basalt plain (Qrm).

Soil Profile Morphology:

Surface Soil

Ap	0-10 cm	Very dark grayish brown (10YR3/2 moist); clay loam fine sandy; pH 5.7:	SW85 Profile. Note: Surface (A1) horizon has been stripped from the profile
A2	10-25 cm	Very dark grayish brown (10YR3/2 moist), conspicuously bleached (10YR6/2 dry); clay loam fine sandy;rusty root channel mottling; pH 5.9; abrupt change to:
Subsoil
B21t	25-65 cm	Dark gray (10YR4/1 moist); heavy clay; occasional coarse prismatic, parting to irregular moderate blocky structure; mixed rough and smooth faced peds; strong consistence dry; pH 7.4; gradual change to:
B22ss	65-100 cm	Light olive brown (2.5Y5/3 moist) to grayish brown (2.5Y5/2 moist); heavy clay; strongly vertic large slickensides present; 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 gray (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	Low	Non-Sodic	None1
Subsoil (B21 horizon)	Slightly Alkaline	Low	Sodic	Complete
Deeper Subsoil (at 65-100 cm)	Strongly Alkaline	Medium-High	Strongly Sodic	Complete
1 Moderate dispersion after remoulding.

The surface soil is strongly acid. The subsoil is slightly acid becoming strongly alkaline with depth.

Salinity rating is low in the surface becoming very low in the subsoil.

The soil is non sodic in the surface. The upper subsoil is sodic becoming strongly sodic in the deeper subsoil.

The clay content increases markedly at the A/B boundary.

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		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)	Organic Carbon %	Nitrogen %	Exchangeable Aluminium mg/kg	Exchangeable Acidity meq/100g	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	2.6	0.2	13	10	28.4	11.1	21	35	15	21
A2	10-25			<10	8.8	26.1	9.6	17	40	19	19
B21	25-65					35.7	16.4	16	33	16	31
B22	65-100					55.8	26.7	7	18	13	56
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.