SW80

SW80 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-15 cm	Very dark greyish brown (10YR3/2 moist), greyish brown (10YR5/2 dry) loam, fine sandy; weakly pedal; weak consistence (dry):	SW80 Profile
A2e	15-40 cm	Brown (10YR5/3 moist), conspicuously bleached (10YR7/2 dry); loamy sand; sharp change to:
Subsoil
B21t	40-90 cm	Very dark grey (10YR3/1 moist) with fine yellowish brown (10YR5/8) mottles; heavy clay; coarse (up to 400 mm) columnar structure, parting with difficulty to coarse blocky structure; slickensides across ped; gradual change to:
B22gss	90-140 cm	Very dark grey (10YR3/1 moist) with ~ 50% coarse olive brown (2.5Y4/4 moist) mottles; heavy clay; coarse columnar peds continuous from B21; slickensides more prominent than in B21 above; clear change to:
B23g	140+ cm	Conspicuously mottled, gleyed clay; massive.

• Strong texture contrast between surface (A) horizons and subsoil (B) horizons.
• Coarse columnar structure in upper subsoil.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Strongly Acid	Very Low	Non-Sodic	None
Subsoil (B21 horizon)	Slightly Alkaline	Low	Strongly Sodic	Strong
Deeper subsoil (at 140+ cm)	Slightly Alkaline	Low - Medium	Strongly Sodic	Strong - Complete

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl2)	EC 1:5	NaCl %	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-15	5.4	4.5	<0.05		1.2	0.29	0.19	0.07
B21Bt	40-90	7.5	6.4	0.16		4.5	10	0.23	2.7
B22Bgss	90-110	7.5	6.6	0.41	0.06	3.7	8.4	0.2	4.1
B23g	140+	7.5	6.6	0.46	0.09

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	0-15	17	5.6			3.7	62.2	23	8
B21Bt	40-90					2	35.8	14	46
B22Bgss	90-110
B23g	140+

Management Considerations:

Subsoil (B) Horizons

• 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 dense and coarsely structured subsoil is strongly sodic and disperse strongly in water. This will result in restricted root and water movement down the soil profile.