SW76

Soil Profile Morphology:

Surface Soil

A1	0-15 cm	Very dark grey (10YR3/1 moist), grey (10YR 5/1 dry); sandy loam; weakly pedal; pH 5.5:	SW76 Profile
A21ec	15-50 cm	Greyish brown (10YR5/2 moist), conspicuously bleached (10YR7/1 dry); sandy loam; apedal, massive; minor small buckshot (breaking with moderate force); pH 5.6; gradual change to:
A3	50-70/80 cm	Yellowish brown (10YR5/6 moist), brownish yellow (10YR6.5/6 dry); apedal; sporadic bleach; pH 5.9; clear change to:
Subsoil
B21tss	70/80-135 cm	Mottled strong brown (7.5YR5/8 moist), yellowish brown (10YR5/4 moist), brown cutans (10YR5/3 moist); heavy clay; vertic; very coarse blocky structure [80-100 mm]; some very large slickensides, up to 1 m across; pH 6.0; gradual change to:
B22tg	135 cm+	Dark grey (10YR4/1 moist) and white (10YR8/1 moist); heavy clay; red mottles (10R4/8 moist); polyhedral structure; slickensides (50-150 mm); pH 5.4.

• Deep, conspicuously bleached subsurface (A2) horizons.
• Strong texture contrast between surface (A) horizons and subsoil (B2) horizon.
• Vertic features (i.e. slickensides) in subsoil.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Strongly Acid	Low	Non-Sodic	None
Subsoil (B21 horizon)	Moderately Acid	Very Low	Marginally Sodic	*
Deeper subsoil (at 110+ cm)	Strongly Acid	Very Low	-	*
* No results

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl2)	EC 1:5	NaCl %	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-15	5.5	4.8	0.11		2.9	1.2	0.41	0.2
A21ec	30-45	5.6	4.7	<0.05		1.2	0.87	<0.05	0.1
A3	55-70	5.9	4.9	<0.05		0.7	2.1	<0.05	0.32
B21tss	90-120	6	5	0.12		2.3	9	0.1	1.4
B21tg	150-170	5.4	4.5	0.14	0.02

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	49	17	30.1	11.1	14	37.8	19	17
A21ec	30-45	32	8.6	19.7	5.9	16.1	43.6	21	15
A3	55-70	<10	4	19.8	8.1	16	40.6	16.5	24.5
B21tss	90-120	28	10			4.8	10.3	6	74
B21tg	150-170

Management Considerations:

Subsoil (B) Horizons

• The subsoil displays vertic features (i.e. slickensides) which indicates that significant shrinking and GPelling 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.

• Gleying in subsoil increases down slope from profile.