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SW84

Location: Warncoort

Australian Soil Classification: Episodic-Endocalcareous, Massive, Grey VERTOSOL

General Landscape Description: Gently undulating plain.
Site Description: Flat.
Geology: Basalt plain.

SW84 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Very dark grey (10YR3/1 moist); hardsetting surface condition with cracking; massive; clay loam; strong consistence dry; pH 6.8:	SW84 Profile
Subsoil
B21ss	10-60 cm	Very dark grey (10YR3/1 moist); medium clay; prominent large slickensides; strong consistence dry; pH 8.3:
B22ss	60-80 cm	Dark grey (10YR4/1 moist); medium clay; strong consistence dry; slightly calcareous; pH 9.1; clear change to:
B23k	80-100 cm	Clay loam; soft carbonate; pH 9.5; abrupt change to:
B24ssg	100+ cm	Light brownish grey (2.5Y6/2 moist) with faint brownish yellow (10YR6/6 moist) mottles common; light clay; thick lenticular structure; strong consistence dry; moderately calcareous in patches; pH 9.2.

SW84 Surface cracking

Key Profile Features:

• High (>35%) clay content throughout the soil profile.
• Vertic features (slickensides and lenticular peds) in subsoil.

Soil Profile Characteristics:

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Slightly Acid	Low	Sodic	Strong1
Subsoil (B21 horizon)	Moderately Alkaline	Medium	Strongly Sodic	Strong1
Deeper Subsoil (at 80-100 cm)	Very Strongly Alkaline	High - Very High	Strongly Sodic	None2
1 Complete dispersion after remoulding. 2 No aggregate dispersion due to high levels of soluble salts, slight dispersion after remoulding.

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

Salinity rating is low in the surface becoming medium in the subsoil and high to very high in the deeper subsoil.

The soil is sodic in the surface. The subsoil is strongly sodic.

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	6.8	5.8	0.18		5.7	14	0.85	2.8
B21	10-60	8.3	7.4	0.5	0.07	7.2	20	1.2	6.7
B22	60-80	9.1	8.5	1.1	0.16	6.3	21	1.1	10
B23	80-100	9.5	8.7	0.83	0.11	3.9	9.7	0.5	6
B24	100+	9.2	8.5	1	0.16

Horizon	Horizon Depth (cm)	Organic Carbon %	Nitrogen %	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	1.5	0.11	7.6	36.5	19.1	16	26	17	37
B21	10-60				54.9	28.3	7	19	19	53
B22	60-80				53.9	32.7	7	20	18	54
B23	80-100				32.7	16.2	7	10	9	33
B24	100+

Management Considerations:

Surface (A) Horizons

• The surface soil is sodic and disperses completely after remoulding. Care should be taken to avoid disturbing the surface horizon (i.e. trafficking, tillage, over-stocking) when the soil is in a moist condition. Also, raindrop impact on bare soil will exacerbate the hardsetting nature of the soil and will result in surface sealing and/or crust development.
• Tillage of cracking clay soils should be avoided if the soil is wet (i.e. wetter than the plastic limit). At such moisture conditions, excessive tillage, trafficking or over stocking could result in structural damage (i.e. compaction, smearing) occurring. Ideally tillage and trafficking should take place when the soil is drier than the plastic limit.
• When the soil is dry, heavy rains will move from soil cracks. This rapid recharge can be valuable for the survival of plants near wilting. When wet, the soil will swell and further infiltration of water will be relatively slow.

Subsoil (B) Horizons

• The subsoil has a high level of soluble salts, which will restrict the growth of salt-sensitive species.

Notes
Situated in an area of lower drainage or plateau. Very vertic soil, cracking to surface and pugging. Collapsed trench but profile too dry and cracked to pick back effectively

Profile Described By: Richard McEwan (March 1999).