SW84

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Very dark grey (10YR3/1 moist); massive, hardsetting; clay loam; cracking at ground surface; pH 6.8; strong consistence (dry):	SW84 Profile
Subsoil
B21ss	10-60 cm	Very dark grey (10YR3/1 moist); medium clay; prominent slickensides; pH 8.3; strong consistence (dry):
B22	60-80 cm	Dark grey (10YR4/1 moist); medium clay; slightly calcareous; strong consistence (dry); pH 9.1; clear change to:
B23k	80-100 cm	Clay loam; soft carbonate; pH 9.5; abrupt change to:
B24ssg		Light brownish grey (2.5Y6/2 moist); common (>15%), faint, brownish yellow (10YR6/6 moist) mottles; light clay; thick lenticular structure; moderately calcareous in patches; strong consistence (dry); pH 9.2.

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

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Slightly Acid	Low	Sodic	None1
Subsoil (B21 horizon)	Moderately Alkaline	Low - Medium	Strongly Sodic	None1
Deeper subsoil (at cm)	Very Strongly Alkaline	Very High	Strongly Sodic	None
1 complete dispersion after remoulding 2 due to high level of soluble salts

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)	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		7.6	36.5	19.1	16.2	26	16.5	37
B21	10-60			54.9	28.3	7.1	18.7	18.5	53
B22	60-80			53.9	32.7	7.3	19.7	17.5	54
B23	80-100			32.7	16.2	6.8	9.6	8.5	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.

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

• Notes