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Site IS22

Location: Riverside

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

General Landscape Description: Terrace flat.
Geology: Quaternary Coonambidgal Formation: fluvial to lacustrine clays and sands

IS22 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-5 cm	Dark grey (10YR4/1); medium clay; cracking massive (structureless) surface condition when undisturbed; weak subangular blocky structure; very strong consistence dry; moderately sticky consistence wet; pH 6.3; sharp and smooth boundary to:	IS22 Profile
Subsoil
B21	5-25 cm	Dark grey (10YR4/1); light medium clay; subplastic; moderate coarse prismatic structure; strong consistence dry; moderately sticky consistence wet pH 7.1:
B22	25-60 cm	Dark grey (10YR4/1); heavy clay; moderate coarse prismatic structure; weak consistence dry; moderately sticky consistence wet; very few (<2%) hard carbonate segregations; pH 7.2; gradual and smooth boundary to:
B31	60-95 cm	Grey (10YR5/1); heavy clay; plastic; moderate coarse subangular structure; very few (<2%) hard carbonate segregations; pH 6.4; gradual boundary to:
B32	95-115 cm	Light greyish brown (10YR6/2); heavy clay; plastic; moderate coarse subangular structure; very strong consistence dry; moderately sticky consistence wet; very few (<2%) hard carbonate segregations; pH 6.3; gradual boundary to:
B33	115-150 cm	Greyish brown (10YR5/2); heavy clay; plastic; strong coarse angular blocky structure; strong consistence dry; moderately sticky consistence wet; very few (<2%) hard carbonate segregations pH 5.9.

Soil Profile Characteristics:

Horizon	Sample Depth cm	pH		EC dS/m	Sodium Chloride %	Exchangeable Calcium cmol-/kg	Exchangeable Magnesium cmol-/kg	Exchangeable Potassium cmol-/kg	Exchangeable Sodium cmol-/kg	Exchangeable Aluminium mg/kg	Exchangeable Acidity cmol-/kg	Field Capacity -30okPa	Permanent Wilting Point -1500okPa	Coarse Sand %	Fine Sand %	Silt %	Clay %
		H2O	CaCl2
A1	0–5	6.3	5.4	0.12	0.02	7.2	10	0.7	0.8	NA	8	NA	22.7	1	27	27	44
B21	5–25	7.1	NA	0.14	0.03	10.1	16.2	0.8	2.7	NA	8.6	NA	21.1	0	14	20	65
B22	25–60	7.2	NA	0.53	0.11	9.8	16.2	0.7	4.2	NA	6.4	NA	23.8	0	13	23	61
B23	60–95	6.4	NA	0.14	0.14	9.2	15.9	0.6	5.2	NA	6.3	NA	21.9	0	12	24	63
B31k	95–115	6.3	NA	0.74	0.12	7.5	13	0.6	5.2	NA	7.5	NA	21.4	1	13	24	61
B32	115–150	5.9	NA	0.86	0.17	6.9	12.4	0.6	4.5	NA	7.5	NA	20.7	0	14	23	62

Note: NA=not assessed.

Management Considerations:

• Cracking clay soils with self-mulching properties
• Plant available water capacity (PAWC) is considered to be low (estimated at 55 mm). This is based on available laboratory data and assumes an effective rooting depth of 30 cm. The high level of soluble salts in the subsoil will restrict effective rooting depth.
• When the soil is dry, heavy rains will move down 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.
• Tillage of cracking clay soils should be avoided if the soil is wet (ie. wetter than the plastic limit). At such a moisture condition, excessive tillage, trafficking or overstocking can result in structural degradation (eg. compaction, smearing) occurring. Ideally, tillage should take place on clay soils such as these when the soil is drier than the plastic limit, down to at least the tillage depth
• The level of soluble salts is high in the upper subsoil and becomes very high from 55cm depth.

Profile Described By: John Martin, Nabil Badawy, Ron Cawood, Geoff Pope, John Galea, John Turner (1970).

Reference: "Major Agricultural Soils of the Wimmera Irrigation Area". John Martin, Mark Imhof, Lourey Ruth, Rob Nink, Karen DePlater, Paul Rampant, Sonia Thompson, S. Alexander. Department of Natural Resources and Environment, Victoria. 1996.