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Site NE38

Property: Rutherglen Research Institute.
Paddock #: F

Australian Soil Classification: Bleached-Sodic, Eutrophic, Red CHROMOSOL
Northcote Factual Key: Dy 3.43
Great Soil Group: No suitable group.

General Landscape Description: Higher area of plain.
Soil Mapping Unit: Type A.

Site NE38 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-12 cm	Brown (7.5YR4/4); light fine sandy clay loam; weak coarse blocky structure; weak consistence moist; pH 5.4; clear change to:	Site NE38 Profile
A2	12-30 cm	Pinkish brown (7.5YR6.5/4) conspicuously bleached (7.5YR8/2d); light fine sandy clay loam; structureless; firm consistence dry; pH 6.0; clear change to:
Subsoil
B21	30-55 cm	Yellowish red (5YR5/8); light medium clay; weak medium polyhedral, parting to weak fine polyhedral structure; strong consistence dry; manganese stains occur in patches; pH 6.8; gradual change to:
B22	55-80 cm	Brownish yellow (10YR6/6) with dark red (2.5YR4/6) mottles; light medium clay; moderate medium polyhedral, parting to fine polyhedral structure; strong consistence dry; pH 6.0; clear change to:
B23	80-100 cm	Pale yellow (2.5Y7/4) [with yellowish red (5YR5/8) colours associated with root channels]; light medium clay; weakly structured; strong consistence dry; pH 6.8; clear change to:
B24	100-140 cm	Very pale brown (10YR7/3) with brownish yellow (10YR6/8) mottles; light medium clay; moderate coarse polyhedral structure; strong consistence dry; contains many (30%) manganese stains along ped faces and very few nodules (up to 1 cm size); pH 7.0; clear change to:
B3	140 cm+	Light brownish grey (10YR6/2) with yellowish red (5YR5/8) mottles; light medium clay; strong coarse prismatic, breaking to strong coarse blocky structure; strong consistence dry; pH 8.0.

Key Profile Features:

• Strong texture contrast between surface (A) horizons (15% clay) and subsoil (B21) horizon (38% clay).
• Conspicuously bleached subsurface (A2) horizon.

Soil Profile Characteristics:

	The surface horizon is strongly acid. The upper subsoil is mainly slightly acid. The deeper subsoil is alkaline.		The top metre of the soil profile is non-sodic. The deeper subsoil is sodic and dispersive. Note: prismatic structure occurs below 140 cm depth.
	The level of soluble salts is very low throughout the soil profile.		The clay % increases sharply at the A/B horizon interface.

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl2)	EC 1:5	Exchangeable Cations				Exchangeable Aluminium mg/kg	Field Capacity pF 2.5	Wilting Point pF 4.2	Coarse Sand (0.2 - 2 mm)	Fine Sand (0.02 -0.2 mm)	Silt (0.002 -0.02 mm)	Clay (<0.002 mm)
					Ca	Mg	K	Na
					meq/100g
A1	0-12	5.3	4.4	0.11	2.9	0.56	1.5	<0.05	10	28	7	2	53	22	15
A2	12-30	6	5.3	0.09	2.6	0.69	0.64	<0.05		20	5	2	54	29	15
B21	30-55	6.8	5.6	<0.05	3.1	2.1	2.2	0.09		25	13	1	37	25	38
B22	55-80	6	5.1	0.08	3.2	2.2	2.7	0.14		29	13	2	33	23	44
B23	80-100	6.8	5.9	0.06	3.1	2.1	1.5	0.14
B24	100-140	7	6.1	0.09	3.9	4.8	0.9	0.56
B3	140+	8	6.8	0.11	6.9	9.9	0.74	1.8

Management Considerations:

Whole Profile

• Plant available water capacity (PAWC) is considered to be low (estimated at 85 mm) for the top metre of the soil profile. This is based on available laboratory data.
• Exchangeable potassium levels are relatively high throughout the soil profile. According to Baker and Eldershaw (1993) levels of exchangeable potassium (relative to Cation Exchange Capacity) above 10% can result in magnesium deficiency.
  
  

Surface (A) Horizons

• Although the surface horizons are non-sodic, slight dispersion occurs after remoulding. This indicates that some structural degradation may occur if the soil is cultivated in a moist-wet condition.
• The surface horizon has high fine sand (53%) and silt (22%) content. Organic matter is therefore important for maintaining soil aggregation and preventing slaking. The soil is likely to become 'powdery' when cultivated dry, which may result in surface sealing occurring.
• The surface soil has a low nutrient status (based on the sum of the exchangeable basic cations).
  

Subsoil (B) Horizons

• The upper subsoil is non-sodic but disperses completely after remoulding. Deep tillage should therefore be avoided if the soil is in a moist to wet condition.
• Upper subsoil drainage should be reasonable due to the non-sodic conditions. Water movement will be restricted to some degree at the A/B horizon interface due to the reasonably large increase in clay content.
• The subsoil has a low-medium nutrient status (based on the sum of the exchangeable basic cations).
• The large amount of manganese segregations in the deep subsoil may restrict the growth of deep rooted manganese sensitive plants.
• Deep profile drainage will be restricted by the sodic and strongly dispersive deeper subsoil.

Management Details:

• Pasture since 1969.
• Sown to Trikkala clover in 1990.

Profile Described By: Mark Imhof and Paul Rampant (7/5/96).

References:

Baker, D.E. and Eldershaw, V.J. (1993). Interpreting Soil Analysis for Agricultural Land Use in Queensland. Project Report Series. Queensland, Department of Primary Industries.