GP14

Location: Ellinbank Dairy Research Institute.	Australian Soil Classification: Bleached-Acidic, Dermosolic, Redoxic HYDROSOL.
Northcote Factual Key: Gn4.64.	Great Soil Group: brown podzolic.
General Site Description: Valley floor.	Geology: Quaternary unconsolidated alluvium.
Mapping Unit: Ripplebrook	Geographic Reference: 407043E, 5765891N

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Brown (10YR4/3); silty clay loam; strong medium blocky, parting to moderate fine blocky structure; weak consistence moist; pH 5.1; clear change to:	GP14 Profile
A2	10-25 cm	Yellowish brown (10YR5/4) conspicuously bleached (10YR8/2d); silty clay loam; moderate medium blocky, parting to moderate fine subangular blocky structure; weak consistence moist; pH 5.0; clear and wavy change to:
Subsoil
B21	25-75 cm	Pale brown (10YR6/3) with faint brownish yellow (10YR6/6) mottles; silty clay loam (becoming light clay with depth); moderate medium blocky, parting to moderate fine blocky structure; firm consistence moist; contains very few (2%) soft manganese segregations; pH 5.0; clear and wavy change to:
B22	75-90 cm	Light brownish grey (10YR6/2) with yellowish brown (10YR5/8) mottles; light medium clay; moderate coarse blocky, parting to moderate fine blocky structure; firm consistence moist; contains few (5%) soft manganese segregations; pH 5.4.

Key Profile Features:

Lack of strong texture contrast between surface (A) horizons and upper subsoil (B21) horizon (i.e. Dermosolic).
Much of the soil profile is saturated for prolonged periods (i.e. several months per year) in most years.

Soil Profile Characteristics:


The soil profile is strongly acid throughout.	The level of soluble salts are very low throughout the profile.	The soil profile is non-sodic throughout.


The level of exchangeable aluminium is quite high in the strongly acid surface horizons and upper subsoil.	There is negligible change in clay content with depth.

Horizon	Horizon Depth (cm)	pH water	pH CaCl₂	EC dS/m	Exchangeable Cations				Exchangeable Aluminium mg/kg	Field Capacity pF 2.5	Wilting Point pF 4.2	Coarse Sand (0.2 -2.0 mm)	Fine Sand (0.02-0.2 mm)	Silt (0.002-0.02 mm)	Clay (<0.002 mm)
					Ca	Mg	K	Na
					meq/100 g
A1	0-10	4.4	5.1	0.08	2.8	1.1	0.43	0.17	180	39	12.5	2	23	50	26
A2	10-25	4.2	5	<0.05	1.7	0.52	0.3	0.09	260	37.3	10.4	1	24	51	27
B21	25-40	4.2	5	<0.05	1.7	0.82	0.27	0.07	260	34.1	10.6	1	22	53	29
B21	40-75	4.3	5.1	<0.05	2.3	1.7	0.23	0.09	180	33.9	11	1	22	51	29
B22	75-90	4.4	5.4	<0.05	2.9	2.9	0.28	0.14	130

NOTE: Yellow highlighted rows show chemistry for the upper and lower area of the B21 horizon.

Management Considerations:

Whole Profile

Plant available water capacity (PAWC) is considered to be low (estimated at 80 mm) for the top metre of the soil profile. This is based on available laboratory data. A significant proportion (35 mm) of the plant available water is held in the surface (A) horizons.

Much of the soil profile is likely to be saturated for prolonged periods (i.e. several months) in most years (i.e. Hydrosol). Subsurface drainage may be a viable management option for such soils. Tile drains placed at 1-2 m depth and with 20-30 m spacing has proved successful on some soils in the region (Frank Mickan, pers. comm.).

Surface (A) Horizons

The levels of exchangeable aluminium are quite high in the strongly acid surface horizons (180 - 260 mg/kg). These levels are likely to restrict the growth of aluminium sensitive species. A pH/aluminium test sampled from across the paddock would be most appropriate to determine whether lime is needed to raise soil pH. Other factors need to be considered, however, before lime is recommended (e.g. pasture species grown, method of application, local trial responses, soil surface structure and likely cost/benefit).

Manganese toxicity may also occur in strongly acid soils, particularly when poorly drained (as waterlogging may bring manganese into solution).

Deficiencies in molybdenum, potassium and phosphorus are likely to occur in strongly acid soils. If lime is required, an application may assist in alleviating molybdenum deficiency and will increase phosphorus availability, as well as increasing soil pH. Phosphorus tends to become 'fixed' by high levels of exchangeable aluminium.

The surface soil has a very high silt (50%) and fine sand (23%) content. Organic matter is important for maintaining aggregation on such soils. At low organic matter levels, structural deterioration (e.g. exacerbated hardsetting, surface sealing and compaction) is more likely to occur, particularly if cultivation takes place. The surface soil is likely to suffer structural degradation (e.g. pugging, compaction) if overstocking occurs whilst the soil is wet.

The surface soil has a low nutrient status (based on the sum of the basic exchangeable cations).

Subsoil (B) Horizons

Exchangeable aluminium levels remain high throughout the strongly acid subsoil.
The upper subsoil has a low inherent fertility (based on the sum of the basic exchangeable cations).
Root growth may be restricted by seasonal saturation of the subsoil.

Profile Described By: Mark Imhof, Ian Sargeant and Paul Rampant (February 1996).

Location:

Ellinbank Dairy Research Institute

Australian Soil Classification:

Bleached-Acidic, Dermosolic, Redoxic HYDROSOL

Northcote Factual Key:

Gn4.64

Great Soil Group:

Brown podzolic

Map Unit:

Ripplebrook

Geology:

Quaternary unconsolidated alluvium.

Soil Profile Morphology:

Surface soil horizon
Surface Soil	Depth (cm)	Description
A1	0-10	Brown (10YR4/3); silty clay loam; strong medium blocky, parting to moderate fine blocky structure; weak consistence moist; pH 5.1; clear change to:
A2	10-25	Yellowish brown (10YR5/4) conspicuously bleached (10YR8/2d); silty clay loam; moderate medium blocky, parting to moderate fine subangular blocky structure; weak consistence moist; pH 5.0; clear and wavy change to:

Subsoil horizon
Subsoil	Depth (cm)	Description
B21	25-40	Pale brown (10YR6/3) with faint brownish yellow (10YR6/6) mottles; silty clay loam (becoming light clay with depth); moderate medium blocky, parting to moderate fine blocky structure; firm consistence moist; contains very few (2%) soft manganese segregations; pH 5.0; clear and wavy change to:
B21	40-75	(as above as same horizon)
B22	75-90	Light brownish grey (10YR6/2) with yellowish brown (10YR5/8) mottles; light medium clay; moderate coarse blocky, parting to moderate fine blocky structure; firm consistence moist; contains few (5%) soft manganese segregations; pH 5.4.

GP14 Profile

Key Profile Features:

Lack of strong texture contrast between surface (A) horizons and upper subsoil (B21) horizon (i.e. Dermosolic)
Much of the soil profile is saturated for prolonged periods (i.e. several months per year) in most years

Soil Profile Characteristics:

Soil Site Characteristics
	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Extremely Acid	Very Low	Non Sodic	Not Recorded
Subsoil (B21 horizon)	Extremely Acid	Very Low	Non Sodic	Not Recorded
Deep Subsoil (at cm)	Extremely Acid	Very Low	Non Sodic	Not Recorded
Surface (at cm)

Soil Profile Graphs:

Graph: Site GP14 pH levels — The soil profile is strongly acid throughout.

Graph: Site GP14 Salinity levels — The level of soluble salts are very low throughout the profile.

Graph: Site GP14 Sodicity levels — The soil profile is non-sodic throughout.

Graph: Site GP14 Clay% — There is negligible change in clay content with depth.

Graph: Site GP14 Aluminium — The level of exchangeable aluminium is quite high in the strongly acid surface horizons and upper subsoil.

Chemical Analysis

Chemical Analysis
Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl₂)	EC (dS/m)	Exchangeable Cations (meq/100g)				Exchangeable Aluminium mg/kg
					Ca	Mg	K	Na
A1	0-10	4.2	5.1	0.08	2.8	1.1	0.43	0.17	180
A2	10-25	4.2	5	<0.05	1.7	0.52	0.3	0.09	260
B21	25-40	4.3		<0.05	1.7	0.82	0.27	0.07	260
B21	40-75	4.4	5.1	<0.05	2.3	1.7	0.23	0.09	180
B22	75-90	4.4	5.4	<0.05	2.9	2.9	0.28	0.14	130

Physical Analysis

Physical Analysis
Horizon	Horizon Depth (cm)	Field Capacity pF2.5 w/w g/g %	Wilting Point pF4.2 w/w g/g %	Coarse Sand (0.02-2.0mm) %	Fine Sand (0.02-0.2mm) %	Silt (0.02-0.002mm) %	Clay (<0.002mm) %
A1	0-10	39	12.5	2	23	50	26
A2	10-25	37.3	10.4	1	24	51	27
B21	25-40	34.1	10.6	1	22	53	29
B21	40-75	33.9	11	1	22	51	29
B22	75-90

Management Considerations

Whole Profile:

Plant available water capacity (PAWC) is considered to be low (estimated at 80 mm) for the top metre of the soil profile. This is based on available laboratory data. A significant proportion (35 mm) of the plant available water is held in the surface (A) horizons.

Much of the soil profile is likely to be saturated for prolonged periods (i.e. several months) in most years (i.e. Hydrosol). Subsurface drainage may be a viable management option for such soils. Tile drains placed at 1-2 m depth and with 20-30 m spacing has proved successful on some soils in the region (Frank Mickan, pers. comm.).

Surface (A) Horizons:

The levels of exchangeable aluminium are quite high in the strongly acid surface horizons (180 - 260 mg/kg). These levels are likely to restrict the growth of aluminium sensitive species. A pH/aluminium test sampled from across the paddock would be most appropriate to determine whether lime is needed to raise soil pH. Other factors need to be considered, however, before lime is recommended (e.g. pasture species grown, method of application, local trial responses, soil surface structure and likely cost/benefit).

Manganese toxicity may also occur in strongly acid soils, particularly when poorly drained (as waterlogging may bring manganese into solution).

Deficiencies in molybdenum, potassium and phosphorus are likely to occur in strongly acid soils. If lime is required, an application may assist in alleviating molybdenum deficiency and will increase phosphorus availability, as well as increasing soil pH. Phosphorus tends to become 'fixed' by high levels of exchangeable aluminium.

The surface soil has a very high silt (50%) and fine sand (23%) content. Organic matter is important for maintaining aggregation on such soils. At low organic matter levels, structural deterioration (e.g. exacerbated hardsetting, surface sealing and compaction) is more likely to occur, particularly if cultivation takes place. The surface soil is likely to suffer structural degradation (e.g. pugging, compaction) if overstocking occurs whilst the soil is wet.

The surface soil has a low nutrient status (based on the sum of the basic exchangeable cations).

Subsoil (B) Horizons:

Exchangeable aluminium levels remain high throughout the strongly acid subsoil.

The upper subsoil has a low inherent fertility (based on the sum of the basic exchangeable cations).

Root growth may be restricted by seasonal saturation of the subsoil.

Described By:

Mark Imhof, Ian Sargeant and Paul Rampant (February 1996).

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