Gelantipy (Symbol: Gy)

EG83 | EG84 | EG216

Geology
Palaeogene (early to mid Tertiary) basaltic volcanic rocks. The basalts occupy an old abandoned valley that lies about 200 m above the valley of the present drainage system (Webb et al., 1991).

Landform
The undulating to rolling low hills of the Gelantipy map unit have an elevation range of about 600 to 950 m and, apart from the escarpment, a relief range of about 30 to 90 m. The landform may also be described as a dissected plateau, mostly comprised of basalt, with the rocks below the escarpment and above the dissected plateau being the Snowy River Volcanics. In parts, basalt may extend some distance down the escarpment. Slopes are generally less than 32% but on the escarpment are much steeper, with slopes up to about 60%.

It is arbitrarily separated from the W Tree map unit on the basis of its vegetation class, elevation and generally more gentle topography.

This map unit may be subdivided into at least three components: undulating rises, gently undulating plains, and open drainage lines.


Rolling low hills of the Gelantipy map unit. Photo taken south of Gelantipy. Basalt rocks are exposed on the
slopes adjoining the drainage line.

Native vegetation
Montane grassy woodland.

Soils
The soils are quite variable, and seem to depend on their external drainage and slope.

Component 1: Soils on the gently undulating rises.
On the well drained slopes of the undulating rises the surface soils are mostly dark reddish brown clay loams, with minor occurrences of dark greyish brown clay loams. There is little colour change down the profile but there is usually an increase in clay content to medium clay. The reddish colours indicate the soils are high in iron oxide and of the two analysed, one had iron oxides exceeding 5%. These soils have a favourable soil structure and, depending on the depth to rock, a moderate to high nutrient and water holding capacity.

Component 2: Gently undulating plains
Soils similar to those described for component 1 do occur but in areas where the soil is less well drained there is an abrupt change from the clay loam to silty loam surface and subsurface soils and the clay subsoil. Concretions high in iron oxide, or ferruginous segregations, commonly termed ‘buckshot’ are usually found above the clay. These soils have a weakly developed soil structure and tend to set hard when dry.

Reddish brown well structured gradational soil on basalt.

Grey brown poorly structured texture contract soil on basalt. ‘Buckshot’ (ferruginous segregations) occurs above the clay horizon. These soils occur in areas of impeded drainage.

Component 3: Open drainage lines
Other than various types of soil, rock is often exposed on the slopes adjoining the drainage lines.

Land use
Apart from remnants of original vegetation, the land has been cleared and used for grazing or occasionally, horticulture.

Site EG83

Location: Wulgulmerang	Geo. Ref. 608700E 5864800N
Australian soil classification: Haplic, Eutrophic, Brown CHROMOSOL (Stony)	Stony brown texture contrast soil
General landscape description: Plateau
Geology: Tertiary basalt
Site description: Lower slope, <2% slope (Roadside exposure)
Land use: Grazing
Native vegetation: Montane grassy woodland
Map unit: Gelantipy (Component 1)

Soil profile morphology

Surface soil
A1	0 – 30 cm	Brown (7.5YR3/2); silty clay loam; strong coarse polyhedral structure; firm consistence moderately moist; many (20 - 50%) subrounded basalt stones (200 – 600 mm); clear change to:
Subsoil
B2	30 - 55+cm	Brown (7.5YR4/2); medium clay; moderate to strong medium prismatic structure; very firm consistence moderately moist; abundant (50 – 90%) subrounded basalt stones (200 – 600 mm)
Key profile features Moderate texture contrast between the surface and subsoil horizons. Basalt stones throughout the profile, although other roadside cuttings show this to be a variable feature.

Soil profile characteristics

	pH	Salinity rating	Sodicity	Dispersion	Slaking
Surface soil (A1 horizon)	Slightly acid	Very low	Non sodic	None	Slakes partially
Subsoil (B2 horizon)	Slightly acid	Very low	Non sodic	None	Slakes partially

Horizon	Depth cm	Field texture	pH water	pH CaCl2	EC dS/m	Coarse sand %	Fine sand %	Silt %	Clay %	Field cap. % w/w	Wilt. point % w/w	PAW* water % w/w
A1	0-30	CL	6.3	5.7	0.06	11	34	26	25	41	17.9	23.1
B2	30-55	MC	6.7	5.9	0.11	5	26	21	42	47.9	29.3	18.6

* PAW is plant available water. This is the difference between the soil’s water content at field capacity and wilting point.

Depth	OrgC#	Total N	Free Fe2O3	Exch. Al	Exchangeable cations cmol(+)/kg							Ca:Mg	ESP
cm	%	%	% w/w	ppm	Ca	Mg	K	Na	Total	H	CEC
0-15	2.3	0.2	2.1	<1	11	6.4	0.34	0.29	18	9.2	27.2	1.8	1
20-30			2.4		17	13	0.35	0.29	31	10.0	41.0	1.3	1

# Organic carbon

Management considerations

Whole profile

• The profile is slightly acid throughout.
• These soils are well drained due their strongly developed structure.
• Plant available water capacity is considered to be low, estimated at 45 mm based on the laboratory data, and taking into consideration the presence of basalt stones.

Surface (A) horizon

• The soil has low organic matter content. Organic matter will be better maintained under rotational grazing, which enables stronger pasture recovery, rather than set stocking.
• The nutrient holding capacity of the soil is high (based on the sum of the exchangeable basic cations).
• Potassium levels are low to moderate.

Subsoil (B) horizon

• The friable nature of the subsoil allows deep penetration of plant roots until the basalt rock is encountered.
• The friable nature of the subsoil and the presence of rock will lead to problems with sealing of earth dams.

Site EG84

Location: Gelantipy	Geo. Ref. 611800E 5879600N
Australian soil classification: Ferric, Eutrophic, Grey CHROMOSOL (thick surface)	Grey texture contrast soil
General landscape description: Plateau
Geology: Tertiary basalt
Site description: Upper slope, ENE aspect, 11 % slope
Land use: Unused
Native vegetation: Montane grassy woodland
Map unit: Gelantipy (Component 2)

Soil profile morphology

Surface soil
A1	0 – 5 cm	Dark greyish brown (10YR4/2); silty loam; weak crumb structure; firm consistence dry; few (2 – 10%) medium (2 – 6 mm) ferruginous concretions; gradual change to:
A21	5 – 50 cm	Greyish brown (10YR5/2); silty loam; massive; very firm consistence dry; few (2 – 10%) medium (2 – 6 mm) ferruginous concretions; clear wavy change to:
A22	50 – 60 cm	Greyish brown (10YR5/2); silty loam; massive; strong consistence dry; many (20 – 50%) medium (2 – 6 mm) ferruginous concretions; clear wavy change to:
Subsoil
B2	60 – 100+ cm	Grey (10YR5/1) finely mottled with brownish yellow (10YR6/6); heavy clay; strong coarse prismatic structure, very strong consistence dry; very many (>50%) medium to coarse (2 – 20 mm) ferruginous concretions and many (20 – 50%) rounded basalt stones (60 – 200 mm)

Key profile features

• Strong texture contrast between surface (A) horizon and subsurface (B2) horizon.

Soil profile characteristics

	pH	Salinity rating	Sodicity	Dispersion	Slaking
Surface soil (A1 horizon)	Slightly acidic	Very low	Non sodic	None1	Slakes partially
Subsoil (B2 horizon)	Slightly acidic	Very low	Non sodic	None2	Slakes partially

¹ Moderate after remoulding, ² Complete after remoulding

Horizon	Depth cm	Field texture	pH water	pH CaCl2	EC dS/m	Coarse sand %	Fine sand %	Silt %	Clay %	Field cap. % w/w	Wilt. point % w/w	PAW* water % w/w
A2	5-50	ZL	6.1	5.3	<0.05	9	41	30	16	27.9	6.4	21.5
B2	60-100	HC	6.7	6.2	<0.05	8	24	22	46	42.4	22.4	20.0

* PAW is plant available water. This is the difference between the soil’s water content at field capacity and wilting point.

Depth	OrgC#	Total N	Free Fe2O3	Exch. Al	Exchangeable cations cmol(+)/kg							Ca:Mg	ESP
cm	%	%	% w/w	ppm	Ca	Mg	K	Na	Total	H	CEC
5-50	0.76	<0.05	2.2	<1	2.8	1.3	0.07	0.11	4.3	6.4	10.7	2.2	1
60-100			4.1		8.1	12	0.14	0.74	21	7.6	30.6	0.7	2

# Organic carbon

Management considerations

Whole profile

• The profile is slightly acid throughout
• Plant roots would find it difficult to penetrate the massive subsurface (A21 and A22) horizons which would be hard setting when dry
• Plant available water capacity is considered to be low; estimated at 57 mm.

Surface (A) horizons

• The nutrient holding capacity of the soil is low (based on the sum of the exchangeable basic cations and the depth of roots observed)
• Potassium levels are very low and a response to potassium would be expected.

Site EG216

Location: Gelantipy	Geo. Ref. 0615000E 5877700N
Australian soil classification: Haplic, Eutrophic, Red FERROSOL (Stony)	Stony red gradational soil
General landscape description: Plateau
Geology: Tertiary basalt
Site description: Gently undulating plain, <2% slope, few (2 – 10%) scattered rounded basalt stones (200 – 600 mm)
Land use: Grazing
Native vegetation: Montane grassy woodland
Map unit: Gelantipy (Component 1)

Soil profile morphology

A11	0 – 20 cm	Dark reddish brown (5YR3/4); heavy clay loam; strong fine (2 – 5 mm) granular structure; common (10 – 20%) subrounded cobbles (60 – 200 mm) weak consistence moist; gradual change to:
A12	20 – 40 cm	Dark red (2.5YR3/6); light clay; strong fine (5 – 10 mm) polyhedral structure; many (20 – 50%) subrounded cobbles (60 – 200 mm); firm consistence dry; gradual change to:
B2	40 -70 mm	Red (2.5YR4/6); medium clay; strong medium (10 – 20 mm) polyhedral structure; abundant (50 – 90%) subrounded stones (200 – 600 mm); firm consistence dry; becoming too rocky to excavate.
Key profile features Shallow depth to rock. Gradual increase in clay content down the soil profile.

Soil profile characteristics

	pH	Salinity rating	Sodicity	Dispersion	Slaking
Surface soil (A11 horizon)	Moderately acid	Very low	Non sodic	None	Slakes partially
Subsoil (A12 horizon)	Moderately acid	Very low	Non sodic	None	Slakes considerably
Deeper subsoil (40-70 cm)	Moderately acid	Very low	Non sodic	None	Slakes considerably

Horizon	Depth cm	Field texture	pH water	pH CaCl2	EC dS/m	Coarse sand %	Fine sand %	Silt %	Clay %	Field cap. % w/w	Wilt. point % w/w	PAW* water % w/w
A11	0-20	CL	5.8	4.9	0.05	9	27	20	33	41.6	17.9	23.7
A12	20-40	LC	6	4.9	<0.05	7	22	24	40	46.8	21.4	25.4
B2	40-70	MC	5.7	4.5	<0.05	9	20	22	45	55.3	28.3	27.0

* PAW is plant available water. This is the difference between the soil’s water content at field capacity and wilting point.

Depth	OrgC#	Total N	Free Fe2O3	Exch. Al	Exchangeable cations cmol(+)/kg							Ca:Mg	ESP
cm	%	%	% w/w	ppm	Ca	Mg	K	Na	Total	H	CEC
0-20	4.3	0.28		<10	8.1	4.6	0.18	0.27	13.2	13	26.2	1.8	1
20-40	1.1	0.5		27	5.3	7.0	<0.05	0.3	12.6	12	24.6	0.8	1
40-70	0.53	<0.5		130	4.6	11.0	<0.05	0.68	16.3	14	30.3	0.4	2

# Organic carbon

Management considerations

Whole profile

• The profile is moderately acid throughout.
• These soils are very well drained due to their strongly developed subsoil structure. This is due to the high iron oxide content which, although not measured in the laboratory, is likely to exceed 5% in the subsoil.
• Plant available water capacity is considered to be low, estimated at 61 mm based on the laboratory data, the presence of cobbles and stones in the subsoil and the shallow nature of the soil.

Surface (A) horizons

• The soil has moderate to high organic matter content, estimated at 7.3% which gives the soil its strongly developed structure.
• The nutrient holding capacity of the soil is high (based on the sum of the exchangeable basic cations).
• Potassium levels are very low and a strong response to potassium fertilisers would be expected.
• Due to their anticipated high iron oxide contents based on their strong ‘red’ colour and basaltic origin, these soils tend to ‘fix’ phosphorus which makes it unavailable to plants. Regular phosphorus application will assist in overcoming such a deficiency. Addition of molybdenum may also be required and this can be assessed by plant tissue analysis of clover. Zinc and copper can also be 'fixed' by high iron oxide contents.

Subsoil (B) horizon

• The friable nature of the subsoil allows good penetration of plant roots until rock is encountered.
• The friable nature of the subsoil together with the shallow depth to rock would lead to problems with sealing of earth dams.
• The subsurface soil has high levels of exchangeable aluminium (130 ppm) and is moderately acidic. This could restrict the growth of deep-rooted aluminium sensitive species, such as lucerne, as aluminium and manganese toxicity may occur. There should be likely long term benefits of applying lime, preferably incorporated, on this site if the test results are representative of the paddock. A pH/aluminium test is, however, best performed from samples taken across the paddock and bulked together. Other factors need to be considered, however, before lime is recommended (eg. pasture species grown, method of application, local trial responses, soil surface structure and likely cost/benefit).