EGC217

Location: Buchan

Australian Soil Classification: Melanic, Calcic, Red DERMOSOL

Map Unit: Buchan (Component 1)
Previous Site Name: EG217

General Landscape Description: Rolling hills
Site description: Upper slope, 5% slope, western aspect
Land Use: Grazing
Native Vegetation: Grassy woodland
Geology: Devonian limestone, Taravale Formation

Soils and landforms of the Buchan and Suggan Buggan region - Tarravale EG217 landscape

Soil Profile Morphology:

Surface soil
A1	0 – 20 cm	Dark reddish brown (5YR3/2); heavy clay loam (subplastic); strong fine (2 – 5 mm) granular structure; few (2 – 10%) subrounded limestone pebbles (6 – 20 mm); weak consistence moist; clear change to:
Subsoil
B21	20 – 40/50 cm	Dark reddish brown (5YR3/4); medium clay; strong fine (5 – 10 mm) polyhedral structure; common (10 – 20%) subangular limestone pebbles (20 – 60 mm); very firm consistence moist; clear and wavy change to:
B22	40/50 -60 mm	Light brown (7.5YR6/4) mottled with strong brown (7.5YR5/6); silty clay; weak medium (10 – 20 mm) polyhedral structure; few (2 – 10%) subangular limestone pebbles (20 – 60 mm); firm consistence dry; clear change to:
C	60 – 100 mm	White (7.5YR8/1), soft limestone; few (2 – 10%) subangular limestone pebbles (20 – 60 mm); limestone becoming stronger with depth

Key Profile Features:

Lack of texture contrast between the surface (A) horizon and the subsoil (B) horizon.
Moderately shallow profile depth to limestone.

Soil Profile Characteristics:

-	pH	Salinity	Dispersion
Surface soil (A1 horizon)	Slightly Alkaline	Very Low	Non Sodic
Subsoil (B21 horizon)	Moderately Alkaline	Very Low	Non Sodic
Deeper subsoil (60-100 cm)	Strongly Alkaline	Very Low	Non Sodic

¹ Slight dispersion after remoulding. ² Strong dispersion after remoulding.

Chemical and Physical Analysis:

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl₂)	EC dS/m	Organic Carbon %	Total Nitrogen %	Exchangeable Aluminium ppm	Exchangeable Cations				Coarse Sand (0.2-2.0 mm) %	Fine Sand (0.02-0.2 mm) %	Silt (0.002-0.02 mm) %	Clay (<0.002 mm) %	Field Capacity % w/w	Wilting Point % w/w
								Ca	Mg	K	Na
								meq/100g
A1	0-20	7.7	7.2	0.08	4.3	0.36	<10	38	0.99	0.52	0.17	3	9	23	49	38.5	22.8
B21	20-40/45	8.2	7.6	0.06	2.2	0.17	<10	34	0.6	0.38	0.13	8	9	14	37	33.4	18.8
B22	40-60	8.6	7.8	0.04	0.51	<0.05	<10	25	0.22	<0.05	0.13	12	16	9	26	34.2	14.7
C	60-100	8.8	7.8	0.03	0.31	<0.05	<10	24	0.28	<0.05	0.11	19	9	8	16	36.3	10.4

Management Considerations

Whole profile

Plant available water (PAW) here is considered to be moderate, estimated to be 90 mm. Because of the variability in the depth of soil cover within this map unit, many soils will have low to very low water-holding capacity. Effective rooting depth is limited to the depth to rock.

Surface (A) horizons

The surface soil here is slightly alkaline and no response to additional lime would occur.
The soils are low in soluble salts.
Potassium levels are moderate and plant responses to potassium fertiliser are unlikely given the present grazing management.
The nutrient holding capacities of the surface (A1 and B21) horizons are high (based on the sum of the exchangeable calcium, magnesium, potassium and sodium cations).

Subsoil (B) horizons

The subsoil is well drained as there is no sharp increase in clay content at the A/B boundary.
The subsoil horizons are non-sodic and strongly structured, which will enable plant roots to penetrate easily until they reach decomposing limestone that acts as both a physical and chemical barrier.

Profile Described By: Heather Adams, Julieanne Sargant and Ian Sargeant, June 2009.

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