Victorian Resources Online (archived)

GP79

Location: Athlone	*Aust. Soil Class.:* Acidic, Mesotrophic, Brown DERMOSOL (moderate soil depth)
General Landscape Description: Rolling hills.	Site Description: Lower slope (West), rolling low hills.
Geology: Cretaceous sandstone.

GP79 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-15 cm	Dark brown (7.5YR 3/2); very fine sandy clay loam; moderate coarse polyhedral parting to moderate medium polyhedral structure; very firm consistence (dry); pH 4.7; clear change to:	GP79 Profile
A2	15-22 cm	Brown (7.4YR 4/2) conspicuously bleached (10YR 6/3 dry); very fine sandy clay loam; moderate coarse blocky parting to moderate medium blocky structure; very firm consistence (dry); pH 4.6; clear change to:
Subsoil
B21	22-40 cm	Dark yellowish brown (10YR 4/4) conspicuously bleached (10YR 6/3); light clay; moderate coarse prismatic parting to moderate coarse blocky parting to moderate medium blocky structure; strong consistence (dry); pH 4.7; clear change to:
B22	40-70 cm	Dark yellowish brown (10YR 4/4); light clay; moderate coarse blocky parting to strong medium block structure; strong consistence (dry) pH 4.6; abrupt change to:
C	70+ cm	Mottled rock.

Key Profile Features:

Gradual increase in clay content with depth down the profile and medium soil profile depth.

Soil Profile Characteristics:

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Very Strongly Acid	Very Low	Non-Sodic	None
Subsoil (B21 horizon)	Very Strongly Acid	Very Low	Non-Sodic	None
Deeper Subsoil (at 1 m)	Very Strongly Acid	Very Low	Non-Sodic	None

Horizon	Horizon Depth	pH (water)	pH CaCl2	EC 1:5	NaCl	Exchangeable Cations
						Ca	Mg	K	Na
						Meq/100g
A1	0-15	4.7	4.2	0.17		6.1	2.2	0.57	0.21
A2	15-22	4.6	4.0	0.09		3.9	2.2	0.50	0.16
B21	22-40	4.7	4.0	0.06		1.7	1.4	0.44	0.14
B22	40-70	4.6	3.9	0.05		1.4	1.8	0.49	0.14

Horizon	Horizon Depth	Ex Al mg/kg	Ex Ac meq/100g	Field pF 2.5	Wilting Point pF4.2 g/100g	Coarse Sand (0.2-2.0mm) %	Fine Sand (0.02-0.2mm) %	Silt (0.002-0.02mm) %	Clay (<0.002mm) %


A1	0-15	200	24	39.9	16.7	2.8	34.1	29.0	21.5
A2	15-22	450	26	40.2	14.9	3.0	35.6	34.0	20.5
B21	22-40	850	24	36.4	15.5	0.6	32.8	32.0	30.0
B22	40-70	>1000	24	37.5	15.0	0.2	28.4	28.0	41.5

Management Considerations:

Whole Profile

High levels of exchangeable aluminium (increasing to very high levels in deeper subsoil) which will restrict the growth of aluminium sensitive species. High levels of aluminium will also test to "fix” phosphorus and make it less available to plants (and therefore reduce the effectiveness of applied phosphorus fertiliser). Raising the pH levels of the soil by liming will help reduce the level of exchangeable aluminium. A lime test (samples across the whole paddock) may be appropriate to determine the amount of lime needed to raise pH. Other factors need to be considered however before lime is recommended (e.g. species growth, method of application, long trial response, likely cost benefit).

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