LP103

Australian Soil Classification: Vertic (and Hypocalcic), Subnatric, Brown SODOSOL

Northocte Factual Key: Dy 3.43
Great Soil Group: Red-Brown Earth

Site Description: Lower slope of a gently undulating rise (2% slope). Original vegetation included Grey Box (Eucalyptus microcarpa).
Geology: Ordovician Sediments (Sandstone)

Soil Profile Morphology

Surface Soil

A1	0-10 cm	Dark brown (7.5YR4/4); sandy loam;massive structure; weak consistence dry; few fine quartz gravels; pH 5.1; abrupt change to:	LP103 Profile
A21	10-40 cm	Light yellowish brown (10YR6/4), conspicuously bleached (10YR8/3d); coarse light sandy clay loam; massive; weak consistence dry; many fine quartz gravel; pH 6.4; abrupt and wavy change to:
A22	40- 50 cm	Yellow (10YR7/6), conspicuously bleached; sandy clay loam; massive; very firm consistence dry; common medium quartz gravel; pH 7.5; gradual change to:
Subsoil
B21	50-70 cm	Yellowish brown (10YR5/8); medium heavy clay; moderate coarse prismatic structure; strong consistence dry; few fine quartz gravels; slickensides start at 60 cm; pH 7.6; gradual change to:
B22	70-130 cm	Dark yellowish brown (10YR4/4), becoming light olive brown (2.5Y5/4) with depth; medium heavy clay; moderate coarse blocky structure; very strong consistence dry; very few manganese stains; pH 9.0.

Key Profile Features

Strong texture contrast between surface (A) and the top subsoil (B21) horizon.
Conspicuously bleached subsurface (A2) horizon
Moderate amount (45%) of quartz gravel in the subsurface horizon

Key Profile Characteristics

	pH	Salinity Rating	Sodicity
Surface (A1 horizon)	Strongly Acid	Very Low	Non-Sodic
Subsoil (B21 horizon)	Slightly Alkaline	Very Low	Sodic
Deeper subsoil ( 85 cm)	Strongly Alkaline	Very Low	Sodic

The surface is strongly acid, slightly alkaline at the upper subsoil, then strongly alkaline at depth.

The salinity rating is very low.

This profile is sodic.

Low clay content in the surface, with a sharp increase at the A/B interface.

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl₂)	EC dS/m	Exch. Al ppm	Organic Carbon %	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) %	Wilting Point % w/w
							Ca	Mg	K	Na
							meq/100g
A1	0-10	5.1	4.4	0.09	26	3.5	2.4	1.1	0.18	0.20	22	38	29	11	5.9
A21	10-40	6.4	5.3	<0.05			1.2	0.67	<0.05	0.11	18	44	33	10	3.0
A22	40-50	7.5	6.3	0.05			0.95	2.2	0.06	0.39	19	39	32	17	5.0
B21	50-70	7.6	6.6	0.18			4.7	14	0.28	1.9	9	12	15	69	21.5
B22	70-130	9.0	8.1	0.30			3.9	26	0.25	4.4

Management Considerations:

Whole Profile

The whole profile is sodic but is not dispersive. Some restriction to water and root movement in the deeper subsoil would be expected.

Surface (A) Horizons

The very gravelly A2 horizon (7-20 cm) may deflect roots of species that have a tap root system.
The bleached subsurface (A2) horizons indicates that periodic waterlogging occurs on top of the more slowly permeable subsoil. This horizon is likely to become 'spewy' as a result.
The surface horizons have a low inherent fertility (based on the sum of the basic exchangeable cations).

Subsoil (B) Horizons

The coarse structure of the subsoil would impede water and root movement.

Comments

Approximately 40-50 m downslope (approximately 4 m below surface level at pit site) is a depression with a peizometer tube and Spiny rush (Juncas acutus) which is normally indicator species for salinity.

Profile Described By: Mark Imhof, Paul Rampant and Karen DePlater, November 1995

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