LWA18

Location: Minyip

Australian Soil Classification: Epicalcareous-Endohypersodic, Epipedal, Grey VERTOSOL

General Landscape Description: Undulating plain.
Site Description: Demonstration site. Cereal stubble under no-till management.

Image: LWA18 Landscape
LWA18 Landscape - soil site in foreground.

Soil Profile Morphology:

Surface Soil			LWA18 profile
A1	0-12 cm	Very Dark Grey (10YR3/1); light clay; firm surface condition; very weak consistence moderately moist; moderate medium polyhedral, parting to moderate very fine granular structure; slightly calcareous; few roots; pH 8.1; abrupt change to:
Subsoil
B1	12-28 cm	Dark Grey (2.5Y4/1); light-medium clay; very weak consistence moderately moist; moderate fine platy structure, parting to moderate very fine granular structure; distinct slickensides common; very few (<2%) medium calcareous concretions; few roots; pH 8.2; abrupt change to:
B21	28-70 cm	Dark Grey (5Y4/1) with very dark grey (2.5Y3/1) mottles; medium-heavy clay; moderate coarse (20-50 mm) prismatic, parting to strong medium angular blocky structure; strong consistence dry; few (2-10%) coarse calcareous concretions; slighly calcareous; distinct slickensides common; roots common; pH 8.5; diffuse change to:
B22	70-93 cm	Grey (2.5Y5/1) with very dark grey (10YR3/1) mottles; medium-heavy clay; moderate coarse (50-100mm) prismatic, parting to moderate coarse (20-50 mm) prismatic and moderate medium angular blocky structure; strong consistence dry; few (2-10%) medium and coarse calcareous concretions; slightly calcareous; few roots; prominent slickensides common (100 mm long); pH 8.9; gradual change to:
B23	93-120 cm	Grey (5Y5/1) with few (10%) dark grey (2.5Y4/1) mottles; heavy clay; strong very coarse (100-200 mm) prismatic, parting to strong coarse (20-50 mm) angular blocky structure; very strong consistence dry; very few (<2%) coarse calcareous concretions; slightly calcareous; prominent slickensides common (100 mm long); pH 9.2; gradual change to:
B24	120-150+ cm	Greyish brown (2.5Y5/2) with brownish yellow (10YR6/8) mottles; weak to moderate coarse (20-50mm) prismatic, parting to moderate medium angular blocky structure; strong consistence dry; very few coarse calcareous concretions with very few (<2%) medium manganiferous nodules; slightly calcareous; prominant slickensides common up to 75 mm long; pH 9.3.

Soil Profile Characteristics:

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Moderately Alkaline	Low	Non-Sodic	None²
Subsoil (B21 horizon)	Moderately Alkaline	Low	Sodic	None¹
Deeper subsoil (at 95-120 cm)	Very Strongly Alkaline	Low-Moderate	Strongly Sodic	Moderate³

¹ Slight dispersion after remoulding. ² Moderate dispersion after remoulding. ³Strong dispersion after remoulding.

The pH in the surface and upper subsoil is moderately alkaline. The deeper subsoil is very strongly alkaline.

The salinity rating is low in the surface and upper subsoil, becoming moderate in the deeper subsoil.

The surface is non sodic. The subsoil is sodic, becoming strongly sodic with depth.

The clay content is high throughout the soil profile.

Boron levels increase in the deeper subsoil.

Chemical and Physical Analysis:

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl₂)	EC dS/m	NaCl %	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-12	8.1	7.7	0.21		38	5.3	2.9	0.66
B1	12-28	8.2	7.8	0.47	<0.02	34	9.8	2.2	2.6
B21	28-70	8.5	7.9	0.47	0.24	27	11	1.7	3.7
B22	70-93	8.9	8.1	0.49	0.042	21	13	1.9	7.1
B23	93-120	9.2	8.4	0.74	0.09	15	15	2.1	12
B24	120-150	9.3	8.6	0.99	0.13	12	16	2.3	16

Horizon	Horizon Depth (cm)	Boron mg/kg	Organic Carbon %	Total Nitrogen %	Field Capacity pF2.5	Wilting Point pF4.2	Coarse Sand (0.2-2.0 mm)	Fine Sand (0.02-0.2 mm)	Silt (0.002-0.02 mm)	Clay (<0.002 mm)


A1	0-12	2	1.2	0.12	42	21.9	14	16	16	45
B1	12-28	2.2	0.45	0.051	49.2	25.7	11	10	11	62
B21	28-70	2.4			49.5	27.1	11	10	11	62
B22	70-93	3.5			53.2	26.9	11	10	10	62
B23	93-120	9			59.5	29
B24	120-150	19			61.4	30.4

Profile Described By: Melissa Cann (May 2007).

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