Victorian Resources Online (archived)

MP23

Group: Birchip Cropping Demonstration Group
*Aust. Soil Class.:* Epihypersodic, Pedal, Hypercalcic CALCAROSOL	*Northcote Factual Key:*Dy 2.13

MP23 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Dark brown (10YR3/3); heavy clay loam (sandy); hardsetting and massive; strong consistence dry; pH 8.5; sharp and wavy change to:	MP23 Profile
Subsoil
B21	10-25 cm	Yellowish brown (10YR5/4); light medium clay; moderate coarse prismatic, breaking down to medium blocky structure; strong consistence dry; pH 9.4; clear and wavy change to:
B22k	25-100 cm	Light yellowish brown (10YR6/4); light medium clay; moderate prismatic structure; strong consistence dry; contains many soft carbonates; pH 9.9; sharp and wavy boundary to:
B23	100-150 cm	Very pale brown (10YR7/3) and reddish yellow (5YR6/8) mottles; medium clay; coarse prismatic structure; strong consistence dry; contains a band of manganese segregations in 145-150cm zone; pH 9.5; gradual change to :
B31	150-190 cm	Yellowish red (5YR5/8); heavy clay; strong very coarse prismatic structure; very strong consistence dry; pH 5.7.

Key Profile Features:

Soil Profile Characteristics:

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Moderately Alkaline	Low	Non-Sodic	None¹
Subsoil (B21 horizon)	Very Strongly Alkaline	Low	Sodic	None²
Deeper subsoil (at 1 m)	Extremely Alkaline	Very High	Strongly Sodic	Strong

Horizon	Horizon Depth	pH (water)	pH CaCl2	EC 1:5	NaCl	Exchangeable Cations
						Ca	Mg	K	Na
						Meq/100g
A1	0-10	8.5	7.8	0.1		19.6	4.6	2.5	0.2
B21	10-25	9.4	8.3	0.24		14.2	11.1	1.1	3.2
B22k	25-100	9.9	8.9	0.77		2.7	9.8	1.1	10.4
B23	100-150	9.5	8.9	1.5	0.27	3.8	12.3	1.6	14.3
B31	150-190	5.7	5.2	1.54	0.3	2.1	8.6	0.8	7.5

Horizon	Horizon Depth	Boron mg/kg	Field pF2.5 g/100g	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	0-10		27.7	15	32	27	4	31
B21	10-25		34.8	21.7	27	19	4	40
B22k	25-100		38.4	23.8
B23	100-150		46.6	27.6
B31	150-190

Management Considerations:

Surface (A) Horizon

The hardsetting surface condition can be improved by using management practises such as minimum tillage, stubble retention and pasture rotations to improve organic matter levels.

Subsoil (B) Horizons

The top of the subsoil is sodic and as a result root and water movement through the subsoil is likely to be restricted.
The top of the subsoil is sodic becoming strongly sodic by >25 cm and very strongly sodic by 40 cm, with strong dispersion. These conditions are likely to restrict water and root movement into the subsoil. Also, the calcium to magnesium ratio is low (0.3) which will add to the deleterious effect of exchangeable sodium on soil structure.
Very strongly alkaline to extremely alkaline conditions exist in the subsoil. This indicates that certain nutrients (eg. zinc, copper, iron, boron and manganese) may be poorly available to plants.
The level of soluble salts becomes very high in the deeper subsoil. This is likely to restrict the growth of deeper rooted species.

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