Site MP22

Location: Jil Jil.

Group: Birchip Cropping Group.

Australian Soil Classification: Epihypersodic, Pedal, Hypercalcic CALCAROSOL.

General Landscape Description: Level plain within the Culgoa Land System (Rowan and Downes, 1963).

Site MP22 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Dark brown (10YR3/3); clay loam; hardsetting and massive; firm consistence dry; pH 8.4; abrupt change to:	Site MP22 Soil Profile
Subsoil
B21	10-30 cm	Dark brown (10YR3/3); light medium clay; moderate coarse prismatic structure; very firm consistence dry; pH 8.8; wavy change to:
B22k	30-110 cm	Reddish yellow (5YR6/6); light medium clay; moderate coarse prismatic, parting to medium angular blocky structure; contains very few (<2%) ironstone fragments and many (20-50%) fine earth carbonates; pH 9.8; gradual change to:
B23	110-125 cm	Reddish yellow (7.5YR6/6); medium heavy clay; moderate coarse prismatic, parting to medium to coarse blocky structure (smooth-faced peds); contains a few (2-10%) soft carbonates (and a band of manganese segregations in the 120 -125 cm zone); strong consistence dry; pH 8.6; gradual change to:
B31	125 cm+	Brownish yellow (10YR6/8) with light brownish grey (10YR6/2) mottles; medium clay; strong coarse prismatic, parting to coarse angular blocky structure (smooth-faced peds); strong consistence dry; pH 4.9.

Soil Profile Characteristics:

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	moderately alkaline	low	non-sodic	none
Subsoil (B21 horizon)	strongly alkaline	low	non-sodic	none
Deeper subsoil (at 1 m)	extremely alkaline	Very high	strongly sodic	strong

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl₂)	EC 1:5	NaCI %	Exchangeable Cations				Field Capacity pF 2.5	Wilting Point pF 4.2	Coarse Sand (0.2 - 2.0 mm)	Fine Sand (0.02 -0.2 mm)	Silt (0.002 -0.02 mm)	Clay (<0.002 mm)
						Ca	Mg	K	Na
						meq/100g
A1	0-10	8.4	7.6	0.18		20.7	4.2	3.1	0.2	29	16	32	25	4	29
B21	10-30	8.8	8	0.17		5.6	13.4	1.3	1	34	20	36	22	2	34
B22k	30-110	9.8	8.7	0.53	<0.05	5.6	13.4	1.2	6.7	41	26
B23	110-125	8.6	8.1	1.47	0.25	1.8	13.1	1.5	13.9	46	27
B31	125+	4.9	4.3	1.48	.29	0.5	8	.6	6.9

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 upper subsoil is non-sodic but becomes strongly sodic from 45 cm depth. This will result in plant and water movement being restricted in the deeper subsoil. The high level of exchangeable magnesium relative to exchangeable calcium is likely to reinforce the deleterious effects of exchangeable sodium on soil structure and may induce deficiencies in some nutrients.

The level of soluble salts becomes high in the deeper subsoil, which will affect the growth of deeper-rooted salt-sensitive species.

The subsoil is strongly to extremely alkaline throughout. This indicates that phosphorus and trace elements such as iron, manganese, copper and zinc may be poorly available to plants.

Notes: The deeper subsoil (from about 130 cm depth) becomes very strongly acid. This is part of an older land surface that developed on Tertiary Parilla Sandstone.

Profile Described By: Mark Imhof and John Martin (23/1/93).

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