Site MP26

Group: Birchip Cropping Group.

Location: Curyo.

Australian Soil Classification: Hypercalcic, Mesonatric, Red SODOSOL.

General Landscape Description: Low rise (possibly a lunette) on a plain within the Culgoa Land System (Rowan and Downes, 1963).
.

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Dark brown (7.5YR4/4); light sandy clay loam; massive and hardsetting; firm consistence dry; pH 8.6; sharp change to:	Site MP26 Profile
A2	10-20 cm	Brown (7.5YR4/6); light sandy loam; massive; weak to firm consistence dry; thin bleached layer occurs at the interface with the subsoil; pH 8.4; sharp change to:
Subsoil
B21	20-40 cm	Yellowish red (5YR5/8); light medium clay (sandy); moderate coarse to very coarse prismatic structure; pH 9.6:
B22	40-60 cm	Reddish yellow (5YR6/8); medium clay; moderate coarse prismatic structure; very firm consistence dry; pH 8.9; gradual change to:
B23k	60-160 cm	Reddish yellow (7.5YR6/6); light medium clay; moderate medium prismatic structure; strong consistence dry; contains many (20-30%) fine earth carbonate segregations, hard carbonate nodules and some ironstone fragments common (10-20%); pH 9.8; gradual change to:
B31	160 cm+	Reddish yellow (7.5YR6/6); medium heavy clay; strong medium prismatic structure (smooth-faced peds); strong consistence dry; contains a zone of soft manganese segregations at 160-165 cm; pH 6.8.

Soil Profile Characteristics:

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

¹ Strong dispersion after remoulding.

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	8.6	7.9	0.09		14.6	2.7	1.9	0.3	23	8	36	31	4	23
A2	10-20	8.4	7.9		<0.05	5.9	1.2	0.2	0.5	15	3
B21	20-40	9.6	8.6	0.34	<0.05	5.8	10.3	0.8	5.2	37	16	32	26	2	36
B22	40-60	8.9	7.6	0.08		6.8	5.4	0.5	2.2	28	12
B23k	60-160	9.8	8.9	0.92	0.12	2.6	8	0.9	9.1	38	16
B31	160+	6.8	6.4	1.38	0.25	3.4	8.7	0.8	5.7

Management Considerations:

General

• Management strategies for all soils should aim to increase organic matter levels in the surface soil; minimise the degradation of soil aggregates and porosity; promote the development of stable biopores; improve the calcium status of the cation exchange complex (particularly when sodium is a significant part), and break up any hardpans. Less frequent tillage, using less aggressive implements, and working the soil at optimum moisture content can all assist in maintaining soil aggregation and porosity as well as reducing the breakdown of organic matter.

Surface (A) Horizons

• The upper surface soil is strongly alkaline which indicates that phosphorus and some trace elements (e.g. iron, manganese, copper and zinc) may be poorly available to plants.
  
  
• The hardsetting surface horizon requires organic matter for maintaining soil aggregation.

Subsoil (B) Horizons

• The strongly sodic and dispersive subsoil is coarsely structured and likely to significantly restrict root and water movement down the profile.
  
  
• A medium to high level of soluble salts occur from 80 cm in the soil profile and is likely to affect the growth of salt-sensitive species (e.g. lucerne, faba beans and linseed).
  
  
• The subsoil is extremely alkaline which indicates that phosphorus and some trace elements (e.g. iron, manganese, copper and zinc) may be poorly available to plants.

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

Page Top