Site WP3

Location: Morton Plains.

Australian Soil Classification: Calcic, Mesonatric, Red SODOSOL.
Northcote Factual Key: Dy 2.13.
Great Soil Group: red-brown earth.

General Landscape Description: Upper slope of a rise on a gently undulating plain.

Site WP3 Landscape

Soil Profile Morphology:

Surface Soil

A1	0-15 cm	Strong brown (7.5YR4/6); light sandy loam; hardsetting and massive; firm consistence dry; pH 6.6; sharp change to:	Site WP3 Profile
Subsoil
B21	15-30 cm	Yellowish red (5YR5/6); light medium clay (sandy); moderate prismatic structure (shiny faced peds); weak consistence; moderately moist; pH 8.5; gradual change to:
B22	30-70 cm	Yellowish red (5YR5/6); medium clay; strong prismatic structure; firm consistence moderately moist; pH 9.2; clear change to:
B3k	70 -160 cm	Strong brown (7.5YR5/8); medium clay, sandy; prismatic structure; strong consistence dry; soft carbonate common (10-20%); pH 9.6.

Soil Profile Characteristics:

	pH	Salinity	Sodicity	Dispersion
Surface (A1 horizon)	slightly acid	very low	non-sodic	-
Subsoil (B21 horizon)	moderately alkaline	very low	strongly sodic	strong
Deeper subsoil (at 1 m)	extremely alkaline	high	very strongly sodic	slight1

¹ Due to high levels of soluble salts.

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl2)	EC ds/m	Exchangeable Cations				NaCl %	Field Capacity pF 2.5	Wilting Point pF 4.2
					Ca	Mg	K	Na
					meq/100g
A1	0-15	6.6	5.8	0.3	2.1	0.7	0.3	<0.1		2	5
B21	15-30	8.5	7.2	0.1	5.7	5.4	0.7	2.3		28	12
B22	30-70	9.2	8.5	0.84	5.2	8.2	1.2	5.3	0.14	33	15
B3k	70-160	9.6	8.9	0.94	3.2	8.0	1.4	7.3	0.15

Management Considerations:

• 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) 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. The organic carbon level measured at this pit site is quite low.
  
  
• The surface soil has a low inherent nutrient status which can be improved by increasing organic matter levels.
  
  
• The water holding capacity of the surface soil is low. However, the low wilting point (5) value indicates that plants will be able to utilise light rains when the soil is relatively dry.
  

Subsoil (B) Horizons

• The upper subsoil is moderately alkaline (becoming very strongly alkaline with depth). This indicates that certain nutrients such as iron, manganese, zinc and boron may be poorly available to plants.
  
  
• The upper subsoil is strongly sodic and dispersive. This will result in root and water movement being significantly restricted. Sodic subsoils can also create adverse nutrient balances and may even have toxic effects on some plants.
  
  
• The level of soluble salts becomes high in the deeper subsoil (below 30 cm depth). This is likely to restrict the growth of salt-sensitive species.

Profile Described By: Mark Imhof and John Martin (24/1/1993).

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