LP59

LP59 Landscape

Soil Profile Morphology

Surface Soil

A1	0-10 cm	Dark greyish brown (10YR4/2); medium clay; surface flake and surface cracking (with some cracks extending to 1 metre depth); self-mulching surface layer; moderate coarse blocky structure; firm consistence dry; pH 6.3; abrupt change to:	LP59 Profile
A2	10-20 cm	Dark grey (10YR4/1) sporadically bleached; light medium clay; moderate coarse platy structure; strong consistence dry; pH 6.1; clear change to:
Subsoil
B21	20-60 cm	Grey (10YR5/1); light clay; moderate coarse blocky, parting to strong medium polyhedral structure; very strong consistence dry; contains very few (2%) calcareous nodules; pH 8.3; gradual change to:
B22	60-100 cm	Grey (10YR6/1); medium clay; strong medium polyhedral structure; very strong consistence dry; contains very few (3%) calcareous nodules; pH 9.1; gradual change to:
B23	100 cm+	Light brownish grey (10YR6/2) with diffuse brownish yellow (10YR6/6) mottles; medium clay; strong medium to coarse polyhedral structure; very strong consistence dry; pH 9.3.
NOTE: This soil corresponds partly to Kinypanial Friable Clay as described by Skene (1971).

• Clay surface horizon (clay content 58%) which is self-mulching and cracks when dry.
• Clay texture throughout the profile.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	slightly acid	low	non-sodic	very slight1
Subsoil (B21 horizon)	moderately alkaline	very low	sodic	complete
Deeper subsoil (at 1 m)	very strongly alkaline	low	strongly sodic	complete
1 Strong dispersion after remoulding

Horizon	Horizon Depth	pH (water)	EC 1:5	NaCl	Exchangeable Cations
					Ca	Mg	K	Na
					meq/100g
A1	0-10	6.3	0.21		12	5.7	0.1	1
A2	10-20	6.1	0.11		12	5.5	0.2	1
21	20-60	8.3	0.12		11	6.2	1.5	8
B22	60-100	9.1	0.44	0.06	7.1	10	5	21
B23	100+	9.3	0.31	0.11	4.3	10	7.4	32

Horizon	Horizon Depth	Ex Al mg/kg	Ex Ac meq/100g	Field pF2.5	Wilting Point pF4.2	Coarse Sand (0.2-2.0mm)	Fine Sand (0.02-0.2mm)	Silt (0.002-0.02mm)	Clay (<0.002mm)
A1	0-10			32.4	18.7	2	18	20	58
A2	10-20			33.3	17.6
21	20-60			35.7	20.3
B22	60-100
B23	100+

• In 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 ion 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 conditions can all assist in maintaining soil aggregation and porosity as well as reducing the breakdown of organic matter.

• The surface horizon is non-sodic but does disperse when remoulded. This indicates that the soil may disperse when excessively cultivated or over-stocked when wet. This may result in surface sealing. Cracking clay soils such as these are best cultivated when they are dry throughout the cultivation depth. Maintaining surface cover is also important to prevent disruption caused by raindrop action. Gypsum may be an effective ameliorant for such soils – and a gypsum responsiveness test is best performed for the paddock to better guage gyspum requirement.
• The development of platy structure in the subsurface (A2) horizon indicates that the soil has been compacted when in a moist to wet condition.
• The relatively high wilting point (19%) for the surface soil means that plants will not be able to fully utilise light rains falling on relatively dry soil as there will be insufficient moisture to wet the soil above the wilting point value. This will limit growth in a dry spring.
• The overall inherent fertility (based on the sum of the exchangeable cations) is high for the surface horizons.

• The coarsely structured subsoil is sodic and completely disperses in water. This is likely to result in restricted water and root movement through the profile.
• The subsoil profile becomes very strongly alkaline from about 60 cm depth. This indicates that phosphorus and some trace elements such as iron, manganese, zinc and copper may be poorly available to plants and deficiencies may occur. Deficiencies can be determined by plant tissue analysis. Boron toxicity can also occur in strongly alkaline soils.

• Was "crabholey" country prior to clearing.
• Lucerne and barley have been grown.
• Good barley country.
• Roots have been noted to 1 metre.
• Gypsum (2.5 t/ha) has been applied.