LP57

LP57 Landscape

Soil Profile Morphology

Surface Soil

A1	0-10 cm	Strong brown (7.5YR4/6); fine sandy clay loam; hardsetting surface with 1-2 mm wide cracks extending into the B horizon; weak coarse blocky structure; firm consistence moist; pH 6.4; clear change to:	LP57 Profile
Subsoil
B21	10-30 cm	Reddish brown (5YR4/4); light medium clay; strong medium polyhedral structure; very strong consistence dry; pH 7.6; gradual change to:
B22	30-60 cm	Yellowish red (5YR5/6); light medium clay; strong coarse blocky structure; very strong consistence dry; contains a few (5%) fine-earth carbonates and a very few (1%) hard calcareous nodules, as well as a few (2-5%) fine gypsum crystals in the 50-60 cm zone; pH 8.5; gradual change to:
B23	60-80 cm	Strong brown (7.5YR5/6) and yellowish red (5YR4/6); heavy clay; strong coarse polyhedral structure; strong consistence dry; contains very few (2%) hard calcareous nodules; pH 8.0; gradual change to:
B24	80 cm+	Light yellowish brown (2.5Y6/4) and yellowish red (5YR5/8); light medium clay; strong medium polyhedral structure; strong consistence dry; pH 8.6.

• Strong texture contrast between surface horizon (clay content 26%) and subsoil (B21) horizon (clay content 56%).
• Hardsetting surface soil - with a high fine sand (46%) and silt (27%) content.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	slightly acid	low	marginally sodic	none1
Subsoil (B21 horizon)	slightly alkaline	low	strongly sodic	strong
Deeper subsoil (at 1 m)	strongly alkaline	medium - high	strongly sodic	strong
1 Complete dispersion with remoulding.

Horizon	Horizon Depth	pH (water)	EC 1:5	NaCl	Exchangeable Cations
					Ca	Mg	K	Na
					meq/100g
A1	0-10	6.4	0.18		3.2	3.6	0.6	0.5
B21	10-30	7.6	0.19		4.8	7.5	0.9	3.2
B22	30-60	8.5	0.99	0.16	5.7	11	0.9	6.8
B23	60-80	8	3.68	0.2	6.8	10	0.8	8
B24	80+	8.6	1.12	0.17	3.7	9.1	0.6	6.7

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			24.2	8.7	1	46	27	26
B21	10-30			32.4	18.5	1	26	18	56
B22	30-60
B23	60-80
B24	80+

• 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 – i.e. sodic), 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. Practices such as residue retention, minimum tillage and including pasture rotations could be utilised if cropping takes place in order to build up organic matter, reduce erosion risk and increase fertility.
• Plant available water capacity (PAWC) is estimated to be low (estimated at 65 mm) for this profile - based on the laboratory data available. Effective rooting depth will be limited by the strongly sodic.

• The surface soil has a low overall nutrient status (based on the sum of the exchangeable basic cations).
• The surface horizon is hardsetting when dry and has a high fine sand and silt content. Upon wetting and drying, the surface sets hard and may become "powdery" when worked in a dry condition. Tillage should be minimised and stubble retention/pasture rotations practised to build up organic matter.
• The organic carbon level is moderate for the surface soil. Soils such as those with high fine sand and silt levels depend on organic matter for monitoring structure. Improving soil organic matter levels will assist in minimising structural problems such as surface sealing and hardsetting as well as improving soil fertility and water holding capacity.
• The surface horizon is maginally sodic and disperses completely after remoulding. This indicates that excessive cultivation or over stocking of the soil in a wet condition may result in dispersion and surface sealing. Gypsum is usually an effective ameliorant on such soils.

• The coarsely structured subsoil is strongly sodic (together with a low calcium to magnesium ratio) and disperses strongly in water. This is likely to result in restricted water and root movement through the profile.
• The salinity rating becomes medium at a 30 cm depth in the profile. This may restrict the growth of salt sensitive species (e.g. maize and many legumes).