LP89

LP89 Landscape

Soil Profile Morphology

Surface Soil

A1	0-10 cm	Dark reddish brown (5YR3/3); fine sandy clay loam; hardsetting surface condition; moderate blocky structure; firm consistence dry; pH 5.8; sharp change to:	LP89 Profile
Subsoil
B1	10-20 cm	Yellowish red (5YR4/6); heavy clay loam (fine sandy); weak coarse blocky structure; very strong consistence dry; pH 7.4; clear change to:
B21	20-35 cm	Yellowish red (5YR4/6); medium clay; moderate blocky structure (with smooth faced peds); strong consistence dry; pH 8.1; clear change to:
B22	35-50 cm	Strong brown (7.5YR5/6) and yellowish red (5YR5/8); medium heavy clay; weakly structured; very strong consistence dry; pH 8.7; clear change to:
B23	50-70 cm	Strong brown (7.5YR5/6); medium heavy clay; weakly structured; very strong consistence dry; pH 9.2; gradual change to:
B24k	70-100 cm	Yellowish brown (10YR5/6) with yellowish red (5YR5/8) in tubules; heavy clay; moderate coarse prismatic, parting to strong polyhedral structure; very strong consistence dry; contains a few (5%) soft and hard carbonates; pH 9.3.

• Strong texture contrast between surface (A1) horizon and subsoil (B1) horizon.
• Sodic subsoil.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	moderately acid	low	non-sodic	none1
Subsoil (B21 horizon)	moderately alkaline	low	sodic	strong
Deeper subsoil (at 70+ cm)	very strongly alkaline	low-medium	strongly sodic	strong
1 Slight slaking only.

Horizon	Horizon Depth	pH (water)	pH CaCl2	EC 1:5	NaCl	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-10	5.8	5.2	0.19		7.3	0.7	0.7	<0.1
B1	10-20	7.4	6.3	0.13		5.8	4.3	0.9	9
B21	20-35	8.1	6.9	0.19		7.8	8.5	1.4	12
B22	35-50	8.7	7.6	0.29	<0.05	7.8	11	1.8	18
B23	50-70	.2	8.1	0.37	<0.05	6.7	12	1.9	22
B24k	70+	9.3	8.4	0.69	<0.05	4.9	13	1.9	29

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			20.6	7.4	13	44	24	20
B1	10-20			22.4	12.7	10	34	15	41
B21	20-35			34.6	20	4	23	12	60
B22	35-50			40.1	23.3	4	16	11	68
B23	50-70			41.1	23
B24k	70+

Management Considerations:

Whole Profile

• Plant Available Water Capacity (PAWC) is considered to be medium (estimated at approximately 120 mm) for this site. This is based on available laboratory data and assumes an effective rooting depth of 70 cm. Rooting depth will be limited by the strongly sodic deeper subsoil. However, lucerne roots were evident at 1 m depth in this profile.

• Organic matter levels are relatively high. This is a good result as organic matter assists in maintaining soil structure as well as enhancing soil fertility and water holding capacity. This is important on soils such as this with high fine sand (44%) contents. High organic matter levels will assist in minimising structural problems, such as surface sealing (by reducing slaking) and hardsetting. This will lead to improved water infiltration and seedling emergence. Organic matter levels can be maintained and improved by practises such as minimal tillage, stubble retention and pasture rotations. Signs of reasonable topsoil structural condition at this site include the moderate structure and minimal slaking in water.
• The surface soil has a moderate overall nutrient status.

• The upper subsoil (B1) horizon disperses slightly in water and strongly after remoulding. If this horizon is excessively disturbed by cultivation when moist, it may develop into a cultivation pan.
• The deeper subsoil (from a 35 cm depth) is strongly sodic and has a low calcium:magnesium ratio (i.e. <1). As a consequence, it disperses strongly in water. This is likely to result in water and root movement being significantly restricted.
• The deeper subsoil (from 50 cm depth) is very strongly alkaline which indicates that some nutrients (e.g. phosphorus, iron, manganese, and zinc) may be poorly available to plants.
• The salinity rating increases to between low and medium at 70 cm. However, chloride salts seem to be quite low and are not likely to restrict the growth of most plants.

• Cultivated once or twice in last seven years.
• Variable paddock (crabholes and black banks occur further east).
• Stubble retention.
• Wheat has yielded well.

• Profile described by Mark Imhof, Paul Rampant and Karen De Plater (5/7/95)