Site SW5

Site SW5 landscape

Soil Profile Morphology:

Surface Soil

A1	0-15 cm	Brown (10YR4/3); very fine sandy clay loam; weak to moderate medium blocky structure; weak consistence moist; contains few (2- 5%) ferromanganiferous nodules (2-4 mm size); pH 5.9; abrupt change to:	Site SW5 profile photo.
Subsoil
B21	15-25 cm	Yellowish red (5YR5/6); light clay (subplastic); moderate medium blocky structure; weak consistence moist; contains few (2-5%) ferromanganiferous nodules (2 -10 mm size); pH 6.0; clear change to:
B22	25-50 cm	Yellowish brown (10YR5/6) with strong brown (7.5YR5/6) mottles; light clay (subplastic); moderate medium blocky structure; weak consistence, moderately moist; contains a few (5%) ferromanganiferous concretions (2-10 mm size); pH 6.0; clear change to:
B23	50-75 cm	Yellowish brown (10YR5/6) with strong brown (7.5YR5/6) mottles; light medium clay (subplastic); strong coarse polyhedral, parting to fine polyhedral structure; pH 6.8:
B24	75-95cm	Yellowish brown (10YR5/6); light clay (subplastic); strong medium-coarse polyhedral, breaking to strong fine polyhedral structure; very firm consistence, moderately moist; ferruginous concretions (2 - 8 cm size) common (20%); pH 5.9:
B3	95 cm+	Light grey (2.5Y7/0) with brownish yellow (10YR6/6) mottles; light clay (subplastic); strong consistence dry; contains many (50%) ferruginous concretions (2-10 cm size); pH 5.6.

• Lack of strong texture contrast between surface (A) horizon and subsoil (B21) horizon.
• Deeply weathered late Tertiary clay horizon in deep subsoil.
  

The surface soil is moderately acid, as is the upper subsoil. The deeper subsoil (from 50 cm depth) becomes slightly acid. The deep subsoil is moderately acid.	The salinity rating is very low throughout most of the profile and becomes low in the deeper subsoil.
	There is no strong texture contrast at the A/B horizon boundary. The deeper subsoil has a very high clay content.

Horizon	Horizon Depth (cm)	pH (water)	pH CaCl2	EC 1:5	NaCl %	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-15	5.9	5.4	0.19		9.4	1.7	0.64	0.70
B21	15-25	6.0	5.7	0.22		5.4	1.3	0.33	0.47
B22	25-30	6	5.8	0.17		4.1	3.4	0.21	0.65
B23	50-75	6.8	6.3	0.16		3.1	6.0	0.20	0.87
B24	75-95	5.9	5.4	0.61	<0.05	3.5	5.2	0.15	0.84
B3	95+	5.6	4.9	0.32	<0.05	4.3	4.1	0.14	0.94

• Plant available water capacity (PAWC) is considered to be moderate (estimated at 120 mm) for the top metre of the soil profile. This is based on available laboratory data.

• The surface soil has a high organic matter content. Organic matter is important in terms of promoting aggregation of soils such as these with high fine sand and silt contents.
• The nutrient status of the surface soil is moderate (based on the sum of the exchangeable basic cations).

• The subplastic properties of the subsoil may lead to problems with sealing of earth dams. Sealing can be improved by compaction at the optimum water content and treatment with sodium tri-polyphosphate or addition of bentonite (Rolfe 1989).