LP12

Lp12 Landscape

Soil Profile Morphology

Surface Soil

A1	0-10 cm	Dark greyish brown (10YR4/2); medium heavy clay; surface cracking; strong coarse blocky structure; strong consistence dry; contains a few (5%) quartz gravels; pH 6.5; sharp and smooth change to:	Lp12 Profile
Subsoil
B21	10-55 cm	Very dark grey (10YR3/1); heavy clay; strong very coarse blocky, parting to strong medium to coarse blocky structure; very strong consistence dry; many (15-20%) rounded quartz fragments; pH 7.8:
B3k	55-90 cm	Light brownish grey (2.5Y6/2); heavy clay; moderate coarse prismatic, parting to strong coarse blocky structure; very strong consistence dry; contains many (>20%) amount soft carbonates and some dark (manganese) segregations as well as many quartz fragments; pH 9.0; irregular and sharp change to:
C	90-130 cm	Weathered and non-weathered olivine basalt:
2B2	130-135 cm	Light brownish grey (2.5Y6/2); heavy clay; strong coarse polyhedral structure; very strong consistence dry
2C	135+ cm	Weathered olivine basalt.

• Clay texture throughout profile.
• Surface cracking.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	slightly acid	very low	non-sodic	none
Subsoil (B21 horizon)	slightly alkaline	very low	non-sodic	none
Deeper subsoil (at 75 cm)	strongly alkaline	very low	sodic	_

Horizon	Horizon Depth	pH (water)	pH CaCl2	EC 1:5	NaCl	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-10	6.5	5.4	0.05		13.8	7.2	0.8	0.2
B21	10-55	7.8	6.7	0.07		20.4	14.6	0.8	1.4
B3k	55-90	9	8.1	0.24		13.5	16.8	0.6	1.5

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			32.8	21.2	7	29	18	43
B21	10-55			43.5	30.2
B3k	55-90

• Moderate gravel content near surface may interfere with cultivation.
• The clay surface horizon has a high overall nutrient status. Organic carbon and total nitrogen levels are reasonable.
• The surface will be slowly permeable.
• The relatively high wilting point (21%) indicates that plants will not be able to fully utilise light rains falling on relatively dry soils as there will be insufficient moisture to wet the soil above the wilting point. This may result in moisture stress to plants in a dry spring.
• Excessive cultivation, trafficking or overstocking of cracking clay soils when moist to wet, can result in compaction below the soil surface and result in structural decline. Such soils are best cultivated when they are dry (ie. drier than the plastic limit) throughout the cultivation depth.

• The subsoil has a very high overall nutrient status.
• The upper subsoil is non-sodic but is coarsely structured which will restrict movement of finer roots down the profile.
• The deeper subsoil (from 55 cm depth) is strongly alkaline which may limit the availability of certain plant nutrients (eg. phosphorous, iron, manganese and zinc). The deeper subsoil is also sodic which may result in restricted root and water movement below 55 cm depth.

• Profile described by John Martin and Mark Imhof (22/4/94)