LP38

Site LP38 Landscape

Soil Profile Morphology

Surface Soil

A1	0-5 cm	Brown (7.5YR4/4); sandy clay loam; weakly structured; hardsetting surface condition; firm consistence dry; contains many (25%) siltstone fragments and a few (5%) quartz fragments; pH 5.1; clear change to:	Site LP38 Profile
A2	5-25 cm	Yellowish red (5YR5/6) conspicuously bleached; light fine sandy clay loam; structureless; strong consistence dry; contains a common (15%) amount of siltstone and few (10%) quartz gravels; strong consistence dry; pH 4.9; clear and wavy change to:
Subsoil
B21	25-45 cm	Yellowish red (5YR5/6); fine sandy clay loam; weak medium blocky structure; very strong consistence dry; contains few (10%) siltstone and very few (1%) quartz fragments; pH 5.3; wavy change to:
B22	45-55 cm	Yellowish red (5YR5/6); fine sandy clay loam; moderate medium blocky structure; strong consistence dry; pH 6.0; wavy change to:
C	55 cm +	Weathering siltstone material; contains a 1 cm thick layer of yellowish red clay at 65 cm depth.

• Lack of strong texture contrast between surface (A) horizons and subsoil (B) horizons.
  

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	strongly acid	very low	non-sodic	none
Subsoil (25-45 horizon)	strongly acid	low-medium	non-sodic	moderate
Deeper subsoil (45-55 cm)	moderately acid	medium	sodic	strong

Horizon	Horizon Depth	pH (water)	pH CaCl2	EC 1:5	NaCl	Exchangeable Cations
						Ca	Mg	K	Na
						Meq/100g
A1	0-5	5.1	4.3	0.17		1.1	1.4	0.7	0.3
A2	5-25	4.9	4.3	0.31		0.3	1.9	0.4	0.2
B21	25-45	5.3	4.7	0.43		1	3.4	0.3	0.4
B22	45-55	6	5.4	0.55		0.1	3.7	0.3	0.7
C	55

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	0-5	66	15.8	27.1	11.5
A2	5-25	51	7.6	22.5	10.2
B21	25-45	11	5.8	26.6	11.9	3.1	32	43	23
B22	45-55					3.3	34.6	37.5	24.5
C	55

• The surface soil is strongly acid. Aluminium becomes more soluble in soils at low pH levels. The level of exchangeable aluminium measured in the laboratory for this pit site I s reasonably high (i.e. > 50 ug/g) may restrict the growth of highly aluminium sensitive species.
• Deficiencies in the trace element molybdenum (Mo) are likely to occur in strongly acid soil. Soil adsorption of Mo increases as pH decreases, leading to reduced availability to plants. Deficiencies in other nutrients (e.g. potassium, phosphorus and calcium) may also occur.
• The surface horizons have a very low inherent fertility (based on the sum of the basic exchangeable cations).

• The subsoil also has a low inherent fertility (based on the sum of the exchangeable basic cations).
• The subsoil has a high percentage of exchangeable magnesium in relation to other cations. Nutrient imbalances may occur as a result (e.g. calcium deficiency).

• Profile described by Mark Imhof, Paul Rampant and Karen De Plater (21/3/95).