Rutherglen Loam

Rutherglen Loam is the main soil type across the Institute. The soil has a gradual texture and colour boundary between the surface (A) and subsoil (B) horizons, and a subsoil clay ranging from brown or yellowish brown, to yellow and grey mottled colours.

Typical landscape associated with the Rutherglen Loam mapping unit.

Three phases have been recognised within the Rutherglen Loam:

Brown Phase. The Brown Phase has subsoil clay less than 25 cm from the surface. It has a brown or yellowish brown colour in the upper parts of the profile and usually doesn't have a bleached subsurface (A2) horizon.

Normal Phase. The Normal Phase has the subsoil clay between 25 to 40 cm from the surface. It also has a weak to moderately bleached A2 horizon with yellow subsoil clay.

Deep Phase. The Deep or bleached phase has the subsoil clay commonly deeper that 40 cm. This phase also has a moderate or strongly bleached A2 horizon and a yellow and grey mottled, or yellowish subsoil clay. It also usually contains more ferruginous concretions than the other two, and the boundary between the A and B horizons may be sharper.

Rutherglen Loam (Brown Phase) Typical Profile.

Surface
A	0-10 cm	Dark greyish brown to dull brown loam with occasional slight buckshot; 7 to 12 cm thick; clear boundary with:
AB	10-25 cm	Dull brown or dull yellowish brown diffusely mottled loam, or loam increasing to clay-loam; bleaching if present, is only evident in the dry profile; slight fine buckshot irregularly present; at depths varying from 17 to 25 cm grading into:
Subsoil
B1	25-42 cm	Brown (7.5YR 5/8) to yellow-brown diffusely mottled clay (light); very friable when moist; usually some small scattered buckshot; 12 to 22 cm thick; grading into:
B21	42-75 cm	A friable clay as above; generally somewhat heavier, and with varying amounts of red-brown and sometimes brownish grey mottling; sharply separated from:
B22	75-120 cm	Grey and yellow-brown mottled clay as in the normal phase.

Soil Pit Site NE39 is an example of a Rutherglen Loam (Brown Phase) profile.

Rutherglen Loam (Normal Phase) Typical Profile.

Surface
A1	0-25 cm	Dark brownish grey to greyish brown (10YR, value range 4-5, chroma range 2-4) loam sometimes with fine rusty root channel mottling; a trace of (fine) buckshot irregularly present; 10 to 25 cm thick; grading into:
Subsoil
B21	25-75 cm	Yellow-brown or brownish yellow diffusely mottled clay with a "yellow" colour cast when crushed, with light yellowish grey, grey, brownish grey or red-brown variously present in the lower parts of the horizon; friable when moist; scattered to light buckshot irregularly present; sharply separated from:
B22	75-120 cm	Mottled grey and brown dense clay (heavy); usually markedly less friable than the horizon above and sometime intractable when moist; soft black inclusions occur in varying amounts near the horizon boundary and decrease with depth; slight calcium carbonate irregularly present.

Soil Pit Site NE41 is an example of a Rutherglen Loam (Normal Phase)

Rutherglen Loam (Deep Phase) Typical Profile.

Surface
A1	0-15 cm	Grey-brown or dark grey-brown (10YR 4-5/3) loam; often with slight buckshot; 10 to 17 cm thick; separated by a clear boundary from:
A2	15-42 cm	Light brownish grey (10YR 6/2-7/3) diffusely mottled loam or very fine sandy loam; sometimes increasing to clay-loam or fine sandy clay-loam near the horizon boundary; moderately or strongly bleached when dry; light to moderate buckshot, mostly just above the clay; grading into:
Subsoil
B21	42-80 cm	Grey and yellowish brown or yellow-brown, mottled clay, with a "yellowish" colour-cast when crushed; crumbly when moist; slight buckshot irregularly present; sharply separated from:
B22	80-120 cm	Grey and brown, or brownish yellow and grey mottled dense clay as in the normal phase.

Soil Pit Site NE33 is an example of a Rutherglen Loam (Deep Phase) profile.

Variations

Small light grey mottled pockets up to 5 cm across are found irregularly in the deep subsoil at the boundary between the last two horizons. They appear to form a discontinuous thin horizon.

The subsoil clay of Rutherglen Loam in all three phases extends down to depths varying from 70 to 90 cm, and rests abruptly on the underlying layer in most instances.

Although the A horizon of the deep phase is typically deeper than 40 cm, profiles with grey and yellow mottles, or yellowish subsoil as shallow as 30 cm have been included in the phase.

Occurrence

The three phases of Rutherglen Loam form a slope sequence or spectrum within the soil type, with the Brown Phase occurring in higher situations on the plain. The Normal Phase, which is found associated with both Brown and Deep Phases, occurs principally on level and intermediate positions. The Deep Phase is confined to some slightly lower parts of the plain. Differences between the phases are only broadly related to surface features, and accordingly the boundaries drawn to separate them on the map are approximate only.

In addition, the Brown and Normal Phases are associated with soil Type A and Type D in areas mapped into Unit 1. Elsewhere on lower parts of the plain, the Deep and Normal Phases are major components, together with Lilliput Loam and Types D and Type E, of the complex or micro-association of soil types grouped into Unit 2.

Relationship to Other Soil Types

Rutherglen Loam merges into Type A and Type D in some instances, and into Black Dog Fine Sandy Loam and Lilliput Loam in other. These soil types can be regarded as an extension of the slope sequence, with Types A and D the higher members, and Black Dog Fine Sandy Loam and Lilliput Loam the lower components. Rutherglen Loam is distinguished from these and other soil types on the plain by its gradual, instead of sharp boundary between the A and B horizons. Type A differs also in having red clay in the subsoil. Type D has yellow clay like the Brown Phase of Rutherglen Loam. However, in Type D this clay is 20 cm or less from the surface.

The Deep Phase shares in many instances a strongly bleached horizon with Black Dog Fine Sandy Loam and Lilliput Loam. However, in the deep phase of Rutherglen Loam, the A2 horizon (even where it is strongly bleached) always has a distinct brownish color when moist. Whereas in Black Dog Fine Sandy Loam and Lilliput Loam, the grey color of the bleached horizon persists, or is only faintly tinged with brown in the moistened material. Black Dog Fine Sandy Loam also contains markedly more fine sand in the A2 horizon.

Stillards Loam is generally similar to Rutherglen Loam in its profile features, and it can be regarded as the hillside equivalent of the latter.

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