GL41

Site: GL41	Land Unit: Nelson Plains and Dunes
*Aust. Soil Class.:* Haplic, Petrocalcic, Red CHROMOSOL(high free iron) (confidence level 2)

Soil pit GL41 auger

General Land Unit Description:
This land unit occurs in the south western corner of the region. The land unit is generally composed of siliceous sand dunes and plains over calcareous material. The partly consolidated calcareous deposits were formed in an arcuate band (north west / south east trending) formed by the retreat of the Murray Sea. The siliceous dune and sand sheet material is generally of aeolian origin. Although there is a large area of this land unit in the south west of the study area there are also some isolated patches, mainly mixed amongst the Follet land unit that could not be mapped due to restrictions of scale.

The sand varies from orange (GL48), to red (GL39) to a paler colour. The orange and red sands are usually associated with the calcareous material, whereas the paler sands tend to have less carbonate (e.g. GL51, GL38) or the calcareous material is greater than 2 metres deep (e.g. GL50). Another soil variant occurs on the swales in between the dunes. This soil tends to have a heavier textured subsoil which may or may not have calcareous material underneath.

This site is characterised by a strong texture contrast (Chromosol) but it also has a high level of free iron in the subsoil, which is it’s most distinguishing feature. This soil typically occurs on the lower dunes and slopes of some of the dunes. This soil tends to have a heavier textured subsoil compared to the Tenosols and Rudosol, and may or may not have limestone underneath. This soil type has been mapped as the Follet Dunes and Rises land unit, possibly due to the deep sandy topsoil, although due to the limestone at depth, it sits better in the Nelson Dunes and Plains land unit. It is not clear what the origin of the subsoil is, although it is likely that it may be of basalt origin, since high free iron is often associated with this geology. This soil type is similar to site GL42, GL43 and GL80 and they tend to have a higher capability of supporting a range of land uses (e.g. Viticulture), due to their favourable physical and chemical properties.

Site Description:

Slope: 7%	Geology: Quaternary limestone
Landform pattern: Level to gently undulating plain	Position in landscape: Upper slope
Internal drainage: Moderately well drained

Soil Profile Morphology

A11	0-25 cm	Very dark greyish brown (10YR3/2) hydrophobic sand, apedal (single grained), pH 6.7, Gradual transition to:
A12	25-70 cm	Strong brown (7.5YR4/6) sand, apedal (single grained), many large faint yellow mottles and some organic staining; pH 7.3. Clear transition to:
	Subsoil
B2	70-130 cm	Red (2.5YR4/6) light clay, weak polyhedral structure, (5-10 mm), very firm consistence when dry; pH 6.5. Gradual transition to:
B31	130-170 cm	Yellowish red (5YR4/6) heavy fine sandy clay loam, weak structure, firm consistence when dry; pH 6.4. Gradual transition to:
B32	170-190 cm	Yellowish red (5YR4/6) fine sandy clay loam, weak structure, firm consistence when dry, manganese flecks are common. Clear transition to:
C	190+ cm	Limestone

Key profile features:

Deep sandy topsoil
Hydrophobic topsoil
Strong texture contrast between topsoil and subsoil
Limestone at depth

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