Territory Stories

Land Resources of Auvergne Station



Land Resources of Auvergne Station

Other title

A supplement to the Land Resources of the Victoria River District


Napier, Diane; Edmeades, Bart; Lynch, Brian; McGregor, Robert; Northern Territory. Department of Environment and Natural Resources


Hill, J.V.


E-Publications; E-Books; PublicationNT; Jul-18




Auvergne Station; NT Portion 2676; Victoria River Downs; Victoria River District


This report for Auvergne Station is a supplement to Land Resources of the Victoria River District (2012) and completes the land resource assessment of the district which covers 24 properties and approximately 78 760 km² of pastoral land. Land unit mapping at 1:100 000 describes the landforms, soils and vegetation in the district.


Made available via the Publications (Legal Deposit) Act 2004 (NT)

Table of contents

Table of contents; 1. Introduction; 2. Previous mapping; 3. Survey methodology and data collection; 4. Lithology; 5. Landform; 6. Soil; 7. Soil physical and chemical characteristics; 8. Vegetation; 9. Land evaluation; 10. Soil erosion; 11. Land unit descriptions; 12. References; Appendices 1 - 12.




Soils -- Northern Territory -- Auvergne Station; Land use -- Northern Territory -- Auvergne Station; Geology -- Northern Territory -- Auvergne Station; land resource assessment; land units; soil landscapes; vegetation communities

Publisher name

Northern Territory Government

Place of publication





204 pages ; colour photographs, maps, figures, tables ; 30 cm.

File type





Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government



Related links

http://www.ntlis.nt.gov.au/metadata/export_data?type=html&metadata_id=E3F20A909A8123ADE040CD9B21446CC0; http://hdl.handle.net/10070/245323 [Land resources of the Victoria River District]

Parent handle


Citation address


Page content

Land Resources of Auvergne Station A supplement to the Land Resources of the Victoria River District 33 Sodicity Sodicity is a condition in soils that causes dispersion of the clay fraction, restricts water entry, reduces permeability and causes elevated erosion risk when exposed. A soil with an exchangeable sodium percentage (ESP) greater than 6 is regarded as being a sodic soil in Australia (Northcote and Skene 1972). Sodicity is measured as the (ESP) and is calculated as exchangeable sodium over cation exchange capacity (Na/CEC), expressed as a percentage. It has a significant effect on the physical properties of a soil. The threshold above which ESP affects soil physical properties cannot be defined precisely because many factors influence this relationship. In general, soil ESP >6 in the surface soils and >15 in subsoils are considered sodic and potentially dispersive (see Table 7.7). When ESP values are 6-15 and the Mg/Ca ratio >1, then there is a greater susceptibility to dispersion (Baker and Eldershaw 1993). Sodicity directly influences surface structure, water movement and erosion risk. High sodicity levels in the topsoil can lead to impermeability, surface crusting and poor aeration (Baker and Eldershaw 1993). Where ESP levels >20 are present in subsoils, problems with poor soil structure, high soil strength and very slow permeability limit root growth and plant productivity. It can also create tunnel erosion that eventually collapse to form gullies (Australia Academy of Science 2017). Although sodic soils can occur naturally they are often exacerbated by land management. On Auvergne gully erosion and deep tunnelling is evident along some fence lines or tracks in the flat or gently undulating colluvial landscapes dominated by Melaleuca minutifolia communities (6c8A) (Figure 7.5) or the broad drainage areas with Melaleuca viridiflora (6c13A) (Figure 7.6). These soils are extremely sodic below 0.5 cm. The risk is minimised by maintaining a good grass cover particularly late in the Dry season and not creating windrows when grading or maintaining tracks. Table 7.8 provides ESP and sodicity ratings for all sampled soils in the survey area. Figure 7.5 Land unit 6c8A: Erosion along a fenceline and old track.

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