Sodium Toxicity (depth to toxic layer)

Dataset Number1071
Dataset TitleSodium Toxicity (depth to toxic layer)
CustodianData Authority: Department for Environment and Water
Data Provider: Department for Environment and Water


DescriptionMany soils in the drier parts of southern South Australia have very high levels of deep subsoil sodicity (ie exchangeable sodium percentages (ESP) exceeding 25), generally at depths of between 50 and 100 cm, sometimes shallower. These conditions are invariably associated with high pH, moderate salinity and often high boron concentrations, all of which are natural features of these soils. They are not necessarily associated with poor soil structure. There is some evidence to suggest that these high levels of sodicity are toxic to some plants, particularly horticultural species. If there are toxic effects, it is reasonable to assume that in some years, the sodicity is preventing optimum water use efficiency, and could therefore be contributing to rising watertables. In practice, neither gypsum nor any other ameliorant will have any significant effect on these soils, due to the very high rates required and the difficulty of incorporation to the required depth. The use of plants with sodium tolerance is one solution. This implies cultivar selection focussed on sodium tolerance or the use of naturally occurring plants with sodium tolerance.Estimates of ESP are based on extrapolation of laboratory analyses between similar soil materials and soils. Five (plus not applicable) estimated Depth to Sodium Toxicity analysis data classes have been supplied, as percentage values of Soil Landscape Map Units to be used for the calculation of spatial data statistics. Note: the sum of all percentage values for each map unit totals 100%. Five (plus not applicable) legend categories (TOX_NA_D) have been determined by rating the most severely affected landscape component, provided it occupies at least 30% of the area of the Soil Landscape Map Unit.
UsageLink to Soil Attribute Descriptions. This dataset has been derived from the Soil Landscape Map Units spatial dataset to be used for map creation or the calculation of spatial data statistics. Used to supply Government, community groups, industry and the general public with up to date regional, subregional and catchment level land and soil attribute information for southern South Australia. The aim is to produce maps, statistics and reports displaying and describing: Land and soil attributes within southern South AustraliaSELECT 1 FROM DUAL; Land surface features affecting land use, land management and productivitySELECT 1 FROM DUAL; Limitations / suitability of land and soil for a range of agricultural and other uses. Independent professional advice should be sought before using this in commercial decisions. Further information: soil and land attributes. Sodium Toxicity (depth to toxic layer) dataset can be viewed at NatureMaps (>Soils>Soil Chemistry Attributes). Spatial data downloads are available from Data SA.

Data Quality

LineageThe dataset is based on an interpretation of 1:40,000 stereo colour aerial photography and limited field inspection of landscapes and soils by soil scientists. Soil Landscape Map Unit boundaries were determined after an integration of field observations and recordingsSELECT 1 FROM DUAL; laboratory analysesSELECT 1 FROM DUAL; stereoscopic examination of aerial photographsSELECT 1 FROM DUAL; understanding of regional landscape processes and stratigraphySELECT 1 FROM DUAL; existing soil and geological mapping data. To avoid inconsistencies and confusion, any updates to the Soil and Land Attribute mapping are to be managed by DEWNR Soil and Land Program. This data has been released under a Creative Commons licence. Where products are derived from this data, DEWNR are to be acknowledged, and any changes to the original data should be indicated.
CompletenessComplete. The spatial data is subject to amendment as and when more data become available.
Positional AccuracyThe accuracy is to the scale of mapping (50 metres at 1:50,000 and 300 metres at 1:100,000 mapping scale). The spatial data is to be used at the regional, subregional and catchment level, and can be used to provide property overviewsSELECT 1 FROM DUAL; however, cannot be used at the paddock level. South East, Kangaroo Island, Mount Lofty Ranges and the 'bottom' of Yorke Peninsula have been mapped at 1:50,000. Eyre Peninsula, the main part of Yorke Peninsula, Murray Mallee and Northern Agricultural Districts have been mapped at 1:100,000. Map unit boundaries should be treated as transition zones.

Geographic Extent

Extent NameAgricultural Region - South Australia
Min Easting or Longitude132.25
Min Northing or Latitude-38
Max Easting or Longitude141
Max Northing or Latitude-32.25

Dataset Status

Initially Acquired01-JAN-2000
Last Updated01-JUL-2009
Update FrequencyAs required
Maintenance MethodAs required
LicenseingCC BY (Attribution)


TableNameField AliasData TypeDescription
Landscape.SALAD_Toxicity_Sodium_DepthLANSLU CharacterSoil Landscape Map Unit.
Landscape.SALAD_Toxicity_Sodium_DepthTOX_NA_D CharacterDepth to toxic layer (exchangeable sodium percentages (ESP) exceeding 25) (Legend category. See layer file for descriptions).
Landscape.SALAD_Toxicity_Sodium_DepthTNAD1 NumberPercentage of map unit which is not affected by sodium toxicity (or deeper than 100 cm).
Landscape.SALAD_Toxicity_Sodium_DepthTNAD2 NumberPercentage of map unit which has toxic sodium concentrations (ESP exceeding 25) at 50 - 100 cm depths.
Landscape.SALAD_Toxicity_Sodium_DepthTNAD3 NumberPercentage of map unit which has toxic sodium concentrations (ESP exceeding 25) at 25 - 50 cm depths.
Landscape.SALAD_Toxicity_Sodium_DepthTNAD4 NumberPercentage of map unit which has toxic sodium concentrations (ESP exceeding 25) at 10 - 25 cm depths.
Landscape.SALAD_Toxicity_Sodium_DepthTNAD5 NumberPercentage of map unit which has toxic sodium concentrations (ESP exceeding 25) at less than 10 cm depths.
Landscape.SALAD_Toxicity_Sodium_DepthTNADX NumberPercentage of map unit which is not applicable.

Contact Information

OrganisationDepartment for Environment and Water
Science Monitoring and Knowledge
Postal AddressGPO Box 1047