Soils - Overview - NT

Northern Territory Land Resources Information

Background to the NT land resource assessment program

Land Resource surveys in northern Australia began after the Second World War and gained momentum in the early 1960s. The CSIRO initially carried out broad-scale land system surveys over much of Northern and Central Australia, primarily for the purpose of identifying land for agricultural development. The Commonwealth Department of the Interior, which at that time had administrative responsibility for the Northern Territory, began systematic surveys at a higher level of resolution than was provided by the CSIRO work. Areas such as the Daly Basin and the Coastal Plains were targeted, primarily to assess the potential for extensive agricultural development.

Currently, land resource survey and evaluation is a major function of the NT Department of Planning and Infrastructure, with support from the Commonwealth in some areas under the National Landcare Program.

The majority of land unit surveys at high-resolution have been undertaken where township development is proposed; in areas proposed for irrigation eg. in the Ord region, or are associated with mining activities or national parks or to describe the soils of research stations. Seventy five percent of these surveys include some soil profile descriptions. A few have been undertaken to assess the agricultural or horticultural potential of generally small areas. Some physical and chemical data are available for the latter surveys, although sometimes these data are restricted to pH and particle size analysis.

Land unit surveys at medium intensity are similarly located around Darwin, the Daly Basin west of Pine Creek, the Victoria River District, Katherine and Alice Springs. About half of these surveys are surveys of pastoral leasehold areas. The remainder have been undertaken to describe the land units or land resources of township areas, experimental stations, national parks, mining areas or localities where agricultural development is proposed. About three quarters of the surveys undertaken at this scale have associated profile descriptions and a third have some soil physical and chemical data, although these are often only pH and particle size analysis.

Approximately eighty percent of the NT has low intensity survey coverage, predominantly land system surveys or surveys of the pastoral resources of individual leasehold properties. Half of these surveys have associated profile descriptions and a third also have some physical or chemical data. The Territory is covered by surveys undertaken at a scale greater than or equal to 1:250,000. Most of these surveys give general descriptions of soils, a few have some profile descriptions.

The majority of the survey work conducted to date has been undertaken to establish the general nature of the land resource and its broad suitability for the major forms of land use. This work has supported the development of agriculture and extensive pastoral activities.

There are significant amounts of chemical and physical information held digitally in the NT in the NT in various formats. A project is underway to locate and migrate the data to a consistent format.

Map themes

Land systems:	Areas of land with a recurring pattern of topography, geology, soils and vegetation. Scales used for Land System mapping is between 1:250 000 and 1:1 000 000.
Land Units:	Areas of land with a limited range of soil types, landform and vegetation communities. Land Units are typically mapped at scales between 1:25 000 to 1:100 000 and have an area of 0.1 to 20 square kilometres.

Continuity and extent of data

The area of coverage is shown on the attached maps

(i) Map of Land Unit Coverage

(ii) Map of Land Systems coverage

Primary data

Currently there are approximately 7000 site records of profile, land surface and Vegetation descriptions. Several hundred of these are representative sites with data on profile morphology, and physical and chemical analyses.

Thematic data

Interpreted information is included in published reports. Further thematic information has been developed for the Greater Darwin Area, Daly Basin (including Katherine area) and Alice Springs environs. Attributes which are commonly used for land use planning applications include:

Soil classes (dominant and associated)
Surface texture
Waterlogging potential
Depth to hard rock / hard pan
pH
Salinity
Rockiness
Gravels
Flooding
Surface condition
Wind erosion potential
Water erosion potential
Salinity
Acid sulfate potential

Data format

The polygon data are in Arc Info format. Some historic maps and data are available in hard copy only.

Land capability maps

Thematic maps have been developed from land unit and land system data to show the location and extent of land resources capable of supporting a wide range of land uses. Land capability maps are used to determine development potential of land and to identify land management regimes for sustainable land use. Land capability themes commonly used include Pastoral use, Agricultural uses, Horticulture for a variety of crops, On-site effluent disposal, Irrigation.

Standard outputs

Land system / land unit maps and reports.
Attribute maps (individual attributes, or combinations) and statistics, including soil class maps.
These are available in electronic as well as hard copy format. Any geographic coverage is possible, provided that the boundaries are on file, or can be added.

Customised outputs

Customised products can be prepared for individual clients. Generally, more than one data set is used to generate such products. Data sets that are commonly used in combination with soil and vegetation data include infrastructure, (roads, fencelines, water supply), cadastre, groundwater and surface water resources.

Accessing data and information

Primary data can be made available in electronic format at cost of transfer. Interpreted or customised information, including crop potential maps require consultancy services which are charged accordingly.

Contact NT Department of Planning and Infrastructure.