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Digital Atlas of Australian Soils - Metadata
Description of the data set
The Digital Atlas of Australian Soils (the Digital Atlas) is a digital version of the set of ten maps, compiled by K H Northcote et al. in 1960-68 and published by CSIRO and Melbourne University Press in Melbourne, known as the 'Atlas of Australian Soils, Sheets 1 to 10, with explanatory data'. The Digital Atlas was created by the National Resource Information Centre (NRIC), now Science Secretariat, within the Bureau of Rural Sciences in 1991 from scanned tracings of the published hardcopy maps.
The published hard copy maps were at a scale of 1:2 000 000 although it is known that original compilation work was done at 1:250 000 and 1:500 000 scales. The use of the hardcopies was necessary, as the original printer's separates could not be located. This introduced a source of error due to paper stretch and errors due to drafting accuracy but extensive cross-checking, editing and error tracking were performed to limit the effects of these errors. If required, the 'rms' errors can be supplied.
The digital maps derived from the separate hardcopy maps constituting the Atlas of Australian Soils were merged to form a single, topologically structured, Australia-wide polygon coverage. Attribution (map labelling) inconsistencies were remedied, for example, where upper and lower case characters or l's and 1's had been confused. The earliest hard copy maps were provided in polyconic projection and the later ones in simple conic, however the Digital Atlas is maintained using geographical coordinates (longitude/latitude). The Digital Atlas is available as a double precision ARC/INFO® coverage (which means that each coordinate is stored with up to 15 significant digits) but a single precision derivative is also available (in which each coordinate is stored with up to seven significant digits). The notional scale of the data set is 1:2 000 000. Consideration of this limitation is especially necessary if the data set is used for regional analyses.
Explanatory notes accompanied each of the hardcopy atlas maps and the soil landscape descriptions in them (referred to as Legend 2) have been digitally scanned, edited and merged as a rich text format file 'csiro2m.rtf' which is provided with the coverage itself. The original hardcopy explanatory notes should be referred to for an outline of the methodology used to assemble the published hardcopy maps.
Only two soil attributes are maintained in the Digital Atlas coverage. They are stored in the polygon attribute table (cover_name.pat) which accompanies the ARC/INFO® coverage. One of them, called 'map_unit', is the soil landscape alphanumeric identifier which appeared on the published hardcopy maps. The other, called 'map_code', is a numerical equivalent of the first. There is a one to one correspondence between the values of map_unit and the values of map_code. Additional attributes are provided in a lookup table, cover_name.lut.
The lookup table (cover_name.lut) provided with the ARC/INFO® coverage indicates, for each soil landscape, the dominant soil type according to the soil classification system described by K H Northcote in the various editions of his 'A Factual Key for the Recognition of Australian Soils' (1979). More specifically, the lookup table gives the dominant soil types by their class, section and principal profile form ('ppf') according to Northcote's classification. The lookup table also gives a shading symbol that can be tailored to one's system to produce a simple plot showing the Northcote sub-division level for the dominant soil type of each soil landscape. The accompanying illustration shows the Digital Atlas shaded according to dominant soil subdivision using this last attribute.
It is stressed that the mapped units in the Digital Atlas are soil landscapes and that each soil landscape typically comprises a number - usually more than one - of soil types. The lookup table provided with the coverage only gives one soil type for each landscape (the dominant one). Associated soils in the mapped units can be as important as the dominant soil, or more so, depending on the application.
A lookup table, csinterp.lut, which is not routinely provided, contains interpretations of soil properties for the dominant soil of each landscape: soil permeability, water holding capacity, texture, reaction trend, nutrient response and depth characteristics. (See Commonwealth Scientific and Industrial Research Organisation Technical Report 94/1992 by N McKenzie and J Hook, published in 1992, for an outline of the methodology; contact ARDC - contact details below - if you are unable to obtain a copy of this report.) Several other lookup tables are also available.
Space requirements
The Digital Atlas of Australian soils occupies 27.9 MB as a double precision ARC/INFO® coverage and 17.5 MB as a single precision ARC/INFO® coverage. The space requirements for the three formats available for download are given below. Visit the Download: Digital Atlas of Australian Soils page for full list of available formats.
If you download the 'ARC/INFO® export file with full compression' version of the Digital Atlas, you will need about 22.8 MB of space initially. This package comprises:
- The ARC/INFO® export file made with full compression from a double precision coverage with lookup table and further compressed using the gzip compression utility (21.5 MB)
- The explanatory file csiro2m.txt (see above - 1.3 MB)
- An explanatory document in rich text format of negligible size
You will need a further 47.7 MB of space for the decompressed ARC/INFO® export file and you will need 27.9 MB of space for the reconstructed double precision ARC/INFO® coverage and lookup table. After deletion of the compressed and uncompressed export files, the total space occupied is reduced to 29.2 MB.
If you download the 'ARC/INFO® export file with no compression' version of the Digital Atlas, you will need about 14.6 MB of space initially. This package comprises:
- The ARC/INFO® export file made with no compression from a single precision coverage with lookup table and compressed using the gzip compression utility (13.3 MB)
- The explanatory file csiro2m.txt (1.3 MB)
- An explanatory document in rich text format of negligible size
You will need a further 51.9 MB of space for the decompressed ARC/INFO® export file and you will need 17.5 MB of space for the reconstructed single precision ARC/INFO® coverage and lookup table. After deletion of the compressed and uncompressed export files, the total space occupied is reduced to 18.8 MB.
If you download the 'ASCII coordinate and attribute files' version of the Digital Atlas, you will need 19.3 MB of space initially. This package comprises:
- An ASCII coordinate file made with the ARC/INFO® command 'ungenerate' from a single precision coverage and compressed using the gzip compression utility (17.4 MB)
- A comma delimited attribute file in rich text format made from the coverage polygon attribute table (0.5 MB)
- A comma delimited attribute file in rich text format made from the lookup table associated with the coverage (0.1 MB)
- The explanatory file csiro2m.txt (1.3 MB)
- An explanatory document in rich text format of negligible size
The uncompressed ASCII coordinate file occupies 82.5 MB and you will need additional space to construct a digital map.
Revision history of the Digital Atlas
The current version of the Digital Atlas was published on the web on 2 November 1998 and is the first revision of the data set since it was first published on the web in September 1998. It incorporates five new polygon ID numbers (cover_name-id in the polygon attribute table). These are listed and explained below. The first four new ID numbers result from the correction of errors that arose during the conversion of the Atlas of Australian Soils to digital form. The fifth results from assignment of a new ID number to a polygon which previously shared its ID number with another polygon; each polygon in the current version of the Digital Atlas now has a unique ID number. The polygon ID numbers are otherwise unchanged and represent the same polygons as previously (though a few of these polygons will have shape changes due to the changes detailed below).Polygon ID number 22586: represents a new polygon with map_unit = BB 9, located in WA, on Atlas of Australian Soils Sheet 10 N.W. The polygon is located at 120.67E, 26.30S and is bounded by 120E, 121E, 26S and 27S.
Polygon ID number 22587: represents a new polygon with map_unit = AB 14, located in WA, on Atlas of Australian Soils Sheet 10 N.W. The polygon is located at 120.78E, 26.35S and is bounded by 120E, 121E, 26S and 27S.
Polygon ID number 22588: represents a new polygon with map_unit = Oc 40, located in WA, on Atlas of Australian Soils Sheet 6. The polygon is located at 114.27E, 23.85S and is bounded by 113E, 115E, 23 S and 25S.
Polygon ID number 22589: represents a new polygon with map_unit = BA 25, located in NT, on Atlas of Australian Soils Sheet 10 N.E. The polygon is located at 135.28 E, 21.11S and is bounded by 135E, 136E, 21S and 22S.
Polygon ID number 22590: a new (unique) ID number for an existing polygon with map_unit = E 1, located in SA, on Atlas of Australian Soils Sheet 1. The polygon is located at 140.45E, 37.87S and is bounded by 140E, 141E, 37S and 39S.
References
Northcote, K. H. with Beckmann G G, Bettenay E., Churchward H. M., van Dijk D. C., Dimmock G. M., Hubble G. D., Isbell R. F., McArthur W. M., Murtha G. G., Nicolls K. D., Paton T. R., Thompson C. H., Webb A. A. and Wright M. J. (1960-68): 'Atlas of Australian Soils, Sheets 1 to 10, with explanatory data'. CSIRO and Melbourne University Press: Melbourne.
Northcote K. H. (1979): 'A Factual Key for the Recognition of Australian Soils'. 4th Ed. Rellim: Adelaide, South Australia