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SSURGO Soil Map Coverage versus the U.S. General Soil Map Coverage

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The Data Itself
The Web Soil Survey (WSS) Website
Working with Downloaded Data


The Data Itself

Subject SSURGO Soil Map Coverage U.S. General Soil Map Coverage
Number of survey areas in the entire map coverage A little over 3000 One
Can tabular data for a survey area exist with no corresponding spatial data? Yes No
Can spatial data for a survey area exist with no corresponding tabular data? No No
Source maps 1:12,000 or 1:24,000 orthophotos 1:250,000 topographic quadrangles
Minimum size map delineation One to 10 acres 2,500 acres
Distribution bundling Data is bundled by soil survey area, regardless of the number of soil survey areas requested Data is either bundled for the whole U.S. or by a state or territory subset of the U.S., regardless of the number of state or territory subsets requested
Distribution datum North American Datum of 1983 North American Datum of 1983
Distribution projection or grid Geographic coordinates, UTM or State Plane Geographic coordinates only
Distribution spatial format ESRI Shapefile only ESRI Shapefile only
Raster or vector? Vector (polygons, lines, and points) Vector (polygons)
Available feature classes Survey Area Polygon (required), Map Unit Polygon (required), Line Map Units (optional), Point Map Units (optional), Line Spot Features (optional), Point Spot Features (optional) Map Unit Polygon (required)
Distribution tabular format Text files in ASCII, pipe (|) field delimited and double quote text delimited (one file per database table) Text files in ASCII, pipe (|) field delimited and double quote text delimited (one file per database table)
Tabular data includes “fuzzy logic” soil interpretations? Yes No
Underlying tabular data model SSURGO* SSURGO*
Is the dataset available through Web Soil Survey? Yes No

* “SSURGO” is a term that refers to both a specific soil map coverage and a specific data model for aggregated soil data. Although the SSURGO Soil Map Coverage is different from the U.S. General Soil Map Coverage, from a tabular data standpoint, both datasets share the same underlying data model. This is why both datasets can be imported into a “SSURGO template database”.

 


The Web Soil Survey (WSS) Website

Subject SSURGO Soil Map Coverage U.S. General Soil Map Coverage
Number of survey areas in the entire map coverage A little over 3000 One
Is a corresponding survey area status map available? Yes No
Survey area selection A user must select a specific survey area before doing anything else There is no explicit survey area selection process
Version information on the download page Since tabular data can be updated independent of spatial data, tabular, spatial and survey area version are all displayed Since tabular data is never updated independent of spatial data, only survey area version is displayed; the tabular and spatial version will always be the same as the survey area version
Can data for the entire map coverage be downloaded at once? No, only data for a single survey area may be included in a download request Yes
Can data for only part of a survey area be downloaded? Yes, in WSS the data clipped to an Area of Interest (AOI) can be downloaded Yes, a state or territory subset of data for the entire map coverage can be downloaded
Can tabular data be downloaded independent of spatial data, and vice versa? Yes No
Can I choose which SSURGO template database is included in a download? Yes No, the national SSURGO template database is always included
For a download, can I specify the spatial format and coordinate system? Yes and no, the coordinate system can be chosen but the spatial format is always an ESRI Shapefile No, data is always provided in ESRI Shapefile format and in geographic coordinates
Through this website, can I generate soil reports for this data? Yes No
Can I subscribe to a survey area? Yes No

 


Working with Downloaded Data

Subject SSURGO Soil Map Coverage U.S. General Soil Map Coverage
Export packaging Spatial extent is indicated in a file or directory name by a 5 character survey area symbol, e.g., “tx039” Spatial extent is indicated in a file or directory name by a 2 character country, state or territory symbol, e.g., “us”, “tx”, “pr”, etc.
Can tabular data be imported into a SSURGO template database?* Yes Yes
Can more than one set of tabular data be imported into the same SSURGO template database?* Yes, as long as data for the corresponding survey area doesn’t already reside in the database and there is still room in the database No, data for more than one state or territory subset cannot be imported into the same database
Can tabular data for every survey area be imported into the same SSURGO template database?* No Yes, but it takes a very long time and performance after it has been imported may be poor
In a SSURGO template database, can soil reports be generated? Yes Yes, but in general you should select a subset of map units before generating a report due to performance considerations
Can the data be used with Client Soil Data Viewer? Yes For a state subset? Yes, but performance may be poor

For the entire U.S.? No, since U.S. General Soil Map data doesn’t include fuzzy logic soil interpretations, the SDV rules for fuzzy logic soil interpretations will not be available

* “SSURGO” is a term that refers to both a specific soil map coverage and a specific data model for aggregated soil data. Although the SSURGO Soil Map Coverage is different from the U.S. General Soil Map Coverage, from a tabular data standpoint, both datasets share the same underlying data model. This is why both datasets can be imported into a “SSURGO template database”.