URL: www.ftw.nrcs.usda.gov/ssur_data.html COST: Free for download, $50 for CD AGENCY: USDA - Natural Resources Conservation Service (NRCS) FORMAT: ArcInfo Coverage, DLG27, DLG 83, ArcInfo Export File PROJECTION: UTM, NAD83, GRS80

DESCRIPTION: SSURGO is the most detailed level of soil mapping done by the Natural Resources Conservation Service (NRCS). Field mapping methods using national standards are used to construct the soil maps in the Soil Survey Geographic (SSURGO) database. Mapping scales generally range from 1:12,000 to 1:63,360; SSURGO digitizing duplicates the original soil survey maps. This level of mapping is designed for use by landowners, townships, and county natural resource planning and management. The user should be knowledgeable of soils data and their characteristics.

DOWNLOAD: The map extent for a Soil Survey Geographic (SSURGO) data set is a soil survey area, which may consist of a county, multiple counties, or parts of multiple counties. A SSURGO data set consists of map data, attribute data, and metadata.

Go to www.ftw.nrcs.usda.gov/ssurgo_ftp3.html to download the data . First, you must register (if you haven't done so before). After logging in, a link takes you to a long list of available data sets. Each dataset can be downloaded. Metadata is also available. Data is available is Arc/Info coverage format, Modified Digital Line Graph (DLG-3) North American Datum of 1927, Modified Digital Line Graph (DLG-3) North American Datum of 1983, and Arc/Info Export format. A metadata file, readme file, and attribute file are also listed for download. Click the button next to the desired format and download.

ARC/INFO COVERAGE SELECTION: Each data file (cov.zip) includes a number of different datasets (in the form of coverages). One coverage is a polygon layer just of the quad or quads covered by the dataset. Another coverage is the actual soil polygons and attribute data for the entire state. In the case of Connecticut, a number of other coverages were also downloaded so that each quad had it's own soil coverage and a coverage of the quad (basically an outline).

RESULTS: SSURGO digital data was only available for the eastern part of Connecticut. A colorized section of the Connecticut coast is shown to demonstrate the level of detail present in the SSURGO data set.

SOILS: State Soil Geographic Data Base (STATSGO)   URL: www.ftw.nrcs.usda.gov/stat_data.html COST: Free for download, $50 for CD AGENCY: USDA - Natural Resources Conservation Service (NRCS) FORMAT: DLG, PCArcInfo Coverage, GRASS 4.13 vector PROJECTION: Albers Conical Equal Area, NAD27

DESCRIPTION: Soil maps for the State Soil Geographic (STATSGO) database are made by generalizing the detailed soil survey data. The mapping scale for STATSGO is 1:250,000 (with the exception of Alaska, which is 1:1,000,000). The level of mapping is designed to be used for broad planning and management uses covering state, regional, and multi-state areas. Digitizing is done by line segment (vector) format in accordance with Natural Resources Conservation Service (NRCS) digitizing standards. The base map used is the U.S. Geological Survey 1:250,000 topographic quadrangles. The number of soil polygons per quadrangle map is between 100 and 400. The minimum area mapped is about 1,544 acres.

STATSGO data are collected in 1:250,000 quadrangle units. Map unit delineations match at state boundaries. States have been joined as one complete seamless database to form statewide coverage. Composition of soil map units was coordinated across state boundaries, so that component identities and relative extents would match.

Each STATSGO map is linked to the Soil Interpretations Record (SIR) attribute database. The attribute database gives the proportionate extent of the component soils and their properties for each map unit. The STATSGO map units consist of 1 to 21 components each. The Soil Interpretations Record database includes over 25 physical and chemical soil properties, interpretations, and productivity. Examples of information that can be queried from the data base are available water capacity, soil reaction, salinity, flooding, water table, bedrock, and interpretations for engineering uses, cropland, woodland, rangeland, pastureland, wildlife, and recreation development.

STATSGO data are available in the USGS Digital Line Graph (DLG-3) optional distribution format. NRCS soil map symbols are not normally carried within the DLG-3 file; however, these map symbols are made available as a unique ASCII file when NRCS soils data are distributed in the DLG-3 format. STATSGO data are also available in ArcInfo 7.0 coverage and GRASS 4.13 vector formats.

DOWNLOAD: Go to www.ftw.nrcs.usda.gov/statsgo_ftp.html to download the data. Click on the DOS/WINDOWS link or UNIX link depending on your computer system. This takes you to the FTP site. Choose the data type (when downloading for windows, the choices are arc or dlg) then select the folder, right-click, and select "Copy to Folder." NOTE: the arc files are in PC ArcInfo format. This is different from ArcInfo Coverage format. PCArcInfo can be used to export the data to e00 format and then imported as a coverage in ArcView3.x or ArcGIS8x. Or, use the ArcView3.x import utility to convert the file from the interchange format (e00) to a shapefile. ArcGIS8x does not handle PCArcInfo format without conversion.

METADATA: Go to hwww.ftw.nrcs.usda.gov/stat2.html and click on the state for FGDC metadata.

RESULTS: The Connecticut statewide coverage of STATSGO data is shown below. For comparison, another image is shown that is the SSURGO data with black outlines of STATSGO soil polygons on top. Notice the large difference in detail between the two datasets.

Back to Top

Comments or Suggestions? Email us at ewilson@canr.uconn.edu.

GTP Home | CLEAR Home | NEMO Home
News | Training | Research | Data | National Datasets | Contacts | Links

© University of Connecticut | Disclaimers and Copyright Statements