SSIS Soils Data, Minnesota
SSIS data has been superseded by NRCS's SSURGO data. This webpage and the downloadable files remain for historical completeness.
This page provides information on soils data digitized using the University of Minnesota's Soil Survey Information System (SSIS). The source for this data is the Natural Resources Conservation Service county soils survey maps. SSIS is a non-GIS computer program originally created in the mid-to-late 1970s and used to collect and display soil information on a section-by-section basis. Note: this program was active from the mid-1970s until the mid-1990s; no new counties are being done.
Soils data for about 40 Minnesota counties was collected using SSIS. Most SSIS soils data was converted to GIS formats, either by LMIC (now MnGeo) or by the University of Minnesota, using the following process:
- The data was converted to EPPL7 raster format, NAD27, with 5 meter by 5 meter grid cells, using 1:24,000-scale section corners to establish geo-referencing. This step corrected the assumption in SSIS that each public land survey section was a perfect square mile.
- Section files were then combined into regions, usually public land survey townships.
- Files were next converted from EPPL7 into Arc/INFO coverages, changed to NAD83, and finally converted to Arc/Info export and shapefile formats.
For more information, consult the SSIS Soils Data Documentation. To find out more about the data in its original SSIS format (.bas and .dat files), see pages 8 and 10 in the Governor's Council County Soil Surveys report.
For information about other soils data available for Minnesota, see MnGeo's soils page.
For historical completeness, the SSIS files are still online at: ftp://ftp.lmic.state.mn.us/pub/data/phys_biol/soils/county but users who want current soils data should use SSURGO.
Files available for download from the FTP site are in Arc/Info export and shapefile formats, stored in separate folders by format. Each county's township files have been assembled into a self-extracting zip (.EXE) file. After downloading this zip file, simply execute (run) the file. For example, double-click it from Windows Explorer or File Manager. Doing this will automatically extract the following files:
- Data files: an uncompressed Arc/Info export or a shapefile for each
township in the county. An export file ends with an .E00 extension; a shapefile consists of three files:
.SHP, .SHX, and .DBF.
Naming convention: each township file is named 'SL' plus the township number, plus the range number, plus 'W' for each township. For instance, file 'SL10936W.E00' ('SL10936W.SHP' in shapefile format) contains the soils data for Township 109 North, Range 36 West.
(Note: Attributes are in separate files from NRCS.)
- Legend: SOILXXXX.LEG, where 'XXXX' represents the first four letters of the county name.
- Metadata: SOILSSIS.HTM, documentation for the data set.
- README.TXT: some counties contain this file which describes problems or processing specific to that county data set.
- NOTICE.RTF and .TXT: a disclaimer.
SSIS files include soil codes and soil name descriptions; however, no other tabular information on soil properties is included. Users can download tabular information from NRCS's Web Soil Survey to link to the map unit symbols. The Soil Data Mart's tabular data is from the National Soil Information System (NASIS); this replaces their previous MUIR database.