|Originator||U.S. Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS)|
|Title||Gridded Soil Survey Geographic Database (gSSURGO), Minnesota|
|Abstract||The gSSURGO dataset provides detailed soil survey mapping in raster format with ready-to-map attributes organized in statewide tiles for desktop GIS. gSSURGO is derived from the official Soil Survey Geographic (SSURGO) Database. SSURGO generally has the most detailed level of soil geographic data developed by the National Cooperative Soil Survey (NCSS) in accordance with NCSS mapping standards. The tabular data represent the soil attributes and are derived from properties and characteristics stored in the National Soil Information System (NASIS).
The gSSURGO data were prepared by merging the traditional vector-based SSURGO digital map data and tabular data into statewide extents, adding a statewide gridded map layer derived from the vector layer, and adding a new value-added look up table (valu) containing ready-to-map attributes. The gridded map layer is in an ArcGIS file geodatabase in raster format, thus it has the capacity to store significantly more data and greater spatial extents than the traditional SSURGO product. The raster map data have a 10-meter cell size that approximates the vector polygons in an Albers Equal Area projection. Each cell (and polygon) is linked to a map unit identifier called the map unit key. A unique map unit key is used to link the raster cells and polygons to attribute tables.
For more information, see the gSSURGO webpage: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628
|Purpose||The Gridded SSURGO dataset was created for use in national, regional, and state-wide resource planning and analysis of soils data. The raster map layer data can be readily combined with other national, regional, and local raster layers, including the National Land Cover Database (NLCD), the National Agricultural Statistics Service (NASS) Crop Data Layer (CDL), and the National Elevation Dataset (NED).|
|Time Period of Content Date||01/15/2014|
|Currentness Reference||The gSSURGO dataset was created from SSURGO data downloaded from NRCS's Web Soil Survey website during the third week of January 2014. A new release of gSSURGO is planned for each Federal fiscal year, which begins October 1.
See the gSSURGO User Guide for instructions on how to verify SSURGO and gSSURGO data creation dates.
|Maintenance and Update Frequency||Annually|
|Spatial Extent of Data||Minnesota, Conterminous United States|
|Place Keywords||Minnesota, MN|
|Theme Keywords||geoscientificInformation, soil, soils, gSSURGO, SSURGO|
|Theme Keyword Thesaurus||ISO 19115 Topic Category|
|Use Constraints||The U.S. Department of Agriculture, Service Center Agencies should be acknowledged as the data source in products derived from these data.
This data set is not designed for use as a primary regulatory tool in permitting or citing decisions, but may be used as a reference source. This information may be interpreted by organizations, agencies, units of government, or others based on needs; however, they are responsible for the appropriate application. Federal, State, or local regulatory bodies are not to reassign to the Service Center Agencies any authority for the decisions that they make. The Service Center Agencies will not perform any evaluations of these data for purposes related solely to State or local regulatory programs.
Photographic or digital enlargement of these data to scales greater than at which they were originally mapped can cause misinterpretation of the data. Digital data files are periodically updated, and users are responsible for obtaining the latest version of the data.
|Contact Person Information||,
USDA/NRCS Soil Survey Center
Federal Building, Room 152, 100 Centennial Mall North
Lincoln, NE 68508
|Browse Graphic||Click to view a data sample.
Graphic comparing vector SSURGO with 10-meter raster gSSURGO
|Associated Data Sets||For information on other soils data available for Minnesota, see: http://www.mngeo.state.mn.us/chouse/soil.html|
|Section 2||Data Quality|
|Attribute Accuracy||The National Value Added Look Up (valu) Table database: The valu1 table resides in the valu database and is comprised of 57 pre-summarized or ready-to-map attributes derived from the official SSURGO database. These attribute data are pre-summarized to the map unit level using best-practice generalization methods intended to meet the needs of most users. The generalization methods include map unit component weighted averages and percent of the map unit meeting a given criteria. These themes were prepared to better meet the mapping needs of users of soil survey information and can be used with both SSURGO and Gridded SSURGO (gSSURGO) datasets.|
|Completeness||The data were not clipped to a state boundary, thus in some instances feature classes may extend beyond a state's boundary.|
|Horizontal Positional Accuracy||Map Projection Name: USA Contiguous Albers Equal Area Conic, USGS version
Horizontal Units: meters
Horizontal Datum: NAD83
Ellipsoid: Geodetic Reference System 80
The raster map data have a 10-meter cell size that approximates the vector polygons in an Albers Equal Area projection.
|Lineage||This dataset is a digital soil survey and generally is the most detailed level of soil geographic data developed by the National Cooperative Soil Survey. The information was prepared by digitizing maps, by compiling information onto a planimetric correct base and digitizing, or by revising digitized maps using remotely sensed and other information. This dataset consists of georeferenced digital map data and computerized attribute data. The map data are in a soil survey area extent format and include a detailed, field verified inventory of soils and miscellaneous areas that normally occur in a repeatable pattern on the landscape and that can be cartographically shown at the scale mapped. The soil map units are linked to attributes in the National Soil Information System (NASIS) relational database, which gives the proportionate extent of the component soils and their properties.
During the third week of January 2014, all available SSURGO data were downloaded from Web Soil Survey to a local cache. As part of the download process, the tabular data for each survey were imported into individual SSURGO template databases (MS Access format) using a custom set of 'SSURGO Download Tools' for ArcGIS 10.1. For each state or territory, intersecting SSURGO datasets were identified using the 'laoverlap' table (Legend Area Overlap). The selected datasets were merged and converted from shapefile and MS Access tables into a single ESRI file geodatabase for that state or territory. The data were not clipped to a state boundary, thus in some instances feature classes may extend beyond a state's boundary. All datasets were projected from the original Geographic WGS 1984 coordinate system to the appropriate Albers Equal Area Conic coordinate system. Relationship classes between tables and feature classes were created in the geodatabase.
A 10 meter file geodatabase raster layer was created by converting the 'MUPOLYGON' feature class from feature to raster using 'FeatureToRaster' which is a cell-center-based method in ArcGIS 10.1. Where available, the raster layer was aligned to the U.S. Geological Survey's National Land Cover Database (NLCD) 30-meter raster. The 10-meter resolution was chosen to maintain the shape and extent of the original polygons without sacrificing display performance. This resolution also enhances alignment to other national raster layers. Pyramids and a raster attribute table were created. A single attribute 'MUKEY' was added to the raster attribute table to facilitate joins with the attribute data.
|Section 3||Spatial Data Organization (not used in this metadata)|
|Section 4||Coordinate System|
|Horizontal Coordinate Scheme|
|Overview||Value Added Look Up Table Database:
The valu1 table resides in the valu database and is comprised of 57 pre-summarized or ready-to-map attributes derived from the official SSURGO database. These attribute data are pre-summarized to the map unit level using best-practice generalization methods intended to meet the needs of most users. The generalization methods include map unit component weighted averages and percent of the map unit meeting a given criteria. These themes were prepared to better meet the mapping needs of users of soil survey information and can be used with both SSURGO and gridded SSURGO (gSSURGO) datasets. Below is a partial list of the data found in the valu1 table.
- Soil organic carbon: weighted average (g C/m2)
- Available water storage: weighted average (mm)
- National Commodity Crop Productivity Index (NCCPI) Version 2: weighted average index for major components (Dobos, Sinclair, and Robotham, 2012)
- Root-zone depth of commodity crops: weighted average (cm) major components (Dobos et al., 2012)
- Available water storage within the root-zone depth: weighted average (mm) major components
- Drought-vulnerable soil landscapes: The map unit is identified as either drought vulnerable or not drought vulnerable. Drought-vulnerable soil landscape map units have 152 millimeters (6 inches) or less root zone available water storage for major components.
- Potential wetland soil landscapes (PWSL Version 1): percentage of the map unit that meets the criteria for a potential wetland soil landscape (see table metadata for detailed criteria).
A complete description of the tables and their relationships is included on the SSURGO webpage: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053631
Specific information is located in the SSURGO Tables and Columns Report document found on the SSURGO Structural Metadata and Documentation webpage: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053631
Some of the commonly used tables are:
- Mapunit: Includes soil map unit name and prime farmland designation. Uses MUKEY as the join field with spatial data.
- Muaggatt: Includes common soil interpretations for map units. Uses MUKEY as the join field with spatial data.
- Component: Includes interpretations and properties for components of map units. Use of this table requires a relate since there are several records in this table for each single MUKEY in the raster data.
- Chorizon: Includes data by horizon for components. Use of this table requires a relate since there are several records in this table for each single MUKEY in the raster data.
See the gSSURGO User Guide for more details. The User Guide is linked from the gSSURGO webpage: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628
|Publisher||Natural Resources Conservation Service|
|Contact Person Information||,
USDA/NRCS Soil Survey Center
Federal Building, Room 152, 100 Centennial Mall North
Lincoln, NE 68508
|Distributor's Data Set Identifier||gSSURGO|
|Distribution Liability||Although these data have been processed successfully on a computer system at the U.S. Department of Agriculture, no warranty expressed or implied is made by the Service Center Agencies regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. The U.S. Department of Agriculture will warrant the delivery of this product in computer readable format, and will offer appropriate adjustment of credit when the product is determined unreadable by correctly adjusted computer input peripherals, or when the physical medium is delivered in damaged condition. Request for adjustment of credit must be made within 90 days from the date of this shipment from the ordering site.
Neither the U.S. Department of Agriculture, nor any of its agencies are liable for misuse of the data, for damage, for transmission of viruses, or for computer contamination through the distribution of these data sets. The U.S. Department of Agriculture prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.)
MnGeo's data disclaimer is online: http://www.mngeo.state.mn.us/chouse/disclaimer.html
|Ordering Instructions||Click on 'Online Linkage' field below to get to an NRCS webpage detailing the options for free download and for CD purchase.
The gSSURGO User Guide is linked from the gSSURGO webpage: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628
|Online Linkage||I AGREE to the notice in "Distribution Liability" above. Clicking to agree will either begin the download process, link to a service, or provide more instructions. See "Ordering Instructions" above for details.|
|Section 7||Metadata Reference|
|Contact Person Information||Nancy Rader,
GIS Data Coordinator|
Minnesota Geospatial Information Office (MnGeo)
658 Cedar Street, Room 300
St. Paul, MN 55155
|Metadata Standard Name||Minnesota Geographic Metadata Guidelines|
|Metadata Standard Version||1.2|
|Metadata Standard Online Linkage||http://www.mngeo.state.mn.us/committee/standards/mgmg/metadata.htm|