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gSSURGO and gNATSGO Map Unit Grids
A simplified representation of the gSSURGO/gNATSGO spatial data are now available for users that do not require the full distribution of these data (spatial + tabular).
These grids represent a rasterization of the gSSURGO and gNATSGO map unit keys for the conterminous United States at a resolution of 30m, referenced to an Albers Equal Area Conic (NAD83) coordinate reference system (EPSG:6350). Grids are LZW compressed and internally tiled for efficient random access. Cell values are map unit keys, encoded as unsigned 32-bit integers. The grid topology and cell values are identical to the rasters contained within the gSSURGO and gNATSGO file geodatabases (FGDB). The GeoTiff format is used to ensure maximum compatibility. File size is approximately 2.4Gb (each).
Map unit key grids contain links to SSURGO, STATSGO, and raster soil survey “tabular” data (soil properties, conditions, limitations, etc.). Thematic mapping or analysis requires “joining” grid cells to tabular records; using local files or a web-service like Soil Data Access (SDA). Note that map unit keys associated with raster soil surveys (included with gNATSGO) are not currently available in SDA.
Files are re-created as part of the annual SSURGO refresh cycle. Send email to SoilsHotline for suggestions on best practices for aggregating and linking tabular data to these map unit key grids.