This shapefile consists of surface texture features identified from the general soil association units. This dataset consists of general soil association units. The file was developed by the National Cooperative Soil Survey and supersedes the State Soil Geographic (STATSGO) dataset published in 1994. The file consists of a broad based inventory of soils and nonsoil areas that occur in a repeatable pattern on the landscape and that can be cartographically shown at the scale mapped. The data set was created by generalizing more detailed soil survey maps. Where more detailed soil survey maps were not available, data on geology, topography, vegetation, and climate were assembled, together with Land Remote Sensing Satellite (LANDSAT) images. Soils of like areas were studied, and the probable classification and extent of the soils were determined. Map unit composition was determined by transecting or sampling areas on the more detailed maps and expanding the data statistically to characterize the whole map unit. This dataset consists of georeferenced vector digital data and tabular digital data. The map data were collected in 1- by 2-degree topographic quadrangle units and merged into a seamless national dataset. It is distributed in state/territory and national extents. The soil map units are linked to attributes in the National Soil Information System database that gives the proportionate extent of the component soils and properties.
These data provide information about soil features on or near the surface of the Earth. Data were collected as part of the National Cooperative Soil Survey. These data are intended for geographic display and analysis at the state, regional, and national level. These data should be displayed and analyzed at scales appropriate for 1:250,000-scale data.
publication date
The U.S. Department of Agriculture, Natural Resources Conservation Service should be acknowledged as the data source in products derived from these data. Hardcopies utilizing these data shall clearly indicate the source used. User agrees not to misrepresent these data, nor to imply that changes made were approved by the Natural Resources Conservation Service. The Digital General Soil Map of U.S. was designed primarily for regional, multicounty, river basin, State, and multistate resource planning, management, and monitoring. Data are not detailed enough to make interpretations at a county level. This soil survey product is not designed for use as a primary regulatory tool in permitting or citing decisions, but may be used as a reference source. The use of these data is not restricted and may be interpreted by organizations, agencies, units of government, or others; however, users are responsible for the appropriate application. Federal, State, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions that they make. The Natural Resources Conservation Service will not perform any evaluations of these maps for purposes related solely to state or local regulatory programs. When data from the Digital General Soil Map of U.S. are overlayed with other data layers, such as land-use data, caution must be used in generating statistics on the co-occurence of the land-use data with the soil data. The composition of the soil map unit can be characterized independently for the land use and for the soil component, but there are no data on the joint occurrence at a more detailed level. Analyses of the overlayed data should be on a map polygon basis. Additional political, watershed, or other boundaries may be intersected with the soil data. Although the composition of each political and watershed unit may be described in terms of the soil map units, information is not available to assign the components to the boundary units with full accuracy. As with the land-use categories, the analysis should be restricted to the classified components. The estimated minimum area delineated is 625 hectares (1,544 acres), which is represented on a 1:250,000-scale map by an area about 1 centimeter by 1 centimeter (0.4 inch by 0.4 inch). Linear delineations are not less than 0.5 centimeter (0.2 inch) in width. The number of delineations per 1:250,000 quadrangle typically is 100 to 200, but may range up to 400. Delineations depict the dominant soils making up the landscape. Other dissimilar soils, too small to be delineated, are present in a delineation. Digital enlargements of these data to scales greater than at which originally mapped can cause misinterpretation of the data. If enlarged, maps do not show the small areas of contrasting soils that could have been shown at a larger scale. The depicted soil boundaries, interpretations, and analysis derived do not eliminate the need for onsite sampling, testing, and detailed study of specific sites for intensive uses. Thus, these data and interpretations are intended for planning purposes only. Data values for some data elements may be incomplete or missing. Where data are unavailable, a mask should be used to exclude the area from analysis. The spatial and tabular data used to create this product are periodically updated. Data are versioned, and users are responsible for obtaining the latest version of the product.
USDA - Natural Resources Conservation Service
Alaska State Office
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Accuracy is tested by manual comparison of the source with hard copy plots and/or symbolized display of the map data on an interactive computer graphic system. Selected attributes that cannot be visually verified on plots or on screen are interactively queried and verified on screen. In addition, the attributes are tested against a master set of valid attributes. All attribute data conform to the attribute codes in the signed classification and correlation document and amendments and are current as of the date of digitizing.
Certain node/geometry and topology (GT)-polygon/chain relations are collected or generated to satisfy topological requirements. (The GT-polygon corresponds to the soil delineation). Some of these requirements include: chains must begin and end at nodes, chains must connect to each other at nodes, chains do not extend through nodes, left and right GT-polygons are defined for each chain element and are consistent throughout, and the chains representing the limits of the file (neatline) are free of gaps. The tests of logical consistency are performed by using vendor software. The neatline is generated by connecting the explicitly entered four corners of the digital file. All data outside the enclosed region are ignored and all data crossing these geographically straight lines are clipped at the neatline. Data in a specified tolerance of the neatline are snapped to the neatline. Neatline straightening aligns the digitized edges of the digital data with the generated neatline (that is with the longitude/latitude lines in geographic coordinates). All internal polygons are tested for closure with vendor software and are checked on hard copy plots. All data are checked for common soil lines (that is adjacent polygons with the same label). Quadrangles are edge matched in the state, merged into a statewide datasets, and then edge matched to adjacent state datasets. Edge locations do not deviate from centerline to centerline by more than 0.01 inch.
A map unit is a collection of areas defined and named the same in terms of the soil and/or nonsoil areas. Each map unit differs in some respect from all others in a survey area and is uniquely identified. Each individual area is a delineation. Each map unit in the Digital General Soil Map of U.S. consists of one to more than 21 components. In those few areas where detailed maps did not exist, reconnaissance soil surveys were combined with data on geology, topography, vegetation, climate, and remote sensing images to delineate map units and estimate the percentages of components. Map unit components in this product are soil series phases, and the percentage composition represents the estimated areal proportion of each in a map unit. The composition for a map unit is generalized to represent the statewide extent of that map unit and not the extent of any single map unit delineation. These specifications provide a nationally consistent representation of the associated attribute data. The actual composition and interpretive purity of the map unit delineations were based on statistical analysis of transect data. The composition was largely determined by measuring transects on detailed soil survey maps. The number of transects used was proportional to the relative size, number, and complexity of the delineations. The combined data on the length of the map units crossed by the transects were used to determine the percentages of the different soil and nonsoil areas in each map unit. Specific National Cooperative Soil Survey Standards and procedures were used in the classification of soils, design, and name of map units. These standards are outlined in: U.S. Department of Agriculture, Natural Resources Conservation Service, 1999, Soil Taxonomy--A basic system of soil classification for making and interpreting soil surveys (2nd ed.). U.S. Department of Agriculture, Natural Resources Conservation Service, 2003, Keys to Soil Taxonomy (9th ed.). U.S. Department of Agriculture, Natural Resources Conservation Service, 2007, National Soil Survey Handbook, title 430-V. U.S. Department of Agriculture, Natural Resources Conservation Service, 1993, Soil Survey Manual, U.S. Department of Agriculture, Handbook 18. U.S. Department of Agriculture, Natural Resources Conservation Service, 1994. State Soil Geographic (STATSGO) Data Base: Data-use information, Soil Conservation Service. Adherence to National Cooperative Soil Survey standards and procedures is based on peer review, quality control, and quality assurance. Quality control is outlined in documents in possession of the Natural Resources Conservation Service state soil scientist.
The accuracy of these digital data is based on the compilation to base maps that meet National Map Accuracy Standards. The difference in positional accuracy between the map unit boundaries in the field and the digitized map locations is unknown. The locational acuracy of soil delineations on the ground varies with the transition between map units. For example, in areas where changes in soils, climate, topography, and geology occur subtly across a part of a state, the transition between soil map unit boundaries will be gradual. Where these features change abruptly, such as from an area of foothills to a lake plain, the transition will be very narrow. Soil delineation boundaries were digitized within 0.01 inch of the locations on the digitizing source. The digital map elements are edge matched between datasets. The data along each state boundary are matched against the data for the adjacent state. Edge locations generally do not deviate from centerline to centerline by more than 0.01 inch.
base information for development of map unit delineations and transect data for naming map units
reference information for development of map unit delineations and transect data for naming map units where detailed surveys did not exist
base materials for compilation of map unit delineation linework
digitizing source
source material of soil map unit delineations and soil symbols
attribute (tabular) information
Map unit composition was determined by transecting or sampling areas on the more detailed soil maps and expanding the data statistically to characterize the whole map unit.
Soil map unit lines and symbols were drafted in red pencil on a mylar overlay that was punch registered to fit the mylar U.S. Geological Survey (USGS) 1:250,000-scale topographic quadrangle. A detailed and complete edit was performed on all overlays before digitizing. The soil delineation overlays were raster scanned at a scanning resolution of at least 0.01 inches and converted to a vector format or were manually digitized on a digitizing tablet with a resolution of at least 0.001 inch. Four control points corresponding to the four corners of the quadrangles were used for registration during data collection. The control points were either explicitly entered or developed by the software. The datasets were edge matched and merged into statewide coverages. A detailed and complete edit was performed on all digital data.
State coverages were merged into a seamless national coverage. This reduced tabular data redundancy and polygon number. A detailed and complete edit was performed on all digital data.
The National Soil Information System database was developed by Natural Resources Conservation Service soil scientists according to national standards.
The Natural Resources Conservation Service State Soil Scientist or delegate, on completion of data quality verification, determined that the tabular data should be released for official use. A selected set of map units and components in the soil survey legend was copied to a staging database, and rating values for selected interpretations were generated. The list of selected interpretations is stored in the database table named sainterp.
The Natural Resources Conservation Service State Soil Scientist or delegate verified that the labels on the digitized soil map units link to map units in the tabular database, and certified the joined data sets for release to the Soil Data Warehouse. A system assigned version number and date stamp were added and the data were copied to the data warehouse. The tabular data for the map units and components were extracted from the data warehouse and reformatted into the soil data delivery data model, then stored in the Soil Data Mart. The spatial data were copied to the Soil Data Mart without change.
The tabular data were extracted from the Soil Data Mart without change. The spatial data was exported to an ESRI shapefile.
The Natural Resources Conservation Service State Soil Scientist or delegate, upon completion of data quality verification, determined that the tabular data should be released for official use. A selected set of map units and components in the soil survey legend was copied to a staging database, and rating values for selected interpretations were generated. The list of selected interpretations is stored in the database table named sainterp.
The Natural Resources Conservation Service State Soil Scientist or delegate verified that the labels on the digitized soil map units link to map units in the tabular database, and certified the joined datasets for release to the Soil Data Warehouse. A system assigned version number and date stamp were added and the data were copied to the data warehouse. The tabular data for the map units and components were extracted from the data warehouse and reformatted into the soil data delivery data model, then stored in the Soil Data Mart. The spatial data were copied to the Soil Data Mart without change.
The tabular data associated with map units that overlap the clipping region "OK" (Oklahoma) were extracted from the data mart (URL:http://SoilDataMart.nrcs.usda.gov/) without change. The spatial data were clipped to clipping region "OK". The spatial data were exported to an ESRI shapefile.
Surface texture features were selected from gsmsoilmu_a_ok shapefile using the Soil Data Viewer tool and exported as a shapefile.
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A nonconnotative string of characters used to uniquely identify a record in the Mapunit table.
NASIS
Internal feature number.
ESRI
Feature geometry.
ESRI
A symbol that uniquely identifies a single occurrence of a particular type of area (for example, Lancaster County, Nebraska is NE109).
NASIS
The symbol used to uniquely identify the soil map unit in the soil survey.
NASIS
Surface Texture
Soil Survey Manual
Surface texture is the representative texture class and modifier of the surface horizon. Texture is given in the standard terms used by the U.S. Department of Agriculture. These terms are defined according to percentages of sand, silt, and clay in the fraction of the soil that is less than 2 millimeters in diameter. "Loam," for example, is soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand. If the content of particles coarser than sand is 15 percent or more, an appropriate modifier is added, for example, "gravelly." Map Unit Delineations are closed polygons that are geographic mixtures of groups of soils or soils and nonsoil areas. The map unit key uniquely identifies each closed map unit delineation. Each map unit key is linked to a map unit symbol and a map unit name. The map unit key also is the key for linking information in the National Soil Information System tables. Map Unit Delineations are described by the National Soil Information System database. This attribute database gives the proportionate extent of the component soils and the properties for each soil. The database contains estimated and measured data on the physical and chemical soil properties and soil interpretations for engineering, water management, recreation, agronomic, woodland, range and wildlife uses of the soil. The National Soil Information System database contains static metadata. The database documents the data structure and includes such information as what tables, columns, indexes, and relations are defined as well as a variety of attributes of each of these database objects. Attributes include table and column descriptions and detailed domain information. The National Soil Information System database also contains distribution metadata. The database records the criteria used in the set of distributed data.
U.S. Department of Agriculture, Natural Resources Conservation Service, 1999, Soil Taxonomy--A basic system of soil classification for making and interpreting soil surveys (2nd ed.). U.S. Department of Agriculture, Natural Resources Conservation Service, 2003, Keys to Soil Taxonomy (9th ed.). U.S. Department of Agriculture, Natural Resources Conservation Service, 2007, National Soil Survey Handbook, title 430-V. U.S. Department of Agriculture, Natural Resources Conservation Service, 1993, Soil Survey Manual, U.S. Department of Agriculture, Handbook 18. U.S. Department of Agriculture, Natural Resources Conservation Service, 1994. State Soil Geographic (STATSGO) Data Base: Data-use information, Soil Conservation Service.
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Although data in this product have been processed successfully on a computer system at the U.S. Department of Agriculture, no warranty expressed or implied is made by the Agency 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 in 90 days from the date of this shipment from the ordering site. The U.S. Department of Agriculture, nor any of its agencies are liable for misuse of the data. It is also not liable for damage, transmission of viruses, or computer contamination through the distribution of these datasets. The U.S. Department of Agriculture prohibits discrimination in programs on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, and marital or familial status. (Not all prohibited bases apply to all programs.)
spatial
spatial
spatial
keys and attributes
Visit the above mentioned Internet Web Site, select state or territory, then select individual soil survey area of interest. Spatial line data and locations of special feature symbols are in ESRI ArcGIS (ArcView,ArcInfo) shapefile, coverage and interchange (that is, export) formats. The National Soil Information System attribute soil data are available in variable length, pipe delimited, ASCII file format.
USDA - Natural Resources Conservation Service
Alaska State Office
800 West Evergreen, Suite 100