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NSSH Part 638

Soil Data Systems

638.0  Definition and Purpose

  1. The National Cooperative Soil Survey (NCSS) collects, manages, interprets, and disseminates soil survey information using a dynamic soil information system from which many different products can be produced.
  2. Soil data systems consist of multiple automated soil applications or modules that interact with each other to provide information. Soil data systems aid the collection, storage, manipulation, and dissemination of soil information. These applications include attribute and spatial databases and are collectively referred to as the “National Soil Information System.”
  3. The acronym “NASIS” is used to identify the transactional attribute database and user application of the National Soil Information System. Refer to Part 639 of this handbook for more information on NASIS.
  4. Validation and certification routines add assurance about the quality of soil survey information. Validation routines also help ensure that the data populated is correct and complete. Certification guidelines provide verification that the data has been reviewed prior to publication.

638.1  Policy and Responsibilities

  1. Policy

    Soil survey information is maintained in the National Soil Information System. This system is used by NCSS members for data collection through information publication. Users of automated soil applications who are members of NCSS are provided support and training on the use and management of all automated soil applications.
  2. Responsibilities

    1. Primary responsibility for various aspects of the National Soil Information System is with soil survey offices, State offices, soil survey regional offices (SSRO), the National Soil Survey Center (NSSC), and, on some Federal lands, such NCSS partner agencies as the USDI-Bureau of Land Management, USDA-Forest Service, USDI-National Park Service, and others.
    2. Roles and responsibilities of offices within NRCS include the following:

      1. Soil survey offices (SSO), which—
        • Collect and populate soil profile descriptions, field notes, and other point data.
        • Originate or maintain official series descriptions for the MLRA.
        • Compile, analyze, and aggregate point data to identify component-level ranges.
        • Populate component data to identify the component level and horizon level property ranges.
        • Develop the map unit concept for the soil survey.
        • Populate map unit name based on soil survey map unit concept.
        • Analyze spatial map unit boundaries to verify proper line placement, map unit concept, and landscape concept.
        • Ensure the quality of data entered into the NASIS database.
        • Ensure security of NASIS data by not sharing NASIS logins.
        • Notify NASIS Site dataset managers in the soil survey regional office (SSRO) when membership for specific individuals in a NASIS group is no longer needed.
        • Provide quality control of all populated data.
      2. State offices, which—
        • Distribute soil survey information to users.
        • Assist users of soil survey information.
        • Develop soil interpretation criteria in conjunction with other discipline experts and cooperators as needed to meet local interpretation needs.
        • Supplement the system by developing soil interpretive group assignments and forwarding them to the SSRO for inclusion.
        • Maintain current soil information in the National Soil Information System.
        • Certify and export NASIS database dataset to the staging server.
        • Certify spatial dataset at the staging server.
        • Validate and commit NASIS dataset and spatial datasets to the Soil Data Warehouse and Web Soil Survey as the official information for public use.
        • Coordinate in-state training on the use of automated soil applications.
        • Sponsor NCSS members at the State level and below who request accounts for accessing soil applications.
        • Assign competent, trained individuals within the State to edit data in NASIS as necessary to carry out program responsibilities.
        • Inform the SSRO of work being performed on the database and request edit privileges as needed.
        • Notify the appropriate area and field offices and affected partner agencies of significant revisions to the database.
      3. Soil survey regional offices (SSRO), which—
        • Provide the quality assurance and completeness checks of the information in the NASIS database.
        • Provide quality assurance for official soils descriptions within the region.
        • Maintain the soil classification database for the official soil descriptions within the region.
        • Sponsor user training for automated soil applications.
        • Provide continuing user support for all automated soil applications.
        • Manage the system and maintain the soil information in the system.
        • Evaluate proposals for new applications and for enhancements to existing applications.
        • Recommend development priorities to the Chair of the Soil Business Area Analysis Group (SBAAG).
        • Verify that users requesting NASIS accounts are NCSS members or persons working on behalf of NCSS.
        • Obtain the completed security forms from the user and submit them to the Soils Hotline when requesting a NASIS user account.
        • Manage members in NASIS groups.
        • Remove users from NASIS groups as necessary.
        • Notify the Soils Hotline when a user no longer needs a NASIS account or when a NASIS account needs modification (e.g., name change by submitting Form NRCS-IRM-02, “Request for User Access to ITS Resources”).
      4. National Soil Survey Center, which—
        • Sponsors NCSS members at National Headquarters, centers, and institutes who request accounts for accessing soil applications.
        • Develops and implements policy and guidelines for data administration and management, including quality control procedures.
        • Provides application analysis to support system development.
        • Manages the NCSS soil data dictionary as a subset of the NRCS corporate data dictionary.
        • Provides training to SSROs and assists SSRO staffs in providing training to the soil survey office and project office staffs.
        • Assists in system building tasks, such as developing documentation, testing, and data conversion.
        • Coordinates with the Information Technology Center to develop software for soil data systems.
        • Creates and maintains NASIS accounts.
        • Adds and removes users from roles in eAuthentication system.
        • Monitors listserve subscriptions (NASISNEWS, Soil Data Viewer News, Windows Pedon News, and NASIS Reports).
      5. Various offices of NRCS, which develop and maintain—
        • NASIS software and database.
        • Staging server.
        • Soil Data Warehouse.
        • Soil Data Mart.
        • Web Soil Survey.
        • Pedon description applications.
        • Official Series Descriptions.
        • Soil Classification Database.
        • NCSS Soil Characterization Database.

638.2  Components of the National Soil Information System

  1. Transactional Databases

    1. NASIS.—The acronym “NASIS” is used to identify the transactional attribute database and user application for NCSS. The NASIS application and database stores the observations, measurements, and estimated soil properties and qualities collected and developed as part of the soils inventory. The NASIS database is national in scope and is populated and managed by means of the NASIS software application.

      1. NASIS encompasses major data categories of the National Soil Information System, such as—
        • Point data records including soil profile descriptions, laboratory data, field measurements, transect observations, and other site-specific information.
        • Geographic area records including symbols, names, acreages of soil survey areas, and map unit legends of soil survey areas.
        • Map unit records, including national map unit symbols, map unit names, and the physical, chemical, and morphological properties and interpretations for map unit components.
        • Standards, criteria, interpretation criteria, and other data and documents used to establish concepts, assist aggregation, and communicate policy.
      2. Additional information specific to the NASIS database is located in Part 639 of this handbook.
      3. Detailed information on population of the tabular database is located in Part 618 of this handbook.
    2. Staging Server.—The staging server is the convergent step of the pathway where final validation of tabular and spatial data is performed before archiving to the Soil Data Warehouse and publishing to the Web Soil Survey. The two principal points for the collection and editing of data are NASIS (for the attribute data on soil properties and interpretations) and the spatial data showing location and extent of soils and related features. When the state soil scientists certify that these data are accurate and complete for release to the public, they authorize a survey area to be sent to the Soil Data Warehouse and Soil Data Mart via the staging server. This may be a new release or an update of an earlier release, both of which are retained in the warehouse.
    3. Official Series Descriptions (OSD).—The USDA-NRCS official soil series descriptions contain the taxonomic description of each soil series identified in the United States, territories, commonwealths, and island nations served by USDA-NRCS.

      1. “Official soil series description” is a term applied to the description approved by NRCS that defines a specific soil series. These official soil series descriptions document the taxa in the series category of the national system of taxonomic classification. They serve as specifications for identifying and classifying soils. Official series descriptions are maintained in a file storage system (“file share”) that is accessed by the staff in the SSRO. Official series descriptions are updated and processed with a software application named the “SC/OSD Maintenance Tool.” As the SSRO staff add or revise series for which they have responsibility, they transmit these series to the OSD file share where all series are stored.
      2. The OSD file share is both a transactional database maintained by the MOs as well as a publication database available to the public. The read-only Web access to official series descriptions provides the public the capability to view the individual series records, to query the database and produce a report with the selected soils, to produce national reports with all soils in the database, or to view maps identifying the distribution of series within the nation using the series extent mapping tool.
      3. More detailed information on official soil series descriptions is available in Part 614 of this handbook.
    4. Soil Classification Database (SC).—The USDA-NRCS soil classification database contains the taxonomic classification of each soil series identified in the United States, territories, commonwealths, and island nations served by USDA-NRCS. Along with the taxonomic classification, the database contains other information about the soil series, such as office of responsibility, series status, dates of origin and establishment, benchmark soil status, and geographic areas of usage.

      1. The SC database is maintained by the NRCS soil survey regional office (SSRO) staff. As series are added to the official series description file, the soil classification file needs to be updated accordingly. The classification of a soil series listed on the official series description and that listed in the soil classification file are kept in agreement by the SSRO staff. Additions and changes are continually being made as a result of ongoing soil survey work and refinement of the soil classification system. As the database is updated, the changes are immediately available to the user, so the data retrieved is always the most current.
      2. The SC database is both a transactional database maintained by the SSROs as well as a publication database available to the public. The read-only Web access to this soil classification database provides the capability to view the contents of individual series records, to query the database on any data element and produce a report with the selected soils, or to produce national reports with all soils in the database. The standard reports available allow the user to display the soils by series name or by taxonomic classification.
    5. Pedon Description Applications.—Soil descriptions can be entered into the National Soil Information System by using the NASIS software or the PedonPC software. Older software, such as PedonCE and Windows Pedon, can also be used for the collection of point data. Pedon descriptions are stored in the NASIS database and made available to all NCSS soil scientists.

      1. PedonPC.—The PedonPC description program is software used to populate pedon descriptions into a database. The data collected in the PedonPC database is imported into NASIS. Detailed information on the use of PedonPC and the import of pedon data into NASIS is available at this Web address:
      2. AnalysisPC.—AnalysisPC is the complementary database and user application for analyzing pedon data. The database can be used to sort, select, aggregate, and compare data. It can also produce a written copy of the pedon description. Integration with a geographic information system (GIS) software program allows for spatial display of the locations of pedon data. Detailed information on the use of AnalysisPC and the export of pedon data from NASIS is available at this Web address:
    6. Laboratory Information Management System (LIMS).—The National Soil Survey Center’s Kellogg Soil Survey Laboratory (KSSL) manages the internal Laboratory Information Management System. This system is designed to support the collection and analysis of soil samples, provide interpretation, manage and enhance the data, and disburse soil information in support of the NRCS Soil Survey Program. LIMS is a client-server system that allows the laboratory instruments and lab station computers to send analysis results to the central server.

      1. As samples are sent to the Kellogg Soil Survey Laboratory, they are assigned a unique sample number, labeled, and logged into LIMS. Information pertaining to the sample, pedon, site, and project associated with each sample is collected and stored. Each laboratory analysis request can be customized to use a particular preparation, along with other analysis-specific instructions. After the data entry, a project is prioritized and organized for work throughout the laboratory.
      2. LIMS provides an interface to communicate which preparations need to be performed on each sample and to collect weights and other data associated with the preparation of the sample. After dispositions are assigned to the prepared samples, the horizon samples appear on the work list within the laboratory. The raw data is then used to calculate results that are validated by the technicians for accuracy and reliability. LIMS has many reports written for custom application within the laboratory to assist technicians in completing their work.
  2. Publication Components

    1. Soil Data Warehouse (SDW).—The Soil Data Warehouse is a central repository for the current and previous versions of official soil survey data that have periodically been certified and exported from NASIS by state soil scientists since 2003. The data comes to the SDW via the staging server. The most recent versions of the attribute data and of the spatial data are forwarded to the Soil Data Mart, along with a metadata file, for delivery to soil survey users and other user applications via the Web Soil Survey. The metadata file conforms to the standard format of the Federal Geographic Data Committee (FGDC).
    2. Soil Data Mart (SDM).—The Soil Data Mart is an internal (non-public) national central repository of the current version of soil data, both spatial and tabular. It serves as the single point of delivery to the Web Soil Survey of official data which is intended for public use.
    3. Web Soil Survey (WSS).—The Web Soil Survey (accessible at is a Web application that allows various customers to access official soil survey maps and manuscript reports in an interactive mode. Created from the SDM data, customers can display soil maps, generate soil property or interpretive thematic maps, generate manuscript soil reports, and either print or save these products to their local computer. The Web Soil Survey allows customers to build a free custom soil survey manuscript through their selection of various maps and reports.

      1. Data distributed from the Web Soil Survey is in the Soil Survey Geographic database (SSURGO) format. For the tabular data, this format dictates which soil attributes are included, how those attributes are defined, how those attributes are grouped, and how those groups are related. For the spatial component, this format dictates which spatial layers are defined, which spatial layers are mandatory, and the standards to which that spatial data conforms. A metadata file in standard FGDC format is included with each dataset.
      2. Manuscript style reports are provided on Web Soil Survey for the public to retrieve basic soil property, quality, and interpretation information. Datasets can be downloaded that include the attribute and spatial databases for individual soil surveys. Customers can import the data into MS Access databases and into a GIS program for creation of thematic maps.
    4. Soil Data Access.—The Soil Data Access (accessed at is a Web application that provides a suite of Web services whose purpose is to meet requirements for requesting and delivering soil survey data from SDM in both a spatial and a tabular data format. The Web application allows the user to create ad hoc queries to retrieve attribute data by a user-defined structured query. This application also allows the user to query the spatial data by an area of interest or retrieve specific soil attributes outside the normal delivery database.
    5. SSURGO Template Database.—Detailed data from the Web Soil Survey is distributed in what is referred to as “SSURGO” format. SSURGO is the acronym for Soil SURvey GeOgraphic database. It is the most detailed level of mapping completed and is designed for use by landowners and for city and county general landuse planning purposes. For the tabular component, this format dictates which soil attributes are included, how those attributes are defined, how those attributes are grouped, and how those groups are related. For the spatial component, this format dictates which spatial layers are defined, which spatial layers are mandatory, and the standards to which that spatial data conforms.

      1. The tabular component is distributed for use in Microsoft Access database software. This MS Access “SSURGO template database” is a soil survey publication consisting of the tabular data, table relationships, and a series of manuscript-style reports providing soil properties, qualities, and interpretations. The default SSURGO template is the national template (e.g., soildb_US_2002.mdb). States have the ability to customize a template database and provide publication reports for their needs (e.g., soildb_PA_2003.mdb). Additional information on the customization of the template is available in the SSURGO template database customization guide located here.
      2. The spatial component is imported for use into a GIS program. Spatial data is available in several formats based on standards of the Environmental Systems Research Institute, Inc. (ESRI). These formats are ArcView shapefiles, ArcInfo coverages, or ArcInfo Interchange formats. Spatial layers include the soil survey area polygon and the map unit boundary polygons and can include the line map units, point map units, spot features, or a combination of these. Map unit boundary polygons in the digital map data are map unit delineations. The minimum delineation size ranges from 1.43 acres (0.57 hectare) to 5.7 acres (2.3 hectares). Themes for thematic maps are based on map units. Many map unit polygons can be labeled the same, but all point to the same record in the tabular map unit table.
    6. Soil Data Viewer (SDV).—The Soil Data Viewer is a tool built as an extension to the ArcMap module of the ESRI ArcGIS system that uses the SSURGO template database and allows a user to create soil-based thematic maps. The application can be run independent of ArcMap, but output is limited to a tabular report. SDV integrates the spatial shapefile and attribute SSURGO template database and provides users access to soil interpretations and soil properties while shielding them from the complexity of the databases. SDV makes it easy to compute a single value for a map unit and display results, relieving the user from the burden of querying the database, processing the data, and linking to the spatial map. SDV contains processing rules to enforce appropriate use of the data. It provides the user with a tool for quick geospatial analysis of soil data for use in resource assessment and management. Additional information is available at this Web address:
    7. National Cooperative Soil Survey (NCSS) Soil Characterization Database.—The NCSS soil characterization database is a Web application designed to allow users to generate, print, and download reports containing soil characterization data stored and maintained by the National Soil Survey Center’s Kellogg Soil Survey Laboratory (KSSL). The KSSL maintains the soil characterization database as a data mart of laboratory data. This data mart holds the entire set of both legacy and current KSSL data exported from LIMS. Beginning in 2009, characterization data from NCSS cooperating laboratories began to be added to the database. The system uses the same general reporting model as LIMS, with an enhanced Web-based query interface. The database is available at this Web address:
    8. U.S. General Soil Map Database (STATSGO2).—The U.S. general soil map database contains generalized soil associations designed for State or regional land use planning. It consists of a broad-based inventory of soils and miscellaneous areas that occur in a repeatable pattern on the landscape and that can be cartographically shown at the scale mapped. The tabular and spatial components of the STATSGO2 database are available for download from the Web Soil Survey at this Web address: STATSGO2 data are available for the lower 48 continental States, Alaska, Hawaii, Puerto Rico, and the U.S. Virgin Islands. Individual State extents are also available.

      1. The tabular component is distributed in standard SSURGO data format that can be imported into a Microsoft Access database software using the SSURGO template database. This MS Access “SSURGO template database” is a soil survey publication consisting of the tabular data, table relationships, and a series of manuscript reports providing soil properties, qualities, and interpretations. There is a potential for 21 components in each STATSGO2 map unit.
      2. The spatial data is available in an ArcView shapefile, ArcInfo coverage, or ArcInfo Interchange formats. Spatial layers include the soil survey area polygon and the map unit boundary polygons. Approximate minimum delineation size is 625 hectares (1,544 acres) as represented at a scale of 1:250,000 or, in Alaska, 10,000 hectares (25,000 acres) at a scale of 1:1,000,000. Linear delineations in the lower 48 continental States should be not less than 0.5 cm (0.2 inches) in width. The number of delineations per 1:250,000 quadrangle generally ranges from 100 to 200 but may range up to about 400. Map unit boundary polygons in the digital map data are map unit delineations. Therefore, themes for thematic maps are based on map units. Many map polygons can be labeled the same, but all point to the same record in the map unit table.
      3. Additional map and tabular standards are found in National Instruction 430-302, dated August 2001.

638.3  Managing Soil Spatial and Tabular Databases

  1. Soil survey attribute data and, to the extent possible, all other soil survey information (maps, interpretations, and metadata) are maintained in a central, sole-source repository (Soil Data Warehouse). These data are accessible to customers electronically through the Web Soil Survey, which is a dynamic soil survey information delivery system. SSURGO spatial, tabular, and metadata can also be obtained from the Geospatial Data Gateway. New and updated soil survey information, when placed into the Soil Data Warehouse, provides customers with the latest soil survey information. Procedures to enhance the information in the Soil Data Warehouse are part of the normal update of soil survey information.
  2. Managing Tabular Data

    1. Incorrect entries, obsolete terms, and null data are common deficiencies in the Soil Data Warehouse. Data searches of these errors satisfy the need for an evaluation and subsequent change over the extent of the map unit, and additional evaluation is not needed. New data entries or corrections to existing data entries, including taxonomic classification, may be made any time that errors are discovered. Changes that affect the legend, such as component names used in the map unit name, are proposed by the SSO and approved by the SSRO. Correlation decisions must be recorded in NASIS or, if not yet SSURGO-certified, with an amendment to the correlation document, as appropriate.
    2. The SSRO assures the quality of all new and revised soil survey data in the region, conducts a quality assurance review of the revised spatial data, manages the assignment of editing permissions in NASIS, assures that individuals with editing privileges are properly trained, and approves changes to the legend that are proposed by the SSO. The SSRO coordinates with the States to develop a plan that addresses the population of new data or correction of existing NASIS datasets. The purpose of the plan is to minimize the risk of data being included that does not meet NCSS standards, is inconsistent with data in adjoining areas of the same soils, or is of unknown origin. The plan builds quality control and quality assurance into the editing process. The plan may include such information as—
      1. A list of individuals who have permissions to edit the data.
      2. Actions to obtain needed training.
      3. A list of map units, data map unit, and data elements expected to be addressed.
      4. Guidance documents, algorithms, and other aids to be used.
      5. A schedule of when work will be done.
    3. At least annually (more frequently if needed to meet NRCS or cooperator needs), NASIS data is exported to the Soil Data Warehouse for all soil survey areas. Publication of soil databases is managed by the individual non-MLRA soil survey areas currently defined within NASIS.

638.4  Soil Survey Goals and Progress

Soil survey goals and progress are maintained in NASIS. The “Project Object” (refer to sections 608.7 and 639.3 of this handbook) is used to track the goals and progress of soil survey projects. The tables within the Project Object provide information to track the progress of soil survey projects at the national level. The MLRA soil survey leader populates the “Project Mapunit” table with those map units designated in the annual plan of operations. The “Milestone” table provides the MLRA soil survey leader the ability to track certain events of each update project.

638.5  Distribution of Soils Data

NASIS data are distributed using the National Soil Information System and the Web portals created for publication of soils information.

  1. Internal Publication

    1. Soil database information in the Customer Service Toolkit (CST) is provided from Web applications via the National Soil Information System. The state soil scientist is responsible for providing the current official soil database to the CST.
    2. The state soil scientist certifies data downloaded to the CST. Soil data is not downloaded to the CST until it has been certified. Soil data elements are edited and certified for each CST application, such as the Revised Universal Soil Loss Equation (RUSLE), before they are downloaded.
  2. External Publication

    1. Soil database information is distributed to cooperators and the public through the Web Soil Survey and the publication Web outlets detailed in section 638.2 B of this handbook.
    2. The state soil scientist should maintain a file of users who have requested and received digital map unit record data sets from the state office staff. At a minimum, document the requester’s name, the date, and a brief description of data provided.
    3. User documentation or a user guide is provided with each data set that is distributed. As a minimum, include the following information:

      1. The definition of data elements (data dictionary).
      2. Description of the data format.
      3. Disclaimer on the use of the data.
      4. Request that NRCS be acknowledged as the source of the data.