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Winter 2005/2006

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USDA Web Soil Survey Supports Public Access to Volumes of Data

The National Cooperative Soil Survey, which began more than a century ago, is now accessible via a GIS-enabled Web site.

The soil survey is an inventory of the nation's soil resources that is designed to help land managers determine the Federal GIScrops and management practices most suitable for soils on their land parcel. Authorized by Congress in 1896 and placed under the auspices of the U.S. Department of Agriculture (USDA), survey field operations began in 1899. Today, the survey has identified more than 300 soil properties, and by using digital imagery for overlaying data on data, it offers a tool for in-depth soil suitability analysis. GIS helps soil survey data seekers identify the best way to protect soil and water quality, as well as identify how land parcels are suited for specified land uses. GIS has been an important addition to the survey, adding capabilities of data access, analysis, spatial display, and now a high volume of distribution.

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Online users select a plant community and assess the suitability and limitations of a specified ecological site. They can read about the specific details and view a map.

In August 2005, the USDA Natural Resources Conservation Service (NRCS) launched the Web Soil Survey on the Internet. The Web Soil Survey helps USDA meet two of the U.S. president's management agenda items: to eliminate paperwork and to make government services accessible to more people. Prior to the Web Soil Survey going live on the Internet, soil survey maps and data were printed and bound into soil survey books that were free to the public at local USDA Service Centers, NRCS field offices, and public libraries. People would obtain the county's entire soil survey book, then have to flip through it to find specific information. Now soil survey users can connect to the Internet, select a land parcel anywhere in the country, access the survey database, see the specified parcel on a map, generate soil interpretations, and download or print a PDF file.

Ken Harward, Web Soil Survey project manager, says, "The Web Soil Survey is saving a lot of USDA staff time. In the past, county office staff would spend an hour or two working with individual clients. Our customers now see the Web Soil Survey site as self-service technology that they access at their business, residence, or public kiosk. This frees agents to allocate customer service time to those who truly need it."

The Web Soil Survey project was initiated by NRCS' West Texas Telecommunications project and Information Technology Center teams. They began the project by coordinating with federal, state, and local representatives to develop a list of business requirements from which they built a plan for the Web site. The main goal was to meet the needs and levels of the Web site's users.

The Web Soil Survey application is built using Esri ArcIMS, ArcGIS Server, and ArcSDE software. The server software is being fully integrated with the soil survey's master database, which contains all soil information on a national basis. ArcIMS is the front end for delivering the application, while ArcGIS Server delivers the information. In addition, Esri's ArcWeb Services provide address-finding functionality; the user types in an address and ArcWeb Services return the map view of that area.

The Web Soil Survey is an application suite. A front-end application accesses the Soil Data Mart, which is the centralized repository of the Web Soil Survey's spatial and tabular soil data that keys in to the Web site. The GIS application Soil Data Viewer renders soil interpretations on a color map.

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Web Soil Survey allows the user to select any location in the United States and access available soil information, suitability levels, and property potential. Here the Web site user assesses an area for potential cotton lint yield.

Because the Web site provides single-point access, the user can access available historical and current soil survey data. Traditional publications created during the past years are available as PDFs for viewing or downloading for selected areas. On the interactive GIS map, the user can outline an area of interest (from 3 to 10,000 acres) and select a usage option. The application provides suitability levels of the area for the selected land use.

The Soil Data Mart is the authoritative soil survey data source. It ensures that users will get a consistent view of the data whether from the county office, the state office, or the Web. A transactional database is routinely maintained by soil scientists throughout the United States who keep the data up to date for every county in the nation. Earlier dataset versions are maintained in the warehouse and made available for other analyses, such as temporal comparisons. NRCS also employs various Web services for access to plant information, ecological site data, and local county offices' maps and information.

The soil survey is a collaborative effort requiring a set of standards to support data integration. Jim Fortner, USDA soil scientist at the National Soil Survey Center, explains, "The National Cooperative Soil Survey program is a collection of federal agencies, state partners, and local partners. A standard data model is established for collecting data. We are working with these agencies to collect site data. NRCS manages the soil survey database for all partners."

The Web Soil Survey offers approximately 50 national standard interpretations. Users can select interpretations, such as installing a septic tank or sewage lagoon, building a house, or determining production potential of different types of crops. For example, a farmer considering purchasing a farm from a choice of three options wants to evaluate which farm will best suit his needs. Using the Web Soil Survey, he locates each farm on an interactive map and selects an interpretation, such as cotton lint, and the application accesses the database soil types to indicate which farm would be most productive. The information includes the criteria used to generate the interpretation, a breakdown of all the different soil components within the interpretations, and the suitability and limiting factors. A color-coded spatial representation gives the farmer an idea of the selected properties' levels of suitability: Suited, Some Limitations, and Not Suited.

Other rating interpretations are land applications for different wastewaters, including water treatment plants; different land applications methods; productivity of cropland, rangeland, and forestland; and suitability for different recreational developments, such as paths and trails, campsites, and picnic grounds. Sanitary facility site interpretations include landfill and the material for covering the landfill. Urban interpretations help city and county officials manage development. A user considering building a house can find information that may lead to reinforcing a building's foundation. Other interpretations are useful for road construction, tax assessment, and a number of other user needs.

Adding new functionalities to the Web Soil Survey project is a constant endeavor. Dennis Williamson, state GIS specialist for NRCS Texas, explains, "Eventually, USDA customers will be able to log in to their USDA case files and drop in information, such as property boundaries, for quick access to information about selected properties in their files."

Other enhancements on the immediate horizon are adding a scale bar and a tool to zoom to a stated scale. Some states use the Public Land Survey System, based on township, section, and range, so a function will be added to apply these definitions for navigating the map.

The Web Soil Survey is the beginning of a new era for NRCS and delivery of soil survey information. The feedback on the site has been extremely favorable. The Web Soil Survey administrators have already received a great number of compliments from Web site users. One enthusiastic Web site visitor exclaims, "The Web Soil Survey may be the greatest program that the federal government has ever provided!"

For more information, visit the Web Soil Survey at

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