This data set consists of georeferenced digital map data and computerized attribute data. The map data are in a 7.5 minute quadrangle format and include a detailed, field verified inventory of soils and nonsoil areas that normally occur in a repeatable pattern on the landscape and that can be cartographically shown at the scale mapped. A special soil features layer (point and line features) is optional. This layer displays the location of features too small to delineate at the mapping scale, but they are large enough and contrasting enough to significantly influence use and management. The soil map units are linked to attributes in the Map Unit Interpretations Record relational database, which gives the proportionate extent of the component soils and their properties.
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 is public information and 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 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.
Photographic or digital enlargement of these maps to scales greater than at which they were 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 from them do not eliminate the need for onsite sampling, testing, and detailed study of specific sites for intensive uses. Thus, these data and their interpretations are intended for planning purposes only. Digital data files are periodically updated. Files are dated, and users are responsible for obtaining the latest version of the data.
Soil scientists identify small areas of soils or miscellaneous (nonsoil) areas that have properties and behavior significantly different than the named soils in the surrounding map unit. These minor components may be indicated as special features. If they have a minimal effect on use and management, or could not be precisely located, they may not be indicated on the map.
Specific National Cooperative Soil Survey standards and procedures were used in the classification of soils, design and name of map units, and location of special soil features. These standards are outlined in Agricultural Handbook 18, Soil Survey Manual, 1993, USDA, SCS; Agricultural Handbook 436, Soil Taxonomy, Soil Survey Staff, 1975, USDA, SCS; and all Amendments; Keys to Soil Taxonomy, Soil Survey Staff, (current issue); National Soil Survey Handbook, title 430-VI, 1997.
The actual composition and interpretive purity of the map unit delineations were based on data collected by scientists during the course of preparing the soil maps. Adherence to National Cooperative Soil Survey standards and procedures is based on peer review, quality control, and quality assurance. Quality control is outlined in the memorandum of understanding for the soil survey area and in documents that reside with the Natural Resources Conservation Service state soil scientist. Four kinds of map units are used in soil surveys: consociations, complexes, associations, and undifferentiated groups.
Consociations - Consociations are named for the dominant soil. In a consociation, delineated areas are dominated by a single soil taxon and similar soils. At least one half of the pedons in each delineation are of the same soil component so similar to the named soil that major interpretations are not affected significantly. The total amount of dissimilar inclusions of other components in a map unit generally does not exceed about 15 percent if limiting and 25 percent if nonlimiting. A single component of a dissimilar limiting inclusion generally does not exceed 10 percent if very contrasting.
Complexes and associations - Complexes and associations are named for two or more dissimilar components with the dominant component listed first. They occur in a regularly repeating pattern. The major components of a complex cannot be mapped separately at a scale of about 1:24,000. The major components of an association can be separated at a scale of about 1:24,000. In each delineation of either a complex or an association, each major component is normally present, though their proportions may vary appreciably from one delineation to another. The total amount of inclusions in a map unit that are dissimilar to any of the major components does not exceed 15 percent if limiting and 25 percent if nonlimiting. A single kind of dissimilar limiting inclusion usually does not exceed 10 percent.
Undifferentiated groups - Undifferentiated groups consist of two or more components that do not always occur together in the same delineation, but are included in the same named map unit because use and management are the same or similar for common uses. Every delineation has at least one of the major components and some may have all of them. The same principles regarding proportion of inclusions apply to undifferentiated groups as to consociations.
Minimum documentation consists of three complete soil profile descriptions that are collected for each soil added to the legend, one additional per 3,000 acres mapped; three 10 observation transects for each map unit, one additional 10 point transect per 3,000 acres.
A defined standard or level of confidence in the interpretive purity of the map unit delineations is attained by adjusting the kind and intensity of field investigations. Field investigations and data collection are carried out in sufficient detail to name map units and to identify accurately and consistently areas of about .2 acres.
For example, on long gently sloping landscapes the transition occurs gradually over many feet. Where landscapes change abruptly from steep to level, the transition will be very narrow. Soil delineation boundaries and special soil features generally were digitized within 0.01 inch of their locations on the digitizing source. The digital map elements are edge matched between data sets. The data along each quadrangle edge are matched against the data for the adjacent quadrangle. Edge locations generally do not deviate from centerline to centerline by more than 0.01 inch.
The map unit symbol uniquely identifies each closed delineation map unit. Each symbol is linked to a map unit name. The map unit symbol is also the key for linking information in the Map Unit Interpretations Record tables. The map unit symbols are not carried within the modified Digital Line Graph file; however, they are made available in a companion attribute file. The attribute file links the minor codes in the Digital Line Graph files to the map unit symbols.
Map Unit Delineations are described by the Map Unit Interpretations Record database. This attribute database gives the proportionate extent of the component soils and the properties for each soil. The database contains both 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 soil Map Unit Interpretations Record database consists of the following relational tables: codes (database codes) - stores information on all codes used in the database comp (map unit component) - stores information for soil map unit components compyld (component crop yield) - stores crop yield information for soil map unit components forest (forest understory) - stores information for plant cover as forest understory for soil map unit components helclass (highly erodible lands class) - stores the highly erodible land classification for wind and water assigned to the soil map units. Table not populated. hydcomp (hydric component information) - stores data related to the hydric classification, criteria, landform, etc. inclusn (map unit inclusion) - stores the names of soils included in the soil map units interp (interpretation) - stores soil interpretation ratings (both limitation ratings and suitability ratings) for soil map unit components layer (soil layer) - stores characteristics of soil layers for soil map unit components mapunit (map unit) - stores information that applies to all components of a soil map unit mucoacre (map unit county acres) - stores the number of acres for the map unit within a county muyld (map unit yield) - stores crop yield information for the soil map unit plantcom (plant composition) - stores plant symbols and percent of plant composition associated with components of a soil map unit. Table not populated. plantnm (plant name) - stores the common and scientific names for plants used in the database rangenm (range name) - stores the range site names. Table not populated. rsprod (range site production) - stores range site production information for soil map unit components. Table not populated. ssacoac (soil survey area county acreage) - stores the acreage for the county within the boundary of the soil survey area ssarea (soil survey area) - stores information that will apply to an entire soil survey area taxclass (taxonomic classification) - stores the taxonomic classification for soils in the database windbrk (windbreak) - stores information on recommended windbreak plants for soil map unit components wlhabit (wildlife habitat) - stores wildlife habitat information for soil map unit components woodland (woodland) - stores information on common indicator trees for soil map unit components woodmgt (woodland management) - stores woodland management information for soil map unit components yldunits (yield units) - stores crop names and the units used to measure yield
Special features are described in the feature table. It includes a feature label, feature name, and feature definition for each special and ad hoc feature in the survey area.
U.S. Department of Agriculture. 1992. Keys to Soil Taxonomy. Soil Surv. Staff, Soil Conserv. Serv.
U.S. Department of Agriculture. 1993. National Soil Survey Handbook, title 430-VI. Soil Surv. Staff, Natural Resources Conservation Service.
U.S. Department of Agriculture. 1993. Soil Survey Manual. Soil Surv. Staff, U.S. Dep. Agric. Handb. 18.
U.S. Department of Agriculture. 1994. Soil Survey Geographic (SSURGO) Data Base: Data use information. Soil Conserv. Serv.
U.S. Department of Agriculture. State Soil Survey Database Data Dictionary. Soil Conserv. Serv.
Detail Description
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 its 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.)