The Soils datalayer has been automated from published soils surveys as provided on various media by the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). All soils data released by MassGIS have been "SSURGO-certified," which means they have been reviewed and approved by the NRCS and meet all standards and requirements for inclusion in the national release of county-level digital soils data. Soil survey areas are roughly based on county boundaries.
The SSURGO-certified soils dataset is generally the most detailed level of soil geographic data developed by the National Cooperative Soil Survey. The information was prepared by digitizing maps, by compiling information onto a planimetric correct base and digitizing, or by revising digitized maps using remotely sensed and other information. The data include a detailed, field verified inventory of soils and miscellaneous areas that normally occur in a repeatable pattern on the landscape and that can be cartographically shown at the scale mapped. Data for survey areas were developed using various scale base maps: some areas at a 1:25,000 or 1:12,000 scale, or at larger scales where source materials (e.g. 1:5,000 MassGIS ortho imagery) were available. Details for a specific survey area are provided in the NRCS-produced metadata that are distributed with the spatial data.
The soil map units are linked to attributes in the National Soil Information System (NASIS) relational database, which gives the proportionate extent of the component soils and their properties.
At MassGIS the soils datalayer is stored in ArcSDE for Oracle as the statewide feature class SOILS_POLY. Two companion layers, SOILSPOT_PT and SOILSPOT_ARC, represent "special" or "ad hoc" features such as gravel pits, wet areas, bedrock escarpments and others. These layers display 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.
With the November 2012 update, soils data are available statewide.
Maps that use NRCS SSURGO data must show the source (NRCS) and date and, space permitting, contain the following notation:
"This Soil Survey Geographic (SSURGO) data base was produced by the U.S. Department of Agriculture, Natural Resources Conservation Service and cooperating agencies for the Soil Survey of _______ County, (state). The soils were mapped at a scale of ______ with a _______ acre minimum size delineation. Enlargement of these maps to scales greater than that at which they were originally mapped can cause misunderstanding of the detail of mapping. If enlarged, maps do not show the small areas of contrasting soil that could have been shown at a larger scale. The depicted soil boundaries and interpretations derived from them do not eliminate the need of onsite sampling, testing, and detailed study of specific sites for intensive uses. Thus, this map and its 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."
Scale and minimum mapping unit, along with all other details of production and editing of both the spatial and attribute data, may be found in the FGDC-style metadata produced for each survey area by NRCS. These metadata files (in plain text format) are distributed with the data by MassGIS.
Limitations on Use
This data set is not designed for use as a primary regulatory tool in permitting or siting 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.
Each SOILS_POLY polygon contains the following fields:
|MUSYM||Map Unit symbol. This field is included in data distributed by NRCS from the SSURGO Data Mart Web site and uniquely identifies each closed delineation mapunit.|
|MUKEY||Map Unit Key for linking information in the National Soil Information System (NASIS) tables. This field is included in data distributed by NRCS from the SSURGO Data Mart Web site.|
|SS_AREA||Abbreviation for soil survey area (MassGIS added this field):
|MUSYM_AREA||Concatenation of MUSYM and SS_AREA, to correlate the map unit symbol to its soil survey area. In some cases, a mapunit may have different properties in different survey areas. Useful for some table joins. MassGIS added this field.|
|SLOPE||Slope of the landscape, derived from the last character of the MUSYM field, if present. MassGIS added this field. Possible SLOPE codes are:
Each special/ad hoc feature (SOILSPOT_ARC and SOILSPOT_PT) contains the following fields:
|AREASYMBOL||The identifying symbol given to the specified geographic area to which the legend applies.|
|SPATIALVER||A sequential integer number used to denote the serial version of the spatial data for a soil survey area.|
|FEATSYM||A symbol that, within the context of a particular soil survey area, uniquely identifies a point or line spot feature. Current codes include:
|FEATKEY||A non-connotative string of characters used to uniquely identify a record in the Feature Description table.|
|SS_AREA||Abbreviation of the survey area (field added by MassGIS)|
|LABEL||Equal to the FEATSYM field, kept in the data distributed by MassGIS for legacy application purposes.|
Soils Survey Area Index
The SOILSTAT_POLY attribute table contains the following fields storing status information for each survey area:
|SS_AREA||Abbreviation of the survey area|
|SURVEY_ARE||Full survey area name|
|COUNTY||County name (the survey area may comprise part of a county)|
Current STATUS and STATUS_DESC values, all coded as:
SC - SSURGO CERTIFIED (Available for distribution)
|URL||Link to download soils data for the area|
View the Soils Survey Area Index
At the beginning of the soils data production project at MassGIS, editing was done based on 1/3-USGS Quad tiles. The index for these tiles is stored in ArcSDE in the polygon layer SOILINDEX_POLY. Status for each 13-quad was tracked in the table SOILINDEX_POLY_STATUS. Once production shifted to NRCS offices the 1/3-quad layer and table were no longer used.
Prime Farmland Soils
In ArcSDE, MassGIS has created the spatial view SOILS_POLY_PRIMEFARMLAND, based on the FARMLNDCL field in the SOILS_POLY_MAPUNIT table.
The layer is comprised of three important farmland categories. Urban built-up land and water are excluded from all three categories, but forested lands are included in all three categories if they meet the appropriate criteria.
The data for each of the 13 soil surveys was acquired and compiled over various time periods. Since then, development of important farmland soils has occurred in some areas and that land is no longer available for agriculture.
Categories of prime farmland include:
|Prime Farmland||Land that has the best combination of physical and chemical characteristics for economically producing sustained high yields of food, feed, forage, fiber, and oilseed crops, when treated and managed according to acceptable farming methods.|
|Farmland of Unique Importance||Land other than prime farmland or farmland of statewide importance that might be used for the production of specific high value food and fiber crops. Examples of such crops are tree nuts, cranberries, fruit, and vegetables. In Massachusetts, Unique soils are confined to mucks, peats, and coarse sands. Cranberries are the primary commercial crop grown on these soils. The presence of other crops on these soils is usually, possibly always, limited to small, incidental areas.|
|Farmland of Statewide Importance||This is land, in addition to prime and unique farmlands, that is of statewide importance for the production of food, feed, fiber, forage, and oil seed crops, as determined by the appropriate state agency or agencies. Generally, these include lands that are nearly prime farmland and that economically produce high yields of crops when treated and managed according to acceptable farming methods.|
To create this theme using shapefiles or personal geodatabase feature classes, join SOILS_POLY to SOILS_POLY_MAPUNIT on the MUKEY field and display on FARMLNDCL
Related Database Tables
These tables are contained in Microsoft Access 2000 databases (one for each available survey area) created by NRCS and which conform to the SSURGO II National Soil Information System (NASIS) attribute structure. 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 Access databases are available by clicking on the "Download this layer" link at the top of this page (this will take you to the Oliver Soils Index selector, and the Access databases are contained in each download Zip file). When the Access databases are first opened, a Soil Reports form appears that allows the user to quickly query the database and create a report for that survey area. For descriptions of the Access tables, see the "SSURGO Metadata" reports inside each Access database.
For documentation of all the tables in the Access databases see the NRCS website.
In the ArcSDE database internal to MassGIS, combined tables exist for the following relational tables:
|Table Name||Description||What it Contains|
|SOILS_POLY_COCROPYLD||Component Crop Yield||Lists commonly grown crops and their expected range in yields when grown on the referenced map unit component. Yields for the map unit as a whole are given in the Mapunit Crop Yield table (SOILS_POLY_MUCROPYLD).|
|SOILS_POLY_COFORPROD||Component Forest Productivity||Lists the site index and the annual productivity in cubic feet per acre per year (CAMI) of forest overstory tree species that typically occur on the referenced map unit component.|
|SOILS_POLY_COHYDRICCRITERIA||Component Hydric Criteria||Lists the hydric soil criteria met for those referenced map unit components that are classified as a "hydric soil."|
|SOILS_POLY_COINTERP||Component Interpretation||Lists the predictions of behavior and limiting features for specified uses made for the referenced map unit component.|
|SOILS_POLY_COMONTH||Component Month||Lists the monthly flooding and ponding characteristics for the referenced map unit component. This table has one row for each month of the year for each component key.|
|SOILS_POLY_COMPONENT||Map Unit Component||Lists the map unit components identified in the referenced map unit, and selected properties of each component.|
|SOILS_POLY_COPWINDBREAK||Component Potential Windbreak||Lists the windbreak plant species commonly recommended for the referenced map unit component. A windbreak plant listed in this table may be used alone or in combination with other plants.|
|SOILS_POLY_CORESTRICTIONS||Component Restrictions||Lists the root restrictive feature(s) or layer(s) for the referenced map unit component.|
|SOILS_POLY_COSOILMOIST||Component Soil Moisture||Describes the typical soil moisture profile for the referenced map unit component during the month referenced in the Component Month table. The soil moisture profiles for each month, taken as a group of twelve months, describe the representative situation for the component throughout the year.|
|SOILS_POLY_COTREESTOMNG||Component Trees To Manage||Lists the trees commonly recommended for managing on the referenced map unit component.|
|SOILS_POLY_MAPUNIT||Mapunit||Identifies the map units included in the referenced legend. Data related to the map unit as a whole are also given. Includes map unit (MUSYSM) and map unit description (MUNAME) for all unique map units across the state.|
|SOILS_POLY_MUAGGATT||Mapunit Aggregated Attribute||Records a variety of soil attributes and interpretations that have been aggregated from the component level to a single value at the map unit level. They have been aggregated by one or more appropriate means in order to express a consolidated value or interpretation for the map unit as a whole.|
|SOILS_POLY_MUCROPYLD||Mapunit Crop Yield||Lists commonly grown crops and their expected yields for the referenced map unit as a whole. Yields for individual map unit components are given in the Component Crop Yield table (SOILS_POLY_COCROPYLD).|
|SOILS_POLY_MUTEXT||Mapunit Text||Notes and narrative descriptions related to the referenced map unit.|
These additional non-relational tables provide further information:
|SOILS_POLY_CODES*||Database codes||Stores information on all codes used in the database|
|SOILS_POLY_LEGEND||Summary information on all available survey areas||Survey area names, codes, total acreage, scale of data development|
|SOILS_POLY_MDSTATTABS||Table Static Metadata||Records metadata (names, descriptions, etc.) about the tables that make up the tabular data set in each Access database. Each record in this table represents one table.|
|SOILS_POLY_MDSTATTABCOLS*||Table Column Static Metadata||Table records the metadata for all columns of all tables that make up the tabular data set. Each record in this table represents one column of a particular table.|
The following table provides descriptions of the codes used in the SOILSPOT layers:
|SOILS_POLY_FEATURE||Special "spot"feature codes||Stores information on all codes used in the 'FEATSYM' and 'LABEL'fields in the SOILSPOT arc and point layers.|
* = MassGIS added additional 'Description' fields (254-character length) so that the full description in the original NRCS field may be represented in dBASE exported versions of these tables. The full description may span up to three fields in these tables.
For lists and descriptions of all the tables and the codes in the SSURGO 2 database, please refer to the SSURGO Metadata PDF documents found here.
What MassGIS Distributes
MassGIS distributes soils data online by survey area (see download link above). Soils data downloads include:
- Soils (polygons) and Special Features (points) in Shapefile format
- NASIS-formatted related tables in Microsoft Access 2000 databases inside self-extracting executables. These NASIS tables may be used to produce reports and generate thematic soils maps, and are necessary for use with NRCS Soil Data Viewer product (see the next section, Displaying the Data).
- FGDC-compliant metadata text files with specifics for each survey area (such as dates of compilation and other details).
Displaying the Data
The soils polygons have very few attributes. Users should have a solid understanding of the many related data tables (listed above) to properly map and analyze these data.
To decipher the many ways in which the soils data may be interpreted and displayed, using the related tables, USDA/NRCS has developed the Soil Data Viewer, a free extension for ArcGIS 8.3, 9.0/9.1, and 9.2, 10 and 10.1.
Visit the Soil Data Viewer page and click on "Download and Install Soil Data Viewer." It works with the soils data available from MassGIS for one survey area at a time.
In addition, NRCS has an online soils viewer ("Web Soil Survey") that displays a number of user-specified characteristics of soils. See http://websoilsurvey.nrcs.usda.gov/app/.
These datalayers are maintained by NRCS. With the November 2012 update, soils data are available statewide. MassGIS will download from NRCS any updates and incorporate them into MassGIS' database.
Further information is available in the form of documents produced and maintained by the NRCS. These documents include:
- SSURGO Metadata - documents, diagrams and reports describing the SSURGO standard, as well as the tools and procedures that are necessary to effectively use this data, can be found here.
- The National Soil Survey Handbook, a multi-chapter guide that provides the main operational and procedural guidance for the soil survey program. All Handbook chapters are viewable on the Web and available for download in Microsoft Word 6.0 format. Please visit this page for the handbook.
- The Soil Survey Manual, a single volume book which provides the major principles and practices needed for making and using soil surveys and for assembling and using data related to them. The Manual is intended primarily for use by soil scientists engaged in the classification and mapping of soils and in the interpretation of soil surveys. Although the Manual is oriented to the needs of those actively engaged in preparing soil surveys for publication, workers and students who have limited soils experience or are less familiar with the soil survey process also will be able to use the information. The Manual may be viewed in Microsoft Word and Adobe PDF formats on the web at this page.
- The NASIS (National Soil Information System) Web site at this page. NASIS consists of multiple interrelated soil applications and databases. This data system aids in the collection, storage, manipulation and dissemination of soil information.
- Massachusetts Soil Survey - The Web site http://nesoil.com/massachusetts_soil_survey.htm contains information on Massachusetts soils surveys, including detailed descriptions of soil map units.