The following is excerpted from information provided by the USDA, NRCS:
"This data set is a digital soil survey and generally is 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 planimetrically correct base and digitizing, or by revising digitized maps using remotely sensed and other information.
"This data set consists of georeferenced digital map data and computerized attribute data. The map data are in a soil survey area extent format and 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. 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 National Soil Information System relational database, which gives the proportionate extent of the component soils and their properties."
The following is excerpted from information provided by the USDA, NRCS:
"SSURGO depicts information about the kinds and distribution of soils on the landscape. The soil map and data used in the SSURGO product were prepared by soil scientists as part of the National Cooperative Soil Survey."
This data set was compiled by Indiana University, Indiana Geological Survey, using data believed to be accurate; however, a degree of error is inherent in all data. This product is distributed "AS-IS" without warranties of any kind, either expressed or implied, including but not limited to warranties of suitability to a particular purpose or use. No attempt has been made in either the design or production of these data to define the limits or jurisdiction of any federal, state, or local government. These data are intended for use only at the published scale or smaller and are for reference purposes only. They are not to be construed as a legal document or survey instrument. A detailed on-the-ground survey and historical analysis of a single site may differ from these data.
CREDIT:
It is requested that the dataset be cited in any products generated from this data. The following source citation should be included: [Soils_Deep_Horizon_Texture_SSURGO_USDA_IN: Soil Survey Geographic (SSURGO) Database for Indiana, 2012, (U.S. Department of Agriculture, 1:12,000, Geodatabase Polygon Feature Class)].
WARRANTY:
Indiana University, Indiana Geological Survey warrants that the media on which this product is stored will be free from defect in materials and workmanship for ninety (90) days from the date of acquisition. If such a defect is found, return the media to Publication Sales, Indiana Geological Survey, 611 North Walnut Grove Ave., Bloomington, Indiana 47405 2208, and it will be replaced free of charge.
LIMITATION OF WARRANTIES AND LIABILITY:
Except for the expressed warranty above, the product is provided "AS IS", without any other warranties or conditions, expressed or implied, including, but not limited to, warranties for product quality, or suitability to a particular purpose or use. The risk or liability resulting from the use of this product is assumed by the user. Indiana University, Indiana Geological Survey shares no liability with product users indirect, incidental, special, or consequential damages whatsoever, including, but not limited to, loss of revenue or profit, lost or damaged data or other commercial or economic loss. Indiana University, Indiana Geological Survey is not responsible for claims by a third party. The maximum aggregate liability to the original purchaser shall not exceed the amount paid by you for the product.
"The attribute 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 amendment(s)."
It should also be noted that SSURGO data for each county are collected separately, therefore inconsistencies in soil attributes may exist across county lines due to differences in interpretations made by soil scientists who collected the data.
"Certain node/geometry and topology GT- polygon/chain relationships 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 are free of gaps. The tests of logical consistency are performed using vendor software. 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 (i.e., adjacent polygons with the same label). Edge locations generally do not deviate from centerline to centerline by more than 0.01 inch.
"The Soil Survey of Adams County, Indiana is edge matched to the adjacent SSURGO certified Soil Surveys of Allen County, Indiana, Van Wert County, Ohio and Mercer County, Ohio. The soil labels in Adams County do not match the labels in the adjacent surveys. Most of the feature edges in Adams County do not match the feature edges in the adjacent surveys. The soil survey boundary for Adams County matches the Indiana county boundary coverage that is archived at the Soil Data Mart. The soil survey area boundaries match."
"A map unit is a collection of areas defined and named in terms of their soil components or miscellaneous areas or both. Each map unit differs in some respect from all others in a survey area and each map unit has a symbol that uniquely identifies the map unit on a soil map. Each individual area, point, or line so identified on the map is a delineation.
"Soil Scientists identify small areas of soils or miscellaneous 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.
"A map unit has specified kinds of soils or miscellaneous areas (map unit components), each with a designated range in proportionate extent. Map units include one or more kinds of soil or miscellaneous area. Miscellaneous areas are areas that have little or no recognizable soil.
"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, NRCS; Agricultural Handbook 436, Soil Taxonomy, 1995, USDA, NRCS; and all Amendments; Keys to Soil Taxonomy, (current issue) USDA, NRCS; National Soil Survey Handbook, title 430-VI,(current issue) USDA, NRCS.
"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 use a single name from the dominant component in the map unit. Dissimilar components are minor in extent. The soil component in a consociation may be identified at any taxonomic level. Soil series is the lowest taxonomic level. A consociation that is named as a miscellaneous area is dominantly that kind of area and minor components do not significantly affect the use of the map unit. 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 consist of two or more dissimilar components that occur in a regularly repeating pattern. The total amount of other dissimilar components is minor extent. The following arbitrary rule determines whether complex or association is used in the name. The major components of an association can be separated at the scale of mapping. In either case, because the major components are sufficiently different in morphology or behavior, the map unit cannot be called a consociation. In each delineation of 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 are not consistently associated geographically and, therefore, do not always occur together in the same map delineation. These components are included in the same named map unit because their use and management are the same or very similar for common uses. Generally they are grouped together because some common feature, such as steepness, stoniness, or flooding, determines their use and management. If two or more additional map units would serve no useful purpose, they may be included in the same unit. Each delineation has at least one of the major components, and some may have all of them. The same principles regarding the proportion of minor components that apply to consociations also apply to undifferentiated groups. The same principles regarding proportion of inclusion 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."
"The accuracy of these digital data is based upon their compilation to base maps that meet National Map Accuracy Standards at a scale of 1 inch equals 1,000 feet. The difference in positional accuracy between the soil boundaries and special soil features locations in the field and their digitized map locations is unknown. The locational accuracy of soil delineations on the ground varies with the transition between map units.
"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."
"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 2.5 acres."
STEP 1 - AGGREGATING THE SOIL SURVEY TABULAR DATA FILES:
Soildb_IN_2002.zip was opened and a file named "soildb_IN_2002.mdb" was extracted. Soildb_IN_2002.mdb is a Microsoft Access database template constructed by the NRCS to aid in importing and utilizing the soil survey tabular data files. Soildb_IN_2002.mdb was opened and a preexisting form was used to import all tabular data from the tabular folder for a single county (soil survey area). The same process of importing was run for the remaining 91 counties in Indiana and the file was then renamed SSURGO_SoilsDB_Indiana_AllCounties_2012.mdb.
STEP 2 - AGGREGATING THE SOIL SURVEY SPATIAL DATA FILES:
The "spatial" folder for each county contained an ESRI polygon shapefile named "soilmu_a_[soil survey area].shp," which contains the soil survey map unit boundaries. Basic attributes inside these shapefiles include the following: serial version of the data (field named "SPATIALVER"), soil survey area (field named "AREASYMBOL"), map unit symbol (field named "MUSYM"), and mapunit key (field named "MUKEY"). The shapefiles for all 92 counties (soil survey areas) in Indiana were loaded into ESRI ArcMap (10.0). ArcToolBox was opened and the "Merge" tool was then used to produce a single state-wide polygon feature class named "SSURGO_Indiana_AllCounties_2012" into the File Geodatabase named INDIANA_SSURGO_2012.GDB.
SSURGO_SoilsDB_Indiana_AllCounties_2012.mdb was opened and the following steps outline the process by which a single horizon record was isolated for each map unit.
STEP 1 - SELECTION OF DESIRED ATTRIBUTES:
In SSURGO_SoilsDB_Indiana_AllCounties_2012.mdb, a custom query named "a1_text_all2" was designed by IGS personnel to extract the fields needed to create this data set, into a table named "SSURGO_Soil_Properties_IN." These included the fields relating to soil texture characteristics that would ultimately be joined to polygons within the "SSURGO_Indiana_AllCounties_2012" layer (field names: "texture," "texdesc," "sandtotal_r," "silttotal_r," "claytotal_r," "geomdesc," and "pmgroupname", along with fields that serve to identify a particular horizon and its depth range (field names: "mukey," "muname," "hzname," "hzdept_r," and "hzdepb_r"). An additional three fields ("comppct_l", "comppct_r", and "comppct_h") were extracted to be used only as selection criteria in a subsequent step below. Also, two fields ("comppct_avg" and "depthdif") were calculated by IGS personnel to be used as selection criteria. How they were derived is shown below.
"comppct_avg" = (("comppct_l" + "comppct_h")/2)
"depthdif" = ("hzdepb_r" - "hzdept_r")
STEP 2 - SELECTING THE DEEPEST SOIL HORIZONS, BASED ON THE HORIZON BOTTOM DEPTH FIELD:
IGS personnel designed another query named "a2_text_bot_try7" to begin isolating attributes pertaining to the deepest horizon record from the table named "SSURGO_Soil_Properties_IN." This query utilized the "Max()" function to the attribute field named "hzdepb_r." This refined the data such that only the deepest horizon records (those with the largest "hzdepb_r" values) were returned. This query successfully refined the horizon data to a single record per map unit for 21 of the counties, but failed to achieve the desired results for the remaining 71 counties because some map units had more than one record for the deepest horizon. The field named "METHOD" indicates whether the data for a map unit was successfully refined during this step using the string value: "STEP 2."
STEP 3 - SELECTING HORIZONS BELONGING TO SOIL COMPONENTS THAT REPRESENT THE LARGEST PERCENTAGE OF THEIR RESPECTIVE MAP UNITS, BASED ON THE REPRESENTATIVE COMPONENT FIELD:
For all map units where the previous query (STEP 2) returned multiple records for the deepest horizon, IGS personnel designed another query named "a2_text_bot_try7pt2" to select the horizon record that belongs to the component having the largest value (the "Max()" function was used) in the field named "comppct_r" (which is the percentage of a map unit covered by a component). This step successfully refined horizon records for an additional 51 counties, but there remained 20 counties where this query failed to achieve the desired results because multiple components shared the same maximum value in the "comppct_r" field, or the field was null. The field named "METHOD" indicates whether the data for a map unit was successfully refined during this step using the string value: "STEP 3."
STEP 4 - SELECTING HORIZONS BELONGING TO SOIL COMPONENTS THAT REPRESENT THE LARGEST PERCENTAGE OF THEIR RESPECTIVE MAP UNITS, BASED ON THE AVERAGE COMPONENT PERCENTAGE FIELD:
For all mapunits where the previous query (STEP 3) returned multiple records for the deepest horizon, IGS personnel then designed another custom query named "a2_text_bot_try7pt3." This step selected records based on the maximum values from the calculated field named "comppct_avg," which is the average of the fields named "comppct_l" and "comppct_h". The fields "comppct_l" and "comppct_h" can be thought of as a range where "comppct_l" is the lowest estimation of the area that a component might cover in its respective map unit, and "comppct_h" is the highest estimation. The percentage value contained in the field named "comppct_r" falls within this range and has been deemed by USDA soil scientists to be the expected percentage that a component comprises of its respective mapunit, therefore earning the "representative" designation. Taking the average of "comppct_l" and "comppct_h" produces a value similar to "comppct_r" in that the resultant value also lies somewhere within the range of the high and low percentage values. In fact, there were some instances where the "comppct_avg" value equaled the "comppct_r" value exactly, and the query thus failed to refine the results any further. However, for the components where the "comppct_avg" value was even slightly different than the "comppct_r" value, this query was able to further refine the horizon records. Using this criterion, an additional two counties were successfully refined (with 18 counties remaining). This criterion failed when none of the horizon records belonged to a component with a "comppct_avg" value larger than the others. The field named "METHOD" indicates whether the data for a map unit was successfully refined during this step using the string value: "STEP 4."
STEP 5 - SELECTING THE THICKEST HORIZON, BASED ON THE DIFFERENCE BETWEEN THE TOP & BOTTOM HORIZON DEPTH FIELDS:
For all map units where the previous query (STEP 4) returned multiple records for the deepest horizon, IGS personnel then designed another custom query named "a2_text_bot_try7pt4" to select the horizon records with the maximum value in the calculated "depthdif" field, which is essentially the thickness of a horizon. In other words, this filter selected the thickest remaining horizon records to represent the soil characteristics of their respective map units. This query achieved the desired results for the remaining counties, leaving only a few instances where a single horizon record wasn't isolated for a map unit. These were addressed manually, selecting the horizons at greater depths. The field named "METHOD" indicates whether the data for a map unit was successfully refined during this step using the string value: "STEP 5."
STEP 6 - PRODUCE TABLE CONTAINING THE HORIZON RECORDS ISOLATED BY PREVIOUS QUERY RESULTS
The final results produced in STEP 5 by the query named "a2_text_bot_try7pt4" were made into a table named "SSURGO_Texture_AllCounties_2012" within the database named "SSURGO_SoilsDB_Indiana_AllCounties_2012."
The "MUNAME" field for map units lacking soils data, for any of the reasons (1-3) below, was standardized to have the values: "Water," "Disturbed Areas/Urban Land," "Pits/Quarries/Mining Regolith, and "Unweathered Sand Deposits." Map units that fall into these categories will have null values in the soil attribute fields.
1) No soil exists because the map unit represents an area of water, unweathered sand deposits (psamments), pits, or mining activity. 2) Soil horizons have been disturbed by construction (namely udorthents). 3) Soil samples could not be taken due to urban landcover.
The table named "SSURGO_Texture_AllCounties_2012" was then exported from the database as a dBASE file with the truncated title "TEXTURE."
The polygon feature class named "SSURGO_Indiana_AllCounties_2012" was loaded into ESRI ArcMap, and the table named "TEXTURE" was imported. The "Join" function was then used to add the attributes to the polygons in SSURGO_Indiana_AllCounties_2012 based on their common "MUKEY" field. SSURGO_Indiana_AllCounties_2012 was then exported as a new feature class named "SSURGO_Mapunits_w_Texture_Properties" to the file geodatabase INDIANA_SSURGO_2012.gdb.
An attribute field ("COUNTY") was added to SSURGO_Mapunits_w_Texture_Properties identifying the location of each map unit by county. This field was populated using a spatial join operation between SSURGO_Mapunits_w_Texture_Properties and a polygon shapefile of Indiana county boundaries titled "Landsurvey_County_Poly_IN.shp" (IGS). SSURGO_Mapunits_w_Texture_Properties was then exported as a new feature class named "Soils_Deep_Horizon_Texture_SSURGO_USDA_IN_Singlepart" to the file geodatabase INDIANA_SSURGO_2012.gdb.
The "Dissolve" tool in ArcToolbox was applied to Soils_Deep_Horizon_Texture_SSURGO_USDA_IN_Singlepart based on the field named "MUKEY" and with the "Create multipart features" option selected. The output of the operation was a new polygon feature class with the name "Soils_Deep_Horizon_Texture_SSURGO_USDA_IN," which was placed into the file geodatabase named "INDIANA_SSURGO_2012.gdb." This operation aggregated all components with the same values in the "MUKEY" field into single, multipart polygon features. Execution of the "Dissolve" tool reduced the polygon feature count from 1,330,079 to 6,597.
"Map Unit Delineations are closed polygons that may be dominated by a single soil or miscellaneous area component plus allowable similar or dissimilar soils, or they can be geographic mixtures of groups of soils or soils and miscellaneous areas.
"The map unit symbol uniquely identifies each closed map unit delineation. Each symbol corresponds to a map unit name. The map unit key is used to link to 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 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 National Soil Information System database contains static metadata. It documents the data structure and includes such information as what tables, columns, indexes, and relationships 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 a distribution metadata. It records the criteria used for selecting map units and components for inclusion in the set of distributed data.
"Special features are described in the feature table. It includes an area symbol, feature label, feature name, and feature description for each special and ad hoc feature in the survey area."
Keys to Soil Taxonomy (current issue), USDA, SCS.
National Soil Survey Handbook, Title 430-VI, part 647 (current issue), USDA, NRCS.
Agricultural Handbook 18, Soil Survey Manual, 1993, USDA, SCS.
It is requested that the data set be cited in any products generated from this data. The following source citation should be included: [Soils_Deep_Horizon_Texture_SSURGO_USDA_IN: Soil Survey Geographic (SSURGO) Database for Indiana, 2012, (U.S. Department of Agriculture, 1:12,000, Geodatabase Polygon Feature Class)].
WARRANTY:
Indiana University, Indiana Geological Survey warrants that the media on which this product is stored will be free from defect in materials and workmanship for ninety (90) days from the date of acquisition. If such a defect is found, return the media to Publication Sales, Indiana Geological Survey, 611 North Walnut Grove Ave., Bloomington, Indiana 47405 2208, and it will be replaced free of charge.
LIMITATION OF WARRANTIES AND LIABILITY:
Except for the expressed warranty above, the product is provided "AS IS", without any other warranties or conditions, expressed or implied, including, but not limited to, warranties for product quality, or suitability to a particular purpose or use. The risk or liability resulting from the use of this product is assumed by the user. Indiana University, Indiana Geological Survey shares no liability with product users indirect, incidental, special, or consequential damages whatsoever, including, but not limited to, loss of revenue or profit, lost or damaged data or other commercial or economic loss. Indiana University, Indiana Geological Survey is not responsible for claims by a third party. The maximum aggregate liability to the original purchaser shall not exceed the amount paid by you for the product.