1 Creating Statewide DHS Interpretation Maps with gSSURGO

2 There are two USDA websites relevant to this discussion of mapping with gSSURGO: The Geospatial Data Gateway The gSSURGO home page

3 The Geospatial Data Gateway is the official repository for gSSURGO databases (state-tiled) Begin by clicking on the ‘Order by State’ link in the lower right corner of the Geospatial Data Gateway homepage.

4 gSSURGO databases can be downloaded from the Geospatial Data Gateway. Begin by clicking on the ‘Order by State’ link in the lower right corner of the Data Gateway homepage. Scroll to the bottom of the list to find the ‘Soils’ group. Select ‘Gridded Soil Survey Geographic (gSSURGO)’ which resides under ‘Soils’. Download sizes can vary from a few megabytes to a few gigabytes.

5 An ArcToolbox for creating gSSURGO databases and creating soil maps can be downloaded from the gSSURGO homepage. The easiest way to find this page is open your preferred internet search engine and enter the terms ‘gSSURGO and NRCS’. Documentation for gSSURGO and for the ArcToolbox can be found on the page as shown below.

6 The ‘gSSURGO Mapping’ toolset is a part of the ‘Soil Data Development’ toolbox for gSSURGO and is compatible with ArcGIS Desktop versions 10.1 – Previously known as the ‘SSURGO Download’ tools. Other toolsets include ‘Download SSURGO’ and ‘gSSURGO Database’. These will not be covered in this presentation but are documented in the ‘Development User Guide.’

7 In the ArcMap screenshot below, we have two different soil layers along with some other reference layers in the Table of Contents (TOC). Soil maps can be created using the traditional soil polygon layer (Map Unit Polygons – WV) or the 10 meter raster layer (MapunitRaster_wv_10m). Notice that the raster layer is displayed on top with the default ‘Stretched’ values and the polygon layer is set to not display at this scale. This is for performance reasons.

The ‘Map Soil Properties and Interpretations’ tool can create soil maps in a similar manner as Soil Data Viewer. The user can select options to produce either soil interpretation maps or soil property maps. This presentation will focus on some specific soil interpretations for ‘Disaster Recovery Planning’, also known as DHS interpretations. These can be any interpretation that has been published to the public database. 8

The current version of the ‘Map Soil Properties and Interpretations’ tool has 15 parameters. Many of these parameters may be enabled or disabled, depending upon choices made above. Disabled parameters will be grayed-out. Most parameters will have a default setting. These normally do not be changed unless the user has a specific reason for doing so. 9

1 If a single soil polygon or raster layer containing MUKEY is found in the ArcMap table of contents (TOC), that layer will be automatically be displayed in the first parameter. If multiple soil layers are present in the TOC, the user will have to choose from the drop down menu. Soil maps based upon large raster layers will display more rapidly, but map symbology for unique values requires some work from the user. 10

2 The ‘SDV Folder’ parameter has 17 different choices. The ‘Wildlife Management’ choice at the bottom is not enabled. 11

All of the DHS interpretations are found by selecting ‘Disaster Recovery Planning’. 12 2

The “SDV Attribute” choice list is based upon the selection for “SDV Folder”. Selecting ‘Disaster Recovery Planning’ will display seven national DHS interpretations plus any state interpretations. In this screenshot, ‘Poultry Disposal by Composting’ is a West Virginia (WV) interpretation. 13 3

The “SDV Attribute” field has been set to ‘Poultry Disposal by Composting (Catastrophic)(WV)’. To exclude state interpretations from the choice list, check the option to “Display only National Interps” at the bottom of the menu. 14

13 PROBABLY SHOULD MOVE THIS DOWN. The Map Interp Fuzzy Values option will produce a soil map based upon fuzzy values rather than the rating class. Fuzzy ratings will range from 0 to

4 The choices for “Aggregation Method” will vary according to the selected ‘SDV Attribute”. Normally it is safe to leave this setting at the default value. For interpretations the default is almost always ‘Dominant Condition’ which looks at all component ratings and percentages to determine the map unit rating. 16

17 Below is an example of the console messages from the “Map Soil Properties and Interpretations” tool for ‘Poultry Disposal by Composting’. Always make sure that the “Close this dialog…” box is unchecked because these messages include important information such as: 1.Name of the input database 2.Output table containing the rating information used to create the map layer 3.Name and location of the layer file (.lyr) that preserves the original map layer joins and symbology.

18 Map created by the ‘Map Soil Properties and Interpretations’ tool for ‘Poultry Disposal by Composting’. Aggregation Method used: Dominant Condition Soil map layers created using the MapunitRaster will require the user to manually set the symbology. Raster symbology does not allow the user to reorder the map legend.

19 Map created by the ‘Map Soil Properties and Interpretations’ tool for ‘Poultry Disposal by Composting’. Aggregation Method used: Least limiting The ‘Least limiting’ aggregation method may bring forth map units having a component with a ‘Slightly’ or ‘Not limited’ rating not evident in the previous map. These would probably have a comppct < 50.

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22 This ArcTool does have the option to map the fuzzy values (0.0 – 1.0) rather than the rating classes. For this interpretation, ‘Slightly limited’ would be zero and 1.0 would be ‘Severely limited’.

23 Sometimes the standard interp map can be an overwhelming sea of red. This map focuses on the map unit polygons having one or more components with a ‘Slightly limited’ rating. Map legend is based upon the associated component percent.

24 Running the ‘Map Interpretation Reasons’ tool for ‘Poultry Disposal by Composting’.

25 Map created by the ‘Map Interpretation Reasons’ tool for ‘Poultry Disposal by Composting’. Aggregation Method used: Dominant Condition This tool creates a series of map layers, one for each of the rating reasons in the cointerp table. Polygons are colored based upon the percentage of the map unit that has that condition. This is ‘Bedrock < 24 inches.

26 Description - ENG - Poultry Disposal by Composting (Catastrophic) (WV) Composting catastrophic mortalities is a method of disposing of large quantities of dead birds as a result of a catastrophic or disease related incident. Composting in this scenario is a managed process where decomposition converts carcasses into a stable organic material. Additionally this process can deactivate harmful pathogens and viruses that may be present. The carcasses are mixed with a carbonaceous material, like mulch or wood chips at a recommended rate to achieve the optimum carbon to nitrogen (C:N) ratio. The mixture is formed into a windrow and placed on a thick base (12 inches or more) of similar uncompact carbonaceous material. Once constructed to its designed size, a final cover of carbonaceous material is placed over the windrow as a cap ensuring all parts of the carcasses are covered …………… ………………. …………… ………………. Aggregation Method: Dominant Condition; Tiebreak rule: Higher Component Percent Cutoff: 0% GeoDatabase: E:\Geodata\2016\gSSURGO_FY2016\gSSURGO_WV.gdb Rasterlayer: MapunitRaster_wv_10m Rating Table: SDV_PoulDCd_DCD Layer File: E:\Geodata\2016\gSSURGO_FY2016\Poultry_Disposal_by_Composting_(Catastrophic)_(WV)_DC D.lyr Created by Steve Peaslee on using script gSSURGO_Mapping.py Layer Property - Description

27 The ‘Map Soil Properties and Interpretations’ tool automatically creates a layer file for each map layer and displays the name and location of this file in the console messages. The layer description information also includes the name and location of the layer file. The tool creates layer symbology and temporarily joins the rating table to the soil polygon featureclass (MUPOLYGON). These settings are saved to the layer file and then the layer is added to the ArcMap table of contents (TOC). Adding the MUPOLYGON featureclass to future ArcMap sessions will not automatically recreate the map legend. This can only be accomplished by adding the layer file (.lyr) to ArcMap. The layer files are stored in the same folder as the geodatabase. An example might be something like: C:\Geodata\Temp\Percent_Sand_WTA_0_to_25cm.lyr. If the gSSURGO databases are moved or copied to a new location, always keep the layer files and databases together and do not change the names of the gSSURGO databases. Failure to follow these instructions will break the layer files. Since the layer file names are not necessarily unique, it is a good idea to keep each gSSURGO database in its own, separate folder. Storing multiple gSSURGO databases in the same folder can result in layer files being accidently overwritten. The output rating table names always begin with ’SDV_’ and are created within the gSSURGO database. The rating tables can be joined to the MapunitRaster or Mupolygon layers using the ‘MUKEY’ column. Symbology will have to be manually created, but for large databases, drawing performance is greatly improved by using the raster. Unlike Soil Data Viewer, the output data is not automatically deleted. Layer Files (.lyr)

28 Fairly complete metadata is automatically created for the output rating table and stored in the gSSURGO database. This information can be found by selecting the rating table in the ArcCatalog Catalog Tree and viewing the Description tab. A title and complete narrative from the interpretation is added to the Abstract section of the metadata…..

29 All menu settings used to run the tool script are appended to the end of the narrative section in the rating table metadata. This includes aggregation method, tiebreak rule, component percent cutoff, input database, soil layer. If a horizon- level soil property is being mapped, top and bottom depth will also be included. Output table and layer file is also listed along with the user name and date of creation.

30 Example of ‘List Map Categories’ tool output to the console window. This text can be pasted to a Word document for future reference using the mouse to highlight and then Ctrl-C to copy.

31 For more information or to download the ArcTools, please visit the gSSURGO webpage at A similar set of tools developed by Jason Nemecek and Chad Ferguson for mapping with gSSURGO can be found here: State-tiled gSSURGO can be downloaded from the Geospatial Data Gateway at: Since our USDA web pages have an annoying habit of moving every couple of years, a safe alternative is to perform a search for the terms: gSSURGO and NRCS I can be contacted at: or HELP! If you have problems with any of the ArcTools, it is easiest for me to diagnose using the complete set of arcpy messages from the console window. Simply highlight ALL text from top to bottom and copy using Ctrl-C, then paste into an along with any background information you feel might be useful. I don’t like screenshots or graphics because they are often difficult to read compared to the original text.