SoilWeb: An Online Soil Survey Browser

SSURGO Map Units

STATSGO Map Units

Our online soil survey can be used to access USDA-NCSS 1:24,000 scale detailed soil survey data (SSURGO) in many parts of the lower 48 states. Where this data is not yet available, 1:250,000 scale generalized soils data (STATSGO) can be accessed instead. An interactive map interface allows for panning and zooming, with highways, streets, and aerial photos to assist navigation (Figure 1). Soil polygons become visible near a scale of 1:30,000. Alternatively, a GPS point, CA Zip code, or a street address can be used to zoom in on a specific location. General usage notes and information on how our online soil survey work can be found here. Statistics on who is using our online soil survey can be found here. Technical details on SoilWeb can be found in this publication. Please note that we are currently transitioning to a new server, and planning to have our local copy of the SSURGO, STATSGO, and OSD databases updated in the coming months.

The SoilWeb app is a portable version of the UC Davis California Soil Resource Lab’s Web-based interface to digital soil survey data from USDA’s Natural Resources Conservation Service (NRCS).

 
Select an Interface to SoilWeb

• An iPhone App for real-time, location-based soil queries! [details] [SSSA News Brief] [ANR News Article] [UCD Aggie Article]
• Similar App for AndroidOS smartphones
• Google Maps interface
• Google Earth Interface
• A Text-only interface to SSURGO
• HTTP SoilWeb API:
  1. WMS queries (access our data in QGIS etc.)
     • WMS GetCapabilities request

     
     

  2. Text-based queries
     • map unit lookup based on single lon/lat coordinate pair
     • map unit lookup based on lon/lat bounding box
     • map unit lookup based on lon/lat bounding box, with grouped legend
     • graphical map unit summary (Colusa County)
     • soil profile sketch by soil series name(San Joaquin series)
     • fuzzy map unit name lookup (see url for usage)

  Accessing Soil Survey Data via Web-Services

  Soil Survey Data

   
  Online Querying of NRCS Soil Survey Data
  Sometimes you are only interested in soils data for a single map unit, component, or horizon. In these cases downloading the entire survey from Soil Data Mart is not worth the effort. An online query mechanism would suffice. The NRCS provides a form-based, interactive querying mechanism and a SOAP-based analogue. These services allow soil data lookup from the current snapshot of all data stored in NASIS.

   
  An Example Implementation
  A simple front-end to the SDM-SOAP query mechanism was implemented using the NuSOAP PHP library. We plan to integrate this functionality into our online soil survey in the near future. Although the documentation on how to craft a working SOAP query is very limited, you can get a response by creating a message like this:

  POST /Tabular/SDMTabularService.asmx HTTP/1.0
  Host: SDMDataAccess.nrcs.usda.gov
  User-Agent: NuSOAP/0.7.3 (1.114)
  Content-Type: text/xml; charset=ISO-8859-1
  SOAPAction: "http://SDMDataAccess.nrcs.usda.gov/Tabular/SDMTabularService.asmx/RunQuery"
  Content-Length: 596
  
  <?xml version="1.0" encoding="ISO-8859-1"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"><SOAP-ENV:Body>
      <RunQuery xmlns="http://SDMDataAccess.nrcs.usda.gov/Tabular/SDMTabularService.asmx">
        <Query>SELECT * from component where mukey = '458913' ORDER BY comppct_r DESC;</Query>
      </RunQuery>
  </SOAP-ENV:Body></SOAP-ENV:Envelope>

   
  Here is approximately how it is done in PHP:
  

  // load NuSOAP library
  require_once('nusoap.php');
  
  // query template:
  $query = 'SELECT ... etc.';
  
  //create client object
  $query_url = 'http://SDMDataAccess.nrcs.usda.gov/Tabular/SDMTabularService.asmx';
  
  // SOAP server needs this
  $soapaction = 'http://SDMDataAccess.nrcs.usda.gov/Tabular/SDMTabularService.asmx/RunQuery';
  
  // open a new client
  $client = new soapclient($query_url);
  
  // make the XML request by hand
  $msg = $client->serializeEnvelope('
      <RunQuery xmlns="http://SDMDataAccess.nrcs.usda.gov/Tabular/SDMTabularService.asmx">
        <Query>' . $query . '</Query>
      </RunQuery>
  ') ;
  
  // send the request
  $result = $client->send($msg, $soapaction);
  
  // extract the result
  print_r($result['RunQueryResult']['diffgram']['NewDataSet']['Table']);

   
  More Examples

  • MUKEY query by polygon:
    

    http://sdmdataaccess.nrcs.usda.gov/Spatial/SDMNAD83Geographic.wfs?Service=WFS&Version=1.0.0&Request=GetFeature&OutputFormat=XmlMukeyList&Typename=MapunitPolyNoGeometry&FILTER=<Filter>
    <Intersect>
    <PropertyName>Geometry</PropertyName>
    <gml:Polygon>
    <gml:outerBoundaryIs>
    <gml:LinearRing>
    <gml:coordinates>-118.908508862,38.8086306467 -118.919673024,38.7901219483 -118.874871427,38.7756131355 -118.862298961,38.7924133734 -118.902681975,38.806449763 -118.908508862,38.8086306467</gml:coordinates>
    </gml:LinearRing>
    </gml:outerBoundaryIs>
    </gml:Polygon>
    </Intersect>
    </Filter>
    

  Dynamic Export of Soil Survey Data to KML through Soil-Web

   
  Overview
  We have recently added a KML export function to our online soil survey (Soil-Web). The Google Earth icon is displayed at map scales of 1:35000 or larger, and clicking on it will create a KML file containing the SSURGO polygons within the current viewport. The KML file contains labeled centroids, with links to the map unit descriptions which are normally found on Soil-Web. You will need a current version of Google Earth in order to take advantage of the KML produced by our website.

  To use this feature, zoom into a region of interest (at a scale of 1:35000 or larger) and click on the small Google Earth icon in the tool bar. If you have Google Earth installed, you may be prompted by the web browser software to open the resulting file directly in Google Earth. Optionally, download this KMZ file which can be used to seamlessly view soil survey content!

  
  
  KML Export for Soil-Web The small blue and white icon will export to KML

   
  For large numbers of polygons expect about 2 seconds for KML file generation, with a size ranging from 1 - 4 MB.

   
  Examples

  2D polygons in Soil-Web: SSURGO polygons (yellow) as normally displayed in our online soil survey.

  3D soil polygons as viewed in Google Earth: SSURGO polygons exported from our online soil survey to KML, and displayed in Google Earth.

   
  Methods
  All of the NCSS digital soil survey information on our site is stored in a PostGIS database, with geometry stored in a projected coordinate system (Albers Equal Area). The asKML() function found in PostGIS 1.2.1 makes converting our geometry to Google Earth compatible KML extremely simple- and it performs the required inverse projection on the fly! The general approach that we are using involves a series of steps, all of which are performed dynamically in PostGIS:

  1. select geometry overlapping the bounding box defined by the current viewport in AEA coordinates, using the PostGIS spatial indexing system
  2. compute the intersection between the boinding box and the overlapping polygons
  3. compute label locations for the new geometry
  4. convert the polygon geometry to KML
  5. convert the label geometry to KML
  6. add styling to the KML chunks with a PHP wrapper
  7. return a KML file to the browser, after setting the required headers:
     
     header("Pragma: public"); // required
     header("Expires: 0");
     header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
     header("Content-Type: application/kml; charset=utf8");
     header('Content-Disposition: attachment; filename="ssurgo.kml"') ;

   
  PHP is used to produce the final styled KML document, which is then returned to the browser. This file can be saved locally and opened with Google Earth. Note that KML can only be exported once you have zoomed in to at least a scale of 1:35000 or more.

   
  Give it a try!

  Initial SoilWeb Concept on Paper

  I found some of the original notes on what I envisioned our online soil survey interface would someday look like. Our Google Earth application came out pretty similar.

  SoilWeb 0.1

  PINN Data in GE 2

  Major updates to CA, AZ, NV online soil survey system

  After a bit of a delay, I have finally migrated all of the USDA-NCSS digital soil survey (AZ, CA, NV), 2005se Tiger, and other misc. data from shapefile format to a PostGIS database. In doing so, seamless access to the entire set of detailed (SSURGO) and generalized (STATSGO) polygon data is now possible through our online soil survey. At the Map unit level, links to adjacent soil polygons, along with a local area calculation are just some of the new possibilities of a spatially-enabled database (PostGIS). Note that DOQQ data is not locally stored for AZ and NV. Clicking on the "print" icon in the map interface at scale of < 1:7000 will fetch DOQQ data from Terraserver in these areas. Also the LandSat mosaic for AZ needs to be re-done with i.landsat.rgb, found in GRASS6.1-CVS. A quick comparison of LandSat channel blending is here. Subsequent changes will include thematic mapping of soil properties and visualizations of difference in soil properties across scales. See a simple summary, in case-study format on the PostGIS website. Thanks to Paul Ramsey for doing the write-up.

  
  

  Fig 1: map interface

  
  

  Fig 2: UMN Mapserver Application

  
  

  Fig 3: STATSGO polygon detail

  
  

  Fig 4: SSURGO polygons

  
  

  Fig 5: SSURGO polygon detail

  
  

  Fig 6: soil data summary

  
  

  Fig 7: land suitability ratings

   
  Background
  Nearly 2 years have elapsed since we put together an online soil survey for AZ, CA, and NV, based entirely on open source tools. GDAL and GRASS were used to pre-process spatial data, MySQL and PostGIS are used to store spatial and attribute data, UMN Mapserver is used to render map images, and PHP-Apache is used to glue it all together. Our first public prototype was advertised just as the USDA-NRCS announced their Web Soil Survey. We often advise parties interested in soils data to use both methods of accessing soil survey information, as each has its respective strong points. Our goal is to provide people a simple means of quickly accessing specific soil properties, with inline definitions to specialized terminology and interpretations. Several methods exists for locating soil data at a given location:

  • clickable map (Fig 1)
  • street address
  • CA zip code
  • latitude longitude from NAD83/WGS84 datum
  • CA PLSS Township, Range, Section, and Section fractions

   
  Example Session
  Figures 2 through 7 represent an example session of interactively panning, zoooming, and eventially querying a SSURGO polygon near Fresno, Ca. An AJAX-style UMN Mapserver application was created, based on the excellent dBox sample code provided by the Mapserver team. Once a user has located a soil polygon of interest (SSURGO or STATSGO), attributes associated with this polygon can be queried with the "info" tool . At this point, depending on the scale, the user is presented with a list of soil types (components) found within the queried polygon (SSURGO example). Clicking on of these links brings up a page on that specific soil type (Figs 6 and 7). Graphical summaries of key soil physical and chemical properties assist with quick recognition of key diagnostic features (sample page). A break-down of the US Soil Taxonomy terminology serves as an educational tool for interested parties. Links to outside sources of relevant data are automatically constructed and included in this summary as well:

  • USDA-NRCS Offical Soil Series Descriptions
  • USDA-NCSS Pedon Laboratory Data
  • Nitrate Groundwater Contamination Index
  • definitions of terms and interpretations from the Soil Survey Handbook

   
  Finally, our online soil survey, Soil Web, will be used as the foundation for a new educational website on the soils of Pinnacles National Monument, CA. Details on this project can be found on this page.

  
  
  Due to spam reasions, comments are not enabled on this page. Please send me an email if you have any questions or comments regarding the project. [dylan.beaudette AT gmail DOT com] .
  
  
  A further post will include the database schema (PostgreSQL and MySQL) for USDA-NCSS soil survey products, as well as some example code for importing and indexing the data.
  
  
  
  
  

  Migrating to Ka-Map! Online Soil Survey for AZ, CA and NV

   
  Note: This is an update to a previous announcement on the migration to PostGIS.

  Our online soil survey, Soil-Web, has now been migrated to a tile-based Ka-Map application. Seamless access to USDA-NCSS soil survey information has never been simpler with a Google-like click and pan-able map interface. Pre-rendered tiles for AZ, CA and NV result in much faster access times, and smooth panning / zooming. A new query interface, based on PostGIS functionality, facillitates soil survey lookup at multiple scales. Users may query by point: by selecting the query tool (looks like an "i") and clicking anywhere on the map. Generalized and detailed soils information at that point are then displayed in the left column of the kap-map application. Clicking an dragging with the query tool selected will search for all soils data which intersects the box. The white box on the figure above simulates the effect of choosing the query tool, and creating a box by clicking and dragging. The results of this simulated query are shown in the left column of the ka-map application. Clicking on the map unit names printed in the query results will take the user to details on that map unit. PLSS coordinates are also listed for each query.

  Ka-Map: STATSGO Preview

  Ka-Map: SSURGO Preview

  Ka-Map: Soils Query

   
  Background
  Nearly 2 years have elapsed since we put together an online soil survey for AZ, CA, and NV, based entirely on open source tools. GDAL and GRASS were used to pre-process spatial data, MySQL and PostGIS are used to store spatial and attribute data, UMN Mapserver is used to render map images, and PHP-Apache is used to glue it all together. Our first public prototype was advertised just as the USDA-NRCS announced their Web Soil Survey. We often advise parties interested in soils data to use both methods of accessing soil survey information, as each has its respective strong points. Our goal is to provide people a simple means of quickly accessing specific soil properties, with inline definitions to specialized terminology and interpretations. Several methods exists for locating soil data at a given location:

  • clickable map (Fig 1)
  • street address
  • CA zip code
  • latitude longitude from NAD83/WGS84 datum
  • CA PLSS Township, Range, Section, and Section fractions

  Planned Improvements in SoilWeb

   
  Core Functionality

  • sync SSURGO data with recent snapshot from SDM
  • sync STATSGO data with recent snapshot from SDM
  • update OSD database (used to make colored soil profile sketches)
  • automatic caching of soil profile images [done 2011-06-14]
    Saves several DB queries for commonly accessed soil profile sketches, should improve performance 10-20%.
  • add soil profile sketch by series name query to API [done 2011-06-05]
    Try it out.
  • list distance to map unit boundary [done 2011-03-16]
    
  • SoilVeg Data in Calaveras/Tuolumne counties [done 2011-03-05]
    SoilVeg data are automatically loaded when the mobile version of SoilWeb is used within Calaveras and Tuolumne counties.
  • explore linkages to SDA
  • semi-automated syncing with SDM
  • migration to new server, upgrade to PHP5, PGSQL 9, PostGIS 2
  • performance enhancements
  • fix logging / update usage stats

   
  Google Earth App

  • Auto-list corresponding block diagrams [done 2011-06-09]
    Links to NCSS block diagrams are generated based on soil series within each map unit.
  • NRCS logo/affiliation [done 2011-06-05]
  • automatic caching of map unit details within KML [done 2011-06-13]
    This gives a 2-8x performance boost when the current viewport contains multiple polygons of the same map unit.
  • nicer-looking info bubbles
  • better KML document/folder structure
  • proper documentation

   
  Android App

  • NRCS logo/affiliation [done 2011-06-24]
    Preliminary version of the splash screen here.
  • demo mode [done 2011-03-15]
    Demo mode highlights SoilWeb when a GPS signal is not available or when outside the geographic extent of the SSURGO database.
  • OSD query [done 2011-06-12]
    A simple interface to the OSD query system. Exact matches are re-directed to the corresponding OSD page.
  • map interface
  • proper documentation

   
  iPhone App

  • NRCS logo/affiliation [done 2011-06-24]
    Preliminary version of the splash screen here.
  • demo mode
  • OSD query
  • map interface
  • proper documentation

  Saving Chunks of SSURGO Data in SoilWeb for Google Earth

  

  SoilWeb is an interactive, multifaceted interface to USDA-NCSS soil survey information. Our SoilWeb application for Google Earth streams soil map units and point data as you navigate across the lower '48 states. Currently, our system imposes a 30,000 ac. limit (defined by the Google Earth viewport) for streaming detailed soil survey (SSURGO) map unit boundaries. This limit, combined with a 2 second delay before streaming is initiated, helps to reduce CPU load on our server. When viewing landscapes from directly overhead the 30,000 ac. limit is usually sufficient for most soils investigations. However, tilting the camera for oblique views of the landscape (an excellent way of visualizing soil-landscape relationships) causes the viewport to encompass much larger areas, usually exceeding SoilWeb's limit for detailed linework. The solution to this problem is summarized below, and can also be used to save "chunks" of detailed soil survey information for later use or offline browsing.

  Fig 1: right-click on the layer highlighted above and choose "copy"

   
  Step 1: Zoom to a region of interest, just below the 30,000 ac. limit, and pause for 2 seconds while our server processes your query. You can use the small status bar in the upper-left corner of the viewport to determine the current area, survey areas, and time required for processing. Once the linework has been displayed, right-click on the "Soil Polygons" sub-folder of the SoilWeb entry within the list of layers (Fig 1), and choose "copy". This will create a temporary snippet of KML that describes all map unit line work, labels, and associated links visible within the current viewport and place it on your clipboard. You can inspect this KML snippet by pasting it into a text editor.

  Fig 2: right-click on the "Temporary Places" folder and choose "paste"

   
  Step 2: Next, right-click on the "Temporary Places" folder within the list of layers (Fig 2), and choose "paste". This will create a new KML folder within your Temporary Places. You can make this KML snippet permanent by right-clicking on your new snippet and choosing "save place as", or by dragging your snippet into the "My Places" folder above. Finally, disable the SoilWeb network link and adjust the camera position for optimal viewing of your new KML snippet.

  Soil Properties Visualized on a 1km Grid

  Fresno Area Urban Areas vs Irrigated LCC: grey regions are current urban areas

  A couple of maps generated from a 1km gridded soil property database, derived from SSURGO data where available with holes filled with STATSGO data. Soil properties visualized at this scale illustrate several important soil-forming factors operating within California: sediment source in the Great Valley, the interplay between precipitation and ET, and removal of salts. This database and the details on its creation should be available within a couple of months. This builds on a related post highlighting some of these maps packaged in KMZ format. Check back in a couple of weeks of updates.

  
  
  
  
  
  
  
  
  
  

  1km Grid: Soil Water Storage: cm of water

   
  Soil Water Storage
  The maximum equivalent depth of water (cm) held within the soil profile. Depends on soil texture, soil depth, and rock fragment content. Geographic patterns illustrate basin (higher water storage) vs. upland (lower water storage) soils, and west-side (higher water storage) vs. east-side (lower water storage) valley alluvium. Major rice-growing regions of the Sacramento Valley (in Colusa and Butte Co.) are clearly visible.

  
  
  

  1km Grid: Soil pH
   
  Soil pH
  The equilibrium pH of water after mixing in a 1:1 ratio with soil. Depends on sediment source, drainage, climate, and landscape position. Geographic patterns illustrate predominantly lower pH values (acid soils) in regions with higher rainfall, and predominantly higher pH values (alkaline soils) in more arid regions. West-side valley alluvium is typically more basic, while east-side valley alluvium is more acidic.

  
  
  

  1km Grid: Electrical Conductivity
   
  Electrical Conductivity (salinity)
  The ease of which an electric current can pass through a soil-water mixture, and an index for the ionic strength (i.e. salinity) of the soil solution. Depends on salt content of the parent material, water table depth, climate, and land management. Geographic patterns illustrate closed basins and arid regions (west-side of the San Joqauin Valley, Owens Valley, Mojave Desert) characterized by salt accumulation. Highly leached soils (soils where precipitation is much greater than evapotranspiration) are generally not affected by salt accumulation.

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  SoilWeb for the iPhone

   
  About
  SoilWeb for the iPhone is a portable version of our online interface to USDA-NRCS digital soil survey data. The application uses the GPS built into the iPhone to acquire your current location, and then submits an HTTP request to our server via the SoilWeb API. A graphical summary of the soils mapped at your current location is presented on-screen, with links to details through our online soil survey, or via the USDA-NRCS official series description (OSD) archive. SoilWeb for the iPhone can be downloaded free of charge from the iPhone App Store. If you are using a computer, then you will likely want to use our Google Earth interface to the these data. Here is a link to a presentation on how the application works.

   
  Graphical User Guide
  

  
  
  

  
  
  
   
  Online Help Images
  

  

  SoilWeb Usage Statistics

  

  

  

  Streaming Soil Survey Data in Google Earth (updates)

  STATSGO KML thumbnail

  SSURGO KML Thumbnail

  A short update to a previous post on the visualization of NCSS/USDA soil survey data in Google Earth. The use of the NetworkLink construct, combined with the spatial indexing present in PostGIS, allows for very rapid lookup and presentation of this massive database. Scale-dependant switching between the detailed (SSURGO) and generalized (STATSGO) databases is done through simple area calculation in PostGIS.

  Here is the link to the KMZ file. Here is a link to our conventional viewer application, based on Ka-Map / Mapserver, using the same PostGIS back-end (previous post on this). This PLSS KML file is very useful along-side soil survey information.

   
  Feedback is always welcome!

   
  Updates:

  • added link to download-able KMZ file, no longer need to manually create a network link
  • KMZ (compressed KML) is now used to for streaming soil survey data (5x-10x smaller files)
  • graphical component summaries are presented in the map unit info "bubble"

  Soil-Web Graphical Component List

  Three New Soils-Related KMZ Demos

  LCC KMZ
  Soil Texture KMZ

   
  Updated versions of three soils-related KMZ files: 1-km scale, aggregate LCC, CA Storie Index, and soil texture data, derived from SSURGO. These are part of a series of KMZ / raster datasets that will be published soon. See attached files at the bottom of the page. Enjoy!

  Updated SoilWeb for the iPhone + Alpha Android Version

  Major updates to the SoilWeb iPhone Application. Improved graphical interface, new online help, calibrated GPS accuracy, and more. Also started a preliminary version for Android-based phones, should be available within a week or two (see below).

  

  
  
  
   
  Online Help Images
  

  

  Android-SoilWeb Preview 1

  Android-SoilWeb Preview 2

  Android-SoilWeb Preview 3

  Updates to SoilWeb

  Soil Profiles in Color

  Added color support to the mini-profiles used in graphical map unit summaries, the Google Earth interface, and iPhone application. SSURGO doesn't contain soil color data, so colors (in Munsell notation) were extracted from the OSD database, and converted into RGB triplets. Using horizon information from the OSD database also results in much more realistic horizonation, as compared to what is stored in older SSURGO databases. Example of the Yolo series soil, from the Yolo County (1972) soil survey:

  vs.