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

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.

 
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.

 
Initial access to Pinnacles soil survey products and educational materials through two different interactive webpages. The standard interface is functionally very similar to our lab's online soil survey. Currently, the standard interface provides simple querying of the existing SSURGO products and pedon data that has been collected in the field. The "info" tool on the left hand side of the interface can be used to interactively query these features. The underlying infrastructure accepts soil data both in SSURGO and PedLogic formats. A newer interface based on the Ka-Map product will provide the flexibility required to include all of the many forms of educational materials that will be part of our final product. Some of these new materials will include:

• Annotated landscape, vegetation, and soil pit photographs
• Block diagrams illustrating various geologic, terrian, and environmental factors related to the distribution of soils
• Depth profiles of soil information from both lab and field sources.
• Links to several transects which highlight variation as a function of (x)
• Links to trails and trail markers, for a reference to reality
• Information related to the collection of soils data in the field
• Misc. products related to soils and soil forming factors: eroson/deposition, hydrologic modeling...

Links:
Ka-Map Interface
10 random pedons from the PINN database

Sample images returned from click on soil pit location: Auto-generated from soil attributes, hover mouse over a horizon for more information on that horizon.