Prior to establishment of the Soil Data Warehouse, soil data was loosely versioned, at best.  Version was reflected either in a SSURGO archive date, in a NASIS SSURGO export’s corresponding distribution generation date, or possibly in the soil survey area’s corresponding export certification date.  Export certification date was not even a required field.

With the establishment of the Soil Data Warehouse, soil data is now explicitly and formally versioned.  Version information is now tracked for the following entities:

Soil Survey Area
Soil Survey Area Tabular Data
Soil Survey Area Spatial Data

The Soil Data Warehouse recognizes that fact that, at the present, survey area tabular data is maintained and managed independent of its corresponding spatial data.

The Soil Data Warehouse provides the capability to distribute soil survey area tabular data that has no spatial data counterpart.  This is sometimes done for survey areas where mapping or updating is still in progress.  The distribution of soil survey area spatial data without a tabular data counterpart is not permitted.

When data for a soil survey area is checked into the Soil Data Warehouse, and both tabular and spatial data are available, every map unit in the spatial data must have a counterpart in the tabular data.  A map unit is the tabular data is not required to have a spatial counterpart.  This permits both tabular and spatial data to be released before the survey area map is complete.

For a survey area for which both spatial and tabular data exist, as long as the set of map unit has not changed, a new spatial version can be created without creating a new tabular version, and vice versa.  In general, tabular data for a soil survey area is updated more frequently than the corresponding spatial data.

Whenever a new tabular data version for a soil survey area is created, a new overall survey area version is created.

Whenever a new spatial data version for a soil survey area is created, a new overall survey area version is created.

A version (survey area or tabular data or spatial data) is characterized by two attributes:

Version Number – A sequential integer number.

Version Established Date – The date and time when a particular version was established.

For example:

06/30/2003 – Tabular data for survey area CO644 is added to the warehouse.  There is no corresponding spatial data available yet.  No data for this survey area existed in the warehouse before this date.

Current Survey Area Version: 1
Current Survey Area Version Established Date: 06/30/2003
Current Tabular Data Version: 1
Current Tabular Data Version Established Date: 06/30/2003
Current Spatial Data Version: none
Current Spatial Data Version Established Date: none

09/15/2003 – Spatial data for survey area CO644 is added to the warehouse.  The corresponding tabular data is not updated.  The underlying set of map units for survey area CO644 has not changed.

Current Survey Area Version: 2
Current Survey Area Version Established Date: 09/15/2003
Current Tabular Data Version: 1
Current Tabular Data Version Established Date: 06/30/2003
Current Spatial Data Version: 1
Current Spatial Data Version Established Date: 09/15/2003

03/09/2004 – Tabular data for survey area CO644 is updated in the warehouse.  The corresponding spatial data is not updated.  The underlying set of map units for survey area CO644 has not changed.

Current Survey Area Version: 3
Current Survey Area Version Established Date: 03/09/2004
Current Tabular Data Version: 2
Current Tabular Data Version Established Date: 03/09/2004
Current Spatial Data Version: 1
Current Spatial Data Version Established Date: 09/15/2003

The older retired versions for survey area CO644 are still available in the Soil Data Warehouse.

How do you know the version of the data you are using, and how do you know if you have the most current version?

For each survey area currently in the database, survey area version and tabular data version is available in the table named “sacatalog”.  Also, every soil report displays the survey area version of the data in that report, in the page footer of each page in the report.

In order to determine if you have the most current version of data for a soil survey area, you have to first access Web Soil Survey using your web browser:

http://websoilsurvey.nrcs.usda.gov

Select the tab labeled “Download Soils Data”, open section “Soil Survey Area (SSURGO), select the state or territory in question, and scroll, if necessary, to find the soil survey area in question.