GSDA:Obtaining Soil Type (SSURGO) Data from the Geospatial Data Gateway
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The United States Department of Agriculture (USDA) is a governmental agency which supports the preservation of natural resources and environments through the Natural Resources Conservation Service (NRCS). Their Geospatial Data Gateway is the main link where resource data can be acquired.
Soil type mapping is a major aspect of maintaining natural environments. Soil type data is supplied in two key forms; one of these is the Soil Survey Geographic (SSURGO) Database, and the other is the State Soil Geographic (STATSGO) Database. STATSGO data is defined on a state-wide level, whereas SSURGO is county-wide survey data. The SSURGO data also has a finer resolution than STATSGO.
Currently, SSURGO data is the only soil type that can be obtained through the Geospatial Data Gateway. Most of the United States is covered, but not all. The NRCS is still converting the county data into Shapefile format, it is projected to be completed by 2008. STATSGO data is accessible by other USDA NRCS means.
To download SSURGO soil type data from the Geospatial Data Gateway:
- Go directly to the gateway at http://datagateway.nrcs.usda.gov/. Or choose the Obtain SSURGO soil type data from the Geospatial Data Gateway link.
- Click the Get Data link on the top of the page. This will take you to step one of acquisition and open a map viewer.
- Zoom in on the desired area by either single clicking or drawing a bounding box around the area you wish to view.
- Continue to zoom in on the map until the desired region is displayed.
- NOTE: As you zoom in closer names for counties, cities, interstates become visible; making it easier to locate your area of choice.
- Select the Define Order Area tool located on the right-hand side.
- Drag a bounding box around the area of interest.
- NOTE: Upon completing the order area box, you will immediately proceed to step two of acquisition, where a list of available products is displayed.
- Scroll to the bottom of the page and check the box next to the Soil Survey Geographic (SSURGO 2.1) DB option.
- NOTE: A description of your chosen products, including size, will be tallied on the bottom of the window.
- Click the Continue to Step 3 button in the bottom left corner. You will be taken to step three of acquisition.
- Open the dropdown list for Vector Projection and select the UTM Zone 12 NAD 83 option or equivalent.
- NOTE: You may choose the projection of your choice, but remember it for later when, and if you need to convert to another. Leave the other fields; Vector Extent, and Vector File Format defaulted to Standard Extent, and ESRI Shape File respectively. The reason for using the shapefile format is that it can be directly imported into WMS.
- Click the Continue to Step 4 button in the bottom left corner. You will be taken to step four of acquisition.
- Fill in the required delivery information fields. Make sure the FTP Download option is selected as the delivery method.
- Click the Continue to Step 5 button in the bottom left corner. You will be taken to step five of acquisition.
- Review the information on the order confirmation page to make sure all is correct.
- Click the Place Order button in the bottom left corner and wait for the final confirmation page.
- NOTE: The final confirmation page will give you an order number and wait period for when you shall receive an e-mail notification that your order is ready to download.
- Wait patiently for the e-mail. It should have From The NRCS Data Gateway in the subject line.
- Open the e-mail.
- Click on the download link. It should initialize the download automatically.
- Save the file to your computer.
- Decompress the zip file (Help - Decompressing Files)
Now you have the SSURGO soil type data for the area that you requested. It can directly be imported into WMS since it is already in shapefile format.