Similar to the biological sciences, soil science organizes soils into a taxonomy which classifies soils into orders and suborders. Soil orders begin to distinguish soils by some very basic differences. For example, there is one order for the permafrost soils, these are called gelisols. Volcanic soils are called andisols. Soils dominated by organic materials (such as in a river delta) are called histosols.
According to the USDA, there are twelve soil orders in the United States. Click here for a list of the twelve suborders from the University of Idaho.
To use the Soil Orders of the United States map, first enter a city or town or any address in the United States in the bottom left box and click 'locate'. The map will zoom to your location and will use color to portray the different soil orders in your area. Click 'show' on the Map Legend bar inside the map to show a legend explaining what soil order each color means. As you zoom in more is revealed to you. At finer scales, the satellite imagery service turns on so you can find your farm or house, and soil polygon borders become more vague and even disappear once you zoom beyond the resolution of the data.
As you zoom out, more generalized datasets take over such as the US STATSGO 1:250,000 soils dataset and the World Soils Dataset from USDA. These maps are still of soil orders but the information has been generalized for the map viewer.
Click 'show' on the Soil Photo and Soil Texture bars to show more. The Soil Texture bar shows where your choice falls on the US Soil Texture Triangle, a graphic which compares the soil you clicked with specific terms such as loam, sand, sandy loam, clay, and silt. Click 'show' on the soil photo bar in the map to show a representative picture of the soil order. This can help you understand what the soil might look like.
Click on any soil map unit shown to learn more. An information pop-up will appear specifying the dominant soil order and suborder, and what percentage of this particular soil map unit is the dominant order and suborder. The map also tells you the prime farmland class of the soil map unit.
At the bottom of the pop-up there will be a link which says “learn more about” the soil order. Click the link to learn more about this soil order from a page written by the University of Idaho. These pages were written specifically for beginners and go a long way toward providing an understanding of what is going on in the soil map unit.
There is also a second, beta version of the soil orders map which allows you to display prime farmland as an overlay over the soil map unit polygons. The map works the same way except you may just click the checkboxes at the bottom of this map to display prime farmland and hydric soils.
The soil orders map services are cached on arcgis.com in web mercator projection and are also available to the map developer. The map service is therefore embeddable into your own map application or arcgis.com map.
US Natural Resources Conservation Service (NRCS) SSURGO soil surveys, 1:24000. Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Soil Survey Geographic (SSURGO) Database for [Survey Area, State]. Available online at http://soildatamart.nrcs.usda.gov
US Natural Resources Conservation Service (NRCS) STATSGO US General Soil Map, 1:250,000 Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. U.S. General Soil Map (STATSGO2) for [State]. Available online at http://soildatamart.nrcs.usda.gov
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