By Michael Dangermond, Esri Cartographic Product Engineer
If you are like many of us, the extent of your expertise about soil is limited to how to get it out of your child’s clothing. Why not take a minute to think about how important soils are to life on this planet? When we close our eyes and think of living things in our environment, what we know about life is primarily learned from our experience on or above the surface of the earth. Consider this — soil, when healthy, teems with an immense community of living organisms. One estimate is that a hectare of soil supports about 20,000 kilograms of living things, which is approximately equal to the weight of 40 horses! (There is about 20 times this amount of non-living organic matter in the same volume of soil.) Although these living organisms make up only about 5% of soil organic matter, they are vital to many soil processes.
Soil has always been an important part of our economic infrastructure, and with good reason. The soil is one of the most important components of a country’s natural capital. In the United States, agriculture is a $150 billion industry, and the United States exports half of the grain available to world trade. The high yield per acre of American farms is largely due to the high levels of science and knowledge focused on the American agricultural sector.
Fig. 1 Relationships between soil food web, plants, organic matter, and birds and mammals. Image courtesy of USDA Natural Resources Conservation Service. Source: http://soils.usda.gov/sqi/concepts/soil_biology/soil_food_web.html
An important contributor to the advancement of soil science and the knowledge about U.S. soils is SSURGO, a national dataset at a scale of about 1:18,000 that contains extensive information about the mapped soil units. This data set is maintained by and distributed through the National Resource Conservation Service (NRCS).
Fig. 2: Screenshot of the newly released Esri/NRCS Beta soils application, Sacramento Valley, California, USA
The Mapping Center Team has been consulting with the NRCS and working with SSURGO data for a couple of years now. We are now ready to release a beta version of a soils Web map service on ArcGIS.com. This map service is viewed through a Web map application that can be queried to provide detailed information about the soils. It is designed to be educational, aimed at revealing basic soil information from the NRCS SSURGO dataset which will show you more about the information that is currently hidden to some extent within the data. We have processed the data and linked the many related tables so that your online experience will make learning about the soils much faster and easier than working with the raw data.
To use the beta soils Web map application, enter an address, a state, or a town in the address lookup in the bottom left corner of the browser window. Next, zoom in or out until you find the scale you like. There are actually three soils datasets displayed in this application – what you see depends on the map scale. If you zoom out to the smallest scales you will see the NRCS global soil orders data. Zooming in to the medium map scales, we have displayed the NRCS state-level soils dataset – STATSGO. If you zoom in to the largest scales, the SSURGO data are displayed. In addition, the Esri imagery map service will appear in the background to help you find your location of interest.
When you find the location, click on a soil map unit (one of the polygons on the map) for some basic information. In this beta version, we show you a few basic facts about the map unit you chose, including the name of the soil, the dominant soil order, and whether or not the soil in the map unit is suitable for prime farmland. Click on “show” on the Soil Photo, Soil Texture or Map Legend tools in the application for some more information. Clicking “show” on the Soil Photo tool displays a sample photo from the NRCS website of the soil order you chose. Expanding the Soil Texture tool opens a new window with the U.S. soil texture triangle. The appropriate region on the soil triangle will appear shaded if you chose a soil type with a description of its texture in its name. With either of these two tools open, you can click on other map units to learn how the soil texture and profile photo compare with the other soils in the area.
In terms of the amount of information in the Web mapping application, we are just exposing the tip of the iceberg. In this prototype, we have selected a few of the attributes that we think will be the most informative or interesting to the viewers. We are now working on enhancements that will allow you to see more details about the chemical properties of soils, properties of soils relevant to the building trades, soil properties for agriculture and forestry. Watch Mapping Center in the coming months for more news about the updates and other enhancements to this application.
Thanks to Aileen Buckley, Mapping Center Lead, for her help with this blog entry. Thanks also to the NRCS for the wealth of information on their Web site. It came in very handy while writing this blog entry!