The soil (pedosphere) is the thin, critical interface between earth and atmosphere, supporting much of the terrestrial life on the planet, filtering much of the water we drink, and catalyzing many of the chemical transformations upon which we depend.
Knowledge about characteristics of soils, and soil interactions with other factors, helps people predict and control the influences of human and natural phenomena as we seek to create a "Productive Nation in Harmony with a Healthy Land."
In the previous web tutorials on soils you have looked at a number of
different soil profiles. These have shown a small segment of the tremendous
diversity of soils. In Minnesota, making detailed soil maps of where these
soils are located is the function of Minnesota's Soil Survey Program.
This survey is of Le Sueur County in south central Minnesota. For those of you not familiar with the political geography of the state, go to MN Map.
What exactly is a soil survey? Well, you should suspect it has something to do with soil and survey. Since we already know what a soil is, let's determine a definition for survey. Webster defines survey (v): "to determine the boundaries, extent and position of something;" in this case, the "something" is "the soil".
The soil survey is an inventory of the soil resource that involves three
main elements:
1) a map showing the geographic relationships of each soil
2) a text describing the soils
3) tables giving physical and chemical data and interpretations for
various uses.
Soil maps come in different scales. This map of the state is considered
an order 5 soil survey
The regular soil survey (scale of 1:20,000 or 1:24,000) is considered
to be an order 2 soil survey. Therefore an order 5 soil survey has the
largest scale (1: 5,000,000) and an order 1 has the smallest scale (1:
1000). Order 1 soil surveys are used for a detailed inventory of the soils
on a parcel. This might be used for agricultural research or for locating
a waste disposal site.
Scale is used to indicate how many inches on the map represents inches on the ground. For a scale of 1:190,080, one inch on the map will represent 190,080 inches on the ground. Since there are 63,360 inches per mile, if you divide 190,080 by 63,360 you get 3, or 3 miles.
1:190,000 is about the scale that a general county soil survey map is published; this is an order 3 soil survey. We will be using the Sherburne County Soil Survey as an example of a soil survey, since it is available on the WEB in PDF format. You can look at the General Soil Mapping Units to get the idea that these represent broad categories of soils for Dade County.
In the laboratory, you will be working on exercises using the Le Sueur County Survey to help you become familiar with using this important document. You will also have access to a computer program that will allow you to access the soils information in a survey for Sibley County.
Modern soil surveys began in the late 1930s with the advent of aerial photography which was used as a base for the soil map. Prior to that the survey was conducted on a map created by the scientist. This picture shows a soil scientist conducting a soil survey in Texas in the early 1900Early Soil Survey. Many thousands of acres were mapped on photo backgrounds by the Natural Resource Conservation Service (NRCS, formerly the Soil Conservation Service) for planning with individual landowners. Soil survey publications with photo background soils maps were first issued in the early 1950s.
In more recent years, the value of soil survey information has been realized by many non-farm users. Large sums of money, often several thousand dollars per acre, can be saved through the use of soil surveys in locating proper land for construction. The failure to consider soils information can prove to be a costly mistake. Experience gained from selecting soils for farming and forestry is being applied equally well to selecting sites for housing, highways, airports, schools, factories, parks, cemeteries, recreational areas, and many other land uses.
The NRCS and the Minnesota Agricultural Experiment Station have the joint authority and responsibility for soil surveys in Minnesota. A memorandum of understanding was prepared in 1952 between these agencies. See this web page for more information about the Minnesota Soil Survey Program Minnesota Soil Survey. Between 1976 and 1993, the soil survey program was in an acceleration mode with the goal of having modern soil surveys for all counties by 2000. Field work to complete this is being conducted by the NRCS, The University of Minnesota Experiment Station, and the U.S. Department of Agriculture Forest Service. The present cost is about $1.50 per acre. This Status Map gives the most recent update on the progress being made on completing all of Minnesota with an inventory of the soil. Be sure to look at the soil surveys on display in the lab.
Land use planning is a term used to deal with the planning of people's activities on the land in an orderly fashion--not haphazardly. I am sure you only have to look around your home town to see areas that have not been planned adequately. One of the basic components in land use planning is using the soil resource according to its capacity. Whatever the use of the land, knowing information about the soil is going to be important now and in the future. This map shows land in Sherburne County on an ortho photo (an accurate depiction of the land surface area) and a soil map super imposed on the photo. The use of GIS systems allows many factors to be considered in planning the use of land, the soil being one of the most important.Ortho Photo Soils Map.
Land is a finite commodity--we have only so many acres. We also have
only so many acres of what is termed "prime" land. See NRCS
Prime
Farmland Definition (this will pull up an 'Acres of Prime Farmland 1997'
map; go to the 'Definitions' section near the bottom of the page). Once this land is used for other pursuits, such
as houses or shopping centers, it will never again be used for agriculture.
For information about national soil survey efforts go to
National
Soil Survey Center.
