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100 years old.

National Cooperative Soil Survey celebrates centennial

This year marks the centennial of what some consider the largest and most valuable natural resource database in the world - the U.S. National Cooperative Soil Survey program.

Soil surveys are used in wetlands identification, agricultural production, conservation planning, wildlife management, building and home site selection, road building, waste disposal and pollution control. They provide a scientific inventory of soil resources, including soil maps, and physical and chemical properties, potentials and limitations.

Engineers, farmers, ranchers, planners, zoning commissions, tax commissioners, homeowners and developers use soil surveys, which provide information about moisture, stability, permeability and flooding.

The soil survey program conducted by the National Cooperative Soil Survey is a nationwide partnership of federal, regional, state and local agencies and institutions. The USDA's Natural Resources Conservation Service (NRCS) oversees the soil survey's federal responsibilities.

Soil survey history

In 1894, Milton Whitney, associated with state agricultural experiment stations in Connecticut, North Carolina, South Carolina and Maryland, became the first chief of the Division of Agricultural Soils at the USDA. He developed the idea of mapping soil characteristics to promote agricultural development.

During field work, soil scientists encountered angry bulls, bears, rattlers, desperadoes and moonshiners. The sight of a stranger digging in a field aroused a range of reactions, wrote former Soil Conservation Service Information Director D. Harper Simms in 1970. For example, he described an Oregon soil surveyor who had just finished studying a soil profile. As he replaced his last shovelful of earth, an armed posse arrived. The surveyor had to dig the hole again to prove that he was neither a grave robber nor a murderer trying to dispose of a body.

The first soil survey field operations began in summer 1899 at four sites: Salt Lake Valley, Utah; Cecil County, Maryland; Pecos Valley, New Mexico; and the Connecticut Valley of Massachusetts and Connecticut. Western U.S. surveys in dry climates mapped areas to determine suitability for food production under irrigation. Eastern surveys focused on whether imported tobacco varieties could be grown there.

Hugh Hammond Bennett, the father of soil conservation, discovered the effects of sheet erosion in 1905 while mapping soils in Louisa County, Virginia. His crusade to reduce soil erosion led to a national program to protect natural resources within the USDA's Soil Conservation Service, later renamed the Natural Resources Conservation Service.

In the 1930s and 1940s, surveyors began digging long trenches or series of pits rather than single pits to collect information. They sought details such as available nutrients and drainage patterns. Later surveyors used aerial photographs for their maps to develop more accurate boundaries.

By the 1950s and 1960s, the modern system for classifying soils had evolved. Scientists focused on soil morphology, properties and qualities emphasizing the parts of soil. Ten soil orders were formally designated by the USDA in 1965.

Early transportation for soil surveyors was on foot, horseback, horse-and-buggy, wagon, bicycle and rowboat. Today, pickup trucks - many with power augers - are common.

Today's soil surveys

Soil survey leadership has always been with the USDA and its partners, which today include federal, and state, local and county governments, universities and private consultants. Soil scientists within these organizations have a basic education in agriculture, geography or earth sciences. Besides federal government agencies, state agencies and private companies hire soil scientists to make on-site evaluations.

Soil scientist field work has changed little over the years as studies focus on land and vegetation. The scientists identify soil types by examining soil layers, usually up to 6.6 feet (2 meters) deep. They also determine the slope, erosion hazards, color, acidity or alkalinity and proportions of sand, silt, clay and organic matter. Soils are classified according to a national system and each soil type is outlined on an aerial map before leaving the field.

Soil scientists walk up to 8 miles a day while mapping soils. They use a soil landscape model to make predictions. The number of samples or observations needed is based on the surveyor's skill and the model.

Mapping rates in the United States range from about 300 to 600 acres (120 to 240 hectares) a day for a detailed soil survey. Depending on the area size, it can take three to five years to complete a soil survey for a county.

Soil surveys are conducted on about 21 million acres (8.4 million hectares) annually, compared with 720,000 acres (288,000 hectares) 100 years ago. Today's surveyors also face environmental and agricultural challenges unknown to their predecessors.

Survey information can determine a soil's carbon storage rate. An acre of sand stores from 9,000 to 18,000 pounds (4,050 to 8,100 kilograms) of soil organic carbon. Loam and clay store from 50,000 to 160,000 pounds (22,500 to 72,000 kilograms) in the top 3 feet (90 centimeters) of soil. Organic soils store 500,000 to 1.4 million pounds (225,000 to 630,000 kilograms) of carbon in the top 3 feet (90 centimeters).

U.S. soils are similar to those found throughout the world. For example, large areas of soils in the Midwestern United States are similar to soils in Russia. Soil in the eastern United States is similar to Korea's and eastern China's.

Prairie soils, productive for agriculture, are found throughout the central United States. They are called Mollisols and are among the 12 orders of soils in soil taxonomy. The other orders are: Alfisols, Andisols, Aridisols, Entisols, Gelisols, Histosols, Inceptisols, Oxisols, Spodosols, Ultisols and Vertisols.

The quality of a soil depends on its use. Although soil renews itself, the renewal is a slow process. Overuse can degrade soil rapidly and permanently.

Soil survey update

Soil survey mapping has been completed on more than 90% of the nation's private land, 75% of American Indian land and 80% of public land. About 90% of the United States' soil has been surveyed but only about 59% of this mapping reflects modern land-use needs. The other 41% needs to be updated.

Work is under way to provide soil surveys in more usable formats such as on CD-ROMS and the Internet. Also, NRCS and its partners are digitizing soil surveys so the information can be used with other geospatial data in overlays that relate landscape to natural resources information.

NRCS maintains databases that contain digital information on more than 25 physical and chemical properties for the more than 20,000 soils characterized in the 12 soil orders. The most detailed resource is the Soil Survey Geographic Database (SSURGO).

Soil information is available from USDA and NRCS offices, local soil conservation districts, the Cooperative State Research, Education and Extension Service and land grant colleges and institutions. Also, each NRCS state office has a soil scientist who oversees soil surveys.

For more information on soil surveys and updates on centennial activities, visit the NRCS web sites at or

Soil Survey Time Line

1896 Soil surveys authorized in USDA Appropriations Act.

1938 First USDA soil classification system published.

1950s Soil Conservation Service takes responsibility.

1965 Survey adopts new classification system of 10 soil orders.

1998 Soil taxonomy revised to recognize 12 soil orders.

Diana Morse is public affairs specialist with the USDA Natural Resources Conservation Service, P.O. Box 2890, Washington, D.C. 20013, USA; 202-720-4772, fax 202-720-1564,
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Title Annotation:the centenary of the U.S. National Cooperative Soil Survey program; Sustainability
Author:Morse, Diana
Publication:Resource: Engineering & Technology for a Sustainable World
Date:Aug 1, 1999
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