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Scientific Investigations Report 2006-5012

County-Level Estimates of Nutrient Inputs to the Land
Surface of the Conterminous United States, 1982–2001

By Barbara C. Ruddy, David L. Lorenz, and David K. Mueller

This document is available in pdf format:Acrobat Icon SIR 2006-5012 (2.24 MB)—ONLINE ONLY
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Errata Sheet

pdf format errata sheet

The citation for this report, in USGS format, is as follows: Ruddy, B.C., Lorenz, D.L., and Mueller, D.K., 2006, County-Level Estimates of Nutrient Inputs to the Land Surface of the Conterminous United States, 1982–2001:
U.S. Geological Survey Scientific Investigations Report 2006-5012, 17 p.


Nutrient input data for fertilizer use, livestock manure, and atmospheric deposition from various sources were estimated and allocated to counties in the conterminous United States for the years 1982 through 2001. These nationally consistent nutrient input data are needed by the National Water-Quality Assessment Program for investigations of stream- and ground-water quality. For nitrogen, the largest source was farm fertilizer; for phosphorus, the largest sources were farm fertilizer and livestock manure. Nutrient inputs from fertilizer use in nonfarm areas, while locally important, were an order of magnitude smaller than inputs from other sources. Nutrient inputs from all sources increased between 1987 and 1997, but the relative proportions of nutrients from each source were constant. Farm-fertilizer inputs were highest in the upper Midwest, along eastern coastal areas, and in irrigated areas of the West. Nonfarm-fertilizer use was similar in major metropolitan areas throughout the Nation, but was more extensive in the more populated Eastern and Central States and in California. Areas of greater manure inputs were located throughout the South-central and Southeastern States and in scattered areas of the West. Nitrogen deposition from the atmosphere generally increased from west to east and is related to the location of major sources and the effects of precipitation and prevailing winds. These nutrient-loading data at the county level are expected to be the fundamental basis for national and regional assessments of water quality for the National Water-Quality Assessment Program and other large-scale programs.





Purpose and Scope


Data Sources

Association of American Plant Food Control Officials

Census of Agriculture

U.S. Census Bureau

National Atmospheric Deposition Program

Estimation of County-Level Nutrient Inputs

Nutrient Inputs from Fertilizer Use

Nutrient Inputs from Livestock Manure

Nutrient Inputs from Atmospheric Deposition

Description of the County-Level Nutrient-Input Dataset

Spatial and Temporal Patterns in Nutrient Inputs

Allocation of Nutrient Inputs to Specific Land Uses

Spatial Distribution of Nutrient Inputs

Temporal Changes in Nutrient Inputs


References Cited

Nutrient-input data (Available in Excel format)

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