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What is NRI?The National
Resources
Inventory (NRI)
is an
inventory of
land cover
and use,
soil
erosion,
prime
farmland,
wetlands,
and other
natural
resource
characteristics
on
non-Federal
rural land
in the
United
States. The
NRI provides
a record of
the Nation's
conservation
accomplishments
and future
program
needs.
Inventories have been conducted at 5-year intervals by the U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS), to determine the conditions and trends in the use of soil, water, and related resources nationwide and statewide. The 1997 NRI is the most extensive inventory yet conducted, covering some 800,000 sample sites, representing the Nation's non-Federal land-some 75 percent of the Nation's land area. At each sample point, information is available for four years-1982, 1987, 1992 and 1997. From this time series, changes and trends in land use and resource characteristics can be estimated and analyzed for a 15-year period. In future inventories NRI data will be collected continuously, allowing for annual analysis of dynamic environmental trends. NRI data are statistically reliable for national, regional, state, and substate analysis. The NRI was scientifically designed and conducted and is based on recognized statistical sampling methods. The data are used in national, state, and local planning, university research, and private sector analysis. They help shape major environmental and land-use decisions. Understanding the NRI Design (NRCS NRI Training Module 3) Understanding the Data Collection Process (NRCS NRI Training Module 4) History of NRCS Resource Inventories History of NRCS Resource Inventories
Hugh Hammond Bennett, the first Chief of NRCS (formerly SCS), recognized soil erosion as a national problem and documented it in "Soil Erosion-A National Menace", issued by USDA in 1928. This publication led to the first formal study of erosion, the "1934 National Erosion Reconnaissance Survey", conducted by NRCS's forerunner, the Soil Erosion Service. This survey was the first well-documented nationwide resource inventory ever conducted. Six months after it was completed, Congress passed the Soil Conservation Act of 1935, establishing NRCS. In June of 1945, NRCS published the Soil and Water Conservation Needs Estimates for the United States, by States. This became the Conservation Needs Inventory (CNI) and set the stage for future inventories. The CNI was repeated in 1958 and 1967. The Rural Development Act of 1972 lead to the development of the present inventory program, beginning with the 1977 NRI. The 1982 NRI was more comprehensive than the 1977 inventory and became the first inventory in the current trending database. Subsequent inventories in 1987, 1992 and 1997 were designed to provide consistent information enabling the NRI to produce a 15-year trend line for the conditions and uses of the Nation's natural resources. More History How Reliable is the Database?SAMPLE DESIGNNRI data are collected at scientifically selected sample sites located in every county and parish throughout the United States. The sample design is the result of more that 40 years of research and application. It is important to distinguish the NRI as a sample as opposed to a census. Samples for the NRI are selected using a stratified, two stage, area sampling scheme. Although sampling rates vary across strata, the sampling units constitute about 3 percent of all the total land and water areas of the 48 conterminous States, Hawaii, Puerto Rico, and the U.S. Virgin Islands. Understanding the NRI Design (NRCS NRI Training Module 3) DATA COLLECTIONData for the 1997 NRI were collected predominantly using remote sensing techniques. Glossary of NRI terms. Understanding the NRI Data Collection Process (NRCS NRI Training Module 4) TYPES OF DATA REPORTSA variety of types of data reports can be derived from analyzed NRI data.
RELIABILITYMargin of Error computations are automatically generated with most NRI data analyses using the U-CARP statistical package developed as part of a cooperative agreement with Iowa State University. A Margin of Error defines the confidence interval associated with each estimate within the report. All Margin of Error estimates are for the 95% confidence level. A confidence interval/margin of error has a convenient interpretation. Specifically, for a 95% confidence interval, the probability that the interval covers the true mean value is equal to 0.95. This means that if we draw an infinite number of samples for a specified population (e.g. cropland acres, erosion rates, etc.), and if for each sample we compute the confidence interval, then 95% of those intervals will contain the true mean. The measure "95%" represents the degree of our confidence that the interval contains the true population mean. To make this concept more concrete, consider a watershed. We want an estimate of the number of acres of cropland in this watershed. The number of acres of cropland constitutes our population. From the NRI data, suppose that we estimate the number of cropland acres to be 50,000 and the confidence interval to be (47,000 - 53,000). This means that the probability that the actual number of acres of cropland in the watershed de facto is between 47,000 and 53,000 is 0.95. The sample design for the 1997 NRI is designed to provide acceptable margins of error at the 95% confidence level for geographic areas based on USDA Major Land Resource Areas definitions. Analysis based on smaller geographic areas may produce results with meaningless margins of error. Database CharacteristicsData collected in the 1997 NRI provide a basis for analysis of 5-, 10- and 15-year trends in resource conditions. Many data items in the 1997 NRI are consistent with previous inventories. In addition, the NRI is linked to NRCS's extensive Soil Interpretations Records database to provide additional soils information. Data from other sources can be integrated with the NRI through spatial linkages in a Geographic Information System. Data elements consistent within the NRI database among the last four (1982, 1987, 1992 and 1997) NRI's:
Get More InformationLori Van Hulle,
State
Resource
Inventory
Specialist
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![Photo of a Deer on buffer near Bass Creek in Wisconsin. [NRCS Photo]](../images/EQIPBASSCREEKBUFFERDEER2.jpg)
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