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 are conducted at 5-year intervals by the U.S. Department of Agriculture's Soil Conservation Service (SCS) to determine the conditions and trends in the use of soil, water, and related resources nationwide and statewide.
The 1992 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 three years--1982, 1987, and 1992. From this time series, changes and trends in land use and resource characteristics over the period can be estimated and analyzed.
Many of the data elements and definitions used to collect the 1992 data were developed to be compatible with data contained in the Commerce Department's Census of Agriculture and with databases managed by the USDA Forest Service, USDA National Agricultural Statistics Service, and the Interior Department's U.S. Geological Survey and U.S. Fish and Wildlife Service.
The purpose of the NRI is to provide information that can be used for effectively formulating policy and developing natural resource conservation programs at the national or state level. Through legislation--the Rural Development Act of 1972, the Soil and Water Resources Conservation Act of 1977, and other supporting acts--Congress mandates that the NRI be conducted every 5 years. This information allows Congress, Federal agencies, and others to evaluate existing programs, propose potential new programs, and allocate USDA financial and technical assistance to address priority natural resource concerns.
SCS has a long history of using natural resource inventories and monitoring to set priorities and focus on needs.
Hugh Hammond Bennett, the first chief of 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 SCS's forerunner, the Soil Erosion Service. This survey, the first well-documented nationwide resource inventory ever conducted, determined the degree of erosion caused by wind and water on all 1.9 billion acres (770 million hectares) in the United States. Six months after it was completed, Congress passed the Soil Conservation Act of 1935, establishing the Soil Conservation Service.
By the early 1940's, SCS realized it needed natural resource information to develop programs and set priorities for the various types of conservation needs throughout the country. After assembling and analyzing the resource data already available, SCS published the "Soil and Water Conservation Needs Estimates for the United States, by States" in June, 1945. This became the "Conservation Needs Inventory" (CNI), and set the stage for future such inventories.
In 1956, SCS was assigned responsibility to lead the cooperative endeavor to maintain and update the Conservation Needs Inventory. Seven other USDA agencies assisted, as they had a vested interest in land use, soil and water conservation, and the management of land resources. The development of these data, collected from sample areas, resulted in the 1958 CNI. This inventory was the first time since 1934 that new data were actually collected in the field, and the first time that SCS used statistical sampling to collect natural resource inventory data.
The 1967 CNI was an update of the 1958 CNI. Beginning with the 1967 CNI, data were collected on specific sample points within randomized sample units. This collection method proved to be less costly in terms of field work, and was easier to process. By the mid-1970's, SCS had developed a way to link resource inventory data to soils data collected by the agency's nationwide soil mapping program, the National Cooperative Soil Survey.
The Rural Development Act of 1972 led to the development of the present inventory program. The Act's wording clearly recognized that questions of rural and urban growth, prime farmland, flood plains, and conservation practices were needed to provide community guidance for balanced rural-urban growth. It also required that the frequency of natural resource inventories be increased from approximately once every 10 years to 5-year intervals.
SCS undertook the 1975 Potential Cropland Study in response to the recognition that urban development was taking place on some of the Nation's best cropland. The study also addressed issues of wetland preservation and conversion of marginal lands to cropland. For the first time, SCS used the statistical techniques that would characterize later inventories.
The 1977 NRI gathered data on items historically inventoried by SCS, such as soil capability, land use, and conservation treatment needs, and on new items, including potential cropland, prime farmland, wetlands, and flood-prone areas. The 1977 NRI used nearly 70,000 sample areas and was statistically reliable to the state level.
The 1982 NRI was more comprehensive than the 1977 NRI, both in terms of the information gathered and the number of sample areas used. Among the data it provided was information on the extent and distribution of highly erodible croplands throughout the Nation. The NRI provided statistical tables and maps showing the distribution of the highly erodible cropland, also known as "Highly Erodible Lands" (HEL). These statistics were the basis for the development of the Conservation Reserve Program, Conservation Compliance, Sodbuster, and Swampbuster conservation provisions of the Food Security Act of 1985.
The 1987 NRI featured a number of changes in how the data were gathered and analyzed. Previous NRIs had been conducted by SCS field office employees, who manually entered the data onto worksheets. Almost 30 percent of the 1987 sample data were collected using remote sensing, and SCS used teams at the state and substate levels to collect the data and enter it into computers. New software allowed SCS state offices to provide data to the public much more quickly than in previous years.
The 1992 NRI relied more on remote sensing and computer-based technologies to carry out the inventory process. Aerial photography was used, where available, to collect the new data, verify the 1982 and 1987 data, and fill in missing data for those years. Data collectors updated the 1982 and 1987 databases to 1992 technology standards, enabling SCS to produce a 10-year trend line for the Nation's natural resource use, conditions, and trends.
Congress, State and Federal agencies, and many organizations and individuals use NRI information. Legislators use information from the NRI in the formulation of conservation and environmental legislation. The NRI provides valuable information concerning the effect of legislative actions on protecting land from erosion and slowing the rate of loss of wetlands, wildlife habitat diversity, and prime farmland.
NRI data are also used by Federal and state agencies in regional and state environmental planning to determine the magnitude and location of soil and water resource problems and to develop staffing plans to address them.