NRI Database Characteristics
Data 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.
Scientific citations on NRI
Data elements consistent within the NRI
database among the
last four (1982, 1987, 1992 and 1997) NRI
's (links are to glossary
New data elements added for the 1992 NRI and continued in
Data elements added for the 1997 NRI:
NRI data is collected at scientifically designed
sample sites located in every county and parish throughout the United States.
The sample design is the result of more than 40 years of research and
It is important to distinguish the NRI as a sample
as opposed to a census. Samples for the NRI are selected using a two-stage
stratified area sample scheme (See figure at right). The
sampling unit, or primary sampling unit (PSU) is an area or segment of
land. The second-stage sampling units are points located within the PSUs.
See PSU image to the right.
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.
This image illustrates a Primary Sampling Unit (PSU), which are 100 acres in
size in New Hampshire, with three data points within this PSU.
Link to National
NRI website on Statistical Design for scientific citations.
Data for the 1997 NRI was collected predominately
using remote sensing techniques. To find out more about the data
collection methods, visit the National
NRI Website on Data Collection Methods.
of Data Reports
A variety of data reports can be derived from
- Area reports on acreage
within a specified area that does or does not meet the user defined condition, practice, or
- Non area reports about year
specific units of measure other than acreage that meet user defined condition, practice, or use.
Trending analyses 5-year,
10-year and 15-year time spans for some data elements in the 1997 NRI.
- Changes reports on the shift
from one use, condition, or practice to another.
Getting NRI Data
Find out how to get NRI Data