The NRI is a scientifically based, longitudinal panel survey designed to facilitate examining trends in land use and erosion rate changes over time on non-Federal land, including privately owned land and land owned by tribes, trusts, and state and local governments. The sample sites are drawn from a very large, permanent statistical sampling frame distributed across all geographic regions, states and counties of the United States, employing rigorous sample survey protocols. Sample sites utilized by the NRI inventories were formerly called Primary Sample Units (PSUs) and are now referred to as segments. Within each of Missouri’s 8,700 segments (each approximately 160 acres in size), data are collected for up to three points. There are 26,000 permanent segment point locations in Missouri. Missouri’s annual sample of approximately 1,800 segments is divided into two major types:
Core Panel Segments – 900 segments that have been observed annually from 2000 onward. These are used primarily for short-term trend determinations.
Supplemental Panel Rotation Segments – consist of 900 segments from the pool of non-core segments. These are rotated through the annual inventory sample and primarily contribute to long term trending estimates.
The USDA’s Natural Resources Conservation Service, in cooperation with the Iowa State University’s Center for Survey Statistics and Methodology, conducted NRI surveys every five years from 1982 to 1997 and annually since 2000.
The 2012 NRI Summary Report (published in July, 2015) is the most recent NRI data release. It contains both national and state-level estimates for the 30 year period 1982-2012. A 2010 interim report was published between the 2007 and 2012 five-year releases and there are tentative plans to release a 2015 interim report in late September, 2018. Comparisons using NRI data published prior to the 2012 report can produce incorrect inferences.
NRI estimates generated from the NRI survey results are based upon definitions and data collection protocols that have been developed to support NRCS programs and analytical needs; with the primary emphasis on conservation and agricultural related environmental issues. For this reason, NRI estimates for a particular resource category may differ from those compiled by other agencies. Caution is encouraged when comparing and reconciling estimates from different sources.
USDA agencies produce some of the Nation’s longest running, most comprehensive land use inventories reported at the national, regional and state levels. In addition to the USDA-NRCS National Resources Inventory, there is the USDA-ERS Major Land Uses (MLU) series; the USDA-NASS Census of Agriculture; and the USDA-USFS Forest Inventory and Analysis Program.