ASSESSING OHIO'S SOIL, WATER, AND RELATED RESOURCES USING
THE USDA NATIONAL RESOURCES INVENTORY (NRI)
Bob Parkinson, Soil Scientist & State GIS/Resource Inventory Specialist
USDA-Natural Resources Conservation Service, Ohio State Office
bob.parkinson@oh.usda.gov
KEYWORDS: NRI
ABSTRACT
The National Resources Inventory (NRI) is a statistically-based scientific survey that has been
designed and implemented to assess conditions and trends of soil, water, and related resources
on non-Federal lands in the United States. The USDA Natural Resources Conservation Service
(NRCS) conducts the NRI. The NRI provides scientifically valid, timely, and relevant information
that is also used to formulate effective agricultural and environmental policies and legislation,
implement resource conservation programs, and enhance the public's understanding of natural
resources and environmental conditions.
INTRODUCTION
The NRI is a compilation of natural resource information on non-Federal land in the United
States - nearly 75 percent of the total land area. This inventory captures data on land cover and
use, soil erosion, prime farmland, wetlands, habitat diversity, selected conservation practices,
and related resource attributes at more than 800,000 scientifically selected sample sites. The
1997 NRI covers all 50 States, Puerto Rico, the U.S. Virgin Islands,
and some Pacific Basin locations.
The NRI provides a record of trends in the Nation's resources over time and documents
conservation accomplishments as well. At each sample location, information is available for
1982, 1987, 1992, and 1997, so that trends and changes in land use and resource
characteristics over a 15-year time period can be examined and analyzed. Because the NRI is
based on recognized statistical sampling methods and is scientifically designed and executed,
NRI data are valuable in examining issues at national, regional, state and sub-state levels. The
NRI is currently being updated for inventory year 2002.
NRI information is available at: http://www.nrcs.usda.gov/technical/NRI/ and
http://www.oh.nrcs.usda.gov/.
METHODS
NRCS generates statistical estimates from the NRI database for numerous conservation-related
topics by various geographic areas for different inventory years and distributes the information
to conservation agencies and the general public.
The NRI database is a statistical database. Tabulations made from the NRI database are
estimates -- not absolute facts. These tabulations produce estimates rather than facts because
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they are based upon sample data derived from a survey -- rather than data coming from a
census, or complete measurement. Each estimate has some degree of statistical uncertainty
associated with it; this statistical uncertainty affects analyses of the data and interpretation of
results.
NRI data were collected at more than 800,000 sample sites nationwide. This is a very large
sample, which means that the data can be legitimately used to analyze issues at many
geographic levels -- national, regional, state, and sub-state. Sub-state levels can include Major
Resource Land Area (MLRA), watershed (2 digit to 8 digit hydrologic unit areas) or multi-county
areas. However, the NRI was not designed for analyzing issues at the county level.
The Ohio subset has about 21,000 sample sites or points contained within 7,000 sample areas
called Primary Sample Units (PSUs). Each PSU is about 160 acres in size. Data have been
collected for each PSU and sample site since 1982 and continue to be collected at regular
intervals. This "raw" PSU and sample site data are aggregated using statistical expansion
factors to create estimates for a wide range of natural resource topics.
Queries made to the NRI data base by NRCS Resource Inventory Specialists provide statistical
estimates that are processed into natural resource information including tabular data, charts
and thematic maps within a geographic information system and is distributed for use. A
sample of this information is presented for use and reference.
The "raw" data are available on CD-ROM at:
http://www.nrcs.usda.gov/technical/NRI/1997/obtain_data.html. The data do not come in a
summarized or aggregated form. Users of the database decide which portions of the data are
needed, and how to aggregate and summarize the data most effectively. The data must be
aggregated to develop meaningful statistics and analyses. To use the individual sample point
data as other than a part of the statistical database is inappropriate. Measures of uncertainty
(margins of error, standard errors, or confidence intervals) should be taken into consideration in
all data analyses. Data users who have limited experience in using sample survey data are
advised to seek professional assistance regarding the statistical implications of the data. It is
advisable to work in teams when utilizing the NRI for a scientific project. This analysis team
should include someone who has statistical analysis skills, can explain and interpret statistical
uncertainty and sampling error, and can offer guidance for the generation and interpretation of
the NRI estimates.
RESULTS & DISCUSSION
NRI statistics include the actual sample estimate and the standard error of the estimate that
reflects the precision of the estimate. The precision of NRI estimates depends upon the
number of samples within the region of interest, the distribution of the resource characteristics
across the region, and the sampling procedure. Characteristics that are common and spread
fairly uniformly over an area can be estimated more precisely than characteristics that are rare
or unevenly distributed.
Topics included in the NRI are:
• Land Cover/Use
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• Conservation Practices
• CRP
• Erodibility Index
• Geographic Area - sub-state by MLRA; hydrologic unit area (2 to 8 digit HUA); multi-county
areas
• Habitat Composition & Configuration
• Irrigation
• Land Capability
• Prime Farmland
• Soil Characteristics
• Soil Erosion
• Overland Flow/Delivery to Water
• Wetland (future)
• Years: 1982, 1987, 1992, 1997, 2002* (in progress)
Sample tables, charts and maps based on NRI estimates for various geographic areas and years
are presented for topics including:
• statewide broad land use/cover report for Ohio from 1982 to 1997 (Table 1)
• sample chart of Ohio broad land cover/use, 1982 to 1997 (Figure 1)
• 1997 Ohio broad land use/cover by Major Land Resource Area (MLRA) (Table 2)
• sample cropland distribution map by MLRA for Ohio (Figure 2)
• 1997 soil erosion rate estimates using Universal Soil Erosion Equation (USLE) by watershed
(Table 3)
• sample map of Ohio's 8 digit watersheds arrayed by cropland erosion rates (Figure3)
• sample map of Ohio's MLRAs arrayed by the acreage of cropland eroding above USLE "T"
factor (Figure 4)
• sample national map of prime farmland converted from rural to developed land from 1992-
1997 (Figure 5)
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Year 1982 1982 1987 1987 1992 1992 1997 1997
Estimate SE1 Estimate SE Estimate SE Estimate SE
Broad Land Cover/Use
Cropland cultivated 11,479.8 96.3 11,284.1 96.3 10,853.2 97.3 10,254.6 98.6
Cropland noncultivated 967.5 41.9 1,058.0 45.1 1,076.1 44.9 1,372.4 48.3
Pastureland 2,786.4 72.3 2,462.2 68.8 2,325.1 66.0 2,006.3 62.6
Forest land 6,658.0 93.0 6,891.4 95.9 6,921.0 98.2 7,080.8 100.4
Minor land cover/uses 1,035.0 40.9 970.5 38.9 942.8 36.4 1,031.9 38.8
Urban and built-up 2,448.1 61.6 2,652.1 62.5 2,913.0 66.3 3,279.2 70.2
Rural Transportation 334.7 6.3 331.9 6.2 333.5 6.3 332.1 6.3
Water (small) 214.6 6.9 218.3 7.1 222.4 7.1 221.8 7.2
Water (census) 168.2 0.8 168.6 0.6 168.7 0.5 168.7 0.5
Federal land 352.5 0.3 350.0 1.2 373.3 0.1 373.3 0.1
CRP 0.0 0.0 57.7 15.5 315.7 2.9 323.7 5.9
Total 26,444.8 62.7 26,444.8 62.7 26,444.8 62.7 26,444.8 62.7
1
Standard error of the estimate (SE) x 1.96 is the margin of error at the 95% confidence level.
2
Acres in 1,000s
Table 1. Sample statewide broad land use/cover report for Ohio. Acres in 1,000s.
Ohio Broad Land Cover/Use, 1982 to 1997
100%
2,448,100 2,652,100 2,913,000 3,279,200
334,700 331,900
90% 352,500 350,000 333,500 332,100
1,035,000 382,800 386,900 373,300 373,300
1,028,200 1,258,500 391,100
1,355,600 390,500
80%
2,786,400 2,462,200
2,325,100 2,006,300 Urban and Built-Up
70%
Rural Transportation
60% 6,658,000 6,891,400
6,921,000 7,080,800 Federal land
50%
Water
`
40% Minor Land
30% Pastureland
12,447,300 12,342,100 11,929,300 11,627,000
20% Forest land
10% Cropland
0%
1982 1987 1992 1997
Figure 1: Ohio broad land cover/use from 1982 to 1997, charted from Table 1.
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1997 Land Use/Cover MLRA STATE TOTALS
99 100 111 114 121 124 126 139
CATEGORY - 1997 --------------------------------- Acres in 1,000s ------------------------------
------------
Cropland cultivated 2,055.0 81.9 5,774.0 591.2 140.0 420.7 108.9 1,082.9 10,254.6
Cropland cultivated SE1 39.2 9.9 82.9 31.0 11.1 35.8 14.6 39.7 98.6
Cropland noncultivated 17.9 24.4 233.4 113.3 56.5 305.4 385.0 236.5 1,372.4
Cropland noncultivated SE 4.6 4.7 20.9 18.5 7.7 23.4 24.3 21.2 48.3
Pastureland 32.9 12.0 442.0 155.5 63.9 536.5 570.6 192.9 2,006.3
Pastureland SE 6.9 3.4 29.9 13.4 7.9 35.8 33.6 24.4 62.6
Forest land 208.6 116.4 968.7 373.0 250.6 2,265.8 1,785.5 1,112.2 7,080.8
Forest land SE 17.2 12.4 48.8 20.7 15.6 70.8 51.4 37.6 100.4
Minor land cover/uses 101.2 14.8 371.7 60.0 21.9 135.0 101.3 226.0 1,031.9
Minor land cover/uses SE 9.0 3.6 26.7 9.5 3.9 15.2 13.5 19.0 38.8
Urban small and large built-up 301.0 207.8 1,086.8 168.2 209.9 233.9 150.9 920.7 3,279.2
Urban small and large built-up SE 16.2 13.3 50.5 24.3 16.4 24.8 14.4 30.1 70.2
Rural Transportation 44.1 4.1 119.6 19.3 6.9 50.3 41.3 46.5 332.1
Rural Transportation 2.3 0.7 3.9 1.4 0.9 2.5 2.0 2.8 6.3
Water (small) 26.6 5.9 63.9 13.0 6.4 35.0 28.6 42.4 221.8
Water (small) SE 3.3 1.2 3.8 1.6 0.9 2.5 2.8 2.5 7.2
Water (census) 53.6 0.4 42.3 8.1 3.7 14.3 11.3 35.0 168.7
Water (census) SE 2.2 0.2 2.7 0.1 2.5 0.9 0.1 1.2 0.5
Federal land 7.2 1.1 36.1 15.1 0.8 170.5 89.0 53.5 373.3
Federal land SE 1.2 0.5 3.1 0.7 0.8 4.1 1.2 0.5 0.1
Conservation Reserve Program 19.8 0.2 227.5 36.1 0.5 21.3 0.8 17.5 323.7
Conservation Reserve Program SE 0.2 0.2 6.3 0.1 0.5 1.1 0.8 1.9 5.9
Total 2,867. 469. 9,366. 1,552. 761. 4,188. 3,273. 3,966. 26,444.8
9 0 0 8 1 7 2 1
Total SE 38.8 22.6 80.2 53.1 24.9 59.2 44.1 56.8 62.7
1
Standard error of the estimate (SE) x 1.96 is the margin of error at the 95% confidence level.
Table 2. Sample report on 1997 Ohio broad land use/cover by Major Land Resource
Area (MLRA)
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Figure 2. Acreage of 1997 total cropland for Ohio based on acreage estimates from
Table 2.
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Ohio Cropland Erosion by Watershed
1997 USLE Soil Erosion Rate (T/Ac/Yr)
Hydrologic Unit Number and Name HU Estimate SE1
04100001 Ottawa-Stony 4100001 0.9 0.3
04100002 Raisin 4100002 1.9 0.4
04100003 St. Joseph 4100003 2.9 0.3
04100004 St. Marys 4100004 1.9 0.1
04100005 Upper Maumee 4100005 1.1 0.2
04100006 Tiffin 4100006 1.8 0.2
04100007 Auglaize 4100007 1.3 0.1
04100008 Blanchard 4100008 2.0 0.1
04100009 Lower Maumee 4100009 1.0 0.1
04100010 Cedar-Portage 4100010 1.0 0.1
04100011 Sandusky 4100011 1.9 0.1
04100012 Huron-Vermilion 4100012 1.6 0.2
04110001 Black-Rocky 4110001 2.7 0.3
04110002 Cuyahoga 4110002 2.3 0.4
04110003 Ashtabula-Chagrin 4110003 1.0 0.1
04110004 Grand 4110004 1.5 0.2
04120101 Chautauqua-Conneaut 4120101 1.9 0.8
04120200 Lake Erie 4120200 0.0 0.0
05030101 Upper Ohio 5030101 3.8 0.5
05030102 Shenango 5030102 1.1 0.1
05030103 Mahoning 5030103 3.2 0.4
05030106 Upper Ohio-Wheeling 5030106 4.3 1.3
05030201 L. Muskingum-Mid. Island 5030201 1.6 0.3
05030202 Upper Ohio-Shade 5030202 1.9 0.3
05030204 Hocking 5030204 2.9 0.4
05040001 Tuscarawas 5040001 3.5 0.3
05040002 Mohican 5040002 2.8 0.3
05040003 Walhonding 5040003 3.9 0.4
05040004 Muskingum 5040004 4.3 0.8
05040005 Wills 5040005 3.5 0.8
05040006 Licking 5040006 2.8 0.4
05060001 Upper Scioto 5060001 2.6 0.1
05060002 Lower Scioto 5060002 2.5 0.2
05060003 Paint 5060003 2.8 0.3
05080001 Upper Great Miami 5080001 3.0 0.3
05080002 Lower Great Miami 5080002 2.6 0.2
05080003 Whitewater 5080003 3.9 1.6
05090101 Raccoon-Symmes 5090101 1.7 0.3
05090103 Little Scioto-Tygarts 5090103 1.6 0.4
05090201 Ohio Brush-Whiteoak 5090201 4.4 0.4
05090202 Little Miami 5090202 3.1 0.3
05090203 Middle Ohio-Laughery 5090203 2.4 0.5
05120101 Upper Wabash 5120101 2.0 0.3
05120103 Mississinewa 5120103 1.5 0.4
Total 99999 2.5 0.0
1
The standard error (SE) of the estimate x 1.96 is the margin of error at the 95% confidence level
Table 3. 1997 Soil Erosion Rate Estimates using Universal Soil Erosion Equation (USLE) by
watershed.
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Figure 3. Map of 8 digit hydrologic unit areas arrayed by estimated soil erosion
estimates from Table 3.
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Figure 4. Map of 1997 average annual soil erosion exceeding the Universal Soil Loss
Equation "T" value for Ohio cropland by Major Land Resource Area (MLRA) from NRI
statistics.
Figure 5. Map of estimated prime farmland conversion to developed land between
1992-1997 by 8 digit hydrologic unit area from NRI national statistics.
Ohio Geospatial Technology Conference for Agriculture and Natural Resources
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March 24-26, 2003