Soil Erosion

Key Messages:
Description
•
Soil erosion directly or indirectly
Soil erosion involves the detachment and removal of soil material from
impacts soil quality, water use,
one site by the forces of wind or flowing water and its transport to
water quality, air quality, plant
another location. The soil surface is susceptible to erosion when the
management, animal management
live plant or residue cover is inadequate.
livestock unconfined, animal
management livestock confined,
Soil erosion usually degrades soil quality. A soil of poorer quality is less
wildlife aquatic, wildlife terrestrial,
able to withstand further erosion, thus creating a downward spiral of
and energy management.
soil degradation. Organic matter and clay particles may be lost which
have nutrients and pesticides attached, with consequent reductions in
•
In 1997, wind erosion rates
exceeded “T” on more than 47
fertility and crop productivity, biological activity, aggregation and
million acres of cultivated cropland
rooting depth. Other potential effects of erosion on soil quality include
annually.
reduced infiltration, formation of soil surface crusts, changes in soil
texture, and compaction. These changes in turn reduce the capacity of
•
In 1997, sheet and rill erosion rates
the soil to supply and cycle nutrients, filter and degrade toxic
exceeded “T.” on more than 63
materials, store and supply moisture and sustain plant and biological
million acres of cultivated cropland
productivity. They may also result in increased runoff, less biomass
annually.
production and plant cover, and greater susceptibility to further
erosion.
•
Some of America’s cropland
continues to erode at unsustainable
rates.
Water erosion results in the formation of rills and gullies and
streambank cutting at the site of removal, and down-slope deposition
•
In 2001, 103 million acres (about
and sedimentation of downstream channels and water bodies.
28% of total cropland) were eroding
at rates greater than “T.”
Wind blown sediment also can be deposited in channels and water
•
Of the 101 million acres of Highly
courses with
Erodible Land, 2001 NRI data
similar results. Air
indicates that 55 percent continues
born soil particles
to erode in excess of “T.”
can obstruct
visibility along
•
Of the 268.6 million acres of Non-
highways adjacent
Highly Erodible Land, 2001 NRI data
to agricultural
indicates that 18 percent continues
areas subject to
to erode in excess of “T.”
wind erosion.
Sediment transport
Contact:
often carries
nutrients and
NRCS Web site at www.nrcs.usda.gov.
pesticides into
The USDA is an equal opportunity provider
water used for
and employer.
livestock and
human
consumption, and
for recreation.
Figure 1–Erosion on Cropland, based on 1982-2003
NRI data.
Helping People Help the Land

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Economic Effects of Soil Erosion
In addition to the detrimental environmental impact, soil erosion takes a huge toll on our nation’s economy.
Norfleet (2005) identified several components of on-site costs (e.g., lost nutrients, water runoff, and
productivity) and off-site costs (e.g., water quality & quantity and air quality) associated with soil erosion. He
suggests that the cost of keeping soil in place is worth at least $13.67 per ton or $27.5 billion for the 2 billion
tons of soil eroded in 1997, which is equivalent to $27.5 billion in 2004. Total expenditures by the U.S. Army
Corps of Engineers and other industry in 2003 for dredging a total of 233.8 million cubic yards was $887.3
million, equivalent to $910.9 million in 2004 (USACE). If erosion were to continue at the 1982 rate for the
next 50 years, Pierre Crosson (1998), estimates a 5.1 percent decrease in yield for corn and 3.4 percent for
soybeans, or an average loss in productivity of .1 and .07 percent per year, respectively. Given that crop
yields are projected to increase more slowly in percentage terms than food demand over the next several
decades, even small degradation-induced losses of productivity raise concerns (Wiebe, 2003).
Conservation Connection
Residue management practices are among the most effective conservation efforts delivered by the agency to
directly reduce water and wind erosion on cropland. Residue management and conservation tillage systems
benefit air quality, soil quality, water quality and quantity, wetlands, wildlife, animal waste and bio energy.
Many alternative resource management systems can be created from the list of practices (Table 1) to solve soil
erosion problems on cropland. In areas where crop residues are grazed, residue management must be integrated
with grazing management. Producers can change crop rotations; add cover crops, contouring, strip cropping and
terraces; or any combination of these practices, either with a conventional tillage system or with some form of
residue management to create an integrated system to protect the resource base.
Table 1– Applied conservation practices that reduce soil erosion by wind and water on
cropland, based on 2004 NRCS performance results system reports.1
Conservation Practice
Amount
Conservation Practice
Amount
Pasture and Hay Planting
Conservation Cover (ac)
961,268
307,172
(ac)
Conservation Crop Rotation
Residue Management,
3,399,526
1,270,687
(ac)
Mulch Till (ac)
Residue Management, No-
Contour Buffer Strips (ac)
5,642
1,290,839
Till/Strip Till (ac)
Residue Management,
Contour Farming (ac)
445,934
30,522
Ridge Till (ac)
Residue Management,
Cover Crop (ac)
320,227
950,628
Seasonal (ac)
Critical Area Planting (ac)
32,029
Stripcropping (ac)
25,231
Cross Wind Ridges (ac)
2,545
Surface Roughening (ac)
150,973
Cross Wind Trap Strips (ac)
4,842
Terrace (ft)
20,077,723
Tree/Shrub Establishment
Diversion (ft)
658,591
248,288
(ac)
Field Border (ft)
6,227,965
Vegetative Barrier (ft)
4,600
Herbaceous Wind Barriers
Water and Sediment
2,835,460
13,123
(ft)
Control Basin (no)
Irrigation Water
Windbreak/Shelterbelt
685,924
15,323,919
Management (ac)
Establishment (ft)
Windbreak/Shelterbelt
Mulching) (ac)
18,279
287,826
Renovation (ft)

1 The performance amounts in Table 1 are conservation practices strictly applied in 2004. They are not the total existing
amounts of “conservation applied on the land.”
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Residue management systems allow the producer to continue using the land as cropland. Due to either a
decrease in income or incompatibility with the over-all farming enterprise, placing cropland into the conservation
reserve program (CRP) or another permanent-cover type of land use is not as widely used as combining residue
management systems with other conservation practices. Without livestock, fencing, water supply and forage
equipment, forage production may be of little value to a cash grain farmer. All these considerations are part of
the conservation planning process that tailors the system to the producer's needs while remedying natural
resource problems. However, in severe situations it may be most practical to participate in land retirement or set
aside programs such as CRP or convert the land use from cropland to permanent hay or pasture, wildlife land or
woodland.
Figures 2a and 2b show the amount of cropland utilizing conservation tillage systems (no-till, mulch till, and
ridge-till) over time. Total acres of conservation tillage systems rose steadily in the late 1980's to 37.2% of all
planted acres in 1998 (Figure 2b). The implementation of Farm Bill Compliance standards containing residue
management practices was largely responsible for much of this increased adoption. From 1998 through 2000,
total acres in conservation tillage systems remained static at about 109 million acres (Figure 2a); however the
actual percentage of conservation tillage adoption dropped from 37.2% of the 293.4 million acres of planted
cropland to 36.7%
of the 297.5 million
acres of planted
300
45
cropland. After
40
250
about a 5.7%
35
decline in 2002,
200
30
total acres of
25
150
conservation tillage
20
increased by 8.5
100
15
Acres (millions)
percent to almost
10
113 million acres in
50
Percent of cropland
5
2004. This gain
0
0
(largely due to
1990
1992
1994
1996
1998
2000
2002
2004
1990
1992
1994
1996
1998
2000
2002
2004
No-till
Conservation tillage
added acres of no-
No-till
Conservation tillage
Total planted acres
till) is probably a
Figure 2a--Total planted acres and those with a conservation
Figure 2b--Percentage of cropland with a conservation tillage
result of increased
tillage system, of which no-till is a part
system, of which no-till is a part
adoption in the
Source: Conservation Technology Information Center (http://www.ctic.purdue.edu/CTIC/CTIC.html)
southeastern
states, and it can
also be attributed
to increased use of genetically modified seed, which eliminates the need for mechanical weed control (personal
communication, Mike Hubbs, National Agronomist, NRCS). Whereas the total acres in a conservation tillage
system have fluctuated since 1980, no-till adoption has continued to steadily rise from 6% in 1990 to almost
23% of all planted acres in 2004.
Current Conditions and Trends
National
Figure 3–Total acres of cropland with excessive erosion on
•
From 1982 to 1997, there was significant progress to
highly erodible and non-highly erodible cropland. Based on
reduce soil erosion on all cropland (Figure 1). Sheet
1982-2001
and rill erosion dropped by 41 percent during this
Highly erodible and Other Cropland with
Excessive Erosion (>T)
time period. Wind erosion dropped by 43 percent.
180
This translates to a savings of more than 1.2 billion
tons of soil per year on cropland. Since 1997,
160
reductions in erosion on cropland have stagnated
140
87.1
(Figure 1).
120
80.8
•
In 1997, there was 47 million acres of cultivated
100
56
cropland with average annual wind erosion rates
80
50.4
48.7
exceeding “T”, and 63 million acres with annual
60
Non-HEL
Millions of Acres
sheet and rill erosion rates exceeding “T.” 2 (USDA,
40
HEL
82.8
78
2000).
63.1
57.2
55.1
20
0

1982 1987 1992 1997 2001
2
Year
NRI data.
The soil loss tolerance (T) value represents the average annual rate of soil erosion that could occur without causing a decline in
long term productivity.
Conservation Resource Brief
Soil Erosion
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•
The period from 1982 to 2001 experienced 39 percent decrease in total acres of excessively eroding cropland
(Figure 3) (USDA, 2003).
•
The period from 1982 to 1997 achieved a commendable 2.4 percent reduction per year. However, from 1997
to 2001, the average yearly decrease was .9 percent (Figure 3).
•
In 2001 there were still more than 103 million acres (about 28 percent) of all cropland eroding at unacceptable
rates (>T) (Figure 3) (USDA, 2003).
•
From 1982 to 2003, as cultivated cropland was converted to other land uses such as CRP, the highly erodible
cropland (HEL) acreage decreased by 27.8 percent and the non-highly erodible cropland (NHEL) decreased by
13.4 percent (Table 4).
•
From 1982 to 2003, total soil loss on cultivated cropland (NHEL and HEL combined) decreased by 39.2 percent,
from 462 to 281 million tons (Table 3). The erosion rate on all cultivated cropland decreased by 31.8 percent
(Table 2). These reductions are probably the result of decreasing acres of HEL and the application of effective
conservation practices during the time period.
Regional Findings, Cultivated Cropland
NRI 1982 – 2003 data across the Hydrologic Basins of the U.S. (Figure 4) were used to evaluate regional trends on
cultivated cropland. The reductions in erosion rate (tons per acre) and total tons of soil loss are summarized in
Table 2 and Table 3, respectively, for all cropland, non-highly erodible cropland (NHEL), and highly erodible
cropland (HEL). Table 4 indicates the percent reduction in cultivated cropland from 1982 to 2003. The conversion
of cropland to other land uses has resulted in significant reductions in erosion on cultivated cropland; thus, it must
be factored into the overall analysis of soil erosion status in the U.S.
Conservation Resource Brief
Soil Erosion
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Table 2–Erosion Rates (Tons/Acre) and Percent Changed from 1982 to 2003 on Cultivated
Cropland
All Cultivated Cropland
Non-Highly Erodible
Highly Erodible
Rate
Rate
Rate
U.S. Hydrologic
change
change
change
Basin
1982
2003
(pct)
1982
2003
(pct)
1982
2003
(pct)
Arkansas-White-
7.6
5.0
34.6
4.5
3.4
25.2
12.6
8.0
36.4
Red
California / Great
Basin
3.2
2.1
36.4
1.7
1.0
41.9
16.6
13.8
17.1
Great Lakes
4.1
3.1
23.3
3.4
2.6
22.6
10.9
8.9
18.3
Lower Colorado /
9.3
11.5
23.8
5.1
3.4
33.1
11.4
14.6
28.7
Upper Colorado
Lower Mississippi
5.9
3.8
36.7
3.9
3.2
19.4
19.9
9.7
51.5
Missouri
8.7
5.6
35.4
5.1
3.5
31.9
14.5
9.7
32.9
New England/ Mid
Atlantic
5.9
5.1
13.1
2.7
2.6
4.8
10.6
9.7
8.3
Ohio/Tennessee
River
6.1
3.5
42.4
3.6
2.2
38.9
13.6
8.9
34.7
Pacific Northwest
9.2
7.8
15.5
5.6
5.1
9.2
14.9
12.1
18.7
Souris-Red-Rainy /
Upper Mississippi
7.9
5.5
31.4
6.3
4.3
30.9
16.1
11.8
26.7
South Atlantic-Gulf
5.9
4.1
29.5
3.7
3.4
9.3
14.1
9.5
32.7
Texas-Gulf /
16.6
11.7
29.4
7.4
6.4
12.8
29.4
20.2
31.3
Rio Grande
USA Average
8.0
5.5
31.8
4.9
3.6
25.9
15.8
11.0
30.6
Table 3–Soil Erosion (106 tons) and Percent Reduced from 1982 to 2003 on Cultivated Cropland
All Cultivated Cropland
Non-Highly Erodible
Highly Erodible
Erosi
Tons (million)
Tons (million)
Tons (million)
on
reduc
Erosion
Erosion
U.S. Hydrologic
ed
reduced
reduced
Basin
1982
2003
(pct)
1982
2003
(pct)
1982
2003
(pct)
Arkansas-White-
302.0
153.7
49.1
109.5
67.6
38.2
192.6
86.1
55.3
Red
California / Great
30.0
12.4
58.7
13.9
5.4
61.5
16.1
7.0
56.3
Basin
Great Lakes
74.6
46.6
37.5
55.4
35.4
36.1
19.2
11.2
41.5
Lower Colorado /
17.8
13.8
22.4
3.2
1.1
64.5
14.6
12.7
13.4
Upper Colorado
Lower Mississippi
134.7
73.7
45.3
78.0
56.4
27.6
56.7
17.2
69.6
Missouri
825.6
469.8
43.1
300.3
191.7
36.2
525.3
278.0
47.1
New England/ Mid
53.7
31.4
41.6
14.8
10.2
30.8
38.9
21.1
45.7
Atlantic
Ohio/Tennessee
188.2
88.6
52.9
84.4
45.1
46.6
103.8
43.5
58.1
River
Pacific Northwest
143.8
92.9
35.4
52.9
37.0
30.0
90.9
55.9
38.5
Souris-Red-Rainy /
661.6
415.3
37.2
434.2
281.4
35.2
227.4
133.9
41.1
Upper Mississippi
South Atlantic-Gulf
141.3
59.6
57.8
70.2
42.0
40.2
71.1
17.6
75.2
Texas-Gulf /
432.0
235.3
45.5
111.8
79.5
28.9
320.1
155.7
51.4
Rio Grande
461.
280.8
39.2
216.9
147.3
32.1
290.7
159.9
45.0
USA Average
9
Conservation Resource Brief
Soil Erosion
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Table 4–Percent reduction of total cultivated cropland acreage from 1982 to 2003.
U.S. Hydrologic Basin
ALL
NHEL
HEL
Arkansas-White-Red
22.1
17.4
29.7
California / Great Basin
35.0
33.6
47.3
Great Lakes
18.4
17.4
28.4
Lower Colorado / Upper Colorado
37.3
47.0
32.7
Lower Mississippi
13.6
10.3
37.3
Missouri
11.9
6.3
21.1
New England/ Mid Atlantic
32.8
27.3
40.8
Ohio/Tennessee River
18.4
12.6
35.8
Pacific Northwest
23.5
22.9
24.4
Souris-Red-Rainy / Upper Mississippi
8.5
6.3
19.7
South Atlantic-Gulf
40.2
34.0
63.2
Texas-Gulf / Rio Grande
22.9
18.5
29.1
USA Average
17.5
13.4
27.8
Regional trends from 1982 to 2003 on cultivated cropland, Tables 2, 3, and 4:
• The greatest progress has occurred on HEL (reduced rate 30.6 percent, reduced tons 45 percent) compared to
NHEL (reduced rate 25.9 percent, reduced tons 32.1 percent).
• From the data provided to date, it is not possible to determine the acreage of cropland still eroding at
unacceptable rates (i.e., >T). However, throughout all of the Basins, all highly erodible cultivated cropland
continues to erode on average at rates that exceed the maximum allowable T = 5, which is commonly assigned
to deep soils. The 2003 erosion rates on HEL range from 8.0 to 20.2 tons/acre. This indicates that more
progress is needed to accomplish the national objective of long term sustainability of our soil resource on highly
erodible cultivated cropland.
• The upper Colorado/Lower Colorado Basin appears to be an exception to the general rule of progress being made
in the other Basins. In the highly erodible category, despite an acreage reduction (32.7 percent) and a reduction
in tons of soil loss (13.4 percent), the rate of soil erosion on a per acre basis has increased 28.7 percent more
than the rate that was reported in 1982. This suggests that applied conservation practices on cultivated highly
erodible cropland in the Upper Colorado/Lower Colorado Basin have not been totally effective and are not
keeping pace with soil erosion. There may have been a significant focus to retire HEL cropland to CRP while other
conservation measures were not as readily adopted; hence the overall increase in erosion rate on a per acre
basis.
Conclusion: Significant soil erosion reductions on Highly Erodible Land were made by the Conservation
Compliance and Sod Buster provisions of the 1985 and 1990 Farm Bills. However, the Conservation Compliance
and Sod Buster provisions did not require the producer to reduce soil losses to the level considered to be
sustainable (i.e., ? T) on much of the land designated as Highly Erodible because minimum treatment levels,
defined as “Alternative Conservation Systems” typically resulted in soil losses nearly double the sustainable rate.
This is reflected in the 1997 NRI data (USDA, 2000), which shows that the Conservation Compliance efforts have
not reduced soil loss to less than 5 tons per acre per year in any region of the country designated as highly
erodible. The 2001 NRI published data indicate that about 55 percent of all Highly Erodible Land (55.1 million of a
total of 101.1 million acres) continues to erode in excess of “T” (USDA, 2003).
Also, the Compliance provisions were mainly concerned with lands designated as HEL, while Non-Highly Erodible
Lands with excessive erosion rates were not required to be treated. The 2001 NRI data indicate that about 18
percent of all Non-Highly Erodible Land (48.7 million of a total of 268.6 million acres) continues to erode in excess
of “T” (USDA, 2003).
Farmers across the country have made great strides to improve the resource condition, but there is still more to
do. While land conversion and land retirement have had significant impact on soil loss reduction, these activities
along with initiatives on buffers and filters may have slowed progress in some regions on adoption of practices to
reduce erosion on the working lands.
Conservation Resource Brief
Soil Erosion
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Science and Technology Status
The farming industry continues to explore innovative approaches to new technologies. With the advent of precision
farming and variable rate technology, the producer has the ability at the sub-field scale to program a specific
amount of fertilizer and seed that will assure adequate residues for erosion control.
Soil compaction reduces infiltration. Consequently, surface water runoff increases and hazard of soil erosion
ensues. In essence, 80% of the compaction that will occur happens with the first pass. In order to control
compaction, one must control traffic. This means using the same wheel tracks for most operations, for each crop
every year. This improves infiltration greatly on the cropped areas and thereby would reduce erosion.
Mulch tillage systems (systems with tillage across the entire field) require auto-steer technology using guidance
from a Global Positioning System (GPS) to locate traffic lanes year after year. Auto-steer technology keeps all field
operations in the same traffic lanes. Some systems are even capable of
1-inch accuracy. This technology allows controlled traffic with standard agricultural equipment and full-width
tillage. Automatic steering and controlled traffic reduce compaction beneath the row, thereby increasing infiltration
and reducing the hazard of erosion and the need for subsoiling.
Completed:
NRCS and the ARS have jointly developed, and continue to improve-upon, erosion prediction models for
conservation planning. With regard to water erosion, the Revised Universal Soil Loss Equation, version 2 model
(RUSLE2) is used in about 90 percent of NRCS field offices. RUSLE2 is used to generate documented estimates
required in USDA farm bill programs. RUSLE2 and the internally contained Soil Conditioning Index (SCI) and Soil
Tillage Intensity Rating (STIR) are required for determining eligibility and payment category for the Conservation
Security Program. Increasingly, the private sector is using RUSLE2 and its precursor, RUSLE1, on highly disturbed
lands. Many federal, state and local regulations require RUSLE1 and RUSLE2 technology. RUSLE2 implementation
policy is contained in National Instruction 300–RUSLE2, Subpart A, and National Bulletin 450-3-3, dated 4/7/02.
New versions are certified and made available on about a six month interval. Beyond the standard mix of rain-fed
row crops, small grains and forage crops, a variety of specialty cropping systems including fruit and nut crops,
nursery and sod farming, vegetable crops and tropical crops are also available in RUSLE2. In addition, irrigation
water additions are accounted. Outputs include soil loss, detachment, and sediment deposition by segment and at
the end of the slope. Both flat and standing crop residue pools are racked daily and by operation as is live biomass
and canopy cover, surface roughness and a number of other parameters important to the erosion assessment
process.
The NRCS has expanded the databases for use in all states and areas. RUSLE2 databases are now quite extensive,
including Soils, climate, operations, vegetation, and practices used in all states and areas. Over 21,000 locally
adapted crop management and tillage system scenarios are available for use with the model. ARS expects to
complete the User Guide and Science Document by the end of December, 2005. Anticipated publication of peer-
reviewed papers on RUSLE1 and RUSLE2 are planned for 2006 and 2007, depending on the time it takes to
complete the journal review process.
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Resource Investment
Soil Management
Financial
Technical
% of
Program
Assistance Funding
Assistance Funding
% of FA
2002-2005
2002-2005
TA
Conservation Technical
Assistance (CTA)
$0
$856,800,000

79%
Environmental Quality
Incentives Program (EQIP)
$462,473,163
$101,790,731
48%
9%
Ground & Surface Water
Conservation (GSWC)
$12,257,274
$1,419,291
1%
0%
Conservation Innovation
Grants (CIG)
$1,422,435
$7,046
0%
0%
Conservation Security
Program (CSP)
$56,875,908
$8,531,387
6%
1%
Resource Conservation &
Development_ (RC&D)
$0
$19,995,961

2%
Wildlife Habitat Incentives
Program (WHIP)
$2,095,013
$421,327
0%
0%
Agricultural Management
Assistance (AMA)
$5,485,505
$1,281,059
1%
0%
Grassland Reserve
Program (GRP)
$93,175,490
$24,124,509
10%
2%
Farm and Ranch Lands
Protection Program (FRPP)
$320,755,450
$9,514,229
34%
1%
Conservation Reserve
Program (CRP)
FSA Provides FA
$53,248,123

5%
Watershed Protection and
Flood Prevention Program
(WP&FPP)
$2,332,400
$999,600
0%
0%
Total
$956,872,638
$1,078,133,263
100%
100%
The RC&D program provides benefits for a multiple number of resource issues. Dollar amounts given reflect a
percentage of total program funding for RC&D for FY 2002-2004. This figure is pro-rated based on data
analysis conducted for the national program evaluation conducted in FY2004 & FY 2005. Soil management is
captured under the land conservation element in the RC&D statute.
Conservation Resource Brief
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References
Crosson, Pierre (1998). The on-farm economic costs of soil erosion. In Methods for Assessment of Soil
Degradation, edited by R. Lal, W.H. Blum, C. Valentine, and B.A. Stewart. Boca Raton, FL: CRC Press, pp. 495-511
Norfleet, M. Lee (2005). "Is topsoil dirt cheap? Estimating the cost of erosion." Draft Agronomy Technical Note No.
18, USDA, NRCS.
U.S. Department of Agriculture (2000). Summary Report: 1997 National Resources Inventory (revised December
2000), Natural Resources Conservation Service, Washington, DC, and Statistical Laboratory, Iowa State University,
Ames, Iowa, 89 pages. http://www.nrcs.usda.gov/technical/NRI/1997/summary_report/report.pdf (verified
12/1/2005).
U.S. Department of Agriculture (2003). 2001 annual NRI–soil erosion. U.S. Department of Agriculture, Natural
Resources Conservation Service, National Resources Inventory.
http://www.nrcs.usda.gov/technical/land/nri01/erosion.pdf (verified 12/1/2005).
U.S.A.C.E. Actual Dredging Cost Data for 1963-2003, Long-Term Continuing Cost Analysis Data, U.S. Army Corps
of Engineers Dredging Program, Summary of Corps and Industry Activities.
http://www.iwr.usace.army.mil/ndc/dredge/ddhisbth.htm (verified 8/8/2005)
Wiebe, Keith (2003). Linking land quality, agricultural productivity, and food security. Resource Economics
Division, Economic Research Service, U.S. Department of Agriculture. Agricultural Economic Report No. 823.
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