Crop residue removal and tillage - Effects on soil erosion and nutrient loss in the corn belt


Lindstrom, M.J.; Gupta, S.C.; Onstad, C.A.; Holt, R.F.; Larson, W.E.

Agriculture Information Bulletin 442

1981


Soil erosion in the United States is occurring at a rate of about twice the tolerance limit established by the Soil Conservation Service. If no conservation practices are used, the rate of soil erosion would increase by about 33 percent. Crop residue removal for alternative use may intensify an already serious problem. In this study, we calculated the amounts of crop residues produced in the Corn Belt, the amounts of nutrients contained in the residue, and the effect of crop residue removal on soil erosion. We use the Universal Soil Loss Equation (USLE) and current cropping practices to predict soil erosion for five residue and tillage management systems to determine the amounts of residue that can be removed from the major land resource areas (MLRA) in the Corn Belt without undue damage to the soil. Results from this study identify areas where crop residues feasibly may be removed for alternative use and also identify areas where crop residue in conjunction with conservation tillage systems is necessary to maintain soil erosion losses within tolerance limits.

(qo
United
States
(.\*
Department
of
Agriculture
Agricultural
Research
Service
Agriculture
Information
Bulletin
Number
442
JTOITA
Crop
Residue
Removal
and
Tillage
Effects
on
Soil
Erosion
and
Nutrient
Loss
in
the
Corn
Belt
Abstract
Lindstrom,
M.
J.,
S.
C.
Gupta,
C.
A.
Onstad,
R.
F.
Holt,
and
W.
E.
Larson.
1981.
Crop
Residue
Removal
and
Tillage
—Effects
on
Soil
Erosion
and
Nutrient
Loss
in
the
Corn
Belt.
U.S.
Department
of
Agriculture,
Agriculture
Information
Bulletin
No.
442.
Soil
erosion
in
the
United
States
is
occurring
at
a
rate
of
about
twice
the
tolerance
limit
established
by
the
Soil
Con-
servation
Service.
If
no
conservation
practices
are
used,
the
rate
of
soil
erosion
would
increase
by
about
33
percent.
Crop
residue
removal
for
alternative
use
may
intensify
an
already
serious
problem.
In
this
study,
we
calculated
the
amounts
of
crop
residues
produced
in
the
Corn
Belt,
the
amounts
of
nutrients
contained
in
the
residue,
and
the
effect
of
crop
residue
removal
on
soil
erosion.
We
use
the
Universal
Soil
Loss
Equation
(USLE)
and
current
cropping
practices
to
predict
soil
erosion
for
five
residue
and
tillage
management
systems
to
determine
the
amounts
of
residue
that
can
be
removed
from
the
major
land
resource
areas
(MLRA)
in
the
Corn
Belt
without
undue
damage
to
the
soil.
Results
from
this
study
identify
areas
where
crop
residues
feasibly
may
be
removed
for
alternative
use
and
also
identify
areas
where
crop
residue
in
conjunction
with
conservation
tillage
systems
is
necessary
to
maintain
soil
erosion
losses
within
tolerance
limits.
KEYWORDS:
soil
erosion,
crop
residues,
tillage,
nutrients,
conservation
Preface
In
this
publication,
we
present
the
detailed
data
con-
densed
in
a
series
of
articles
that
appeared
in
the
Journal
of
Soil
and
Water
Conservation,
March
-April
1979,
vol.
34.
The
information
was
later
reissued
by
the
Soil
Conservation
Soci-
ety
of
America,
Ankeny,
Iowa,
in
Special
Publication
No.
25,
"Effect
of
tillage
and
crop
residue
removed
on
erosion,
runoff,
and
plant
nutrients."
Here
we
are
concerned
only
with
residue
removal
effects
in
the
Corn
Belt
and
refer
to
the
following
specific
articles:
Crop
residues:
Energy
production
or
erosion
control
—W.
E.
Larson
Predicting
the
effects
of
tillage
and
crop
residue
management
on
soil
erosion
—S.
C.
Gupta,
C.
A.
Onstad,
W.
E.
Larson
Tillage
and
crop
residue
effects
on
soil
erosion
in
the
Corn
Belt
—M.
J.
Lindstrom,
S.
C.
Gupta,
C.
A.
Onstad,
W.
E.
Larson,
R.
F.
Holt
Crop
residue,
soil
erosion,
and
plant
nutrient
relationships
—R.
F.
Holt.
The
data
are
not
discussed
here
but
are
presented
for
study
by
interested
individuals
so
that
they
can
use
them
for
future
studies
or'to
make
their
own
conclusions.
Contents
Introduction
1
Computation
procedure
1
Results
and
discussion
10
Summary
12
References
cited
33
List
of
tables
Page
Table
1.
—Average
crop
acreage
(1972-76)
for
major
land
resource
areas
(MLRA)
within
States
in
the
Corn
Belt
2
Table
2.
—Dry
weight
ratio
of
straw
to
grain
for
selected
crop
residues
3
Table
3.
—Percentages
of
N,
P,
and
K
in
crop
residues
3
Table
4.
—Average
residue
yield
per
acre
and
nutrient
content
of
residue
for
corn,
soybeans,
and
small
grain
for
the
major
land
resource
areas
(MLRA)
within
States
and
total
residue
with
associated
nutrient
contents
produced
within
the
MLRA
4
Table
5.
—Crop
rotations
assigned
with
cultivated
area
and
percentage
of
cultivated
area
and
C
values
for
the
5
tillage
and
residue
management
systems
7
Table
6.
—Total
area
considered
and
average
cultivated
acreage
and
percentage
of
area
cultivated
(1972-76)
for
major
land
resource
areas
(MLRA)
within
States
in
the
Corn
Belt
10
Table
7.
—Calculated
weighted
average
soil
loss
(tons/acre/year)
and
weighted
average
soil
loss
tolerance
(T)
for
the
5
tillage
and
residue
management
systems
for
major
land
resource
areas
(MLRA)
within
States
in
the
Corn
Belt
11
Table
8.
—Rainfall
factor
(R)
used
for
major
land
resource
areas
(MLRA)
within
States
in
the
Universal
Soil
Loss
Equation
11
Table
9.
—Soil
erodibility
factor
(K)
distribution
for
the
major
land
resource
areas
(MLRA)
within
States
12
Table
10.
—Slope
gradient
factor
distribution
and
slope
length
factor
for
the
major
land
resource
areas
(MLRA)
within
States
13
Table
11.
—Acreage
and
percentage
of
cultivated
area
for
assigned
crops,
weighted
average
soil
loss,
and
percentage
area
where
predicted
soil
loss
is
less
than
the
soil
loss
tolerance
level
(T)
by
slope
categories
for
the
major
land
resource
areas
(MLRA)
within
States
14
Table
12.
—Percentage
of
area
where
predicted
soil
loss
is
less
than
the
soil
loss
tolerance
level
(T)
by
tillage
and
residue
manage-
ment
system,
amounts
of
residue
that
become
available
for
removal
by
each
tillage
and
residue
management
system,
and
associated
nutrient
removal
by
crops
in
the
major
land
resource
areas
(MLRA)
within
States
17
Table
13.
—Coefficient
of
variation
in
crop
acreage,
total
acreage,
and
residue
yield
per
acre
for
the
major
land
resource
areas
(MLRA)
within
States
33
Issued
October
1981
Crop
Residue
Removal
and
Tillage
Effects
on
Soil
Erosion
and
Nutrient
Loss
in
the
Corn
Belt
M.
J.
Lindstrom,'
S.
C.
Gupta,'
C.
A.
Onstad,
3
R.
F.
HoIV
and
W.
E.
Larson
5
Introduction
Growing
emphasis
on
energy
self-sufficiency
prompted
us
to
investigate
energy
production
from
solar
biomass.
Recent
estimates
show
that
total
biomass
production
for
food,
lumber,
paper,
and
fiber
could
provide
an
estimated
25
per-
cent
of
current
U.S.
energy
needs
(3).
8
This
would
include
use
of
all
biomass,
including
grains
now
used
for
human
or
animal
feeds
and
exports.
If
current
energy
prices
double,
fuels
from
biomass
may
possibly
curtail
the
amount
of
U.S.
energy
now
consumed
by
10
percent.
This
contribution,
however,
would
require
major
shifts
in
agricultural
and
forestry
production
and
uses
made
of
their
products.
A
number
of
reports
suggest
that
crop
residues
represent
an
immediate
source
of
biomass
for
energy
production.
The
nine
leading
crops
in
the
United
States
produce
about
400
million
tons
of
crop
residue
per
year
(5);
other
researchers
have
made
similar
estimates
(1,
3,
9).
The
leading
residue
-producing
crops
are
corn,
wheat,
and
soybeans.
Crop
residues
have
a
heating
value
of
about
3
million
kilocalories
per
dry
metric
ton,
about
half
the
heating
value
of
coal,
and
a
third
that
of
oil.
The
energy
value
of
the
-
400
million
tons
of
crop
residues,
therefore,
is
about
twice
the
energy
used
in
agriculture,
or
about
5
per-
cent
of
the
Nation's
total
energy
use.
However,
a
more
realistic
estimate
of
the
obtainable
net
energy
from
crop
residues
and
their
byproducts,
given
current
cropping
practices
and
technology,
may
be
3
4
Soil
scientist,
agricultural
engineer,
and
director,
U.S.
Department
of
Agriculture,
Agricultural
Research
Service,
North
Central
Soil
Conservation
Research
Laboratory,
Morris,
Minn.
56267.
2.
5
Soil
scientist
and
research
leader,
USDA-ARS,
Soil
Science
Bldg.,
1529
Gortner
Ave.,
University
of
Minnesota,
St.
Paul
55108
6
Italic
numbers
in
parentheses
refer
to
References
Cited
p.
33.
only
1
to
2
percent
of
the
Nation's
current
energy
needs.
Crop
residues,
however,
are
also
important
for
environmental
protection
and
food
production
and
should
not
be
considered
as
a
waste
product.
When
returned
to
the
soil,
crop
residues
retain
plant
nutrients
and
help
maintain
soil
porosity
and
tilth
for
easier
soil
tillage
and
good
plant
growth.
When
removed
from
the
soil,
crop
residues
remove
large
amounts
of
nutrients
that
must
be
replaced
by
mineral
fertilizers
or
other
sources,
such
as
animal
manure.
Residues
also
enhance
water
infiltration,
which
affects
soil
-water
storage
and
plant
use.
Left
on
the
soil
surface,
residues
curtail
soil
detachment
by
raindrop
impact
and
reduce
the
velocity
of
runoff,
which
consequently
reduces
the
runoff's
potential
to
detach
and
transport
soil
(12).
Proper
use
of
crop
residues
can
be
the
best
means
to
control
wind
and
water
erosion
and
maintain
the
quantity
and
quality
of
water
running
off
agricultural
land.
Each
ton
per
acre
of
residue
on
the
soil
surface
reduces
soil
loss
from
water
erosion
by
65
percent
(11).
Soil
loss
from
cropland
in
the
major
land
resource
areas
(MLRA)
of
the
United
States
is
about
3
billion
tons
a
year
(7).
This
is
an
average
of
about
9
tons
per
acre
per
year,
about
twice
the
estimated
tolerance
limit.
If
no
conservation
practices
were
applied,
the
soil
loss
would
be
about
33
percent
greater,
or
about
4
billion
tons
per
year.
We
started
this
study
to
deter-
mine
the
amounts
of
crop
residues
produced
in
the
Corn
Belt,
the
amounts
of
nutrients
contained
in
the
crop
residues,
the
effect
of
their
removal
on
water
erosion,
and
the
amounts
of
crop
residue
that
can
be
removed.
The
only
restraint
placed
on
residue
removal
for
this
deter-
mination
is
soil
erosion.
We
used
the
Universal
Soil
Loss Equation
(USLE)
(13)
to
predict
soil
erosion
for
five
residue
and
tillage
manage-
ment
systems,
and
from
this
information
we
determined
the
amounts
of
residue
that
could
be
removed
without
undue
damage
to
the
soil.
Computation
Procedure
The
USLE—
A
=
where
A
=
R
=
K
=
L
=
s=
c=
and
P
=
erosion
control
practice
factor
was
used
to
calculate
soil
erosion
(13).
The
basic
unit
for
computation
was
soil
series
by
slope
gradient
classification
obtained
from
the
Soil
Conservation
Service
(SCS)
Conser-
vation
Needs
Inventory
(10).
The
high
number
of
calculations
(tens
of
thousands)
dictated
computer
analysis.
Although
the
data
and
results
are
based
on
individual
soil
mapping
units
in
the
basic
calcula-
tion,
the
projections
are
not
con-
sidered
applicable
to
any
particular
farm
or
soil.
Instead,
the
results
and
conclusions
are
presented
by
MLRA's
within
States
(2)
for
most
of
the
central
feed
grain
and
livestock
region
(fig.
1).
Crop
acreage
and
yield
data
for
6
years
(1972-77)
were
compiled
by
counties
in
the
study
units
(MLRA's
within
States).
The
majority
of
the
analyses
for
study
units
were
based
on
production
data
for
at
least
5
years;
in
a
few
instances,
however,
data
for
only
3
years
were
available.
MLRA
112
in
Oklahoma
was
ex-
cluded
in
the
analysis
because
we
could
not
obtain
current
production
statistics.
MLRA
110
in
Wisconsin
and
MLRA
111
in
Michigan
were
excluded
because
each
involved
less
than
one
county,
and
produc-
tion
data
for
MLRA
109
in
Illinois
were
included
with
data
for
MLRA
108
in
Illinois
because
of
difficulties
in
separating
the
county
data
into
the
respective
MLRA's.
The
MLRA's
are
based
on
similar
soil
types
and
climatic
conditions
and
do
not
follow
county
boundaries;
therefore,
when
a
county
is
located
in
two
or
more
MLRA's,
the
county
data
were
included
with
the
MLRA
that
con-
tained
the
greatest
area.
State
crop
reporting
statistical
RKLSCP
computed
soil
loss,
rainfall
factor,
soil
erodibility
factor,
slope
length
factor,
slope
gradient
factor,
cropping
management
factor,
1
Table
1.
-Average
crop
acreage
(1972-76)
for
major
land
resource
areas
(MLRA)
within
States
in
the
Corn
Belt
MLRA
and
crop
Cultivated
area
MLRA
and
crop
Cultivated
area
MLRA
and
crop
Cultivated
area
SD
102
Acres
Percent
KS
106
Acres
Percent
OH
111
Acres
Percent
Corn
Soybeans
Small
Grain
Hay
1,593,537
366,413
1,569,319
866,670
36.3
8.3
35.7
19.7
Corn
Soybeans
Small
Grain
Hay
619,424
159,632
208,404
208,822
51.8
13.3
17.4
17.5
Corn
Soybeans
Small
Grain
Hay
1,984,257
1,895,700
902,589
506,211
37.5
35.8
17.1
9.6
MN
102
NB
107
KS
112
Corn
1,169,954
42.4
Corn
177,752
55.7
Corn
735,448
31.4
Soybeans
494,356
17.9
Soybeans
80,032
25.1
Soybeans
632,900
27.0
Small
Grain
822,262
29.8
Small
Grain
30,688
9.6
Small
Grain
448,602
19.1
Hay
275,953
10.0
Hay
30,818
9.7
Hay
528,242
22.5
IA
102
KS
107
MO
112
Corn
Soybeans
Small
Grain
Hay
155,899
80,619
22,696
20,262
55.8
28.8
8.1
7.3
Corn
Soybeans
Small
Grain
Hay
59,623
44,581
15,218
23,984
41.6
31.1
10.6
16.7
Corn
Soybeans
Small
Grain
Hay
582,892
497,635
228,597
465,906
32.8
28.0
12.9
26.3
NB
102
IA
107
MO
113
Corn
Soybeans
Small
Grain
Hay
1,852,975
490,654
401,851
561,917
56.0
14.8
12.2
17.0
Corn
Soybeans
Small
Grain
Hay
2,709,430
1,374,093
338,081
309,607
57.3
29.0
7.2
6.5
Corn
Soybeans
Small
Grain
Hay
439,144
583,809
165,886
260,306
30.3
40.3
11.5
18.0
MN
103
MO
107
IL
113
Corn
3,431,806
50.8
Corn
609,434
44.0
Corn
427,467
28.4
Soybeans
Small
Grain
1,913,019
750,205
28.3
11.1
Soybeans
Small
Grain
449,894
112,121
32.5
8.1
Soybeans
Small
Grain
686,802
294,835
45.6
19.6
Hay
659,142
9.8
Hay
212,746
15.4
Hay
98,301
6.5
IA
103
IA
108
IL
114
Corn
3,008,917
51.1
Corn
2,689,126
50.8
Corn
860,246
33.5
Soybeans
2,518,481
42.8
Soybeans
1,573,481
29.7
Soybeans
1,130,356
44.0
Small
Grain
171,607
2.9
Small
Grain
398,272
7.5
Small
Grain
409,425
16.0
Hay
187,958
3.2
Hay
635,650
12.0
Hay
166,500
6.5
MN
104
IL
108
IN
114
Corn
467,129
43.1
Corn
4,963,322
54.9
Corn
407,056
45.7
Soybeans
364,930
33.7
Soybeans
3,188,678
35.3
Soybeans
270,841
30.4
Small
Grain
131,396
12.1
Small
Grain
504,380
5.6
Small
Grain
115,155
12.9
Hay
119,619
11.0
Hay
381,280
4.2
Hay
97,618
11.0
IA
104
IA
109
OH
114
Corn
1,388,020
51.2
Corn
484,002
38.4
Corn
103,036
33.0
Soybeans
825,468
30.5
Soybeans
345,306
27.4
Soybeans
110,301
35.3
Small
Grain
236,922
8.7
Small
Grain
86,553
6.9
Small
Grain
34,179
10.9
Hay
259,301
9.6
Hay
343,282
27.3
Hay
65,101
20.8
MN
105
MO
109
IA
115
Corn
452,678
43.6
Corn
724,524
31.3
Corn
17,017
37.3
Soybeans
141,884
13.7
Soybeans
833,027
36.0
Soybeans
11,036
24.2
Small
Grain
155,870
15.0
Small
Grain
181,567
7.8
Small
Grain
7,851
17.2
Hay
288,339
27.8
Hay
576,476
25.0
Hay
9,727
21.3
IA
105
IL
110
MO
115
Corn
569,923
47.3
Corn
1,127,936
48.9
Corn
459,143
28.6
Soybeans
183,401
15.2
Soybeans
1,016,435
44.1
Soybeans
398,421
24.8
Small
Grain
98,725
8.2
Small
Grain
98,238
4.3
Small
Grain
199,571
12.4
Hay
354,046
29.4
Hay
63,881
2.8
Hay
548,913
34.2
WI
105
IN
110
IL
115
Corn
671,147
32.6
Corn
362,936
53.5
Corn
1,066,569
39.3
Soybeans
45,247
2.2
Soybeans
245,856
36.3
Soybeans
1,012,471
37.3
Small
Grain
309,316
15.0
Small
Grain
47,232
7.0
Small
Grain
417,576
15.4
Hay
1,036,019
50.2
Hay
22,113
3.3
Hay
215,939
8.0
IL
105
IL
111
IN
115
Corn
103,254
47.3
Corn
83,589
48.5
Corn
477,821
50.3
Soybeans
10,693
4.9
Soybeans
74,129
43.0
Soybeans
268,922
28.3
Small
Grain
25,569
11.7
Small
Grain
11,254
6.5
Small
Grain
163,537
17.2
Hay
78,560
36.0
Hay
3,181
1.9
Hay
39,016
4.1
NB
106
IN
111
Corn
1,016,730
55.3
Corn
2,877,307
46.6
Soybeans
318,811
17.3
Soybeans
2,205,363
35.7
Small
Grain
319,767
17.4
Small
Grain
742,255
12.0
Hay
184,580
10.0
Hay
350,437
5.7
2
N.
DAK_
DAIL
S.
DAK.
103
_
----
-
------
NEBR.
KANS.
xc
i
<
z
olz
(
42
r
ti
106
107
112
IOWA
108
109
105
-
%
113
WIS._
14
13
LAND
RESOURCE
AREAS
Figure
1.
—Major
land
resource
areas
102
to
115
in
the
Corn
Belt.
bulletins
were
the
source
of
county
data.
These
data
are
shown
in
table
1
as
average
crop
acreage
for
the
study
units.
To
simplify
computation,
sorghum
acreage
was
considered
to
be
corn,
and
all
small
-grain
acreage
was
converted
to
an
oat
equivalent.
The
sorghum
area
in
most
of
the
study
units
was
insignificant;
however,
the
amount
of
sorghum
acreage
included
in
the
corn
acreage
for
MLRA
KS
106
was
17
percent;
for
KS
112,
68
percent;
for
KS
112,
47
percent;
and
for
NE
106,
40
percent.
Converting
small
grains
to
an
oat
equivalence
may
produce
some
errors
because
of
dif-
ferences
in
straw
-grain
ratio.
We
did
not
consider
this
to
be
a
major
problem,
however.
Crop
residue
production
was
calculated
by
multiplying
grain
yields
by
a
straw
to
grain
ratio
(table
2).
Residue
yields
times
average
nutrient
percentage
(table
3)
were
computed
to
give
nutrient
content
in
the
residue.
Average
residue
Table
2.—
Dry
weight
ratio
of
straw
to
grain
for
selected
crop
residues
Crop
Straw
-to
-
grain
ratio
Corn
(Zea
mays
L.)
Soybeans
(Glycine
max
(L.)
Merr
)
Wheat
(Triticum
aestivum
L.)
Winter
Spring
Barley
(Hordeum
vulgare
L.)
Rye
(Secale
cereale
L.)
Oats
(Avena
sativa
L.)
1.0
1.5
1.7
1.3
1.5
1.5
2.0
111
o
*-
o
yields
and
associated
nutrient
content
per
acre
and
total
residue
and
nutrients
per
study
units
by
Table
3.
—Percentages
of
N,
P,
and
K
in
crop
residues
Crop
N
P
K
.
.
.
Percent
.
.
.
Corn
(Zea
mays
L.)
1.11
0.18
1.33
Soybeans
(Glycine
max
(L.)
Merr.)
.
2.25
.22
1.05
Wheat
(Triticum
aestivum
L.)
.67 .07 .97
Barley
(Hordeum
vulgare
L.)
.75
.11
1.25
Rye
(Secale
cereale
L.)
.50
.12
.70
Oats
(Avena
sativa
L)
63
.16
1.65
Text
continues
on
page
6.
3
Table
4.
-Average
residue
yield
per
acre
and
nutrient
content
of
residue
for
corn,
soybeans,
and
small
grain
for
the
major
land
resource
areas
(MLRA)
within
States
and
total
residue
with
associated
nutrient
contents
produced
within
the
MLRA
MLRA
and
crop
Average
yield
per
acre
Total
yield
and
nutrient
content
Residue
N
P
K
Residue
SD
102
Pounds
Tons
Corn
2,924
32.5
5.3
38.9
2,329,910
25,895
4,423
30,994
Soybeans
2,148
48.3
4.7
22.6
393,473
8,849
861
4,140
Small
grain
3,866
24.8
5.6
59.1
3,033,258
19,460
4,394
46,373
MN
102
Corn
2,960
33.0
5.3
39.4
1,731,590
19,246
3,100
23,048
Soybeans
1,994
45.0
4.4
20.9
492,799
11,098
1,088
5,166
Small
grain
3,103
20.4
3.5
39.7
1,275,904
8,387
1,439
16,322
IA
102
Corn
4,252
47.2
7.7
56.6
331,433
3,679
600
4,412
Soybeans
3,013
67.8
6.6
31,6
121,440
2,733
266
1,274
Small
grain
6,904
43.5
11.0
113.8
78,347
494
125
1,291
NB
102
Corn
3,795
42.1
6.8
50.5
3,516,391
39,005
6,300
46,788
Soybeans
2,308
51.9
5.1
24.2
566,166
12,732
1,251
5,937
Small
grain
4,139
26.3
6.1
63.5
831,550
5,284
1,226
12,759
MN
103
Corn
4,153
46.1
7.5
55.2
7,126,488
79,103
12,869
94,718
Soybeans
2,543
57.2
5.6
26.7
2,431,925
54,712
5,356
25,539
Small
grain
3,505
22.6
4.5
49.6
1,314,847
8,477
1,688
18,605
IA
103
Corn
5,672
63.0
10.2
75.5
8,533,289
94,781
15,345
113,587
Soybeans
3,020
67.9
6.6
31.7
3,802,277
85,502
8,311
39,918.
Small
grain
6,072
38.3
9.6
99.6
521,033
3,286
824
8,546
MN
104
Corn
4,215
46.8
7.6
56.1
984,544
10,931
.
1,775
13,103
Soybeans
2,044
46.0
4.5
21.5
373,013
8,393
821
3,923
Small
grain
3,274
20.9
4.7
49.6
215,115
1,373
309
3,259
IA
104
Corn
5,186
57.6
9.3
69.0
3,598,997
39,975
6,454
47,887
Soybeans
2,699
60.7
5.9
28.3
1,113,763
25,053
2,435
11,680
Small
grain
4,682
29.5
7.4
76.8
554,623
3,495
877
9,098
MN
105
Corn
5,108
56.7
9.2
67.9
1,156,049
12,833
2,082
15,368
Soybeans
2,180
49.1
4.8
22.9
154,661
3,483
341
1,625
Small
grain
3,544
22.6
5.2
54.9
276,202
1,761
405
4,279
IA
105
Corn
5,229
58.1
9.4
69.6
1,490,149
16,556
2,679
19,833
Soybeans
2,559
57.6
5.6
26.9
234,652
5,282 514
2,467
Small
grain
4,654
29.3
7.4
76.7
229,753
1,446
365
3,786
WI
105
Corn
4,613
51.2
8.3
61.3
1,547,866
17,181
2.785
20,571
Soybeans
1,905
42.9
4.2
20.0
43,107
971
95
452
Small
grain
5,012
31.7
8.0
82.2
755,177
4,903
1,237
12,713
IL
105
Corn
5,209
57.8
9.4
69.3
268,910
2,984
485
3,578
Soybeans
2,473
55.6
5.4
26.0
13,219
297
29
139
Small
grain
4,478
28.2
7.1
73.6
57,244
361
91
941
NB
106
'
Corn
3,609
39.6
6.0
47.8
1,834,842
20,131
3,050
24,300
Soybeans
2,360
53.1
5.2
24.8
376,181
8,464
829
3,953
Small
grain
3,782
25.1
3.1
40.3
604,599
4,013
496
6,443
KS
106
Corn
3,532
38.7
5.9
46.8
1,094,027
11,986
1,827
14,495
Soybeans
2,194
49.4
4.8
23.0
175,116
3,943
383
1,836
Small
grain
3,476
23.1
2.9
37.1
362,269
2,407
302
3,866
KS
107
Corn
4,479
49.5
7.9
59.5
133,517
1,476
236
1,774
Soybeans
2,652
59.7
5.8
27.8
59,103
1,331
129
620
Small
grain
3,770
25.1
2.9
38.5
28,688
191
22
293
NB
107
Corn
3,922
43.5
7.0
52.1
348,572
3,866
622
4,630
Soybeans
2,451
55.1
5.4
25.7
98,063
2,205
216
1,028
Small
grain
5,064
32.3
7.4
78.3
77,694
496
114
1,201
IA
107
Corn
4,654
51.7
8.4
61.9
6,305,115
70,039
11,380
83,857
Soybeans
2,944
122.7
12.5
37.3
2,022,940
84,301
8,588
25,627
Small
grain
5,843
36.9
9.2
95.0
987,619
6,238
1,555
16,059
4
Table
4.
-Average
residue
yield
per
acre
and
nutrient
content
of
residue
for
corn,
soybeans,
and
small
grain
for
the
major
land
resource
areas
(MLRA)
within
States
and
total
residue
with
associated
nutrient
contents
produced
within
the
MLRA-Continued
MLRA
and
crop
Average
yield
per
acre
Total
yield
and
nutrient
content
Residue
N
P
K
Residue
MO
107
Pounds
Tons
Corn
3,394
37.6
6.0
45.2
1,034,118
11,457
1,828
13,773
Soybeans
2,359
53.1
5.2
24.8
530,740
11,945
1,170
5,579
Small
grain
3,309
22.2
2.3
32.1
185,482
1,245
129
1,800
IA
108
Corn
5,288
58.7
9.5
70.3
7,109,915
78,926
12,773
94,523
Soybeans
2,892
65.1
6.4
30.4
2,275,490
51,217
5,035
23,917
Small
grain
4,337
27.4
6.8
70.9
863,732
5,456
1,354
14,119
IL
108
Corn
6,217
69.0
11.2
82.7
15,427,246
171,235
27,795
205,233
Soybeans
3,132
70.5
6.9
32.9
4,993,151
112,401
11,001
52,454
Small
grain
4,734
30.5
5.9
65.7
1,193,792
7,692
1,488
16,569
IA
109
Corn
4,605
51.1
8.3
61.2
1,114,463
12,366
2,009
14,810
Soybeans
2,410
54.2
5.3
25.3
416,128
9,358
915
4,368
Small
grain
3,414
21.7
5.1
53.6
147,737
939
221
2,320
MO
109
Corn
3,058
33.9
5.4
40.6
1,107,797
12,281
1,956
14,708
Soybeans
2,071
46.6
4.6
21.7
862,641
19,410
1,916
9,038
Small
grain
3,335
22.3
2.3
32.3
302,718
2,024
209
2,932
IL
110
Corn
5,564
61.8
10.0
74.0
3,137,862
34,853
5,640
41,734
Soybeans
2,856
64.3
6.3
30.0
1,451,418
32,678
3,202
15,247
Small
grain
4,741
30.7
5.7
64.3
232,888
1,508
280
3,158
IN
110
Corn
6,061
67.3
10.9
80.6
1,099,787
12,213
1,978
14,626
Soybeans
2,946
66.3
6.5
30.9
362,134
8,150
799
3,798
Small
grain
4,802
31.6
4.6
56.1
113,402
746
109
1,325
IL
111
Corn
6,097
67.7
11.0
81.1
254,821
2,829
460
3,390
Soybeans
3,000
67.5
6.6
31.5
111,186
2,502
245
1,168
Small
grain
4,402
29.2
3.7
47.5
24,768
164
21
267
IN
111
Corn
5,475
60.8
9.9
72.8
7,876,484
87,470
14,243
104,734
Soybeans
2,825
63.6
6.2
29.7
3,114,855
70,131
6,837
32,750
Small
grain
4,481
29.6
4.1
50.5
1,662,874
10,985
1,522
18,742
OH
111
Corn
4,622
51.3
8.3
61.5
4,585,816
50,896
8,235
61,016
Soybeans
2,585
58.2
5.7
27.1
2,450,571
55,165
5,403
25,687
Small
grain
4,490
29.6
4.3
52.5
2,026,493
13,358
1,941
23,693
KS
112
Corn
3,325
36.2
5.4
44.0
1,222,572
13,312
1,986
16,180
Soybeans
1,924
43.3
4.2
20.2
608,723
13,702
1,329
6,392
Small
grain
3,309
22.0
2.8
35.6
742,190
4,935
628
7,985
MO
112
Corn
2,986
32.8
5.0
39.6
870,374
9,559
1,457
11,541
Soybeans
1,897
42.7
4.2
19.9
472,057
10,625
1,045
4,951
Small
grain
3,201
21.4
2.2
31.0
365,824
2,446
251
3,543
MO
113
Corn
3,295
36.5
5.9
43.8
723,402
8,014
1,295
9,617
Soybeans
1,953
43.9
4.3
20.5
569,944
12,815
1,255
5,984
Small
grain
3,355
22.5
2.3
32.5
278,265
1,866
191
2,696
IL
113
Corn
4,325
48.0
7.8
57.5
924,333
10,259
1,667
12,290
Soybeans
2,219
49.9
4.9
23.3
762,110
17,136
1,683
8,001
Small
grain
3,375
22.6
2.5
33.5
497,593
3,332
369
4,938
IL
114
Corn
5,022
55.7
9.1
66.8
2,160,164
23,958
3,914
28,732
Soybeans
2,530
56.9
5.6
26.6
1,430,013
32,159
3,165
15,034
Small
grain
3,548
23.7
2.6
35.1
726,218
4,852
532
7,185
IN
114
Corn
5,311
59.0
9.6
70.6
1,080,917
12,008
1,954
14,369
Soybeans
2,532
57.0
5.6
26.6
342,898
7,719
758
3,602
Small
grain
3,604
24.0
2.8
37.3
207,515
1,382
161
2,148
OH
114
Corn
4,393
48.8
7.9
58.4
226,313
2,514
407
3,009
Soybeans
2,316
52.1
5.1
24.3
127,701
2,873
281
1,340
Small
grain
3,128
20.8
2.4
32.2
53,459
355
41
550
5
Table
4.
-Average
residue
yeild
per
acre
and
nutrient
content
of
residue
for
corn,
soybeans,
and
small
grain
for
the
major
land
resource
areas
(MLRA)
within
States
and
total
residue
with
associated
nutrient
contents
produced
within
the
MLRA-Continued
MLRA
and
crop
Average
yield
per
acre
Total
yield
and
nutrient
content
Residue
N
P
K
Residue
N
P
K
IA
115
Pounds
Tons
Corn
5,216
57.9
9.4
69.4
44,379
493
80
590
Soybeans
2,606
58.6
5.7
27.4
14,378
323
31
151
Small
grain
3,229
21.0
3.6
41.5
12,674
82
14
163
MO
115
Corn
3,575
39.6
6.3
47.5
820,810
9,091
1,446
10,905
Soybeans
2,101
47.3
4.6
22.1
418,601
9,423
916
4,403
Small
grain
3,115
20.9
2.2
30.2
310,832
2,086
220
3,014
IL
115
Corn
5,091
56.5
9.2
67.7
2,714,951
30,131
4,906
36,103
Soybeans
2,684
60.4
5.9
28.2
1,358,584
30,577
2,987
14,276
Small
grain
3,612
24.1
2.7
36.5
754,038
5,032
564
7,621
IN
115
Corn
5,821
64.6
10.5
77.4
1,390,698
15,434
2,509
18,492
Soybeans
2,686
60.4
5.9
28.2
361,095
8,121
793
3,792
Small
grain
3,764
25.2
2.7
37.3
307,760
2,061
221
3,050
crops
are
shown
in
table
4.
Hay
was
considered
not
to
be
a
source
of
residue.
The
proportion
of
crops
reported
in
this
study
compared
with
total
U.S.
production
is
84
percent
for
corn,
51
percent
for
soybeans,
and
13
percent
for
small
grains.
Values
for
the
factors
necessary
to
compute
the
USLE
were
obtained
from
the
following
sources:
R
from
published
values
(13);
-
K
for
each
soil
series
from
the
SCS
Midwest
Technical
Service
Center
(TCS
Advisory
Soils-LI-1);
L
from
the
respective
SCS
state
offices
(as
an
average
slope
length
for
each
slope
gradient
class);
S
from
soil
survey
data
from
the
Con-
servation
Needs
Inventory
(10);
and
C
from
respective
SCS
State
offices
for
tillage
and
rotation
systems.
P
was
assumed
equal
to
1.0,
which
corresponds
to
straight
up-and-
down
slope
tillage
with
no
conserva-
tion
practices.
We
assigned
crop
rotations
to
the
soil
series,
slope
-gradient
classifications
to
determine
the
C
values.
The
assignment
was based
on
the
crop
production
statistics
(table
1).
Row
crops
(corn
and
soy-
beans)
were
assigned
to
the
less
erosive
gentle
slopes,
and
small
grain
and
hay
were
included
into
the
rotation
as
slope
steepness
in-
creased,
but
with
the
stipulation
that
the
amount
of
each
crop
assigned
agreed
within
1
percen-
tage
point
of
the
crop
production
statistics
data.
For
example,
on
a
Nicollet
soil
(Aquic
Hapludoll)
with
a
1
-percent
slope
in
MLRA
MN
102,
the
rotation
assigned
was
corn
-
soybeans;
on
a
Clarion
soil
(Typic
Hapludoll)
with
a
9
-percent
slope,
the
rotation
assigned
was
corn
-oats
-
hay
-hay.
We
estimated
soil
loss
for
five
residue
and
tillage
management
systems:
Al
-
A2
A3
A4
A5
Conventional
tillage,
all
residue
removed.
Conservation
tillage,
1,500
pounds
residUe
remaining.
Conservation
tillage,
3,500
pounds
residue
remaining.
No
till,
1,500
pounds
residue
remaining.
No
till,
3,500
pounds
residue
remaining.
Small
-grain
and
soybean
residues
were
assumed
to
be
twice
as
effec-
tive
as
corn
residue
on
a
weight
basis.
Therefore,
in
systems
A2
and
A4,
750
pounds
per
acre
and
in
systems
A3
and
A5,
1,750
pounds
per
acre
of
residue
were
considered
remaining
for
these
crops
in
the
rotation.
The
conventional
tillage
system
was
considered
equivalent
to
a
fall
moldboard
plow,
spring
disk,
and
harrow.
The
conservation
tillage
system
was
considered
to
be
a
subsurface
tillage
(chisel)
that
left
66
percent
surface
coverage,
and
the
no
-till
system
was
considered
to
leave
90
percent
surface
coverage.
We
assumed
for
the
residue
-tillage
systems
that
residue
was
harvested
to
the
limits
imposed
by
the
condi-
tions
Al
through
A5
before
tillage.
For
example,
in
the
case
of
condi-
tions
A2,
all
residue
greater
than
1,500
pounds
per
acre
for
corn
or
750
pounds
per
acre
for
small
grain
or
soybeans
was
harvested
and
removed.
These
residue
and
tillage
systems
correlated
well
with
most
SCS
State
technical
guides
for
the
C
in
the
USLE.
The
crop
rotation
used
within
the
study
units
is
shown
in
table
5
with
the
assigned
C
values.
We
compared
calculated
soil
loss
for
each
residue
and
tillage
-
management
system
combination
with
assigned
rotations
with
the
soil
loss
tolerance
(T)
limit
for
each
soil
series,
slope
-gradient
classification.
If
the
calculated
soil
loss
was
less
than
the
T
value,
we
assumed
that
residue
could
be
removed
without
appreciably
affecting
short-term
soil
productivity.
T
values
are
defined
as
the
maximum
soil
loss
that
is
con-
sidered
safe
for
continued
long-
term,
maximum
productivity
of
the
soil.
In
our
analysis,
we
did
not
con-
sider
the
total
area
in
a
study
unit.
Areas
not
considered
include
all
slopes
greater
than
20
percent;
soil
classification,
such
as
gravel
pits,
sandbars
or
sanddunes,
dumps,
marshes,
and
others
that
were
obviously
not
agricultural
soils;
soil
series
with
T
values
less
than
or
equal
to
2;
and
soil
series
that
were
pointed
out
by
State
SCS
personnel
to
be
nonagricultural
soils.
Total
acres
considered
within
study
units
and
acres
cultivated
are
shown
in
table
6.
Cultivated
acres
were
deter-
mined
from
State
crop
reporting
statistics.
We
used
the
percentage
of
cultivated
area
to
determine
6
Text
continues
on
page
10.
Table
5.
-Crop
rotations
assigned
with
cultivated
area
and
percentage
of
cultivated
area
and
C
values
for
the
5
tillage
and
residue
management
systems
MLRA
and
crop
rotation
-
-
Area
-
-
C
value
MLRA
and
crop
rotation
Area
C
value
SD
102
Acres
Percent
Al
A2
A3
A4
A5
MN
104
Acres
Percent
Al
A2
A3
A4
A5
COHH
483,719
6.1
0.21
0.17
0.11
0.14
0.08
CSB
794,020
55.0
0.46
0.37
0.21
0.29
0.19
COHHH
277,385
3.5
.17
.14
.09
.11
.07
COHH
123,158
8.5
.10
.07
.04
.05
.03
CSBO
1,984,084
25.0
.43
.36
.23
.29
.17
H
20,448
1.4
.01
.01
.01
.01
.01
CCO
2,082,224
26.2
.46
.35
.22
.28
.17
CCOH
79,336
5.5
.26
.24
.14
.21
.12
COO
1,951,095
24.6
.35
.28
.19
.22
.13
CCO
92,639
6.4
.36
.31
.16
.24
.13
H
1,155,960
14.6
.01
.01
.01 .01
.01
COHHH
20,599
1.4
.07
.04
.03
.03
.02
MN
102
CSBOH
181,398
12.6
.26
.24
.14
.21
.12
CSB
272,085
5.4
.46
.37
.21
.29
.19
CSBO
132,969
9.2
.36
.25
.14
.16
.11
COHH
429,665
8.4
.10
.07
.04
.05
.03
IA
104
H
86,108
1.7
.01
.01
.01 .01
.01
CSB
1,196,685
33.3
.46
.36
.21
.29
.21
CCOH
161,925
3.2
.26
.24
.14
.21
.12
COHH
355,285
9.9
.10
.07
.04
.05
.03
CO
22,711
.5
.30
.28
.14
.21
.11
H
132,172
3.7
.01
.01
.01
.01
.01
CSBCO
1,916,968
37.7
.40
.33
.18
.26
.14
CCOH
4,828
.1
.22
.17
.10
.13
.08
CCSB
493,001
9.7
.44
.37
.21
.28
.15
CO
382,583
10.6
.30
.28
.14
.21
.11
COO
1,033,719
20.3
.28
.24
.13
.18
.10
CCSB
1,393,959
38.7
.46
.36
.24
.29
.18
COHHH
277,417
5.5
.07
.04
.03 .03
.02
CSBOH
133,552
3.7
.19
.15
.10
.13
.08
CSBO
390,590
7.7
.36
.25
.14
.16
.11
MN
105
IA
102
CSB
125,236
7.9
.46
.37
.21
.29 .19
CSB
177,040
47.2
.46
.36
.24
.29
.21
COHH
480,179
30.4
.10
.07
.04
.05
.03
COHH
39,699
10.6
.10
.07
.04
.05
.03
H
54,384
3.4
.01 .01
.01
.01
.01
H
5,120
1.4
.01
.01
.01
.01
.01
CCOH
181,097
11.5
.26
.24
.14
.21
.12
C
89,504
23.9
.42
.35
.18
.19
.13
C
114,286
7.2
.42
.37
.17
.28
.12
CCO
2,483
.7
.36
.31
.16
.24
.13
CCSB
344,105
21.8
.44
.37
.21
.28
.15
CSBO
52,507
14.0
.37
.32
.16
.25
.13
COHHH
166,663
10.5
.07
.04
.03
.03
.02
CSBOH
8,970
2.4
.18
.14
.10
.12
.08
CSBO
115,749
7.3
.36
.25
.14
.16
.11
NB
102
IA
105
COHH
607,424
10.7
.15
.12
.08
.11
.07
CSB
512,766
23.9
.46
.36
.21
.29
.21
CCOH
1,734,768
30.6
.27
.23
.14
.19
.13
COHH
23,280
1.1
.10
.07
.04
.05
.03
C
962,112
17.0
.52
.35
.19 .29
.13
H
347,266
16.2
.01
.01 .01
.01
.01
CSB
1,178,895
20.8
.55
.42
.20
.35
.18
CCOH
477,299
22.3
.22
.17
.10
.13
.08
CCSB
758,282
13.4
.54
.41
.20
.35
.18
C
322,616
15.1
.42
.35
.18
.19
.13
H
227,132
4.0
.01
.01 .01 .01 .01
CCSB
209,075
9.8
.46 .36
.24
.29
.18
CO
208,515
3.7
.30
.28
.14
.21
.11
COHHH
252,035
11.8
.09
.06
.04 .04
.03
MN
103
WI
105
CSB
4,697,417
54.8
.46
.37
.21
.29 .19
C
640,920
13.3
.50
.35
.18
.30
.12
COHH
400,410
4.7
.10
.07
.04
.05
.03
CSB
211,197
4.4
.58
.40
.21
.35
.14
H
146,176
1.7
.01 .01 .01 .01
.01
COHH
518,951
10.8
.08
.04
.03 .03
.02
CCOH
911,971
10.6
.26
.24
.14
.21
.12
CCOH
391,515
8.1
.18
.12
.08
.10
.07
C
297,270
3.5
.42
.37
.17
.28
.12
H
577,255
12.0
.01
.01
.01
.01 .01
CO
14,124
.2
.30
.28
.14
.21
.11
COHHH
2,472,270
51.4
.07
.04
.03 .03
.02
CSBCO
317,734
3.7
.40
.33
.18
.26
.14
IL
105
CCO
1,350,720
15.8
.36
.31
.16
.24
.13
CSB
216
<.1
.49
.32
.18
.30
.12
COHHH
437,143
5.1
.07
.04
.03
.03
.02
CSBO
36,392
7.3
.35
.26
.14
.16
.10
IA
103
CCOH
16,544
3.3
.17
.14
.09
.10
.05
CSB
5,850,909
80.6
.46
.36
.21
.29
.21
H
84,226
16.8
.01
.01
.01
.01
.01
H
32,927
.5
.01 .01
.01 .01
.01
C
174,210
34.8
.48
.32
.18
.30
.12
CCOH
795,906
11.0
.22
.17
.10
.13
.08
COHHH
97,693
19.5
.07
.04
.03
.03
.02
CCO
38,288
.5
.36
.31
.16
.24
.13
CSBOH
49,204
9.8
.25
.19
.12
.15
.08
-.
1
CCSB
544,737
7.5
.46
.36
.24
.29
.18
COHH
42,527
8.5
.09
.05
.04
.04
.03
CCSBO
214
<.1
.34
.24
.12
.14
.09
co
Table
5.
-Crop
rotations
assigned
with
cultivated
area
and
percentage
of
cultivated
area
and
C
values
for
the
5
tillage
and
residue
management
systems
-Continued
MLRA
and
crop
rotation
- -
Area
- -
C
value
MLRA
and
crop
rotation
Area
C
value
Acres
Percent
Al
A2
A3
A4
A5
Acres
Percent
Al
A2
A3
A4
A5
NB
106
IA
108
COHH
157,413
5.0
0.15
0.12
0.08
0.11
0.07
CCOH
1,234,126
14.6
0.22
0.17
0.10
0.13
0.08
CCOH
713,620
22.5
.27
.23
.14
.19
.13
C
830,966
9.8
.42
.35
.18
.19
.13
C
100,397
3.2
.52
.35
.19
.29
.13
CO
96,933
1.1
.30
.28
.14
.21 .11
CCO
34,290
1.1
.40
.21
.12
.17
.08
CSBCO
209,817
2.5
.40
.33
.18
.26
.14
CCSB
1,417,327
44.7
.54
.41
.20
.35
.18
CCO
21,486
.3
.36
.31
.16
.24
.13
COO
334,874
10.6
.30
.26
.15
.20
.12
IL
108
H
1,979
.1
.01
.01 .01 .01
.01
CSB
6,334,257
52.3
.53
.32
.18
.29
.11
CO
4,217
.1
.35
.27
.13
.20
.07
CCOH
1,363,569
11.3
.18
.13
.09
.09
.05
CCSBO
306,015
10.0
.44
.30
.18
.25
.13
COHHH
30,951
.3
.06
.04
.03
.03
.02
COHHH
97,906
3.1
.12
.10
.06
.07
.05
H
1,709
<.1
.01
.01
.01
.01
.01
KS
106
CCO
762,801
6.3
.32
.23
.12
.14
.09
CSB
662,950
26.7
.58
.42
.20
.35
.14
CCSB
3,323,189
27.4
.51
.31
.16
.29
.11
C
284,330
11.5
.53
.42
.20
.35
.14
IA
109
COHH
306,979
12.4
.18
.17
.08
.15
.07
CSB
1,830,398
54.6
.46
.36
.21
.29
.21
H
42,496
1.7
.01
.01 .01 .01 .01
COHH
381,707
11.4
.10
.07
.04
.05
.03
CO
236,769
9.5
.36
.32
.14
.28
.11
H
614,988
18.4
.01
.01
.01
.01
.01
CCOH
950,563
38.3
.30
.27
.12
.23
.10
CCOH
431,098
12.9
.22
.17
.10
.13
.08
NB
107
CCO
81,500
2.4
.36
.31
.16
.24
.13
COHH
820
.2
.15
.12
.08
.11
.07
CCSB
11,474
.3
.46
.36
.24
.29
.18
CCOH
193,053
38.3
.27
.23
.14
.19
.13
MO
109
C
13,498
2.7
.52
.35
.19
.29
.13
CSB
3,098,775
59.4
.57
.30
.18
.23
.11
CSB
164,625
32.6
.55
.42
.20
.35
.18
COHH
329,110
6.3
.10
.07
.04
.05
.03
CCSB
132,296
26.2
.54
.41
.20
.35
.18
H
655,225
12.8
.01
.01
.01
.01
.01
KS
107
SBO
338,813
6.5
.37
.20
.12
.14
.07
CSB
165,420
59.8
.58
.42
.20
.35
.14
SBOHH
12,918
.3
.10
.07
.05
.06
.04
CSBO
9,870
3.6
.50
.35
.16
.30
.12
SBOHHH
770,025
14.8
.08
.04
.03
.03
.02
COHH
92,521
33.4
.18
.17
.08
.15
.07
IL
110
CCO
8,834
3.2
.44
.35
.16
.30
.12
CSB
3,112,421
80.0
.49
.32
.18
.30
.12
IA
107
CCOH
1,313
<.1
.17
.14
.09
.10
.05
CSB
3,946,398
58.1
.46
.36
.21
.29
.21
H
55,478
1.4
.01
.01
.01
.01
.01
COHH
389,693
5.7
.10
.07
.04
.05
.03
C
179,549
4.6
.48
.32
.18
.30
.12
H
18,560
.3
.01
.01 .01
.01
.01
COHH
31,155
.8
.08
.05
.04
.04
.03
CCOH
924,797
13.6
.22
.17
.10
.13
.08
CSBO
363,747
9.4
.36
.24
.13
.15
.09
C
1,043,934
15.4
.42
.35
.18
.19
.13
CSBOH
145,307
3.7
.20
.15
.11
.11
.06
CCO
470,687
6.9
.36
.31
.16
.24
.13
IN
110
MO
107
CSB
668,266
61.5
.49
.32
.18
.30
.12
CSB
1,819,709
64.2
.57
.30
.18
.23
.11
COHH
45,443
4.2
.09
.05
.04
.04
.03
COHH
415,664
14.7
.10
.07
.04
.05
.03
CO
861
.1
.31
.32
.11
.13
.08
CCOH
435,170
15.4
.23
.14
.09
.11
.08
COHHH
21,188
2.0
.07
.04
.03
.03
.02
H
103,250
3.6
.01 .01
.01
.01
.01
C
171,501
15.8
.48
.32
.12
.30
.12
CSBO
35,033
1.2
.45
.25
.15
.19
.09
CSBO
178,976
16.5
.33
.24
.19
.20
.15
COHHH
26,537
.9
.08
.05
.03
.03
.02
IA
108
CSB
167,536
75.3
.53
.32
.18
.29
.11
CSB
4,925,426
58.2
.46
.36
.21
.29
.21
CCOH
3,756
1.7
.18
.13
.09 .09
.05
COH
4,613
.1
.19
.15
.08
.11
.06
COHH
.
6,346
2.9
.08
.05
.04
.04
.03
COHH
874,087
10.3
.10
.07
.04
.05
.03
C
8,759
3.9
.48
.32
.12
.30
.12
H
268,985
3.2
.01
.01
.01
.01
.01
CSBO
36,074
16.2
.36
.24
.13
.15
.09
Table
5.
-Crop
rotations
assigned
with
cultivated
area
and
percentage
of
cultivated
area
and
C
values
for
the
5
tillage
and
residue
management
systems
-Continued
MLRA
and
crop
rotation
- -
Area
- -
C
value
MLRA
and
crop
rotation
Area
C
value
IN
111
Acres
Percent
Al
A2
A3
A4
A5
IL
114
Acres
Percent
Al
A2
A3
A4
A5
C
486,709
5.0
0.51
0.31
0.18
0.29
0.11
H
107,948
2.4
0.01
0.01
0.01
0.01
0.01
CSB
5,340,308
54.8
.53
.32
.18
.29
.11
SBO
351,708
7.9
.34
.24
.12
.14
.09
COHH
615,329
6.3
.08
.05
.04
.04
.03
COHHH
56,703
1.3
.06
.04
.03 .03
.02
CCOH
837,788
8.6
.18
.13
.09
.09
.05
SBOHHH
26,329
.6
.07
.04
.03
.03
.02
H
35,412
.4
.01
.01 .01 .01
.01
CSBOH
196,518
4.4
.21
.16
.10
.12
.07
CSBO
2,421,348
24.9
.36
.24
.13
.15
.09
SBOHH
163,837
3.7
.09
.05
.04
.04
.03
COH
214
<.1
.10
.06
.05
.05
.04
IN
114
OH
111
C
34,486
1.7
.51
.32
.16
.29
.11
CSB
3,496,076
41.5 .56
.31
.19
.25
.13
CSB
1,048,504
50.6
.60
.32
.18 .28
.11
CSBO
3,205,981
38.0
.33
.25
.20
.23
.12
COHH
69,332
3.3
.08
.05
.04
.04
.03
COHHH
811,136
9.6
.08
.05
.04
.04
.03
CCOH
482,528
23.3
.18
.13
.09
.09
.05
H
138,243
1.6
.01 .01 .01
.01
.01
CSBO
318,412
15.4
.37
.23
.14
.13
.10
SBO
45,259
.5
.33
.24
.19
.20
.11
COHHH
119,935
5.8
.07
.04
.03 .03
.02
COO
4,755
.1
.30
.26
.15
.20
.12
OH
114
CSBOH
727,386
8.6
.20
.18
.12
.14
.09
CSB
442,732
42.9
.56
.31
.19
.25
.13
KS
112
COHH
1,297
.1
.08
.05
.04
.04
.03
CSB
1,682,876
34.4
.58
.42
CSBO
82,555
8.0
.33
.25
.20
.23
.12
H
70,497
1.4
.01
.01
.20
.35
.14
COHHH
253,089
24.5
.07
.04
.03
.03
.02
SBO
485,207
9.9
.40
.32
.01
.14
.01
_
.01
H
62,462
6.1
.01
.01
.01
.01
.01
COHH
1,826,784
37.3
.18
.17
.08
.28
.11
SBO
68,923
6.7
.32
.24
.19
.20
.15
CSBO
355,017
7.3
.50
.35
.16
.15
.30
.07
.12
CSBSB
121,253
11.8
.56
.31
.19
.25
.13
CSBOH
475,644
9.7
.32
.28
.13
.24
.10
IA
115
MO
112
CSB
37,165
48.4
.46
.36
.21
.29
.21
CSB
2,132,647
47.2
.57
.30
.18
COHH
12,599
16.4
.10
.07
.04
.05
.03
COHH
1,523,752
33.7
.10
.07
.04
.23
.11
CO
7,558
9.8
.30
.28
.14
.21
.11
H
419,253
9.3
.01
.01 .01
.05
.03
COO
9,448
12.3
.28
.24
.13
.18
.10
SBO
321,530
7.1
.37
.20
.12
.01
.14
.01
.07
H
10,078
13.1
.01 .01
.01
.01
.01
SBOHH
11,695
.3
.10
.07
.04
.05
.03
MO
115
CSBO
113,439
2.5
.45
.25 .15
COHHH
1,284,568
26.3
.08
.04
.03
.03
.02
MO
113
.19 .09
CSBO
186,097
3.8
.45
.25
.15
.19
.09
CSB
2,050,426
59.1
.57
.30
SBO
360,350
7.4
.37
.20
.12
.14
.07
COHH
635
<.1
.10
.07
.18
.23
.11
CSB
1,939,610
39.7
.57
.30
.18
.23
.11
H
89,006
2.6
.01
.01
.04
.01
.05
.03
COHH
432,210
8.9
.10
.07
.04
.05
.03
SBO
285,059
8.2
.37
.20
.12
.01
.14
.01
.07
H
682,974
14.0
.01 .01
.01
.01
.01
SBOHH
915,735
26.4
.10
.07
.04
.05
.03
IL
115
CSBO
229
<.1
.45
.25
.15
CSB
2,560,141
46.5
.53
.32
.18
.29
.11
COHHH
125,965
3.6
.07
.03
.02
.19 .09
CSBO
2,073,723
37.7
.37
.23
.14
.15
.09
IL
113
.02 .02
H
136,562
2.5
.01 .01
.01
.01
.01
CSB
73,135
3.2
.53
.32
.18
.29
.11
COHHH
363,285
6.6
.07
.04
.03
.03
.02
CSBSB
893,148
39.2
.55
.38
.20
.29
CSBOH
335,188
6.1
.21
.16
.10
.12
.07
COHH
618
<.1
.09
.05
.04
.04
.11
.03
C
37,172
.7
.59
.29
.12
.26
.10
CSBO
737,567
32.4
.36
.24
.13
.15
.09
IN
115
H
3,098
.1
.01
.01
.01
.01
C
209,301
12.7
.51
.31
.16
.29
.11
SBO
267,900
11.8
.34
.24
.12
.01
CSB
596,561
36.2
.53
.32
.18
.29
.11
COHHH
199,296
8.8
.08
.04
.03
.14
.03
.09
COHH
54,949
3.3
.08
.05
.04
.04
.03
CSBOH
102,009
4.5
.21
.16
.10
.12
.02
CSBO
503,983
30.6
.37
.23
.14
.15
.09
IL
114
.07
CCOH
149,193
9.1
.18
.13
.09
.09
.05
CSB
1,492,500
33.5
.60
.32
.18
.28
CO
129,108
7.8
.31
.20
.11
.13
.08
XI
CSBSB
773,246
17.4
.61
.33
.18 .28
.11
.11
H
2,883
.2
.10
.01
.01
.01
.01
CSBO
1,282,964
28.8
.37
.25
.13
.15
.10
Table
6.
-Total
area
considered
and
average
cultivated
acreage
and
percentage
of
area
cultivated
(1972.76)
for
major
land
resource
areas
(MLRA)
within
States
in
the
Corn
Belt
MLRA
Total
area
Cultivated
area
Acres
Percent
Acres
Percent
SD
102
7,934,467
92.2
4,396,190
51.1
MN
102
5,084,189
95.0
2,762,645
51.6
IA
102
375,323
94.7
279,537
70.5
NB
102
5,677,128
95.1
3,307,535
55.4
MN
103
8,572,965
93.0
6,754,339
73.3
IA
103
7,262,767
97.1
5,887,136
78.7
MN
104
1,444,567
95.4
1,083,261
71.5
IA
104
3,599,064
91.1
2,709,913
68.6
MN
105
1,580,699
76.4
1,038,970
50.2
IA
105
2,144,337
83.0
1,206,195
46.7
WI
105
4,812,108
71.4
2,062,002
30.6
IL
105
591,226
85.9
218,127
37.4
NB
106
3,168,038
99.5
1,840,032
57.8
KS
106
2,484,096
84.5
1,196,329
40.7
NB
107
504,292
96.8
319,333
61.3
KS
107
276,645
81.6
143,437
42.3
IA
107
6,794,069
95.8
4,731,346
66.7
MO
107
2,835,363
94.4
1,384,275
46.1
IA
108
8,466,439
96.1
5,296,708
60.1
IL
108
12,116,608
95.4
9,038,274
71.2
IL
109
3,351,165
91.5
1,259,187
34.4
MO
109
5,214,866
94.4
2,315,658
41.9
IL
110
3,888,970
98.6
2,306,656
58.5
IN
110
1,086,235
99.5
678,244
62.1
IL
111
222,471
93.8
172,190
72.6
IN
111
9,737,108
96.9
6,175,706
61.5
OH
111
8,428,836
97.8
5,289,049
61.4
KS
112
4,896,025
81.2
2,345,239
38.9
MO
112
4,522,316
95.8
1,775,127
37.6
MO
113
3,467,055
94.3
1,449,204
39.4
IL
113
2,276,771
89.7
1,507,510
59.4
IL
114
4,451,753
89.8
2,566,744
51.8
IN
114
2,073,197
86.4
890,786
37.1
OH
114
1,032,311
86.2
312,699
26.1
IA
115
76,848
83.0
45,650
49.3
MO
115
4,885,809
75.7
1,606,177
24.9
IL
115
5,506,071
84.0
2,712,883
41.4
IN
115
1,645,978
96.9
949,412
55.9
the
acreage
for
each
soil
type
considered.
In
MLRA
MN
103,
for
example,
the
Nicollet
soil
occupied
978,415
acres,
but
only
73.3
percent
of
the
MLRA
is
cultivated.
There-
fore,
in
our
analysis,
we
only
considered
73.3
percent
or
716,099
acres
to
be
actually
cultivated.
Results
and
Discussion
Calculated weighted
average
soil
loss
(based
on
acreage
cultivated
for
each
soil
series,
slope
-gradient
classification)
and
T
values
for
the
study
units
are
shown
in
table
7.
The
soil
-loss
values
reflect
the
components
of
the
USLE.
Tables
8,
9,
and
10
show
R
values,
K
-value
distribution,
slope
-gradient
distribution,
and
slope
lengths
used
in
this
analysis.
These
values
are
inherent
factors
that
cannot
be
changed
but
must
be
considered
in
management
system
design.
The
Al
residue
and
tillage
system
gives
an
intolerable
soil
loss
for
a
majority
of
the
study
units,
indicating
that
total
residue
removal
is
not
feasible.
As
the
residue
and
tillage
systems
become
conservative
in
nature,
Al
to
A5,
the
soil
-loss
values
decrease.
In
some
MLRA's,
however,
the
weighted
average
soil
loss
still
exceeds
the
T
level.
A
more
detailed
breakdown
of
calculated
soil
loss
and
percentage
of
area
less
than
T
by
crop
rotation
and
slope
-gradient
classification
is
shown
in
table
11.
The
slope
gradients
for
table
11
and
following
tables
are
our
classification
and
not
necessarily
the
classification
found
in
the
SCS
Conservation
Needs
In-
ventory
(10).
This
analysis
identifies
the
rotations
by
slope
and
residue
-
and
tillage
-management
system
where
residue
can
be
removed
practically
from
a
soil
-erosion
standpoint.
The
intermediate
slopes
(3
to
5
and
6
to
12
percent)
often
are
identified
as
having
serious
erosion
potential,
even
with
the
A5
residue
and
tillage
management
system,
primarily
because
of
the
high
percentage
of
row
crops
in
the
rotation.
The
amounts
of
residue
that
can
be
removed
safely
for
each
residue
and
tillage
management
system
for
each
crop
are
shown
in
table
12,
along
with
the
amounts
of
nitrogen,
phosphorus,
and
potassium
that
would
be
removed
with
the
residue.
The
nutrients
represent
the
amounts
of
nutrients
that
would
have
to
be
replaced
through
an
outside
system
just
to
maintain
a
balance.
In
determining
the
amount
of
residue
that
would
become
available
for
removal
with
the
various
residue
-
and
tillage
-management
systems,
we
have
shown
only
the
amounts
that
become
available
for
a
specific
system.
We
have
not
included
the
residue
that
would
have
been
available
for
a
less
restrictive
system.
In
MLRA
SD
102
for
corn,
for
example,
we
indicate
that
73.7
percent
of
the
corn
acreage
would
have
a
soil
loss
less
than
T
for
con-
dition
A2
and
that
248,388
tons
of
residue
is
available
for
removal.
This
does
not
include
the
1,206,614
tons
that
is
available
for
removal
from
10
Table
7.
-Calculated
weighted
average
soil
loss
(tonslacrelyear)
and
weighted
average
soil
loss
tolerance
(1)
for
the
5
tillage
and
residue
management
systems
for
major
land
resource
areas
(MLRA)
within
States
in
the
Corn
Belt
MLRA
Tillage
and
residue
management
systems
Al
A2
A3
A4
A5
T
Tons
Table
8.
-Rainfall
factor
(R)
used
for
major
land
resource
areas
(MLRA)
within
States
in
the
Universal
Soil
Loss
Equation
SD
102
4.4
3.6
2.3
2.8
1.7
4.8
MN
102
2.9
2.4
1.3
1.8
1.0
4.9
IA
102
11.6
9.4
5.3
6.2
4.2
4.8
MLRA
NB
102
11.3
9.1
5.3
7.7
4.7
4.9
MN
103
3.5
2.9
1.6
2.3
1.4
4.8
SD
102
IA
103
5.3
4.1
2.4
3.3
2.2
4.9
MN
102
MN
104
4.9
4.0
2.3
3.2
1.9
4.7
IA
102
IA
104
6.4
5.2
3.2
4.1
2.6
4.6
NB
102
MN
105
9.1
6.9
4.0
5.2
3.1
4.8
MN
103
IA
105
20.8
16.3
9.8
11.8
7.9
4.8
IA
103
WI
105
5.4
3.3
2.2
2.7
1.5
4.3
IL
105
10.6
7.3
4.7
5.8
3.3
4.6
MN
104
IA
104
NB
106
14.2
11.1
6.1
9.3
5.3
4.4
KS
106
10.4
8.9
4.1
7.6
3.2
3.9
MN
105
KS
107
21.2
17.7
8.3
15.3
6.7
4.9
IA
105
NB
107
21.8
18.2
10.7
15.1
9.8
4.9
WI
105
IA
107
20.7
16.4
9.2
12.2
7.9
4.9
IL
105
MO
107
16.8
9.5
5.8
7.3
4.0
4.7
NB
106
IA
108
17.6
13.8
7.8
10.1
6.7
4.8
KS
106
IL
108
9.2
5.9
3.5
4.9
2.2
4.7
NB
107
IA
109
13.2
10.3
6.2
8.2
5.7
3.8
KS
107
MO
109
16.7
9.1
5.6
6.9
3.6
4.2
IA
107
IL
110
7.7
5.1
3.0
4.4
2.0
4.3
MO
107
IN
110
5.9
3.9
2.2
3.5
1.7
4.7
IA
108
IL
111
12.1
7.7
4.3
6.0
2.8
4.9
IL
108
IN
111
7.3
4.7
2.8
3.6
1.8
4.2
OH
111
5.3
3.7
2.8
3.2
1.8
4.1
IA
109
KS
112
6.4
5.1
2.4
4.4
1.8
4.1
MO
109
MO
112
9.6
5.6
3.3
4.2
2.2
3.9
IL
110
IL
113
8.4
5.6
3.1
4.0
1.9
3.4
IN
110
MO
113
18.1
10.2
6.1
7.6
4.0
3.8
IL
111
IL
114
11.3
7.2
4.0
5.1
2.8
3.8
IN
111
IN
114
12.5
7.7
4.9
5.8
3.0
4.3
OH
111
OH
114
8.4
5.1
3.6
4.2
2.5
4.2
KS
112
IL
115
13.2
8.4
5.1
6.1
3.3
4.6
MO
112
IN
115
15.4
9.8
5.8
7.4
3.8
4.7
IA
115
7.2
5.9
3.4
4.7
3.1
3.9
MO
113
MO
115
14.8
8.2
5.4
6.2
3.6
4.3
IL
113
the
51.8
percent
of
the
corn
acreage
having
a
soil
-loss
value
less
than
T
for
condition
Al
but
only
accounts
for
the
additional
22.9
percent
of
the
corn
area
where
the
soil
-loss
level
decreased
to
less
than
T
for
condi-
tion
A2.
An
additional
area
where
soil
loss
is
less
than
T
is
indicated
for
condition
A3
in
MLRA
SD
102,
but
corn
residue
yields
were
less
than
3,500
pounds
per
acre;
there-
fore,
no
additional
residue
can
become
available
for
removal.
Total
values
for
residue
availability
and
nutrients
removed
are
the
addition
of
systems
Al,
A4,
and
A5.
This
combination
represents
the
max-
imum
that
can
become
available.
In
total,
87
million
tons
of
crop
residues
(58
percent
of
total
pro-
duced)
can
become
available
for
removal
from
the
combinations
of
residue-
and
tillage
-management
systems.
Of
this
total,
60
percent
is
corn,
26
percent
soybeans,
and
13
percent
small
grain.
In
system
Al,
IL
114
IN
114
OH
114
IA
115
MO
115
IL
115
IN
115
R
values
used
125
125
150
150
150
175
150
175
150
175
150
200
175
200
150
200
175
200
200
180
200
200
180
150
180
150
150
225
225
200
200
200
175
175
200
225
200
200
11
Table
9.
-Soil
erodibility
factor
(K)
distribution
for
the
major
land
resource
areas
(MLRA)
within
States
MLRA
value
Acres
Percent
MLRA
value
Acres
Percent
SD
102
<.24
220,454
2.8
IL
108
<.24
371,171
3.0
.24-.32
7,559,750
95.3
.24-.32
10,065,166
83.1
>.32
154,263
2.0
>.32
1,680,271
13.9
MN
102
<.24
180,280
-3.6
IA
109
<.24
35,229
1.0
.24-.32
4,862,714
95.6
.24-.32
1,648,488
49.2
>.32
41,195
.8
>.32
1,667,448
49.8
IA
102
<.24
4,429
1.2
MO
109
<
.24
6,678
.1
.24-.32
324,773
86.5
.24-.32
2,997,766
57.5
>.32
46,121
12.3
>
.32
2,210,422
42.4
NE
102
<.24
1,087,630
19.2
IL
110
<.24
244,228
6.3
.24-.32
4,356,460
76.7
.24-.32
2,943,685
75.7
>.32
233,038
4.1
>.32
701,057
18.0
MN
103
<.24
901,685
10.5
IN
110
<.24
76,298
7.0
.24-.32
7,393,504
86.2
.24-.32
820,829
75.6
>.
32
277,776
3.2
>.32
189,108
17.4
IA
103
<.24
91,058
1.2
IL
111
<.24
671
.3
.24-.32
6,891,211
94.9
.24-.32
119,531
53.7
>.32
280,498
3.9
>.32
102,269
46.0
MN
104
<.24
87,878
6.1
IN
111
<.24
179,536
1.8
.24-.32
1,172,355
81.2
.24-.32
3,036,496
31.2
>.32
184,354
12.7
>.32
6,521,076
67.0
IA
104
<.24
303,191
8.4
OH
111
<.24
8,597
.1
.24-.32
3,204,491
89.0
.24-.32
2,435,939
28.9
>.32
91,382
2.6
>.32
5,984,300
71.0
MN
105
<.24
80,476
5.1
KS
112
<.24
0
0
.24-.32
589,474
37.3
.24-.32
3,614,723
73.8
>.32
910,749
57.6
>.32
1,281,302
26.2
IA
105
<.24
56,077
2.6
MO
112
<.24
146,387
3.2
.24-.32
738,658
34.4
.24-.32
2,819,498
62.4
>.32
1,349,602
63.0
>.32
1,556,431
34.4
WI
105
<.24
639,148
13.3
MO
113
<.24
21,591
.6
.24-.32
1,984,084
41.2
.24-.32
1,134,011
32.7
>.32
2,188,876
45.5
>.32
2,311,453
66,7
IL
105
<.24
26,217
5.2
IL
113
<.24
3,001
.1
.24-.32
241,050
48.1
.24-.32
122,269
5.4
>.32
233,959
46.7
>.32
2,151,501
94.5
NE
106
<.24
10,122
.3
11114
<.24
5,747
.1
.24-.32
2,254,632
71.2
.24-.32
748,303
16.8
>.32
903,284
28.5
>.32
3,697,703
83.1
KS
106
<.24
6,104
.2
IN
114
<.24
2,471
.1
.24-.32
1,022,664
41.2
.24-.32
125,315
6.0
>.32
1,455,328
58.6
>.32
1,945,411
93.9
KS
107
<.24
3,224
1.2
OH
114
<.24
2,125
.2
.24-.32
252,242
91.2
.24-.32
67,335
6.5
>.32
21,179
7.6
>.32
962,851
93.3
NE
107
<.24
6,517
1.3
IA
115
<.24
24,985
32.5
.24-.32
378,476
75.0
.24-.32
29,606
38.5
>.32
119,299
23.7
>.32
22,257
29.0
IA
107
<.24
44,373
.6
MO
115
<.24
73,616
1.5
.24-.32
5,578,690
82.1
.24-.32
2,564,247
52.5
>.32
1,171,006
17.3
>.32
2,247,946
46.0
MO
107
<.24
50,202
1.8
IL
115
<.24
326,378
5.9
.24-.32
2,245,164
79.2
.24-.32
2,252,797
40.9
>.32
539,997
19.0
>.32
2,926,896
53.2
IA
108
<.24
168,221
2.0
IN
115
<.24
95,720
5.8
.24-.32
6,310,733
74.5
.24-.32
376,983
22.9
>.32
1,987,485
23.5
>.32
1,173,275
71.3
35
percent
of
the
total
residue
is
available
for
removal.
For
the
conservation
-tillage
systems,
an
additional
10
percent
becomes
available
in
condition
A2,
and
a
7
-
percent
increment
becomes
available
in
condition
A3,
giving
a
total
of
52
percent
for
the
conser-
vation
plus
conventional
-tillage
systems.
For
the
no
-till
systems,
an
additional
16
percent
becomes
available
in
system
A4,
with
a
7
-
percent
increment
in
system
A5,
giving
a
total
of
58
percent
for
the
conventional
plus
the
no
-till
system.
Of
these
residues
available
for
removal,
60
percent
is
obtainable
in
condition
Al,
assuming
a
100
-
percent
harvest
efficiency
of
residue;
78
percent
is
available
in
condition
A2;
and
88
percent
is
available
in
condition
A4.
The
last
two
conditions
leave
1,500
pounds
of
corn
residue,
or
750
pounds
of
soybeans
or
small
-grain
residue
per
acre.
Another
consideration
in
a
residue
-harvesting
program
is
the
reliability
of
residue
production,
realizing
that
crop
acreage
and
residue
yields
vary
from
year
to
year.
Table
13
gives
an
estimate
of
this
variation
by
showing
the
coefficient
of
variation
for
crop
acreage
and
residue
yield.
These
coefficients
are
a
relative
measure
of
variation,
defined
as
the
standard
deviation
expressed
as
a
percentage
of
the
mean.
Summary
This
analysis
shows
that
soil
erosion
by
water
is
a
serious
problem
in
the
Corn
Belt.
For
example,
in
the
Al
residue-
and
tillage
-management
system,
only
36
percent
of
the
cropland
would
have
a
soil
loss
level
less
than
T
established
by
the
SCS.
Other
estimates
(7)
also
show
that
soil
erosion
exceeds
the
T
level
for
the
majority
of
the
Corn
Belt.
Therefore,
widespread
removal
of
crop
residues
would
increase
erosion
potentials
and
intensify
an
already
serious
problem.
Residue-
and
tillage
-manage-
ment
systems
will
reduce
soil
loss
and
allow
a
portion
of
the
residue
to
be
removed
from
an
increased
area,
but
a
significant
area
(our
analysis
indicates
22
percent)
will
still
exceed
the
T
level.
For
these
areas,
additional
conservation
treatments
will
be
necessary
to
reduce
soil
loss
to
acceptable
levels.
Our
calculation
assumed
the
P
in
the
USLE
to
be
1.0,
meaning
straight
-row
cultiva-
12
Text
continues
on
page
16.
Table
10.
-Slope
gradient
factor
distribution
and
slope
length
factor
for
the
major
land
resource
areas
(MLRA)
within
States
Slope
grad-
MLRA
fent
Per-
centage
of
area
Slope
Acres
length
Slope
grad-
MLRA
ient
Per-
centage
of
area
Acres
Slope
length
Slope
grad-
MLRA
ient
Per-
centage
of
area
Acres
Slope
length
Percent
Feet
Percent
Feet
Percent
Feet
SD
102
1
51.81
4,111,094
200
NB
107
1
42.74
215,521
300
13
0.08
6,951
100
3
13.22
1,049,282
150
2
2.27
11,434
125
14
.16
13,371
100
5
22.80
1,808,792
150
4
11.68
58,894
125
15
2.41
203,496
100
7
10.16
806,192
125
6
3.98
20,058
100
16
.09
7,701
100
9
.29
23,270
125
10
8.91
44,954
100
17
.46
38,417
100
11
1.45
114,707
100
14
16.35
82,437
100
19
.02
2,098
100
13
.27
21,130
100
20
14.08
70,994
100
20
.08
6,850
100
MN
102
1
53,82
2,736,196
100
KS
107
1
12.06
33,352
300
KS
112
1
23.06
1,128,811
250
4
38.17
1,940,475
125
2
11.01
30,461
125
2
53.19
2,604,391
150
9
6.50
330,665
100
5
36.73
101,607
100
5
21.30
1,043,051
100
15
1.51
76,853
75
10
25.20
69,704
100
10
2.45
119,772
100
20
15.01
41,521
100
IA
102
1
19.11
71,729
200
MO
112
1
26.55
1,200,842
400
3
40.97
153,780
200
IA
107
1
26.52
1,801,791
250
3
43.72
1,977,249
250
7
28.20
105,847
200
3
30.89
2,098,820
250
7
23.72
1,072,898
250
11
16
10.35
1.36
38,847
5,120
200
200
7
11
16
16.71
18.79
7.09
1,135,273
1,276,574
481,611
250
250
250
11
17
4.89
1.11
221,170
50,157
200
200
NB
102
1
2
4
6
10
14
30.60
12.53
17.40
11.18
20.06
8.24
1,736,982
711,080
987,818
634,591
1,138,759
467,898
300
30
0
2
5
0
250
150
150
MO
107
1
3
7
11
17
37.28
13.65
31.18
14.24
3.64
1,057,053
387,051
884,113
403,896
103,250
300
250
250
200
150
MO
113
1
3
6
7
11
27.74
26.78
1.81
25.88
12.70
961,784
928,401
62,705
897,393
440,243
450
300
300
300
275
17
5.09
176,529
125
MN
103
1
59.15
5,071,010
100
IA
108
1
25.61
2,168,029
250
4
31.38
2,690,017
1
25
3
30.10
2,
,
601
250
548
IL
113
0
.01
191
250
9
7.30
625,575
100
7
23.68
2,004,456
250
1
68.46
1,558,695
250
10
.16
13,673
100
11
14.67
1,242,433
250
3
22.77
518,312
300
15
2.01
172,690
75
16
5.94
502,920
250
6
7.01
159,715
300
10
1.62
36,832
200
IA
103
1
63.38
4,602,920
150
IL
108
0
.01
847
250
15
.13
3,026
100
3
24.27
1,762,856
150
1
56.08
6,794,684
250
7
9.01
654,093
150
3
25.03
3,033,174
300
IL
114
1
59.85
2,664,168
250
11
2.27
164,998
150
6
10.82
1,310,565
300
3
22.34
994,348
300
16
1.07
77,900
150
10
5.80
703,275
250
6
10.99
489,125
300
15
2.26
274,063
100
10
5.34
237,637
200
MN
104
1
60.60
875,348
200
15
1.49
66,475
100
4
30.18
435,959
250
IA
109
1
18.87
632,423
150
9
7.18
103,731
200
3
22.76
762,788
150
IN
114
1
56.70
1,175,456
400
15
2.04
29,529
150
7
26.85
899,891
150
4
19.54
405,128
300
11
18.84
631,399
150
9
15.16
314,300
250
IA
104
1
39.40
1,417,962
250
16
12.67
4
,
664
150
24
15
8.60
178,313
200
3
48.05
1,729,393
250
7
9.78
352,049
250
MO
109
1
27.51
1,434,540
400
OH
114
0
27.51
283,938
200
11
16
2.03
.74
73,132
26,528
250
2
50
3
7
18.57
31.86
968,504
1,661,307
250
250
1
3
14.69
15.51
151,610
160,114
200
200
11
14.20
740,301
200
4
10.62
109,675
220
MN
105
0
.11
1,704
100
17
7.87
410,214
150
5
.38
3,911
220
1
4
9
15
17.60
41.47
29.63
11.19
278,238
655,506
468,389
176,862
100
250
200
150
IL
110
0
1
3
.11
63.21
25.92
4,404
2,458,058
1,008,091
250
250
300
7
8
9
10
.84
1.86
12.26
1.90
8,705
19,184
126,552
19,604
200
200
200
200
6
8.65
336,405
300
11
.28
2,924
200
IA
105
1
3
9.45
17.68
202,578
379,118
250
250
10
15
1.61
.50
62,688
19,324
200
100
13
14
.72
3.60
7,481
37,193
100
100
7
26.48
567,856
250
15
5.66
58,447
100
11
31.35
672,318
250
16
1.08
11,113
100
16
15.04
322,467
250
IN
110
1
78.59
853,709
300
17
.69
7,147
100
4
17.58
190,914
350
19
77
,
(
0
):
100
WI
105
0
4.31
207,477
100
9
2
.
97
3
2,2
8
1
300
20
.74
1
.
66
17,104
(
10)
1
17.59
846,306
100
15
.86
9,331
200
4
25.23
1,213,910
200
IA
115
1
26.78
20,577
'150
8
28.76
1,384,194
150
IL
111
1
55.64
123,793
250
3
43.99
33,805
150
15
24.11
1,160,221
100
3
25.32
56,339
300
7
16.39
12,598
150
6
10.39
23,113
300
11
7.38
5,669
150
IL
105
1
21.49
107,726
250
10
5.79
12,880
200
16
5.46
4,199
150
3
14.26
71,474
300
15
2.85
6,346
100
6
23.31
116,855
300
MO
115
1
29.00
1,416,856
300
10
24.14
121,016
250
IN
111
1
65.99
6,425,621
300
3
10.94
534,501
300
15
16.79
84,155
100
4
24.60
2,395,600
200
7
28.86
1,410,109
300
9
7.71
750,393
200
11
21.53
1,052,099
250
NB
106
1
18.80
595,614
300
15
1.70
165,494
150
17
9.67
472,244
225
2
3.66
115,856
125
4
23.51
744,894
125
OH
111
0
32.89
2,772,445
150
IL
115
0
.06
3,049
250
6
35.19
1,114,895
100
1
20.08
1,692,916
150
1
51.67
2,844,786
250
10
12.89
408,323
100
3
8.19
690,695
140
3
16.96
933,592
300
14
4.25
134,705
100
4
24.76
2,087,031
140
6
12.89
709,617
300
20
1.70
53,751
100
5
3.47
292,479
140
10
11.74
646,383
200
6
.00
219
140
15
6.70
368,644
100
KS
106
1
15.16
376,621
300
7
.08
6,598
149
2
20.78
516,074
125
8
.08
6,521
149
IN
115
1
62.06
1,021,461
400
5
54.62
1,356,794
100
9
4.50
378,965
149
4
19.68
323,915
300
10
9.02
224,058
100
10
1.68
141,539
149
9
12.81
210,789
300
20
.42
10,549
100
11
.96
80,544
149
15
5.46
89,813
200
13
Table
11.
-Acreage
and
percentage
of
cultivated
area
for
assigned
crops,
weighted
average
soil
loss,
and
percentage
of
area
where
predicted
soil
loss
Is
less
than
the
soil
loss
tolerance
level
(T)
by
slope
categories
for
the
major
land
resource
areas
(MLRA)
within
States
MLRA
Slope
Cultivated
area
Assigned
rotation
Corn
Soy-
beans
Calculated
soil
loss
Area
<
T
Oats
Hay
Al
A2
A3
A4
A5
Al A2
A3
A4
A5
Percent
Acres
Percent
-
-
- -
Percent
- -
-
-
Tons
Percent
SD
102
0-2
4,111,094
51.8
18.5
7.9
13.8
11.7
2.0
1.6
1.0
1.3
0.8
99.5
100.0
100.0 100.0
100.0
3-5
2,858,074
36.0
15.2
.4
17.7
2.6
7.1
5.6
3.7
4.4
2.6
7.6
44.4
95.4
44.8
99.5
6-12
944,169
11.9
2.5
0
4.2
5.1
7.3
5.9
4.0
4.7
2.8
25.8
28.6
56.7
50.5
99.8
>
12
21,130
.3
0
0
0
.3
.8 .8
.8
.8
.8
100.0
100.0
100.0 100.0 100.0
MN
102
0-2
2,736,196
53.8
'27.2
15.2
10.0
1.4
1.8
1.4
.8
1.1
.6
100.0
100.0
100.0 100.0
100.0
3-5
1,940,475
38.2
13.8
2.6
18.4
3.3
4.5
3.7
2.0
2.8
1.6
81.0
85.4
100.0 100.0
100.0
6-12
330,665
6.5
1.3
0
1.3
3.8
3.0
1.9
1.3
1.4
.9
98.9
99.1
99.1
99.1
100.0
>
12
76,853
1.5
.1
0
.1
1.4
1.5
1.2
1.0
1.0
.9
86.7
99.4
100.0
100.0 100.0
IA
102
0-2
71,729
19.1
8.9 8.9
1.1
.1
2.7
2.2
1.4
1.7
1.2
93.6
100.0
100.0 100.0 100.0
3-5
153,780
41.0
18.9
18.9
3.1
.1
8.3
6.6
4.2
5.3
3.6
.8
1.1
98.8
12.5 98.8
6-12
144,694
38.6
27.9
1.0
3.9
5.7
19.8
16.1
8.5
9.5
6.2
.3
.7
16.8
1.7
29.2
>
12
5,120
1.4
0
0 0
1.4
2.5 2.5 2.5 2.5 2.5
100.0
100.0 100.0
100.0 100.0
NB
102
0-2
2,448,062
43.1
31.1
9.1
1.6
1.4
4.4
3.2
1.6
2.7
1.3
76.8
84.8
100.0
99.5
100.0
3-5
987,818
17.4
8.9
5.8
1.3
1.4
13.1
10.1
5.0
8.4
4.5
19.4 19.4
28.0
20.2
52.5
6-12
1,773,350
31.2
13.9
0
7.2
10.1
16.5
14.0
8.6
11.6
8.0
7.6
7.6
10.0
8.4
10.7
>
12
467,898
8.2
2.1
0
2.1
4.1
23.4
18.7
12.5
17.2
10.9
0
0
0 0
0
MN
103
0-2
5,071,010
59.2
30.6
26.2
1.7
.8
2.2
1.7
1.0
1.4
.9
99.9
100.0
100.0
100.0 100.0
3-5
2,690,017
31.4
18.6
2.2
7.7
2.9
6.1
5.3
2.9
4.3
2.4
5.6
24.6
98.7
94.6
99.8
6-12
639,248
7.5
1.6
0
1.6
4.2
3.9
2.4
1.6
1.8
1.1
94.1
99.6
100.0
99.8
100.0
>
12
172,690
2.0
.1
0
.1
1.9
1.7
1.3
1.2
1.2
1.1
90.1
99.6
99.9 99.9 99.9
IA
103
0-2
4,602,920
63.4
32.2
31.2
0 0
2.5
2.0
1.2
1.6
1.1
99.7
100.0 100.0 100.0
100.0
3-5
1,762,856
24.3
12.8
11.4
0
0
7.6
6.0
3.6
4.8
3.4
.1
1.4
98.8
91.0
99.2
6-12
819,091
11.3
5.8
.2
2.8
2.6
13.7
10.7
6.3
8.2
5.0
0 0
68.6
.4
72.4
>
12
77,900
1.1
.3
0'
.2
.6
24.3
19.0
11.5
14.7
9.3
42.2
42.2
42.2
42.2 42.2
MN
104
0-2
875,348
60.6
29.4
29.3
1.9
0
3.0
2.4
1.4
1.9
1.2
98.9
100.0
100.0 100.0 100.0
3-5
435,959
30.2
11.8
4.4
8.4
5.6
8.0
6.9
3.9
5.6
3.2
8.9
10.6
90.0
22.5
99.8
6-12
103,731
7.2
1.6
0
1.6
3.9
6.8
4.8
2.8
3.5
2.1
29.0
42.8
97.0
95.2
98.1
>
12
29,529
2.0
.3
0
.3
1.5
8.4
5.0
3.8
3.8
2.7
22.1
33.4
56.4
56.4
91.9
IA
104
0-2
1,417,962
39.4
20.9
17.8
.2
.5
3.4
2.6
1.6
2.1
1.5
97.4
99.1
100.0
99.9
100.0
3-5
.1,729,393
48.0
26.8
12.3
5.0
3.9
7.7
6.1
3.9
4.9
3.0
18.1
18.4
54.4
25.2
94.4
6-12
425,181
11.8
3.5
.4
3.5
4.4
11.5
10.0
5.5
7.7
4.3
26.7
31.5
45.8 45.8
51.8
>
12
26,528
.7
0
0
0
.7
3.1
3.0
2.8
2.9
2.8
76.5
76.5
76.5
76.5
76.5
MN
105
0-2
279,942
17.7
12.0
4.9
.5
.4
2.6
2.2
1.2
1.7
.9
0
100.0 100.0
100.0
100.0
3-5
655,506
41.5
22.6
8.8
5.5
4.6
11.9
9.9
5.6
7.6
4.3
7.6
8.0
40.9
19.4
55.1
6-12
468,389
29.6
7.3
0
7.3
15.1
8.6
6.0
3.5
4.3
2.6
1.6
8.9
99.4
98.7
99.6
>
12
176,862
11.2
1.7
0
1.7
7.7
9.9
5.8
4.5 4.5
3.1
22.8
25.9
32.8 32.8
100.0
IA
105
0-2
202,578
9.4
4.7
4.6
0
.1
3.7
2.9
1.7
2.3
1.7
72.0
96.9
100.0
100.0
100.0
3-5
379,118
17.7
9.6
7.4
.2
.6
10.8
8.5
4.9
6.6
4.8
5.2
6.8
29.7
16.6
30.1
6-12
1,240,174
57.8
33.0
3.2
8.0
13.6
31.1
24.3
14.3
17.2
11.0
2.1
4.0
6.1
6.0
17.6
>
12
322,467
15.0
0 0
.0
15.0
3.2
3.2
3.2
3.2
3.2
95.7 95.7 95.7
95.7
95.7
WI
105
0-2
1,053,783
21.9
10.9
.2
2.2
8.7
1.4
.9
.5
.8
.3
0
100.0
100.0 100.0 100.0
3-5
1,213,910
25.2
12.3
2.0
3.6
7.2
7.7
5.2
2.9
4.5
2.1
38.1
64.2
64.4
64.2
99.7
6-12
1,384,194
28.8
5.6
0
5.5
17.8
4.1
2.4
1.8
1.8
1.2
52.0
98.7
100.0
98.7
100.0
>
12
1,160,221
24.1
3.8
0
3.8
16.6
8.0
4.7
3.6
3.6
2.5
18.6
21.1
63.4
63.4
96.0
IL
105
0-2
107,726
21.5 21.5
0
0 0
4.9
3.3
1.8
3.1
1.2
53.6
99.0
100.0
99.0
100.0
3-5
71,474
14.3
13.6
.3
.3
.2
13.7
9.2
5.2
8.5
3.4
.9
3.7
11.9
6.4
99.1
6-12
237,871
47.5
11.5
4.6
10.6
20.8
14.2
9.8
6.4
7.2
4.4
8.9
19.8
33.3
33.3
66.4
>
12
84,155
16.8
.8
0
.8
15.1
5.1
3.6
3.0
3.1
2.5
74.8
74.8
74.8 74.8
99.5
NB
106
0-2
711,470
22.5.
12.6
5.6
4.2
0
4.7
3.5
1.9
2.9
1.5
52.6
86.0
100.0
93.0
100.0
3-5
744,894
23.5
15.2
5.7
1.9
.6
12.9
9.8 5.0
8.3
4.4
.2
.2
32.7
.2
59.5
6-12
1,523,218
48.1
25.8
6.0
9.9
6.4
18.0
14.2
7.7
11.8
6.8
0
.6
6.9
.6
18.2
>
12
188,456
6.0
1.6
0
1.4
3.0
24.7
20.3
12.8
16.6
11.2
.5
.5
.5 .5
1.6
KS
106
0-2
892,695
35.9
18.4
12.9
2.1
2.5
5.4
4.1
1.9
3.4
1.4
42.8
51.9
74.2
61.0
100.0
3-5
1,356,794
54.6
'29.7
.5
13.4
11.1
11.9
10.4
4.7
8.9
3.8
0 0
12.7
0
54.7
6-12
224,058
9.0
3.6
0
1.9
3.5
20.6
18.6
8.4
15.9
7.0
15.6 15.6 15.6 15.6 15.6
>
12
10,549
.4
0
0
0
.4
15.8
15.0
8.2
13.5
7.4
31.4
31.4
31.4
31.4
31.4
14
Table
11.
Acreage
and
percentage
of
cultivated
area
for
assigned
crops,
weighted
average
soil
loss,
and
percentage
of
area
where
predicted
soil
loss
is
less
than
the
soil
loss
tolerance
level
(T)
by
slope
categories
for
the
major
land
resource
areas
(MLRA)
within
States
-Continued
MLRA
Slope
Cultivated
area
Assigned
rotation
Calculated
soil
loss
Area
<
T
COrn
So
y
-
Oats
Hay
Al
A2
A3
A4
A5
Al
A2
A3
A4
A5
beans
Percent
Acres
Percent
- - - -
Percent
- -
- -
Tons
Percent
KS
107
0-2
63,813
23.1
11.5 11.5
0.0 0.0
4.7
3.4
1.6
2.8
1.1
52.3 52.3
96.7
96.1
100.0
3-4
101,607
36.7
18.4 18.4
0
0
19.7
14.2
6.8
11.9
4.7
0
0
0
0
89.1
6-12
69,704
25.2
7.9
1.2
6.9
9.2
21.5
18.3
8.5
16.0
7.0
0
0
0
0 0
>
12
41,521
15.0
3.8
0
3.8
7.5
49.9
47.1
22.2
41.6
19.4
0
0 0 0
0
NB
107
0-2
226,955
45.0
25.6
19.4
0
0
4.4
3.3
1.6
2.8
1.4
82.9
96.0
100.0
99.8
100.0
3-5
58,894
11.7
7.6
4.0
0
0
11.1
8.4
4.1
7.2
3.7
0
0
99.2
0
99.2
6-12
65,012
12.9
7.3
1.6
2.0
2.0
20.0
16.2
9.0
13.6
8.3
0
0
0 0 0
>
12
153,431
30.4
15.2
0
7.6 7.6
52.5
44.7
27.2
37.0
25.3
0
0 0 0 0
IA
107
0-2
1,801,791
26.5
14.3
12.2
0 0
3.5
2.8
1.6
2.2
1.6
86.7
99.0
100.0
100.0
100.0
3-5
2,098,820
30.9
18.9
12.0
0 0
11.1
8.8
5.0
6.5
4.7
.6
.7
17.3
2.5
17.3
6-12
2,411,847
35.5
21.9
4.9
5.4
3.3
37.9
30.6
17.0
22.8
14.3
.1
.1
.7
.1
1.0
>
12
481,611
7.1
2.2
0
1.7
3.2
40.5
29.5
17.1
21.8
13.2
2.8 2.8
2.8
2.8
3.0
MO
107
0-2
1,057,053
37.3
18.6 18.6
0 0
6.0
3.2
1.9
2.4
1.2
4.8
98.1
100.0
98.8
100.0
3-5
387,051
13.6
6.6 6.6
.4
0
15.5
8.2
4.9
6.3
3.0
0 0
82.6
0
95.6
6-12
1,288,009
45.4
18.8
7.2
7.7
11.7
27.1
15.7
9.5
11.9
6.8
0
0
.5
.5
32.2
>
12
103,250
3.6
0
0 0
3.6
2.6
2.6
2.6
2.6 2.6
96.2 96.2 96.2
96.2
96.2
IA
108
0-2
2,168,029
25.6
12.8 12.8
0 0
4.0
3.1
1.8
2.5
1.8
87.0
98.0
99.9
98.0
99.9
3-5
2,548,601
30.1
15.0
14.5
.6
0
13.3
10.4
6.1
8.4
6.0
0
0
5.8
1.0
5.8
6-12
3,246,889
38.4
22.2
2.4
5.2
7.5
29.8
23.5
13.1
16.4
10.5
.4
.5
.9
.5
4.0
>
12
502,920
5.9
.7
0
.7
4.5
18.6
13.5
8.4
10.1
6.6
43.9
43.9
43.9 43.9 43.9
IL
108
0-2
6,795,531
56.1
28.7
26.8
.6
0
4.6
2.8
1.6
2.5
1.0
56.4
98.9
100.0
99.0
100.0
3-5
3,033,174
25.0
16.7
8.3
0
0
13.1
7.9
4.1
7.4
2.8
0
1.1
97.4
1.2
99.3
6-12
2,013,840
16.6
9.0
.1
4.4
3.1
18.6
13.3
8.5
9.0
5.2
.7
1.8
2.6
2.6
41.7
>
12
274,063
2.3
.6
0
.6
1.2
12.8
8.1
6.4 6.4
4.7
.3
6.3
11.0 11.0
27.6
IA
109
0-2
632,423
18.9
9.4
9.4
0 0
3.9
3.0
1.8
2.4
1.8
55.8
76.7
100.0
99.0
100.0
3-5
762,788
22.8
11.4 11.4
0
0
12.3
9.6
5.6
7.8
5.6
0
.8
8.4
.8
8.4
6-12
1,531,290
45.7
17.6
6.6
6.8
14.7
20.4
15.9
9.3
12.4
8.4
12.8
12.8
28.6
12.8
36.7
>
12
424,664
12.7
0
0
0
12.6
2.6
2.5
2.4
2.4
2.4
94.4
94.4
94.4 94.4 94.4
MO
109
0-2
1,434,540
27.5
13.8
13.8
0
0
7.2
3.8
2.3
2.9
1.4
.3
74.9
97.1
94.0
100.0
3-5
968,504
18.6
9.3
9.3
0
0
17.4
9.2
5.5
7.0
3.4
0
0
15.4
.2
25.8
6-12
2,401,608
46.0
8.2
12.9
7.8
17.0
24.5
13.3
8.2
9.9
5.2
10.6 10.6
41.8
41.6
56.6
>
12
410,214
7.9
0 0 0
7.9
2.5
2.5 2.5
2.5 2.5
91.6
91.6
91.6
91.6 91.6
Il
110
0-2
2,462,462
63.3
31.6
31.6
0
.1
4.2
2.8
1.6
2.6
1.0
56.3
95.8
99.5
95.8
99.7
3-5
1,008,091
25.9
14.5
9.8
1.6
.0
12.2
8.0
4.5
7.1
3.0
.7
6.0
38.3
7.0
83.5
6-12
399,093
10.3
2.8
2.6
2.7
2.2
18.3
12.7
8.0
5.0
9.4
9.4
9.5
15.0
11.9
22.2
>
12
19,324
.5
0 0
0
.5
1.8
1.8
1.8 1.8 1.8
100.0
100.0 100.0 100.0
100.0
IN
110
0-2
853,709
78.6
40.8
33.8
4.0
0
3.6
2.4
1.4
2.2
1.0
94.1
96.7
100.0
97.5
100.0
3-5
190,914
17.6
11.8
2.2
2.1
1.5
14.0
9.4
4.9
8.6
4.2
0
17.2
66.7
17.2
69.7
6-12
32,281
3.0
.8
.2
.8
1.2
14.0
9.2
7.0
7.3
5.3
.7
28.2
31.5
31.5
72.8
>
12
9,331
.9
.2
0
.2
.5
16.3
9.3
7.0
7.0
4.6
0 0 0 0
42.5
IL
111
0-2
123,793
55.6
27.7 27.7
.2
0
4.9
3.0
1.7
2.7
1.0
69.1
98.3
100.0
100.0 100.0
3-5
56,339
25.3
14.2
10.3
.8
0
14.5
8.9
4.8
8.0
3.1
0
1.2
50.6
9.3
100.0
6-12
35,993
16.2
5.9
5.1
4.8
.4
32.6
21.7
12.1
14.2
8.1
0 0 0
0
0
>
12
6,346
2.8
.7
0
.7
1.4
14.3
8.9
7.1
7.1
5.3
0
0
0
0
0
IN
111
0-2
6,425,621
66.0
31.6
29.7
4.0
.6
4.5
2.8
1.5
2.4
1.0
50.0
79.0
100.0
79.2
100.0
3-5
2,395,600
24.6
11.8
5.2
5.6
2.0
11.1
7.2
4.2
5.4
2.7
1.2
9.6
45.2
44.2
89.5
6-12
750,393
7.7
2.9
.8
2.1
2.0
18.3
12.4
7.8
8.3
5.1
.8
1.4
6.4 6.4
44.0
>
12
165,494
1.7
.3
0
.3
1.0
11.9
7.6
6.2 6.2
4.8
21.0
23.6
27.9 27.9
28.0
OH
111
0-2
4,465,361
53.0
23.5
23.7
5.7
.1
2.4
1.6
1.1
1.3
.7
69.6
100.0
100.0
100.0
100.0
3-5
3,070,205
36.4
12.2
12.1
9.6
2.6
8.8
6.5
4.9
5.7
3.1
1.9
2.2
19.2
15.8
78.7
6-12
614,386
.
7.3
1.4
0
1.4
4.4
7.2
4.5
3.6
3.6
2.7
1.8
63.0
79.0
79.0
82.6
>
12
278,884
3.3
.4
0
.4
2.6
7.2
4.8
4.0
4.0
3.2
44.3
44.5
47.4
47.4
97.3
KS
112
0-2
3,733,202
76.2
25.2
23.7
12.9
14.5
5.2
4.0
1.9
3.4
1.4
45.1
53.0
98.9
63.0
99.9
3-5
1,043,051
21.3
5.7
3.3
5.7
6.6
10.1
8.0
3.7
6.9
3.0
4.4
4.4
56.3
4.4
76.1
6-12
119,772
2.4
.5
0
.5
1.4
13.0
12.3
5.9
10.8
5.1
16.7 16.7
16.7
16.7
16.7
>
12
0
0
0
0
0
0
0
0 0
0
0 0 0 0
0 0
15
Table
11.
-Acreage
and
percentage
of
cultivated
area
for
assigned
crops,
weighted
average
soil
loss,
and
percentage
of
area
where
predicted
soil
loss
is
less
than
the
soil
loss
tolerance
level
(T)
by
slope
categories
for
the
major
land
resource
areas
(MLRA)
within
States
-Continued
MLRA
Slope
Cultivated
area
Assigned
rotation
Calculated
soil
loss
Area
<
T
Corn
Soy-
Oats
Hay
Al
A2
A3
A4
A5
Al
A2
A3
A4
A5
beans
Percent
Acres
Percent
- -
-
-
Percent
- -
Tons
Percent
MO
112
0-2
1,200,842
26.6
12.8 12.8
0.2
0.7
7.4
3.9
2.4
3.0
1.4
,
3.6
86.7
95.9
87.0
100.0
3-5
1,977,249
43.7
14.7
15.0
7.5
6.5
12.0
6.5
3.9
4.9
2.4
17.5
29.6
29.9
29.6
95.8
6-12
1,294,068
28.6
5.3
.2
5.2
17.9
8.2
5.7
3.4
4.2
2.6
26.7
32.1
63.5
40.7
76.4
>
12
50,157
1.1
0 0 0
1.1
2.8 2.8
2.8
2.8 2.8
30.2
30.3
30.3 30.3
30.3
MO
113
0-2
961,784
27.7
13.9
13.9
0 0
8.8
4.6
2.8
3.6
1.7
2.2
46.9
51.0
51.0
100.0
3-5
928,401
26.8
13.4 13.4
0
0
21.6
11.4
6.8
8.7
4.2
0
0
1.2
0
8.5
6-12
1,400,341
40.4
2.3
13.0
10.7
14.3
22.9
13.8
8.1
10.0
5.5
2.8
2.8
2.8
2.8
9.0
>
12
176,529
5.1
.7
0
.7
3.6
12.4
5.7
4.0
4.0
4.0
16.9
16.9
88.3 88.3 88.3
IL
113
0-2
1,558,886
68.5
22.7
33.5
11.8
.5
5.7
3.9
2.1
2.8
1.3
2.8
22.2
96.8
74.3
100.0
3-5
518,312
22.8
4.3
11.2
5.5
1.8
14.5
10.0
5.3
7.1
3.3
.8
8.3
20.4
8.6
21.9
6-12
196,547
8.6
1.4
.9
2.2
4.2
13.2
7.9
4.8
5.2
3.4
.4
1.2
63.9
63.9
71.3
>
12
3,026
.1
0 0 0
.1
3.5
2.4
2.2
2.2
1.9
78.5 78.5
100.0
100.0
100.0
IL
114
0-2
2,664,168
59.8
24.4
31.8
3.6
0
7.1
3.9
2.2
3.2
1.4
6.5
45.1
99.7
56.3
100.0
3-5
994,348
22.3
7.5 7.5
7.3
0
14.0
9.4
4.9
5.7
3.8
0 0
6.3
4.0
30.2
6-12
726,762
16.3
1.4
4.7
4.7
5.5
22.7
16.2
9.5
11.0
6.9
13.5
13.7
17.3
17.3
38.0
>
12
66,475
1.5
.2
0
.2
1.0
10.8
7.3
5.5 5.5
3.8
14.7
14.7
15.1 15.1
73.8
IN
114
0-2
1,175,456
56.7
26.4
26.0
4.1
.2
7.2
3.9
2.2
3.2
1.4
8.2
60.4
100.0
76.9
100.0
3-5
405,128
19.5
10.0
4.4
3.2
2.0
18.0
10.8
6.4
8.4
4.0
0
2.2
4.3
4.2
50.9
6-12
314,300
15.2
7.4
0
3.8
3.9
21.3
15.3
10.6 10.6
6.0
0
0
.9 .9
2.4
>
12
178,313
8.6
1.9
0
1.9
4.9
19.3
11.4
8.8
8.8
6.1
0 0 0
0
4.9
OH
114
0-2
435,548
42.2
18.4
22.9
.9
0
4.1
2.3
1.4
1.9
1.0
68.5
100.0
100.0
100.0
100.0
3-5
273,700
26.5
9.3
11.8
4.7
.7
13.9
8.6
5.9
7.2
4.1
3.7
4.4
6.9
5.1
56.7
6-12
176,969
17.1
3.6
.6
3.6
9.3
10.5
6.7
5.1
5.5
3.3
.9
11.5
68.0
68.0
88.6
>
12
146,094
14.2
1.6
0
1.6
10.8
7.9
4.9
3.9
3.9
2.9
38.5
40.0
46.0
46.0
87.4
IA
115
0-2
20,577
26.8
13.4 13.4
0
0
3.7
2.9
1.7
2.3
1.7
69.4
69.4
100.0
100.0 100.0
3-5
33,805
44.0
18.5
9.6
9.9
6.0
6.6
5.3
3.0
4.2
2.8
49.7
49.7
67.1
52.2
71.4
6-12
18,267
23.8
5.4
1.2
7.3
9.8
13.5
11.2
6.4
8.6
5.4
32.2
35.6
50.6
35.6
50.6
>
12
4,199
5.5
0 0 0
5.5
2.4
2.4 2.4
2.4 2.4
0
100.0
100.0
100.0 100.0
MO
115
0-2
1,416,856
29.0
14.5 14.5
.1
0
6.8
3.6
2.2
2.8
1.3
5.0
93.4
97.3
97.0
100.0
3-5
534,501
10.9
5.2 5.1
.6
.1
20.0
10.6
6.4
8.1
3.9
.2
.2
2.8
1.2
52.2
6-12
2,462,208
50.4
9.0
5.2
11.8
24.4
20.2
11.2
7.3
8.2
4.7 8.6
19.8
19.9
19.9
53.4
>
12
472,244
9.7
0
0 0
9.7
3.8
3.8
3.8
3.8 3.8
93.5
93.5
93.5
93.5 93.5
IL
115
0-2
2,847,835
51.7
25.2
24.5
2.0
0
5.5
3.3
1.9
2.9
1.2
16.8
85.2
100.0
91.3
100.0
3-5
933,592
17.0
5.9 5.9
5.2
0
12.0
7.4
4.5
5.1
2.9
0
4.2
79.8
29.4
95.0
6-12
1,356,000
24.6
7.4
6.9
7.4
3.0
31.2
20.3
12.6
13.8
8.3
.1
.1
.4
.1
3.4
>
12
368,644
6.7
.8
0
.8
5.0
9.2
5.6
4.4
4.4
3.2
36.8
37.8
39.3
39.3
97.7
IN
115
0-2
1,021,461
62.1
27.8
25.4
8.4
.4
6.2
3.8
2.2
3.1
1.4
12.7
80.4
99.8
87.4
100.0
3-5
323,915
19.7
15.1
1.1
2.9
.6
21.9
13.5
7.3
11.6
4.9
0
11.0
12.4 12.4
19.1
6-12
210,789
12.8
5.5
1.9
4.6
.9
41.6
26.7
16.2
17.6
10.5
0
0 0
0
17.6
>
12
89,813
5.5
1.9
0
1.4
2.2
34.8
23.8
17.4
17.4
10.9
0
0
6.0
6.0
6.0
tion,
up-and-down
slope.
Tech-
niques
that
reduce
the
P
are
contour
cropping
or
strip
cropping,
which
can
be
combined
with
ter-
races
for
even
greater
protection.
Changing
crop
rotations
still
may
be
necessary,
however,
for
certain
potentially
hazardous
situations.
Widespread
residue
removal
would
increase
the
need
for
mineral
fertilizer
to
replace
the
nutrients
removed
in
the
residue.
Added
significance
to
nutrient
replacement
should
also
be
considered
in
terms
of
nutrient
removal
through
soil
loss
and
would
involve
an
enrichment
factor
(4,
8).
Optimum
use
of
crop
residues
will
require
careful
consideration
of
the
alternate
uses
-soil
and
environment
protection,
feed
for
livestock,
or
energy
and
industrial
purposes.
We
think
that
the
need
to
maintain
soil
productivity
should
be
the
first
consideration.
If
residues
are
needed
for
erosion
control
or
maintenance
of
soil
structure,
and
economically
feasible
alternatives
are
not
available,
then
residues
should
remain
on
the
land.
How-
ever,
if
the
soil's
needs
can
be
met
with
partial
or
total
removal
of
crop
residues,
then
there
should
be
no
objection
to
their
removal.
We
caution,
however,
that
any
removal
of
residue
from
the
field
should
be
done
only
with
a
full
understanding
of
the
possible
consequences.
16
Table
12.
-Percent
area
where
predicted
soil
loss
is
less
than
the
soil
loss
tolerance
level
by
tillage
and
residue
management
system,
amounts
of
residue
that
become
available
for
removal
by
each
tillage
and
residue
management
system,
and
associated
nutrient
removal
by
crops
in
the
MLRA's
within
States
MLRA
Tillage
Area
Residue
Nutrient
removal
Portion
of
total
system
<T
available
N
P
K
residue
available
for
removal
Percent
Tons
CORN
Percent
SD
102
Al
51.8
1,206,614
13,410
2,187
16,051
52
A2
73.7
248,388
2,761
450
3,305
11
A3
92.6
0
0
0 0
0
A4
75.3
267,210
2,970
484
3,555
12
A5
99.7
0
0
0
0
0
1,473,824
16,380
2,671
19,606
64
SOYBEANS
Al
94.7
372,767
8,383
816
3,923
95
A2
99.9
13,087
295
28
137
3
A3
100.0
110
2
1
1
<1
A4
100.0
13,475
303
29
141
3
A5
100.0
0
0
0
0
0
386,242
8,686
845
4,064
98
SMALL
GRAIN
Al
39.9
1,210,122
7,763
1,753
18,501
40
A2
52.4
306,139
1,964
444
4,680
10
A3
88.6
600,345
3,852
869
9,178
20
A4
54.0
345,510
2,217
501
5,282
11
A5
99.7
758,407
4,865
1,098
11,595
25
2,314,039
14,845
3,352
35,378
76
CORN
MN
102
Al
92.0
1,592,185
17,696
2,851
21,193
92
A2
93.4
12,090
135
21
160
1
A3
100.0
0
0
0
0
0
A4
100.0
68,378
760
122
910
4
A5
'
100.0
0 0
0
0
0
1,660,563
18,456
2,973
22,103
96
SOYBEANS
Al
92.1
453,855
10,221
1,002
4,758
92
A2
92.1
0
0
0 0
0
A3
100.0
4,760
107
10
50
1
A4
100.0
24,293
547
53
254
5
A5
100.0
0
0
0
0
0
478,148
10,768
1,055
5,012
97
SMALL
GRAIN
Al
91.3
1,165,062
7,658
1,314
14,904
91
A2
95.2
37,542
247
42
480
3
A3
99.9
26,035
171
30
333
2
A4
99.9
82,814
545
93
1,059
6
A5
100.0
713
5
1
9
<1
1,248,589
8,208
1,408
15,972
97
CORN
IA
102
Al
15.1
50,123
556
91
667
15
A2
16.4
2,716
31
5
36
1
A3
52.4
21,093
234
38
281
6
A4
19.3
9,055
101
16
121
3
A5
55.0
20,607
229
37
274
6
79,785
886
144
1,062
24
17
Table
12.
-Percent
area
where
predicted
soil
loss
is
less
than
the
soil
loss
tolerance
level
by
tillage
and
residue
management
system,
amounts
of
residue
that
become
available
for
removal
by
each
tillage
and
residue
management
system,
and
associated
nutrient
removal
by
crops
in
the
MLRA's
within
States
-Continued
MLRA
Tillage
Area
Residue
system
<T
available
Nutrient
removal
N
P
K
Portion
of
total
residue
available
for
removal
Percent
Tons
SOYBEANS
Percent
IA
102
Al
29.2
35,396
797
78
371
29
A2
31.3
1,983
44
4
21
2
A3
95.9
32,854
740
72
345
27
A4
36.7
6,892
155
15
73
6
A5
96.1
30,235
..
680
66
317
25
72,523
1,632
159
761
60
SMALL
GRAIN
Al
15.3
11,992
76
19
198
15
A2
16.3
670
4
1
11
1
A3
72.1
32,681
206
52
538
42
A4
36.6
14,846
93
24
244
19
A5
86.7
29,346
185
47
484
38
56,184
354
90
926
72
CORN
NB
102
Al
45.1
1,587,300
17,607
2,844
21,120
45
A2
50.7
118,463
1,314
212
1,576
3
A3
59.9
25,204
208
45
336
1
A4
58.1
275,388
3,055
493
3,664
8
A5
64.1
16,397
182
30
218
1
1,879,085
20,844
3,367
25,002
54
SOYBEANS
Al
42.8
242,383
'
5,451
536
2,542
43
A2
45.0
8,318
187
18
87
1
A3
61.2
22,252
500
49
233
4
A4
60.8
68,596
1,543
151
719
12
A5
74.6
18,883
424
42
198
3
329,862
7,418
729
3,459
58
SMALL
GRAIN
Al
18.9
157,105
998
232
2,411
19
A2
18.9
0
0 0
0
0
A3
25.1
29,715
189
43
455
4
A4
19.8
6,118
39
9
93
1
A5
25.6
27,613
176
40
424
3
190,836
1,213
281
2,928
23
CORN
MN
103
Al
64.6
4,601,542
51,077
8,310
61,159
65
A2
70.7
280,490
3,113
506
3,728
4
A3
99.5
322,222
3,577
582
4,283
5
A4
97.6
1,502,988
16,683
2,714
19,976
21
A5
99.9
26,341
292
47
350
<1
6,130,871
68,052
11,071
81,485
86
SOYBEANS
Al
92.3
2,244,826
50,503
4,944
23,574
92
A2
92.6
5,623
127
13
59
<1
A3
99.9
55,327
1,244
122
581
2
A4
99.4
121,043
2,723
267
1,271
5
A5
99.9
4,398
99
10
46
<1
2,370,267
53,325
5,221
24,891
97
18
Table
12.
-Percent
area
where
predicted
soil
loss
is
less
than
the
soil
loss
tolerance
level
by
tillage
and
residue
management
system,
amounts
of
residue
that
become
available
for
removal
by
each
tillage
and
residue
management
system,
and
associated
nutrient
removal
by
crops
in
the
MLRA's
within
States
-Continued
MLRA
Tillage
Area
Residue
system
<T
available
Nutrient
removal
N
P
K
Portion
of
total
residue
available
for
removal
MN
103
Al
A2
A3
A4
A5
Percent
32.9
47.5
98.9
97.5
99.9
432,347
151,507
338,062
667,609
16,036
Tons
SMALL
GRAIN
2,788
976
2,180
4,304
103
555
195
434
857
21
6,118
2,144
4,783
9,446
227
Percent
33
12
26
51
1
85
1,115,992
7,195
1,433
15,791
CORN
IA
103
Al
62.8
5,361,270
59,549
9,641
71,364
63
A2
63.3
31,348
348
57
417
el
A3
95.3
1,044,139
11,597
1,877
13,899
12
A4
85.5
1,423,594
15,812
2,560
18,949
17
A5
95.9
338,060
3,755
608
4,500
4
7,122,924
79,116
12,809
94,813
84
SOYBEANS
Al
72.7
2,763,929
62,153
6,041
29,017
73
A2
73.2
13,614
306
30
143
<1
A3
99.3
418,227
9,405
914
4,391
11
A4
97.6
711,047
15,989
1,555
7,465
19
A5
99.4
29,289
659
64
307
1
3,504,265
78,801
7,660
36,789
93
SMALL
GRAIN
Al
0
0
0
0
0 0
A2
.5
2,344
15
4
38
<1
A3
66.8
245,927
1,551
388
4,034
47
A4
.9
3,965
25
6
65
1
A5
70.8
259,205
1,635
410
4,252
50
263,170
1,660
416
4,317
51
CORN
MN
104
Al
69.6
685,561
7,611
1,236
9,124
70
A2
71.4
11,153
124
20
148
1
A3
94.9
39,343
437
71
524
4
A4
76.9
45,743
508
83
609
5
A5
99.8
38,298
425
69
509
4
769,602
8,544
1,388
10,242
79
SOYBEANS
Al
86.5
322,453
7,256
710
3,391
86
A2
87.7
3,047
68
7
32
1
A3
100.0
6,574
148
14
69
2
A4
91.0
10,715
241
23
113
3
A5
100.0
4,842
109
11
51
1
338,010
7,606
744
3,555
90
SMALL
GRAIN
Al
23.6
50,817 324
73
770
24
A2
27.0
5,680
37
8
86
3
A3
90.3
63,343
404
91
959
29
A4
45.5
36,300
232
52
550
17
A5
99.6
54,155
346
78
820
25
141,272
902
203
2,140
66
CORN
IA
104
Al
44.4
1,597,776
17,747
2,865
21,259
44
A2
45.5
28,284
314
51
377
1
A3
66.7
248,020
2,755
455
3,300
7
A4
50.0
143,088
1,589
257
1,904
4
A5
92.1
492,180
5,467
883
6,549
14
2,233,044
24,803
4,005
29,712
62
19
Table
12.
Percent
area
where
predicted
soil
loss
Is
less
than
the
soil
loss
tolerance
level
by
tillage
and
residue
management
system,
amounts
of
residue
that
become
available
for
removal
by
each
tillage
and
residue
management
system,
and
associated
nutrient
removal
by
crops
in
the
MLRA's
within
States
-Continued
MLRA
Tillage
Area
Residue
system
<T
available
Nutrient
removal
N
P
K
Portion
of
total
residue
available
for
removal
Percent
Tons
SOYBEANS
Percent
IA
104
Al
58.5
651,340
14,651
1,424
6,831
58
A2
59.7
9,603
216
21
101
1
A3
74.7
58,922
1,326
129
617
5
A4
60.0
12,515
282
27
131
1
A5
96.1
141,003
3,171
309
1,479
13
804,858
18,104
1,760
8,441
72
SMALL
GRAIN
Al
30.6
169,777
1,070
268
2,785
31
A2
32.2
7,582
48
12
124
1
A3
67.4
122,098
769
193
2,003
22
A4
56.0
118,297
745
187
1,940
21
A5
69.8
47,894
302
76
786
9
335,968
2,117
531
5,511
61
CORN
MN
105
Al
29.3
339,034
3,764
611
4,507
29
A2
30.6
10,424
115
18
139
1
A3
61.3
111,650
1,240
202
1,484
10
A4
51.0
176,519
1,959
318
2,347
15
A5
72.9
80,031
889