United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA-600/S2-81-230 Dec. 1981
Project Summary
Animal Waste Effects Upon
Crop Production, Soil and
Runoff Waters
„, ^,
Maurice L. HortonCBr^L/ WierSma, RonakllR-'Schnabel, Ronald E. Beyer,
and Charles G. Cafison
UL :-- 1882
This investigation was initiated to
study the effects of application of
differing rates of manure to the land on
crops, soil, and runoff water. The study
was conducted under field conditions
in the sub-humid climate of the
Northern Great Plains. Manure appli-
cation rates included levels from 0 to
180 MT/ha/yr. Manure applied to
field plots was incorporated using a
chisel plow as soon afterapplication as
possible. The test crop grown on the
manure treatment plots was corn.
One-half of the field plots were instru-
mented to automatically collect
samples of any runoff waters leaving
the plots.
Soil salinity levels Increased due to
high rates of application so that the
entire profile was saline. Corn yields
were variable and low due to drought
stress and saline conditions. Runoff
occurred only twice during the course
of the study. Chemical analysis of run-
off waters indicated almost no differ-
ences due to plot treatments. Natural
precipitation occurring after the
cessation of manure treatments
leached the surface soil to a non-saline
condition during the first year.
Although crop production was
generally poor on the waste treatment
plots, runoff waters from the plots did
not reflect the waste treatments.
This Project Summary was develop-
ed by EPA's Robert S. Kerr Environ-
mental Research Laboratory, Ada,
OK, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
A result of making agriculture more
cost effective has been and continues to
be a shift from the small diversified
operation towards larger, more special-
ized agricultural enterprises. When live-
stock is raised for human consumption
and concentrated in a small area, large
quantities of animal wastes accumulate,
creating a major disposal problem.
A seemingly large number of alterna-
tives are available to the producer for
waste disposal. These alternatives run
the gamut from land application through
refeeding and methane production to
incineration; however, nearly all
disposal methods leave by-products
which require further disposal. The
prohibitive costs of many of these
methods combined with legislation
prohibiting the dumping of wastes into
waterways ultimately result in applica-
tion of most animal wastes to the soil.
The area of land available to the
operator for disposal, and the distance
wastes must be hauled to the disposal
site are factors which in practice influ-
ence application rates. Hauling
distances influence application costs
and as a result make it attractive to
dispose of wastes close to the production
site.
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The operator with little available land
and large amounts of wastes to be
removed from the production facility
may view the land solely as a disposal
site with little regard for future produc-
tivity. Major concerns with that type of
operation are adequate incorporation of
the wastes to minimize runoff and odor
problems and prevention of leaching of
toxic substances to ground water.
The operator with sufficient land to
serve as a disposal site and a clear com-
mitment to maintaining the productivity
of his land may view animal wastes as a
resource capable of reducing his fertil-
izer costs. This operator must concern
himself with factors that reduce the
value of crops grown on his land, factors
that limit its productivity, or with pollu-
tants that affect the soil or waters.
Nitrates and potassium may accumulate
in plants to levels toxic to animals. Salts
present in the waste may cause the soil
solution to exhibit a high osmotic poten-
tial and limit water availability to plants.
Adsorption of monovalent cations on soil
clays may cause degradation of soil
structure and limit movement of water
into and through the soil.
An experiment was conducted at the
Southeast South Dakota Experiment
Farm to establish relationships between
animal wastes applied to the soil and
their effect on the soil and plants grown
on it. Feeder steers were fed a common
ration differing only in the amount of salt,
sodium chloride {NaCI), added to the
feed. The levels of added NaCI used
during the feeding period were 0.00,
0.25,0.50 and 0.75 percent of the ration
on a dry weight basis.
The manure from these steers was
collected and segregated into two salt
levels: manure collected from animals
fed 0.00 and 0.25 percent added NaCI,
hereafter referred to as "low," and
manure collected from animals fedO.50
and 0.75 percent added NaCI, hereafter
referred to as "high."
Manure was applied as soon after col-
lection as practical to field plots with
dimensions of 36.6by6.1 mestablished
on Egan silty clay loam at the Southeast
South Dakota Experiment Farm. The
field design was a randomized complete
block including treatments of 0, 45, 90,
135 and 180 MT/ha/yr (check, 20, 40,
60, and 80 T/ac/yr) dry waste at both
low and high salt levels. Manure appli-
cations were made during the period
from harvest until spring tillage for 1973
until the 1975 growing season with no
applications thereafter. At the time of
application, each load was weighed and
a sample taken for water content and
chemical analysis.
The objectives of this investigation
were: (1) to determine if, under dryland
conditions, the salts present in manure
applied to the land would accumulate in
the root zone to levels high enough to
seriously limit crop production; (2) to
determine if the ratio of monovalent to
divalent cations present in the manure
would upset the balanceofthesecations
in the soil and cause soil structure prob-
lems; (3) to determine if the salts and
organic matter added by the manure
would affect the ability of the soil to
transmit water; and (4) to determine the
effect of applied wastes upon the quan-
tity and quality of runoff waters.
In a previous study conducted by
Horton, Wiersma, and Halbeisen,' the
effect of salt level and roughage content
of a ration for beef steers upon animal
performance and manure characteris-
tics was investigated. The present study
extended the earlier work to include
effects upon the land and upon runoff
waters leavingthetreated land. Informa-
tion from the two studies will be useful in
determining the value of manure for crop
production during periods of limited
rainfall. Thesoil salinity and runoff water
quality data will be useful in developing
best management practices under
Section 208 P. L 92-500.
Conclusions
1. Soils developed under sub-humid
conditions such as the Northern
Great Plains frequently contain
considerable quantities of salt
within their profiles. When only
the surface is naturally leached
free of salts, addition of large
quantities of manure can salinize
the entire soil profile and affect
crop production.
2. Although exchangeable sodium
level in the soils studied increased
due to manure application, they
remained below the level at which
dispersion of the soil structure
would be expected to occur.
3. Water infiltration rates were
reduced during the year following
high rates ofappliedmanure; how-
'Horton, M L., J. L. Wiersma, and J. L. Halbeisen
1976 Animal Waste Management in the Northern
Great Plains. EPA-600/2-76-188. U.S Environ-
mental Protection Agency. Ada, OK. 84 pps
ever, the infiltration rates recov-
ered to nearly the level of the
untreated soil within one year
following cessation of waste
application.
4. Runoff waters were not signifi-
cantly affected by waste rates two
years following application. Pre-
cipitation was insufficient to
produce runoff earlier.
Recommendations
Waste from cattle feedlots can be a
source of nutrients and organic matter
for growing crops or a source of chemi-
cals which pollute waters and salinize
soils in the environment.
The following recommendations as-
sume that the land upon which wastes
are being applied is to be used for crop
production:
1. Development of the best manage-
ment practices for applying wastes
to the land should account for soil
properties, chemical composition
of the wastes, availability of leach-
ing waters and the crop to be
grown.
2. Incorporation of manure applied to
the land reduces the opportunity
for pollution of surface waters and
utilizes the large buffering capac-
ity of the soil to reduce chemical
effects.
3. Availability of rainfall or irrigation
water will influence crop response
to added nutrients and will influ-
ence leaching of saltsfromthesoil.
Drought conditions reduce the
fertilizer value of manure for crop
production and increase salinity
build-up within the soil.
4. Sincethemajorannualrunofffrom
cropland in the Northern Great
Plains occurs at thetimeof melting
of the winter snowpack,
management of manure applied to
the land so as to minimize the
concentration during snowmelt
should qualify as a best manage-
ment practice.
5. Annual applications of manure in
excess of 45 MT/ha should be
avoided where the soil contains
excess salts within 60 cm of the
surface and where less than 20
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inches of water is applied to the
land as rainfall or irrigation.
Results
Actual amounts of manure applied to
field treatments prior to the 1974 and
1975 growing seasons are given in
Table 1. No additional manure was
applied to any treatments following the
1975 season.
The results of the analysis of the
waste for major cations appear in Table
2. While not literally correct, total cation
concentration is taken to be the sum of
Table 1. Manure Application Rates
Prior to 1974 and 1975
Growing Seasons
Two Year
1974 1975 Total
Treatment MT/ha* MT/ha* MT/ha*
Check
45-L**
45-Hi
90-L
90-H
135-L
135-H
180-L
180-H
0.0
38.5
26.9
101.5
85.3
135.2
119.7
169.6
172.7
0.0
48.6
50.8
92.5
92.3
138.0
139.6
181.8
182.9
0.0
87.1
77.7
194.0
177.7
273.2
259.3
351.3
355.6
*On a dry weight basis.
**L - Low.
= High.
Table 2.
Average Composition of
Manure Applied to Field
Plots Prior to the 1975
Growing Season
Low salt High salt
(%)* (%)*
Na
K
Ca
Mg
Total cations
0.37
3.19
1.05
0.88
5.49
0.75
3.16
1.05
0.89
5.85
the four major cations. In Table 2, it is
shown that Na is the only salt
constituent in the manure which varies
to an appreciable extent with the NaCI
level of the ration. Consequently, the
amount of Na and total salts applied to
field plots varied according to the
amount of NaCI added to the ration.
Total precipitation for 1975 and 1977
was normal. Total precipitation for 1974
was 59 percent of normal and for 1976
was 50 percent of normal. Average or
below average rainfall was recorded
during June and July for all years of the
study. The growing season of 1976 was
one of the worst droughts on record for
the region.
A summary of the electro-conductivity
(EC) of the upper 30 cm of plot soils is
shown m Table 3 for all years of the
study. Detailed EC information including
individual replicated plot values and
accompanying statistical treatment for
all plots to a depth of 150 cm is pre-
sented in the Appendices.
Accepting the U.S. Department of
Agriculture's EC value of 4.0 mmhos/cm
as the value separating non-saline from
saline soils, it is apparent from the data
presented in Table 3 that, given the
limited rainfall during the study, two
consecutive applications of manure
exceeding 45 MT/ha/yr will supply
sufficient salts to salinize the upper 30
cm of the soil profile. The data also
indicate that, with the below normal
rainfall, within two years after the end
of treatment, the upper 30 cm of all plots
was leached sufficiently to be classed in
the non-saline category.
In addition to salinity of the surface
soil, attention must be given to the
salinity condition of the entire root zone
as summarized inTable.4. Prior to onset
of this investigation, the EC of all plots at
a depth of 90 cm exceeded 4.0
mmhos/cm. The results show
completely saline root zones after two
yearly applications of manure at a rate
of 90 MT/ha/yr or greater.
Runoff Waters
Due to below average rainfall, runoff
waters occurred from the plots on only
two occasions—June 22, 1977 and
March 20, 1978. The automatic samp-
ling equipment collected runoff waters
from only four treatments—90-L, 90-H,
180-L and 180-H—in 1977. Runoff
waters were collected manually from all
plots in 1978.
Complete results of the chemical
analyses of runoff waters are given in
the Appendices. The results were quite
variable with few significant differences
Table 3. A verage Electrical Conductivity of the Saturation Extracts for the Surface
30 cm of Plot Soils
Treatment Fall 1973 Fall 1974 Fall 1975 Fall 1976 Fall 1977
(MT/ha) (mmhos/cm) (mmhos/cm) (mmhos/cm) (mmhos/cm) (mmhos/cm)
On a dry weight basis.
Check
45-L*
45-m
90~L
90-H
135-L
135-H
180-L
180-H
Mean
0.70
0.68
0.46
0.72
0.71
0.68
0.74
0.92
0.83
0.72
1.12
2.42
1.93
4.87
3.96
5.89
5.46
4.90
6.02
4.06
1.30
4.52
3.73
5.39
5.96
7.80
7.14
7.23
8.84
5.77
1.67
3.04
3.46
6.36
4.92
6.19
5.79
5.84
6.06
4.81
1.15
1.28
2.04
1.84
2.11
2.87
2.25
3.29
3.08
2.21
*L = Low.
t # = High.
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Table 4. Electrical Conductivity of the Subsurface Soil Following Treatment
Year and
Treatment
Check
45-L*
45-m
90-L
90-H
135-L
135-H
180-L
180-H
30-60 cm
(mmhos/cm)
1974
2.45
1.28
0.64
1.58
1.41
1.51
1.71
2.29
1.90
1975
3.05
2.39
2.10
4.07
4.09
4.67
4.94
4.96
5.05
60-90 cm
(mmhos/cm)
1974
4.01
3.65
4.47
4.89
4.08
4.95
4.20
4.95
4.57
1975
4.28
3.57
2.37
4.38
4.29
5.55
3.73
5.34
4.83
90-150 cm
(mmhos/cm)
1974 1975
5.51
5.68
5.92
6.15
5.36
5.85
5.72
6.31
5.78
*L = Low.
t/y = High.
between the check and treatment plots
except for chloride ions. Incorporation of
the manure into the soil apparently
protected runoff waters from contami-
nation due to waste treatments.
Plant Performance
Plant population data is presented in
Table 5. Populations were significantly
different at 99 percent level for treat-
ments and years. Manure application
rates in excess of 45 MT/ha/yr resulted
in reduced populations when compared
with the check.
Plant height data was collected
during 1975 and 1976. Statistical
analysis of these data showed signifi-
cant differences in plant height among
waste rates at the 99 percent level for all
sampling dates except July 21, 1976.
Plant heights on plots receiving wastes
at rates of 135 MT/ha/yr or more were
significantly different from check height
at the 99 percent level on June 27,
1975. The height of plants on plots
manured at rates of 90 MT/ha/yr or
more were significantly different from
check heights at the 99 percent level on
July 7, 1975, June 10, 1976, and June
22, 1976.
One of the reasons for collecting the
plant height data was to test the idea
that satisfactory plant growth could be
Table 5. A verage Plant Populations
Treatment
Check
45-L*
45-m
90-L
90-H
135-L
135-H
180-L
180-H
Mean
1974
(plants/ha)
49,51 1
48,435
48.436
40.9O2
45,206
39,826
38,210
36,596
30,676
41.977
1975
(plants/ha)
34,351
34.890
34,620
31,660
28,791
28,611
28,702
29.866
28,818
30.756
1976
(plants/ha)
40,364
39,018
40,274
37,135
38,301
35,969
38,032
37,942
36.058
38,151
1977
/plants/ha)
33,463
33.463
32.150
31,494
34.119
31.494
32.807
34,119
32,807
32,879
*L = Low.
tW = High.
attained on saline soils if a portion of the
root zone was maintained in a non-
saline condition. A corollary being that,
despite early growth depression, if plant
roots were able to penetrate to a non-
saline portion of the soil profile, the
plants could recover and attain yields
equal to plants grown on non-saline
soil. Conversely, if the soil were non-
saline and roots penetrated into a saline
portion of the profile, the growth of
plants would fall behind that of plants
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grown on entirely non-saline soil. Col-
lection of good data and .straight-
forward interpretation of the data were
hampered by below normal rainfall
which caused early drought stress and
provided conditions favorable for smut
disease in 1975. Corn borer damage
affected crop growth and yield in 1976.
The greatest infestation of European
corn borer occurred in plots with a
history of low or no applications of
manure. There was a significant dif-
ference in total number of burrows
among waste rates at the 95 percent
level. Visual observations indicated that
corn smut and weed density followed
the pattern set by the corn borer data.
The problems were of greater
magnitude on plots with low accumu-
lated applications. Two possible
reasons for these observations come to
mind: (1) that the causative organisms
were salt sensitive or unable to obtain
sufficient moisture to remain vigorous,
and (2) the chemicals used to control
insects, weeds, and disease were
moisture activated. Better chemical
control would be expected on high appli-
cation plots if the causative organisms
were salt sensitive due to the higher
osmotic potential of water in these plots
and also if moisture activation of the
chemicals was required for control
since those plots had a greater gravi-
metric moisture content when they
were sampled at the time the infiltration
tests were performed.
Maurice L Morton, John L Wiersma, Ronald R. Schnabel, Ronald E. Beyer, and
Charles G. Carlson are with South Dakota State University, Brookings, SO
57007.
R. Douglas Kreis is the EPA Project Officer (see below).
The complete report, entitled "Animal Waste Effects Upon Crop Production. Soil
and Runoff Waters," (Order No. PB 82-113 887; Cost: $9.50. subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
P.O. Box 1198
Ada. OK 74820
S. GOVERNMENT PRINTING OFFICE: I98V559-092/3422
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