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United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74802
Research and Development
EPA-600/S2-83-078 Nov. 1983
&EPA Project Summary
Swine Manure and Lagoon
Effluent Applied to Fescue
Philip W. Westerman, Larry D. King, Joseph C. Burns, and Michael R. Overcash
The utilization potential and the
environmental effects of applying
swine manure and swine lagoon effluent
to tall fescue were evaluated for 4
years. Lagoon effluent was applied to 9
m x 9 m plots by weekly sprinkler
irrigations during the growing season
while swine manure slurry from an
under-slat pit was applied to a similar
plot four times per year. Application
rates were based on nitrogen (N) and
were about 600 and 1.200 kg N/ha/yr
for the lagoon-irrigated plots and about
670 kg N/ha/yr for the manured plot.
These treatments resulted in much
higher applications of N, phosphorus
(P), potassium (K) and other nutrients
than is normally used for fescue
pasture. These treatments were chosen
to evaluate the acceptable maximum
application rate, which is important
when land area for application is
limiting.
Forage yield, quality and stand
persistence, soil nutrient levels, and
water quality and quantity of runoff
were evaluated. The treatments resulted
in good dry matter yields but some
problems were encountered with the
forage shifting away from tall fescue to
tropical annuals and perennials, and
with high nitrate nitrogen (IMOa-N)
levels in the forage.
The results indicated that swine
manure and swine lagoon effluent can
be excellent sources of nutrients for
fescue, but water quality considerations,
NOs-N levels in the forage, stand
persistence and long-term soil effects
must be evaluated when determining
acceptable maximum application rates.
This Project Summary was developed
by EPA's Robert S. Kerr Environmental
Research Laboratory, Ada. OK. to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Swine production systems using confine-
ment housing increased in recent years.
These systems normally dispose of the
swine manure by (1) collecting the
manure ma pit and using a tank wagon to
spread the manure slurry taken from the
pit, or (2) utilizing a lagoon for manure
treatment and storage and pumping
effluent from the lagoon to keep it from
overflowing. Either disposal method has
the potential for being an excellent
utilization scheme for providing nutrients
for growing crops.
The design of the lagoon and the
requirements of the soil-plant receiver
system depend largely on whether the
producer's main objective is (1) manure
treatment and disposal or (2) utilization of
manure nutrients for useful crops. If the
producer is limited by land, he may
desire maximum lagoon treatment and
apply lagoon effluent or manure slurry to
the soil-plant receiver system at maximum
rates, which could be sustained without
causing toxicity to plants or animals fed
the plants, failure of soil structure, or
excessive degradation of ground water
and rainfall runoff. On the other hand, if
the producer is not land-limited and he
desires to utilize lagoon effluent for crop
irrigation and fertilization or manure for
fertilization and soil amendment, he may
design the system to minimize nutrient
losses and apply effluent or manure at
rates based on efficient crop utilization of
nutrients. Then he must decide whether
to base application rate on N,P or another
element. Typically, if N is the base
element, P and K are applied in excess of
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plant utilization. However, if P is the base
element, then additional N must be
applied with commercial fertilizer or a
manure-fertilizer blend might be utilized.
Thus, depending upon the producer's
objectives and the land and crop restrictions,
a wide range of nutrient loading rates
may be found m practice. A major
question arises as to whether the
maximum rate is limited by detrimental
effects to crops, or soil, or by waterquality
of ground water and runoff.
One crop which is often utilized for
application of manure and lagoon effluent
is tall fescue (Festuca arundinacea
Schreb). It can utilize large amounts of N
which is normally considered the limiting
constituent in land application of manure
or lagoon effluent and fescue is water
tolerant and responds well to irrigation.
Fescue is a cool-season perennial,
however, and the continued application
of nutrients and/or irrigation during the
summer may cause problems with
maintaining stand. The peak production
of fescue in the Southeast is March
through May, and September through
November
The objectives of this study were to:
(1) determine dry matter yield, elemental
composition, digestibility, and stand
persistence of fescue receiving
swine manure or swine lagoon
effluent at high rates.
(2) determine soil effects of high rates
of manure or lagoon effluent applica-
tions.
(3) determine effects of the various
treatments on quantity and quality
of rainfall runoff.
Tall fescue on a Cecil sandy clay loam
was utilized in this study as the plant-soil
receiver system. Treatments included
commercial fertilizer, swine lagoon
effluent at two rates during the growing
season, and swine manure slurry applied
four times a year. Application rates were
based on N, and the manure and lagoon
effluent supplied from three to six times
more N than the commercial fertilizer
treatment which used a typical fertilizer
rate for fescue pasture. Also, P, K and
other nutrients were supplied in the
manure or effluent at several times the
normal fertilization rates. Results are
presented for 4 years of monitoring
irrigation applications, crop yield and
composition, soil cores, and runoff.
Conclusions
Utilizing swine manure slurry and
swine lagoon effluent for growing tall
fescue resulted in good dry matter yields
and high crude protein and digestibility,
but the dry matter had excessive N03-N
levels and vegetation shifted away from
tall fescue to tropical annuals and
perennials on the high-rate irrigation
treatment, which indicated that the high
annual rates of application and the
continued application of effluent during
the summer was not a good management
scheme for tall fescue.
The high-rate irrigation treatment
resulted in very high NO3-N levels in the
soil and the manure and low-rate
irrigation treatments also had higher
N03-N levels than the fertilized plot. The
1 200 kg N/ha/yr rate was too high and
the 600 kg N/ha/yr rates were probably
still too high to prevent excessive nitrate
movement to the ground water and
excessive NO3-N uptake by the fescue.
Maximum application rates which would
be considered safe would be somewhat
site specific and also depend on the
amount of N lost during application and
by denitrification.
No problems were encountered with
nutrient imbalance of cations in the soil
but continued P accumulation could
eventually result in reduced iron (Fe)
uptake. Periodic liming may be needed in
some soils to correct for calcium (Ca) and
magnesium (Mg) leaching where lagoon
effluent is applied.
All treatments, including the fertilizer
treatment, had some runoff events with
high nutrient concentrations in runoff.
Applications of manure or fertilizer
without incorporation should be avoided
if rain is predicted within a few days.
Also, the 1200 kg N/ha/yr irrigation
treatment and the manure treatment had
noticeably higher total N and P transport
than the other treatments. Keeping
application rates near normal crop
fertilization rates would utilize a greater
percentage of the nutrients a nd would be
more acceptable environmentally
Recommendations
Results of applying either swine
manure slurry or swine lagoon effluent at
high rates to tall fescue for 4 years
indicated potential problems with applying
three and six times the normally recom-
mended fertilization rate based on N.
Excessive N03-N levels resulted in the
forage and in the soil when the N
application was 600 or 1,200 kg/ha/yr.
Also, some trends indicated potential
agronomic problems if high-rate applica-
tions continued. Based upon these
results the following recommendations
are made:
1. Future studies should concentrate
on fertilization levels in the range of
200 to 600 kg/ha/yr of N. Also,
application rates of manure or
lagoon effluent based on P or K
should also be considered.
2. The application losses of N by NH3-
N volatilization and the soil reduction
of NO3-N by denitrification needs
further study in order to better
adjust application rates and determine
the fate of N.
3. The potential problems of P accumu-
lation need further investigation.
4. The effects of high-rate applications
of manure or lagoon effluent on
water quality of rainfall runoff and
ground water should be studied for
actual field-size systems where
impact on receiving streams or
impoundments could also be evalu-
ated.
5. Other management options should
be evaluated for irrigation of lagoon
effluent on fescue such as using a
lower application rate or no applica-
tions during the summer to help
reduce stand loss of fescue to
tropical annuals and perennials
6. The potential of mixing fescue
having high NO3-N levels with
other forage having low NOs-N
levels for feeding livestock needs to
be evaluated
7. Studies of this type should be
conducted with various crops and
soils, and different management
strategies to determine which
systems are best suited for utilizing
manure and lagoon effluent at
either normal fertilization rates or
maximum disposal rates. Economics
of alternatives should be evaluated.
Some studies, particularly those
with high application rates, should
be of 5 to 10 years or longer
duration to determine trends for
long-term effects where systems
are dedicated to disposal.
Crop Response
The fescue forage was evaluated for
dry matter yield, elemental composition,
and estimated nutritive value. The
quantity of N and other constituents that
could be harvested in fescue forage at
high nutrient application rates without
adversely affecting stands or forage
quality was also of major interest.
The nutrient application rates were
based on N and thus resulted in various
ratios of other nutrients. The average
nutrient application rates over the 4-year
period are shown in Table 1. The N-P-K
ratio of the applied manure was about
3.4-1-1.4. Compared to the normally-
recommended fertilizer ratio of 9-1 -4 for
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fescue, the manure was high in P (about
2.5 times) and all right for K in relation to
N, whereas lagoon effluent was high in
both P and K in relation to N. Both lagoon
liquid and swine manure from the pit had
substantial amounts of ammonia nitrogen
(NH3-N) and NH3-N loss during and after
application would increase the excess of
P and K in relation to N.
Comparing the lagoon-irrigated treat-
ment with the manure treatment receiving
approximately the same amount of N, the
irrigated treatment received much more
(about four times) K, Na and Cl~ while the
manure treatment received more P, Ca
and Zn on an annual basis (Table 1). Other
differences between the treatments were
the amount of water received (about 10 to
25 cm more for the low-rate irrigated
treatments) and the frequency of application
(about 30 weekly irrigations, March to
November, compared to four manure
applications per year).
The treatments resulted in good dry
matter yields, good estimated digestibility
(in vitro dry matter digestibility, IVDMD)
and high crude protein concentrations
(20 to 23%). The major mineral (P, K, Ca
and Mg) concentrations in the forage
were somewhat higher for the lagoon
effluent and manure treatments than
normally found in forage tissue but
should not be a problem. The only fraction
that was considered to be an animal
health hazard was the NOa-N levels (0.64
to 1.2% as nitrate (NOs-) of treatments
receiving either lagoon effluent or
manure. Because of the high quality (high
IVDMD and N concentrations (3.2 to
3.7%) of the dry matter produced, a
possible use of this forage would be a
blend with another feed generally low in
N.
Dry matter yields for the four treatments
are shown in Figure 1. The 4-year
average dry matter yield of the manure
plot (7,60O kg/ha) was similar to the
mean yield of the two fertilized plots
(7,900 kg/ha). The mean yield of the three
low-rate irrigation plots (11,200 kg/ha)
was higher than the manure plot which
received approximately the same N rate.
The high-rate irrigation plot had the
highest average yield (12,500 kg/ha) but
the forage on the plots shifted to mainly
tropical annuals and perennials. Also, N
recovery as percent of N applied was
much lower on the high-rate irrigation
treatment than for other treatments.
The average annual quantities of N and
P removed inthefescueforageareshown
in Table 2. The low-rate irrigated treatment
had a higher percent recovery of N and P
than the manure treatment, which could
be a result of both lower availability of
Table 1. Comparing Application Amounts of Nutrients for Treatments
Treatment
Fertilizer
Manure
Low effluent
High effluent
Number of
plots
2
1
3
1
Annual application*, kg/ ha
N
200
670
590
1,210
P
35
195
120
240
K
65
275
1,065
2,240
Ca
295
140
280
Mg
65
55
120
Na
100
540
1,095
cr
190
665
1,290
Cu
044
0.31
062
Zn
43
1.2
2.4
*Mean annual application rate for 4-year period.
20,000
16,000
I
12,000
8,000
4.000
D - Manure
L - Low Effluent
H - High Effluent
N - Chemical Fertilizer
H
1975
Figure 1. Annual dry matter yield.
Table 2. Amounts of N and P in Forage
1976 1977
Year
1978
Identification
Fertilizer
treatment
Manure Lagoon-irrigated treatments
treatment Low-rate
High-rate
N
kg/ha
Amount applied
Amount in harvested forage
Amount not recovered
Percent recovered in forage
Amount applied
Amount in harvested forage
Amount not recovered
Percent recovered in forage
200
260
-60
130
35
25
10
71
670
280
390
42
195
30
165
15
P
kg/ha
%
590
380
210
64
120
45
75
38
1.210
430
780
36
240
50
190
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nutrients in the manure and higher
losses of nutrients from the manure
during and after application. Also, the
additional water applied when using
lagoon effluent could increase utilization
of nutrients. The amounts of N and P not
recovered in the forage were high and
indicate potential problems with soil
accumulation of P and movement of NOs-
N to ground water.
The manure plot and the irrigated plots
had a striking shift away from tall fescue
to tropical annuals and perennials, with
greater shifts occurring on the plots
receiving effluent. Further, these treatments
had major insect infestations resulting in
appreciable bare ground at times. Fescue
performance would probably be better if a
greater portion of the nutrients were
applied during the peak growth periods
and much less during the summer. The
scheme of application which was used is
more conducive to tropical grasses, or
perhaps tropical grasses grown in sequence
with annual grasses.
Soil Effects
Accumulation of some nutrients in the
soil was evident with the manure and
irrigated treatments. The high-rate
irrigation treatment had high potential for
ground-water pollution because of excess
NOs-N in the soil profile, while the low-
rate irrigation and manure treatments
could also potentially contribute excess
NOs-N to the ground water.
The high application rates of K, Na and
N (mostly as NH3-N) and the relatively low
application rates of Ca and Mg with
irrigated effluent suggest that a nutrient
imbalance may develop, but none had
developed after 4 years, probably because
of the high levels of Ca and Mg initially in
the soil and the rather high soil buffering
capacity due to the clay content. Long-
term irrigation of lagoon effluent should
be supplemented with applications of
dolomitic limestone. Nutrient imbalance
would be less likely to occur from manure
applications than from effluent applications
because lagooning the manure results in
settling or precipitation of Ca and Mg
such that ratios of (Ca + Mg)/(monovalent
cations) in the lagoon effluent are low.
Manure applications and the low
irrigation rate supplied adequate P,
whereas chemical fertilizer did not supply
enough and the high irrigation rate
supplied an excessive amount. Continued
application of excessive P could result in
reduced Fe uptake, but due to the large
amount of Fe in this soil, an Fe deficiency
would take a long time to develop.
18 -
16 -
14 -
!i2
.0
I
c
§ 10
*
fc 8
I
I
-
Mean concentrations for
period: July 1975-Feb 1979
1\
i\
/ *
' / "v N03-N
-1! V
A
/ TKN \
d
NOyN
1
1
1
1
TMT3 TMT5 TMT4 TMT6 TMT7 TMT2
2O2 kg/ha 202 kg/ha 6OO kg/ha 6OO kg/ha 12OO kg/ha 6OO kg/ha
(Fen.) (Pert.) (/rg.J (Irg.) (Irg.) (Manure)
Treatment and Annual Nitrogen Application
Figure 2. Effect of treatments on mean concentrations of N, TKN, and NO3-N in rainfall runoff
for entire period.
Rainfall Runoff
Rainfall runoff was relatively low
during the 44-month period, averaging
2.4% to 7.8% of rainfall for the various
treatments. The high-rate irrigation
treatment had the largest amount of
runoff but there were no other evident
effects of slope or treatment. A statistical
design with replicates would be needed
to better investigate differences in runoff
volume.
Volume-weighted concentrations and
mass transport of nutrients in rainfall
runoff were highest for the manure and
high-rate irrigation treatments. Mean
concentrations of N03-N, total Kjeldahl
nitrogen (TKN) (not including NO3-N) and
N (including N03-N) in rainfall runoff are
shown in Figure 2. Concentrations of N in
runoff from the low-rate irrigation
treatments were not much different from
those of the fertilizer treatments. Because
of generally low runoff amounts, the
mass transport of nutrients was also low.
The highest transport of N was for the
high-rate irrigation plot and the manure
plot, but the amounts transported were
only about 1.3% of the N applied to those
treatments.
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The mean concentrations of P in runoff
increased as loading rate of P increased,
being in the range of about 0.5 to 1.5
mg/l for the fertilized and low-rate
irrigation treatments, and about 6 and 7
mg/l for the manure and high-rate
irrigation treatments, respectively. Overall,
the manure and high-rate irrigation
treatments had higher pollution potential
than the fertilizer treatment and the low-
rate irrigation treatment which had simi-
lar nutrient transport in runoff.
The highest pollution potential for a
particular runoff event was just after an
application of manure, effluent or fertilizer.
A significant runoff event soon after
application of any of these materials
could account for a large portion of the
annual nutrient transport in runoff.
Manure and fertilizer seemed more
available for runoff transport than did
lagoon effluent just after application
because they remained mostly on the soil
surface for several days while lagoon
effluent infiltrated quickly.
Variation of rainfall intensity, runoff
rate and concentrations during a runoff
event was investigated for some periods.
For a particular plot, the concentrations
remained fairly constant throughout an
event, but the mean concentration varied
from one event to another. For one large
event a few days after a manure application,
there seemed to be some variation in
concentration in response to variation in
rainfall intensity and runoff rate, but this
was not evident for other events.
Philip W. Westerman, Larry D. King, Joseph C. Burns, and Michael R. Overcash
are with North Carolina State University, Raleigh, NC 27650.
R. Douglas Kreis is the EPA Project Officer (see below).
The complete report, entitled Swine Manure and Lagoon Effluent Applied to
Fescue," (Order No. PB 83-259 861; Cost: $ 16.00, 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
Ada, OK 74820
. S. GOVERNMENT PRINTING OFFICE: 1983/759-102/0803
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
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