Moisture and urine were applied to a feedlot surface in a 2x2 factorial design. Forced-air wind tunnels were used to determine differences in the net flux of ammonia (NH3) being volatilized. Surface DM, pH and surface temperature were all analyzed within each treatment to determine effect on NH3 net flux. No effects of urine were detected. There were differences detected due to moisture and moisture*time with the dry plots releasing significantly more NH3

Erickson, Galen E.

Klopfenstein, Terry J.

Schulte, Dennis D.

Sherwood, Dawn M.

Stowell, Richard R.

English

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
January 2007 
Feedlot Surface Conditions and Ammonia Emissions 
Dawn M. Sherwood 
University of Nebraska-Lincoln 
Galen E. Erickson 
University of Nebraska-Lincoln, gerickson4@unl.edu 
Terry J. Klopfenstein 
University of Nebraska-Lincoln, tklopfenstein1@unl.edu 
Dennis D. Schulte 
University of Nebraska-Lincoln, dschulte1@unl.edu 
Richard R. Stowell 
University of Nebraska-Lincoln, rstowell2@unl.edu 
Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr 
 Part of the Animal Sciences Commons 
Sherwood, Dawn M.; Erickson, Galen E.; Klopfenstein, Terry J.; Schulte, Dennis D.; and Stowell, Richard R., 
"Feedlot Surface Conditions and Ammonia Emissions" (2007). Nebraska Beef Cattle Reports. 72. 
https://digitalcommons.unl.edu/animalscinbcr/72 
This Article is brought to you for free and open access by the Animal Science Department at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle 
Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 
Page 50 — 2007 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.
Feedlot Surface Conditions and Ammonia Emissions
Dawn M. Sherwood
Galen E. Erickson
Terry J. Klopfenstein
Dennis D. Schulte
Rick R. Stowell1
Summary
Moisture and urine were applied to a 
feedlot surface in a 2x2 factorial design. 
Forced-air wind tunnels were used to 
determine differences in the net flux of 
ammonia (NH
3
) being volatilized. Sur-
face DM, pH and surface temperature 
were all analyzed within each treatment 
to determine effect on NH
3
 net flux. No 
effects of urine were detected. There were 
differences detected due to moisture and 
moisture*time with the dry plots releas-
ing significantly more NH3.
Introduction
 Feedlot surface conditions con-
tinually change due to variations 
in temperature, moisture, manure, 
urine and microbial population. NH

 
emissions continually change due to 
the time of year, time of day, environ-
mental conditions and feedlot surface 
conditions. Past reports indicated an 
increase in NH

 flux during the sum-
mer due to an increase in soil tem-
perature and N level (2006 Nebraska 
Beef Report, pp. 92-9). 
NH

 flux usually follows a diurnal 
pattern with the NH

 concentration 
increasing from early morning, peak-
ing at midday and then decreasing into 
early evening. Our first hypothesis is the 
application of urine will increase NH

 
emissions from the feedlot pen surface. 
Additionally, as plots with moisture 
added begin to dry an increase in NH

 
flux will be observed. According to 
diurnal patterns and temperatures, our 
second hypothesis is NH

 loss will be 
highest during the afternoon.
Procedure
The experiment was conducted 
the first  weeks of August 2005. Each 
week, cattle were removed from the 
pens the afternoon of day 0 and re-
turned to the pens to re-equilibrate the 
surface the morning of day . Treat-
ments were applied to 5.76 ft2 plots 
on a feedlot surface as a 2x2 factorial. 
Factors included water addition at 0 or 
4 gallons, to simulate a 1-inch rainfall 
and/or urine addition of 0 or 0.26 gal-
lons (0.762 % N). Therefore, the four 
treatments were DRY (nothing added), 
DRY+URINE (urine added), WET 
(only water added), and WET+URINE 
(water and urine added). Water was ap-
plied to assigned plots at 6 a.m. on day 
1. Urine was applied immediately prior 
to collection one on day 1 of designated 
plots. Plot location and treatment re-
mained the same throughout  weeks. 
NH

 samples were collected using two 
forced-air wind tunnels every  hours 
on day 1 from 6 a.m. to 9 p.m. On day 
2, samples were collected every 6 hours 
from 8 a.m. to 8 p.m. Wind tunnels di-
rected air over the surface at 0. m/s for 
0 minutes per plot. A fraction of the 
airflow (0.024 m/s) was diverted for 
analysis and NH

 was collected using 
a 0.2 M sulfuric acid trap. The trapped 
NH

 was measured in the lab using a 
spectrophotometer. One-inch cores of 
the feedlot surface were collected, two 
at the beginning of day 1, and two at 
Figure 1. NH
3
 emissions due to urine and time (interaction: P = 0.78; urine effect: P = 0.46).

2.5
2
1.5
1
0.5
0
µg
/m
2 /
s
Urine
No Urine
6:
00
 A
M
9:
00
 A
M
12
:0
0 
P
M
:
00
 P
M
6:
00
 P
M
9:
00
 P
M
8:
00
 A
M
2:
00
 P
M
8:
00
 P
M
Time Points
Figure 2.  NH
3
 emissions due to moisture and time of day (interaction: P = 0.03; moisture effect: 
 P < 0.01).
/5

2.5
2
1.5
1
0.5
0
Dry
Wet
6:
00
 A
M
9:
00
 A
M
12
:0
0 
P
M
:
00
 P
M
6:
00
 P
M
9:
00
 P
M
8:
00
 A
M
2:
00
 P
M
8:
00
 P
M
Time Points
µg
/m
2 /
s
© The Board of Regents of the University of Nebraska.  All rights reserved. 2007 Nebraska Beef Report  — Page 51 
DRY+URINE plots emitting higher 
levels of NH

 on both day 1 and day 2 
(.07 and 2.09 µg/m2/s) versus the WET 
and WET+URINE plots emitting only 
0.65 and 0.72 µg/m2/s of NH

 (Figure 2). 
There was a significant 
moisture*urine effect (P= 0.02) on 
core N with the WET+URINE having 
a higher N level when compared to the 
other three treatments. Soil pH was 
effected by moisture (P<0.01) with 
WET and WET+URINE treatments 
having higher pH values. The WET 
and WET+URINE core moisture was 
twice the amount of that observed in 
the DRY cores (27.6 and 28.7 WET, 
11. and 12.0 DRY; Table 1).
NH

 flux weakly correlated to 
core N (r = 0.67, P = 0.02). As core 
N increased, the NH

 emitted also 
increased (Figure ). A low correla-
tion (r = 0.4, P = 0.04) was observed 
between moisture and NH

 flux. 
Emissions were high on DRY and 
DRY+URINE plots and as the WET 
and WET+URINE plots dried the 
emissions increased (Figure 4). At 
the high moisture of the WET and 
WET+URINE plots, the surface is 
moist and holds the NH

 in solution. 
As the surface dries it allows the NH

 
to volatilize and be released. 
In this trial, NH

 loss appears to 
be related to soil moisture, with the 
greater loss from dry surfaces. The 
NH

 flux followed a diurnal pattern 
with the greatest loss prior to 9 a.m. 
and decreasing into the evening. The 
diurnal trend of the lowest emissions 
during the midday, rather than the 
midday emissions being the highest, 
could be due to the repeated mea-
surement of the plots throughout the 
day. This could have modified the 
microenvironment. The change in 
the microenvironment could have 
reduced the amount of NH

 produced, 
and thus emitted, resulting in  the low 
NH

 flux midday. Low air exchange 
rates within the chamber can also 
modify the microenvironment reduc-
ing NH

 loss. 
1 Dawn M. Sherwood, graduate student; 
Galen E. Erickson, associate professor; and 
Terry J. Klopfenstein, professor, Animal Science, 
Lincoln. Dennis D. Schulte, professor; and Rick 
R. Stowell, assistant professor, Biological Systems 
Engineering, Lincoln.
Table 1.  Core characteristics influenced by moisture and urine.
      P-value
 DRY+  WET+  Moisture
 DRY URINE WET URINE *urine Moisture Urine
Core N 1.18ab 1.12ab 1.11b 1.22a 0.02 0.74 0.49
Core pH 8.01 7.96 8.21 8.2 0.19 <0.01 0.72
Core
Moisture 11. 12.0 27.6 28.7 0.89 <0.01 0.5
a,bMeans with different superscripts differ significantly (P<0.05).
Figure 3.  Correlation between N loss and core N.
18
16
14
12
10
8
6
4
2
0
N
H
 fl
ux
, (
µg
/m
2 /
s)
y = 5.127x - .0945
 0 0.2 0.4 0.6 0.8 1 1.2
Core N (% DM)
r=0.67, P=0.02
Figure 4.  Correlation between N loss and core moisture.
14
12
10
8
6
4
2
0
-2
0 10 20 0 40
% Moisture
r=0.4, P=0.04
N
H
 fl
ux
, (
µg
/m
2 /
s)
y = -0.0814x - 2.980
the end of day 2. They were analyzed 
for DM, pH and N. Soil and surface 
temperatures were recorded at the be-
ginning of each 0-minute period. 
Results
There was no moisture*urine*time 
interaction (P= 0.57), no urine*time 
interaction (P= 0.78) and no main 
effect of urine (P= 0.46; Figure 1) . A 
moisture*time interaction (P= 0.0) 
was observed across all  weeks, the 
highest NH

 loss was observed prior to 
9 a.m. on both day 1 and day 2, with 
NH

 losses decreasing to very low levels 
after 12 p.m. The net flux was affected 
by moisture (P<0.01) with the DRY and 


Feedlot Surface Conditions and Ammonia Emissions

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department January 2007 Feedlot Surface Conditions and Ammonia Emissions Dawn M. Sherwood University of Nebraska-Lincoln Galen E. Erickson University of Nebraska-Lincoln, gerickson4@unl.edu Terry J. Klopfenstein University of Nebraska-Lincoln, tklopfenstein1@unl.edu Dennis D. Schulte University of Nebraska-Lincoln, dschulte1@unl.edu Richard R. Stowell University of Nebraska-Lincoln, rstowell2@unl.edu Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Sherwood, Dawn M.; Erickson, Galen E.; Klopfenstein, Terry J.; Schulte, Dennis D.; and Stowell, Richard R., "Feedlot Surface Conditions and Ammonia Emissions" (2007). Nebraska Beef Cattle Reports. 72. https://digitalcommons.unl.edu/animalscinbcr/72 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Page 50 — 2007 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.Feedlot Surface Conditions and Ammonia EmissionsDawn M. SherwoodGalen E. EricksonTerry J. KlopfensteinDennis D. SchulteRick R. Stowell1SummaryMoisture and urine were applied to a feedlot surface in a 2x2 factorial design. Forced-air wind tunnels were used to determine differences in the net flux of ammonia (NH3) being volatilized. Sur-face DM, pH and surface temperature were all analyzed within each treatment to determine effect on NH3 net flux. No effects of urine were detected. There were differences detected due to moisture and moisture*time with the dry plots releas-ing significantly more NH3.Introduction Feedlot surface conditions con-tinually change due to variations in temperature, moisture, manure, urine and microbial population. NH emissions continually change due to the time of year, time of day, environ-mental conditions and feedlot surface conditions. Past reports indicated an increase in NH flux during the sum-mer due to an increase in soil tem-perature and N level (2006 Nebraska Beef Report, pp. 92-9). NH flux usually follows a diurnal pattern with the NH concentration increasing from early morning, peak-ing at midday and then decreasing into early evening. Our first hypothesis is the application of urine will increase NH emissions from the feedlot pen surface. Additionally, as plots with moisture added begin to dry an increase in NH flux will be observed. According to diurnal patterns and temperatures, our second hypothesis is NH loss will be highest during the afternoon.ProcedureThe experiment was conducted the first  weeks of August 2005. Each week, cattle were removed from the pens the afternoon of day 0 and re-turned to the pens to re-equilibrate the surface the morning of day . Treat-ments were applied to 5.76 ft2 plots on a feedlot surface as a 2x2 factorial. Factors included water addition at 0 or 4 gallons, to simulate a 1-inch rainfall and/or urine addition of 0 or 0.26 gal-lons (0.762 % N). Therefore, the four treatments were DRY (nothing added), DRY+URINE (urine added), WET (only water added), and WET+URINE (water and urine added). Water was ap-plied to assigned plots at 6 a.m. on day 1. Urine was applied immediately prior to collection one on day 1 of designated plots. Plot location and treatment re-mained the same throughout  weeks. NH samples were collected using two forced-air wind tunnels every  hours on day 1 from 6 a.m. to 9 p.m. On day 2, samples were collected every 6 hours from 8 a.m. to 8 p.m. Wind tunnels di-rected air over the surface at 0. m/s for 0 minutes per plot. A fraction of the airflow (0.024 m/s) was diverted for analysis and NH was collected using a 0.2 M sulfuric acid trap. The trapped NH was measured in the lab using a spectrophotometer. One-inch cores of the feedlot surface were collected, two at the beginning of day 1, and two at Figure 1. NH3 emissions due to urine and time (interaction: P = 0.78; urine effect: P = 0.46).2.521.510.50µg/m2 /sUrineNo Urine6:00 AM9:00 AM12:00 PM:00 PM6:00 PM9:00 PM8:00 AM2:00 PM8:00 PMTime PointsFigure 2.  NH3 emissions due to moisture and time of day (interaction: P = 0.03; moisture effect:  P < 0.01)./52.521.510.50DryWet6:00 AM9:00 AM12:00 PM:00 PM6:00 PM9:00 PM8:00 AM2:00 PM8:00 PMTime Pointsµg/m2 /s© The Board of Regents of the University of Nebraska.  All rights reserved. 2007 Nebraska Beef Report  — Page 51 DRY+URINE plots emitting higher levels of NH on both day 1 and day 2 (.07 and 2.09 µg/m2/s) versus the WET and WET+URINE plots emitting only 0.65 and 0.72 µg/m2/s of NH (Figure 2). There was a significant moisture*urine effect (P= 0.02) on core N with the WET+URINE having a higher N level when compared to the other three treatments. Soil pH was effected by moisture (P<0.01) with WET and WET+URINE treatments having higher pH values. The WET and WET+URINE core moisture was twice the amount of that observed in the DRY cores (27.6 and 28.7 WET, 11. and 12.0 DRY; Table 1).NH flux weakly correlated to core N (r = 0.67, P = 0.02). As core N increased, the NH emitted also increased (Figure ). A low correla-tion (r = 0.4, P = 0.04) was observed between moisture and NH flux. Emissions were high on DRY and DRY+URINE plots and as the WET and WET+URINE plots dried the emissions increased (Figure 4). At the high moisture of the WET and WET+URINE plots, the surface is moist and holds the NH in solution. As the surface dries it allows the NH to volatilize and be released. In this trial, NH loss appears to be related to soil moisture, with the greater loss from dry surfaces. The NH flux followed a diurnal pattern with the greatest loss prior to 9 a.m. and decreasing into the evening. The diurnal trend of the lowest emissions during the midday, rather than the midday emissions being the highest, could be due to the repeated mea-surement of the plots throughout the day. This could have modified the microenvironment. The change in the microenvironment could have reduced the amount of NH produced, and thus emitted, resulting in  the low NH flux midday. Low air exchange rates within the chamber can also modify the microenvironment reduc-ing NH loss. 1 Dawn M. Sherwood, graduate student; Galen E. Erickson, associate professor; and Terry J. Klopfenstein, professor, Animal Science, Lincoln. Dennis D. Schulte, professor; and Rick R. Stowell, assistant professor, Biological Systems Engineering, Lincoln.Table 1.  Core characteristics influenced by moisture and urine.      P-value DRY+  WET+  Moisture DRY URINE WET URINE *urine Moisture UrineCore N 1.18ab 1.12ab 1.11b 1.22a 0.02 0.74 0.49Core pH 8.01 7.96 8.21 8.2 0.19 <0.01 0.72CoreMoisture 11. 12.0 27.6 28.7 0.89 <0.01 0.5a,bMeans with different superscripts differ significantly (P<0.05).Figure 3.  Correlation between N loss and core N.181614121086420NH flux, (µg/m2 /s)y = 5.127x - .0945 0 0.2 0.4 0.6 0.8 1 1.2Core N (% DM)r=0.67, P=0.02Figure 4.  Correlation between N loss and core moisture.14121086420-20 10 20 0 40% Moisturer=0.4, P=0.04NH flux, (µg/m2 /s)y = -0.0814x - 2.980the end of day 2. They were analyzed for DM, pH and N. Soil and surface temperatures were recorded at the be-ginning of each 0-minute period. ResultsThere was no moisture*urine*time interaction (P= 0.57), no urine*time interaction (P= 0.78) and no main effect of urine (P= 0.46; Figure 1) . A moisture*time interaction (P= 0.0) was observed across all  weeks, the highest NH loss was observed prior to 9 a.m. on both day 1 and day 2, with NH losses decreasing to very low levels after 12 p.m. The net flux was affected by moisture (P<0.01) with the DRY and 

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Feedlot Surface Conditions and Ammonia Emissions

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