AN ABSTACT OF THE THESIS OF
Jess Charles Holcomb III for the degree of Master of Science in Soil Science presented on January
20, 2011
Title: Enhanced Efficiency Nitrogen Fertilizers for Nitrogen Management in the Columbia Basin,
Oregon
Abstract approved:
Donald A. Horneck
Dan M. Sullivan
Ammonia (NH3) volatilization can result in a substantial amount of surface applied
nitrogen (N) being lost into the atmosphere, making it an environmental pollutant as well as
reducing plant-available N. However, N can also be easily lost from the soil through leaching,
and nitrous oxide (NO2). Enhanced efficiency N fertilizers and cultural practices can be used to
reduce N pollution and keep N plant-available. The use of these fertilizers and practices has not
been examined in the Columbia Basin in Oregon. The objectives of this study were to: (i)
examine the effective irrigation rate needed to reduce loss from volatilization from urea, (ii)
examine the effectiveness of urease inhibitors in minimizing NH3 loss, measure interactions
between inhibitors and irrigation, and measure hydrolysis rates with inhibitors, and (iii) examine
if enhanced efficiency N fertilizers could maintain or increase potato yields, whether petiole NO3
accurately reflected plant N with these products, and if they release N according to plant
uptake.
In the first study, irrigation rates of 0.0 to 22 mm were applied over surface applied urea
using a center pivot irrigation system on a wheat field. Ammonia was collected from each plot
using the modified passive flux method for 23 days after application (DAA). Cumulative loss of N
as NH3 ranged from 3 to 67 kg N acre-1, with the application of 8 mm irrigation reducing loss to
19 kg N ha-1. Peak NH3 loss occurred between 2 and 8 DAA. The reduction of N loss by 90% was
obtained through the application of 15 mm irrigation. Increased wheat N concentration was
associated with decreased NH3 loss.
The second study consisted of recording NH3 loss on a grass seed field from urea,
ammonium sulfate, and Agrotain-treated urea. This study also involved recording NH3 loss on a
wheat field from urea, Agrotain, and an organo acid complex containing co-polymers (OAC)
treated urea at irrigation rates of 0.0, 1.25, and 7.6-mm. Volatilization loss was measured using
the modified passive flux method. Urea, Agrotain, and OAC were incubated with soil at three
temperatures to measure hydrolysis rates. In the grass seed study Agrotain reduced N loss from
NH3 by 71.8% compared to urea, while ammonium sulfate reduced loss by 60.4% compared to
urea. In the wheat study, Agrotain lost 5.72 to 6.24% N applied at the 0.00 and 1.25-mm
irrigation rate, compared to 53.44% to 60.05% N applied for urea and OAC. With the application
of 7.6-mm irrigation, all loss declined with rates of 17.31, 8.11, and 3.17 N applied for urea, OAC,
and Agrotain, respectively. Agrotain also decreased urease activity in the wheat field compared
to urea and OAC. In incubation, Agrotain delayed complete hydrolysis by 7 days at 26.7oC, 15
days at 16.6oC, and 49 days at 4.4oC compared to urea and OAC. Urea and OAC had similar
hydrolysis rates at all temperatures. The use of an effective urease inhibitor, such as Agrotain,
can be used to delay hydrolysis and reduce NH3 loss if urea cannot be incorporated.
In the final study, enhanced efficiency N fertilizers were applied to Russet Norkota and
Russet Burbank potatoes to compare yield and quality with grower standard practices (GSP).
Plant N samples were taken from the third year to examine whether petiole nitrate accurately
reflected plant N with these products. An incubation of all products for 104 DAA was performed
at4.4oC, 16.6oC, and 26.7oC to measure ammonium (NH4) and nitrate (NO3) formation. Similar
yields were measured for both years with Russet Norkota. All N treatments were similar, even
the 80% GSP, suggesting that N rates were in excess of crop need, thereby reducing sensitivity of
N-inhibitor measurements. Reduced yields were measured in two years for Russet Burbank
when enhanced efficiency fertilizers were applied compared to 100% GSP. Enhanced efficiency
fertilizers maintained yields for one year compared to 100% GSP. Yields with N treatments were
usually similar to the 80% GSP, suggesting that N release was not matched with N uptake. In the
incubation study, all products except Nutrisphere-N (NSN) were able to delay N release
compared to urea. Each product was influenced by temperature, with decreased temperature
resulting in a longer delay in conversion of urea to NH4 and conversion of NH4 to NO3 N. Nitamin
and N-fusion had only 100% N available at 26.7oC after 104 day. Enhanced efficiency N
fertilizers cannot sustain or increase yields on a yearly basis, making their incorporation into
Columbia Basin potato production impracticable based on economics.
Enhanced efficiency N fertilizers and cultural practices can reduce N loss. However, a
reduction in N loss does not always lead to sustained or increased yields. The use of cultural
practices can be implemented with minimal expense; however, the fertilizers must present an
economical benefit, either as increased yield or a N reduction to be viable in most cropping
systems.
© Copyright by Jess Charles Holcomb III
January 20, 2011
All Rights Reserved
Enhanced Efficiency Nitrogen Fertilizers for Nitrogen Management in the Columbia Basin,
Oregon
by
Jess Charles Holcomb III
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Presented January 20, 2011
Commencement June 2011
Master of Science thesis of Jess Charles Holcomb III presented on January 20, 2011.
APPROVED:
Co-Major Professor, representing Soil Science
Co-Major Professor, representing Soil Science
Head of the Department of Crop and Soil Science
Dean of the Graduate School
I understand that my thesis will become part of the permanent collection of Oregon State
University libraries. My signature below authorizes release of my thesis to any reader upon
request.
Jess Charles Holcomb III, Author
ACKNOWLEDGEMENTS
Sincere appreciation is expressed to my advisors Dr. Don Horneck and Dr. Dan Sullivan.
Dr. Horneck helped me with all aspects of my projects, always being there if I had questions, and
familiarizing me with the Columbia Basin, the production in it, and all the people. Dr. Sullivan
guided me through my time in Corvallis and the continued help and support that I received
when I was in Hermiston. I would also like to thank my committee member Dr. George Clough
for spending his time to get to know me and my projects, as well as including me in several of
his.
To my wonderful wife Jesi, for moving with me to Hermiston and making it into our
home. She helped me through this entire process, always loving me and supporting me, no
matter what path I took. To my family for inspiring me to set the bar for success so high and
doing everything to make sure I obtained it. To all my friends along the way who made the
journey much more memorable.
To the great staff and faculty at the Hermiston Agricultural Research and Extension
Center for helping me with all of my projects, my daily activities, and all the great times at
HAREC. To Wes and Brenda Wood from Auburn University for helping with the set up of our
ammonia devices and answering all the questions that I asked.
Thanks to all the growers who lent me their time, resources, crops, and land to conduct
my research. Special thanks go to Chet and Art Prior at Eagle Ranch, Kent Madison and Craig at
Madison Farms, and Darrin Ditchen at Golden Valley East. I am grateful for the financial support
that made these projects possible from Agrotain International and the J.R. Simplot Company.
Special thanks to Syngenta for the use of their weather station and IRZ for the use of their soil
moisture probes.
Finally, to everyone at Oregon State University, who gave me the knowledge to continue
down this road and pursue a career in agriculture.
CONTRIBUTION OF AUTHORS
Dr. Don Horneck assisted with data collection and interpretation for chapters 2, 3, and
4. Dr. Dan Sullivan assisted with data interpretation for chapters 2, 3, and 4. Dr. George Clough
along with Dr. Horneck and Dr. Sullivan provided detailed reviews of chapters 2, 3, and 4.
TABLE OF CONTENTS
Page
GENERAL INTRODUCTION……………………………………………………………………………………………….
1
REFERENCES………………………………………………………………………………………………………
5
EFFECT OF IRRIGATION RATE ON AMMONIA VOLATILIZATION…………………………………………
15
ABSTRACT……………………………………………………………………………………………………………
12
INTRODUCTION…………………………………………………………………………………………………..
12
MATERIALS AND METHODS……………………………………………………………………………….
14
RESULTS AND DISCUSSION………………………………………………………………………………..…
17
Environmental Conditions……………………………………………………………………….
17
Ammonia Volatilization Loss……………………………………………………………………
17
Soil and Plant Analyses……………………………………………………………………………
19
CONCLUSIONS……………………………………………………………………………………………………
20
ACKNOWLEDGEMENTS………………………………………………………………………………………
21
REFERENCES……………………………………………………………………………………………………….
21
UREASE INHIBITORS EFFECT ON AMMONIA VOLATILIZATION FROM UREA…….………………
29
ABSTRACT……………………………………………………………………………………………………………
30
INTRODUCTION…………………………………………………………………………………………………..
30
MATERIALS AND METHODS……………………………………………………………………………….
33
Grass Seed Study…………………………………………………………………………………….
33
Wheat Study……………………………………………………………………………………………
34
Incubation Study…………………………………………………………………………………….
35
Statistical Analyses………………………………………………………………………………….
36
RESULTS AND DISCUSSION…………………………………………………………………………………..
36
Grass Seed Study…………………………………………………………………………………….
37
Wheat Study……………………………………………………………………………………………
38
Incubation Study…………………………………………………………………………………….
41
CONCLUSIONS……………………………………………………………………………………………………
41
ACKNOWLEDGEMENTS….…………………………………………………………………………………….
42
REFERENCES……………………………………………………………………………………………………….
42
TABLE OF CONTENTS (Continued)
Page
EFFECT OF SPECIALTY NITROGEN FERTILIZERS ON RUSSET BURBANK AND RUSSET
NORKOTA POTATO YIELD IN THE COLUMBIA BASIN…………………………………………………………
55
ABSTRACT……………………………………………………………………………………………………………
56
INTRODUCTION………………………………………………………………………………………………….
56
MATERIALS AND METHODS……………………………………………………………………………….
60
Potato Field Study…………………………………………………………………………………
60
Incubation Study…………………………………………………………………………………….
61
Statistical Analyses………………………………………………………………………………….
62
RESULTS AND DISCUSSION………………………………………………………………………………..…
62
Russet Norkota………………………………………………………………………………………
62
Russet Burbank……………………………………………………………………………………….
64
Incubation Study…………………………………………………………………………………….
67
CONCLUSIONS……………………………………………………………………………………………………
71
REFERENCES………………………………………………………………………………………………………
71
GENERAL CONCLUSIONS………………………………………………………………………………………………….
97
BIBLIOGRAPHY………………………………………………………………………………………………………………..
100
APPENDICES……………………………………………………………………………………………………………………
110
LIST OF FIGURES
Figure
2.1
2.2
2.3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
4.1
4.2
Page
(a) Air temperature and soil temperature at 2.54-cm; and (b) wind speed
measured every 15 minutes during the study period from 9 March to 2 April
2010…………………………………………………………………………………………………………………….
25
Cumulative loss of NH3 during the period of 9 March to 2 April 2010 following
application of 112 kg urea-N ha-1 to winter wheat as affected by rate of
irrigation……………..………………………………………………………………………………………………
26
Cumulative loss of NH3 during the period of 9 March to 2 April 2010 following
application of 112 kg urea-N ha-1 to winter wheat as affected by rate of
irrigation application.……………………………...............................................................
27
Infrared photo of wheat field displaying layout of irrigation study. Irrigation
rates are randomly selected within each block.……………………………………………………
47
(a) Air temperature and soil temperature at 2.54-cm, soil temperature data
before 4 DAA was lost; and (b) wind speed measured at the grass seed fields…….
48
Cumulative loss of NH3 during the period of 28 September to 13 October 2009
following application of 112 kg N/ha to Kentucky bluegrass as affected by N
source. ………………………………………………………………………………………………………………..
49
(a) Air temperature and soil temperature at 2.54-cm; and (b) wind speed
measure at the wheat field. ………………………………………………………………………………
50
Cumulative loss of NH3 during the period of 9 March to 2 April 2010 following
application of 112 kg N ha-1 to winter wheat as affected by N and irrigation rate
treatments. …………………………………………………………………………………………………………
51
Cumulative loss of NH3 within irrigation rates for the period of 9 March to 2
April 2010 following application of 112 kg N ha-1 to winter wheat for urea,
Agrotain, and OAC. ……………………………………………………………………………………………..
52
Net NH4-N from fertilizer, as affected by N treatment at incubation temperature
(a) 4.4oC, (b) 16.6oC, and (c) 26.7oC………………………………………………………………………
53
Available NH4 at 4.4oC from (a) urease and nitrification inhibitors, (b) polymer
coated urea, and (c) slow release N in incubation as affected by N treatment.….
77
Available NH4 at 15.6oC from (a) urease and nitrification inhibitors, (b) polymer
coated urea, and (c) slow release N in incubation as affected by N treatment…….
78
LIST OF FIGURES (Continued)
Figure
4.3
4.4
Page
Available NH4 at 26.7oC from (a) urease and nitrification inhibitors, (b) polymer
coated urea, and (c) slow release N in incubation as affected by N treatment…….
79
Soil pH at (a) 4.4oC, (b) 15.6oC, and (c) 26.7oC in incubation as affected by N
treatment…………………………………………………………………………………………………………….
80
LIST OF TABLES
Table
2.1
Page
Soil urease activity from 0-2.54 cm soil depth, wheat dry matter, wheat N
concentration, and wheat N uptake sampled 23 DAA.…………...............................
28
Wheat response and soil urease activity (0-2.5 cm) as affected by N treatment
and irrigation rate ……………………………………………………………………………………………….
54
4.1
Modes of action for enhanced efficiency nitrogen fertilizers……………………………….
81
4.2
Nitrogen treatments for Russet Norkota and Russet Burbank for 2007, listing N
source, N rates (kg ha-1), and application timing………………………………………………….
82
Nitrogen treatments for Russet Norkota and Russet Burbank for 2008, listing N
source, N rates (kg ha-1), and application timing………………………………………………….
83
Nitrogen treatments for Russet Burbank for 2009, listing N source, N rates (kg
ha-1), and application timing………………………………………….…………………………………….
84
Mean monthly air temperature, soil temperature, and total precipitation for
years 2007-2009………..……………………………………………………………………………………….
85
Yield, potato class, specific gravity, and internal damage for Russet Norkota in
2007 as affected by N treatment……………………………………………………………………….
86
Petiole nitrate levels for Russet Norkota in 2007 as affected by N treatment and
sampling date (DAP)…………………………………………………………………………………………….
87
Yield, potato class, and specific gravity for Russet Norkota in 2008 as affected by
N treatment…………..…………………………………………………………………………………………….
88
Petiole nitrate levels for Russet Norkota in 2008 as affected by N treatment and
sampling date (DAP)…………………………………………………………………………………………….
89
Yield, potato class, specific gravity, and internal damage for Russet Burbank in
2007 as affected by N treatment……………………………………………………………………….
90
Petiole nitrate levels for Russet Burbank in 2007 as affected by N treatment and
sampling date (DAP)…………………………………………………………………………………………….
91
Yield, potato class, specific gravity, and internal damage for Russet Burbank in
2008 as affected by N treatment……………………………………………………………………….
92
Petiole nitrate levels for Russet Burbank in 2008 as affected by N treatment and
sampling date (DAP)…………………………………………………………………………………………….
93
3.1
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
LIST OF TABLES (Continued)
Table
4.14
4.15
4.16
Page
Yield, potato class, specific gravity, and internal damage for Russet Burbank in
2009 as affected by N treatment……………………………………………………………………….
94
Petiole nitrate levels for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP)…………………………………………………………………………………………….
95
Potato plant N concentration (%) for Russet Burbank in 2009 as affected by N
treatment and sampling date (DAP)…………………………………………………………………….
96
LIST OF APPENDIX FIGURES
Figures
6.1
Page
Absorbance from ammonium as affected by using ammonium standards in deionized water and in 0.013835 M oxalic acid………………………………………………………
111
Absorbance from ammonia samplers tested (a) with 1 drop (4 drops NH4OH/1 L
de-ionized water (DI)) and (b) 3 drops (4 drops NH4OH/1 L DI) as affected by the
frequency of shaking with DI water……………………………………………………………………
112
Concentration from ammonia samplers tested with 1 drop, 2 drops, and 2 mL of
NH3 cleaner and 1 drop (4 drops NH4OH/1 L de-ionized water (DI)) as affected by
the extraction with de-ionized water or KCl solution………………………………………
113
Absorbance of NH4-free water compared to NH4-free water shaken in a burned
tube, tube was burned at 450oC for 16 hours………………………………………………………
114
Absorbance from ammonium standards as affected from the standards being
ammonium or nitrate decomposed in Devarda’s alloy to ammonium…………………
115
Absorbance from ammonium standards from nitrate decomposition in
Devarda’s alloy as affected by the length of time decomposition was allowed in
Devarda’s alloy……………………………………………………………………………………………………
116
Absorbance from ammonium as affected by using ammonium standards in deionized water and in 2 M KCl solution………………………………………………….................
117
Cumulative loss of NH3 during the period of 29 July to 24 August 2009 following
application of 112 kg N/ha to wheat stubble as affect by N source of urea and
Agrotain coated urea…………………………………………………………………………...................
118
6.9
Average diurnal nitrogen loss as ammonia across treatments on wheat stubble…
119
6.10
Cumulative loss of NH3 during the period of 23 October to 9 November 2009
following application of 112 kg N/ha to unburned grass seed field as affect by N
source of urea and Agrotain coated urea……………………………………….......................
120
Percent of plots burned after the application of 112 kg N/ha to unburned grass
seed field as affect by N source of urea and Agrotain coated urea……...................
121
Soil moisture at varying depths for irrigation rates (a) 0.0-mm, (b) 3.8-mm, and
(c) 11.4-mm………………………………………………………………………………………….................
122
Available (a) NO3 and (b) total N (NH4 + NO3) at 4.4oC in incubation as affected
by N treatment…………………………………………………………………………………………………….
123
6.2
6.3
6.4.
6.5
6.6
6.7
6.8
6.11
6.12
6.13
LIST OF APPENDIX FIGURES (Continued)
Figures
6.14
6.15
6.16
Page
Available (a) NO3 and (b) total N (NH4 + NO3) at 15.6oC in incubation as affected
by N treatment……………………………………………………………………………………………………
124
Available (a) NO3 and (b) total N (NH4 + NO3) at 26.7oC in incubation as affected
by N treatment…………………………………………………………………………………………………….
125
Size of fertilizer prills based on product……………………………………………………………….
126
LIST OF APPENDIX TABLES
Table
6.1
Page
Linear regression for absorbance from N standards with concentrations ranging
from 0 to 15 ppm NH4-N as affected by time of color determination………………….
127
Ammonium levels measured after nitrate decomposition as affected by the
initial rate of nitrate added to Devarda’s alloy……………………………………………………
128
6.3
Average 12-hour weather data for diurnal wheat stubble data……………………………
129
6.4
Average ppm nitrogen (N) as ammonia for the sampling period before (Aug 6),
during (Aug 7), and after (Aug 10) a smoke event………………………………………………
130
Cumulative loss of NH3 from plots during 1 hour on 20 November 2009 resulting
from the application of waste water to an alfalfa field through irrigation……………
131
Soil N present as NH4 and NO3 at varying soil depth after the application of 112
kg N as urea/ ha as affected by irrigation rate……………………………………………………..
132
Soil pH at varying soil depths after the application of 112 kg N ha-1 as urea as
affected by irrigation rate……………………………………………………………………………………
133
Accountable N at varying soil depth after the application of 112 kg N ha-1 as urea
as affected by irrigation rate; accountable N = wheat N uptake + soil N
corresponding to soil depth…………………………………………………………………………………
134
Soil pH at varying soil depths after the application of 112 kg N/ha as affected by
irrigation rate and N source…………………………………………………………………………….
135
Soil N present as NH4 and NO3 at varying soil depth after the application of 112
kg N/ha as affected by irrigation rate and N-source…………………………………………
136
Accountable N at varying soil depth after the application of 112 kg N/ha as
affected by irrigation rate and N-Source; accountable N = wheat N uptake + soil
N corresponding to soil depth……………………………………………………………………………
137
Urease activity 104 days after application of N fertilizer as affected by N-source
and incubation temperature………………………………………………………………………………..
138
Potato vine tonnage for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP)…………………………………………………………………………………………….
139
Potato tonnage for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP)……………………………………………………………………………………………
140
6.2
6.5
6.6
6.7
6.8
6.9
6.10
6.11
6.12
6.13
6.14
LIST OF APPENDIX TABLES (Continued)
Table
6.15
Page
Potato plant N uptake for Russet Burbank in 2009 as affected by N treatment
and sampling date (DAP)……………………………………………………………………………………..
141
Potato N concentration (%) for Russet Burbank in 2009 as affected by N
treatment and sampling date (DAP)…………………………………………………………………….
142
Potato N uptake for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP)……………………………………………………………………………………………
143
Linear regression for NH3 loss from 2 DAA to 8 DAA following application of 112
kg urea-N/ha to Winter Wheat as affected by rate of irrigation application…………
144
Linear regression for NH3 loss from 2 DAA to 8 DAA following application of 112
kg urea-N/ha to Winter Wheat as affected by N treatment and rate of irrigation
application. …………………………………………………………………………………………………………
145
6.20
Soil urease activity in incubation as affected by N treatment and temperature…..
146
6.21
Available NH4 at 4.4oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05…………………
147
Available NO3 at 4.4oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05………………….
148
Total N (NH4 + NO3) at 4.4oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05…………………..
149
Available NH4 at 15.6oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05…………………
150
Available NO3 at 15.6oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05………………….
151
Total N (NH4 + NO3) at 15.6oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05………………….
152
Available NH4 at 26.7oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05…………………
153
Available NO3 at 26.7oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05…………………
154
6.16
6.17
6.18
6.19
6.22
6.23
6.24
6.25
6.26
6.27
6.28
LIST OF APPENDIX TABLES (Continued)
Table
Page
Total N (NH4 + NO3) at 26.7oC in incubation as affected by N treatment. Values
followed by the same letter are not significantly different at p=0.05…………………
155
6.30
Soil pH at 4.4oCin incubation as affected by N treatment……………………………………
156
6.31
Soil pH at 15.6oCin incubation as affected by N treatment…………………………………
157
6.32
Soil pH at 26.7oC in incubation as affected by N treatment…………………………………
158
6.29
DEDICATION
To Jesi, my perfect and wonderful wife, my best friend!
ENHANCED EFFICIENCY NITROGEN FERTILIZERS FOR NITROGEN MANAGEMENT IN THE
COLUMBIA BASIN, OREGON
GENERAL INTRODUCTION
Jess Charles Holcomb III
2
Nitrogen (N) and potassium are typically the most abundant minerals found in crops and
are the most limiting nutrients for crop production (Olson and Kurtz, 1982; Hopkins et al., 2008).
One reason for the lack of N in agricultural systems is due to soils not having a mechanism for
long-term storage of large amounts of plant-available N, preventing a N build up (Olson and
Kurtz, 1982; Meisinger et al., 2008). The lack of long-term storage results in N being added
during production to obtain maximum yield. Symbiosis with N-fixing organisms would negate
the need for additional N (Havelka et al., 1982; Meisinger et al., 2008). Nitrogen added to meet
plant demand is subject fixation in the soil along with loss through nitrate (NO3) leaching,
ammonia (NH3) volatilization, and nitrous oxide (N2O) emissions, with the total loss ranging from
10 to 60% of N applied (Nommik and Vahtras, 1982; Goulding, 2000). Leaching of NO3 typically
represents the majority N loss, followed by volatilization, while the loss of N as N2O is usually
negligible except in anaerobic soils (Zebarth and Rosen, 2007). As a result of N loss, an average
crop’s N uptake efficiency ranges from 40 to 75% (Allison, 1955; Elkashif et al., 1983). Low N
uptake efficiency results in the need to over apply N to obtain maximum crop yield (Waddell et
al., 1999).
Nitrate leaching is a prominent concern in well-drained sandy soil, such as are found in
production areas in the Columbia Basin in Oregon and Washington (Peralta and Stockle, 2001;
Alva et al., 2002). Sandy soils along with irrigation and increased N fertilization can result in a
large NO3 loss (Jones and Wagner, 1995; Ryker and Jones 1995; Zvomuya et al., 2003; Zebarth
and Rosen, 2007). Unlike ammonium which is strongly sorbed to soil, NO3 is weakly held by soil
making it more susceptible to leaching (Mulla and Strock, 2008). Excessive irrigation of sandy
soils allows NO3 to leach out of the root zone at a faster rate (Shock et al., 2007). Leaching of
NO3 can be large if a field is not cropped immediately after harvest, as mineralized N from
residue adds to soil N. (Asfary et al., 1983; Goulding, 2000; Peralta and Stockle, 2001; Honisch
et al., 2002). In random surveys in the Columbia Basin, 30 to 33% of all groundwater sources
were above the EPA standard of 10 ppm NO3-N (Alva et al., 2002). Surface water containing
leached NO3 can also be a pollutant, leading to increased vegetative productivity in lakes and
estuaries causing eutrophication (Keeney, 1982).
Loss of N from ammonia volatilization usually ranges from 15 to 40% of N applied, with
loss measured up to 83% N applied (Lightner et al., 1990; Grant et al., 1996; Sommer and
Ersboll, 1996; Ledgard et al., 1999; Martha Jr. et al., 2004; Vaio et al., 2008; Kissel et al., 2009).
3
Urea is especially vulnerable to ammonia volatilization because it must hydrolyze before plant
use according to the following reaction by Kissel et al. (1988):
urea + 2H2O + H+ urease 2NH4+ + HCO3further reacting as:
HCO3- + H+ CO2(g) + H2O and NH4+NH3 + H+
The consumption of H+ during urea hydrolysis results in a pH increase (Zaman et al., 2008).
Increased pH results in more NH3 which increases potential volatilization loss (Kissel et al.,
1988). Ammonia loss not only represents an agronomic loss of N, but also an environmental
pollutant. Agriculture is responsible for an estimated 90% of anthropogenic ammonia emissions
(Boyer et al., 2002), with 12% resulting from fertilizer application and the remainder from
animal production (Ferm, 1998). Most atmospheric NH3 is deposited locally at its origin (Boyer
et al., 2002). The remaining NH3 can be transported long distances as secondary aerosol
particles (Schjoerring et al., 1992; Boyer et al., 2002). Secondary aerosols are created by the
reaction of NH3 with NOx and SOx which results in light scattering atmospheric haze (Ferm, 1998;
Sharma et al., 2007). Ammonium is the limiting factor for haze formation in the Columbia River
Gorge between Oregon and Washington (Pitchford et al., 2008). In the winter of 2003-2004, a
19-week study set in the Columbia River Gorge reported total inorganic N deposition for the
study ranging from 1.09 kg ha-1 to 1.71 kg ha-1 (Fenn et al., 2007). The origins of the N was
attributed to livestock operations and fertilizer applications in the Columbia Basin. This is a
direct concern for the Columbia Basin as an NH3 source. Increased N deposition levels favor
nitrophillic organisms and suppress organisms adapted to low N environments, altering native
ecosystems (Fenn et al., 2003; Geiser and Neitlich, 2007). This has been observed in the
Columbia River Gorge as fewer N-sensitive lichen are now present and there is intrusion by two
non-native nitrophillic lichen species (Gieser and Neitlich, 2007).
Loss of N from N2O is not agronomically important in aerobic soils as emissions from
most crops rarely exceed 2% N applied; however, loss over 10% has been reported (Delgado and
Mosier, 1996; Ruser et al., 2001; Shoji et al., 2001; Venterea et al., 2005). Agriculture is
estimated to produce over 75% of anthropogenic N2O (Isermann, 1994). The atmospheric life of
N2O is about 120 years and has a global warming potential 320 times greater than CO2 (IPCC,
1995). Nitrous oxide is an intermediate product formed during denitrification (Mosier, 1998;
Zebarth and Rosen, 2007). The addition of N to saturated soils increases N2O production (Ruser
4
et al., 2001). Although the Columbia Basin is intensively managed with large quantities of N
being applied in several production areas, the formation of N2O may be minimal as most soils
are sandy and well drained, limiting saturation and anaerobic conditions.
The development of enhanced efficiency fertilizers (EEF’s) can limit N loss to the
environment and/or increase nutrient availability compared to conventional fertilizers (OlsonRutz et al., 2009). Enhanced efficiency fertilizers accomplish this through inhibition of a N
conversion pathway, slow release, or controlled release. Urease inhibitors slow the hydrolysis
of urea allowing soil to buffer a pH increase, therefore reducing loss from volatilization and
allowing time for incorporation, such as Agrotain (Jones et al., 2007). An inhibitor preventing
nitrification, like Dicyandiamide (DCD), slows the conversion of NH4 to NO3; NH4 is less
susceptible to leaching (Vos, 1994). Inhibitors also can be mixed together to get the benefit of
both such as Super-U. Slow-release N is made available through microbial breakdown of a
fertilizer like Nitamin (Vaio et al., 2008; Olson-Rutz et al., 2009). Controlled-release fertilizers
are coated with a soluble membrane that acts as a diffusion barrier which releases N based on
soil temperature or water content, such as Environmentally Smart Nitrogen (ESN) (Hanafi et al.,
2002; Taysom et al., 2007; Wilson et al., 2009). Enhanced efficiency fertilizer products have
been recorded to reduce N loss into the environment (Carmona et al., 1990; Zhengping et al.,
1991; Vos, 1994; Delgado and Mosier, 1996; Grant et al., 1996; Waddell et al., 2000; Shoji et al.,
2001; Zvomuya et al., 2003; Sanz-Cobena et al., 2008; Vaio et al., 2008; Zaman et al., 2008;
Zaman et al., 2009). Nitrogen release rates from EEF’s depending on environmental conditions
and plant N demand have resulted in cases of sustained or increased yields as well as yield
reduction (Lorenz et al., 1972; Lorenz et al., 1974; Cox and Addiscott, 1976; Liegel and Walsh,
1976; Elkashif et al., 1983; Vos, 1994; Shoji et al., 2001; Zvomuya and Rosen, 2001; Zvomuya et
al., 2003; Pack et al., 2006; Taysom et al., 2007). The variability of N release often not coinciding
with plant demand and the premium for EEF’s often makes them unusable compared to a
standard N form (Pasda et al., 2001; Hopkins et al., 2008).
Nitrogen loss reductions also can be obtained through cultural practices. By
mechanically incorporating urea into the soil, N loss associated with NH3 volatilization can be
reduced (Malhi et al., 2003). Volatilization loss can be reduced from surface-applied urea
through incorporation by irrigation or precipitation (Harper et al., 1983; Bouwmeester et al.,
1985; Black et al., 1987; Mugusha and Pluth, 1995). However, an effective irrigation rate
5
needed for reduction have not been fully researched. Splitting applications of N can increase N
use efficiency; less N is available for leaching and it is more likely to remain in the root zone
(Singh and Sekhon, 1976; Elkashif et al., 1983; Lauer, 1985; Lauer, 1986; Westermann et al.,
1988; Vos, 1999). The reduction of N2O can be accomplished by reducing anaerobic soil
conditions brought on by excessive irrigation and soil compaction (Ruser et al., 1998).
The EEF N products and cultural practices are currently being used in the Columbia Basin
but not enough is known about methods or effectiveness in order to maximize yield and reduce
loss. The objective of this study was to: (i) examine the required irrigation rate needed to
minimize NH3 volatilization; (ii) examine the effectiveness of specialty N fertilizers to minimize
NH3 volatilization; (iii) examine whether specialty N fertilizers could maintain or increase potato
yields in the Columbia Basin; and (iv) examine the formation rate of NH4 from EEF N products.
REFERENCES
Allison, F.E. 1955. The enigma of soil nitrogen balance sheets. Adv. Agron. 7:213-250.
Alva, A.K., T. Hodges, R.A. Boydston, and H.P. Collins. 2002. Effects of irrigation and tillage
practices on yield of potato under high production conditions in the Pacific Northwest.
Commun. Soil Sci. Plant Anal. 33:1451-1460.
Asfary, A.F., A. Wild, and P.M. Harris. 1983. Growth, mineral nutrition and water use by potato
crops. J. Agric. Sci., Camb. 100:87-101.
Black, A.S., R.R. Sherlock, and N.P. Smith. 1987. Effect of timing of simulated rainfall on
ammonia volatilization from urea, applied to soil of varying moisture content. J. Soil Sci.
38:679-687.
Bouwmeester, R.J.B., P.L.G. Vlek, and J.M. Stumpe. 1985. Effect of environmental factors on
ammonia volatilization from urea-fertilized soil. Soil. Sci. Soc. Am. J. 49:376-381.
Boyer, E.W., C.L. Goodale, N.A. Jaworski, and R.W. Howarth. 2002. Anthropogenic nitrogen
sources and relationships to riverine nitrogen export in the northeastern U.S.A.
Biogeochemistry 57/58:137-169.
Carmona, G., C.B. Christianson, and B.H. Byrnes. 1990. Temperature and low concentration
effects of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) on ammonia
volatilization from urea. Soil Biol. Biochem. 22:933-937.
Cox, D., and T.M. Addiscott. 1976. Sulphur-coated urea as a fertilizer for potatoes. J. Sci. Food
Agric. 27:1015-1020.
6
Delgado, J.A. and A.R. Mosier. 1996. Mitigation alternatives to decrease nitrous oxides
emissions and urea-nitrogen loss and their effect on methane flux. J. Environ. Qual.
25:1105-1111.
Elkashif, M.E., S.J. Locascio, and D.R. Hensel. 1983. Isobutylidene diurea and sulfur-coated urea
as N sources for potatoes. J. Amer. Soc. Hort. Sci. 108:523-526.
Fenn, M.E., J.S. Baron, E.B. Allen, H.M. Rueth, K.R. Nydick, L. Geiser, W.D. Dowman, J.O.
Sickman, T. Meixner, D.W. Johnson, and P. Neitlich. 2003. Ecological effects of nitrogen
deposition in the western United States. BioSci. 53:404-420.
Fenn, M.E., L. Geiser, R. Bachman, T.J. Blubaugh, and A. Bytnerowicz. 2007. Atmospheric
deposition inputs and effects on lichen chemistry and indicator species in the Columbia
River Gorge, USA. Environ. Pollut. 146:77-91.
Ferm, M. 1998. Atmospheric ammonia and ammonium transport in Europe and critical loads: a
review. Nutrient Cycling in Agroecosystems 51:5-17.
Geiser, L.H. and P.N. Neitlich. 2007. Air pollution and climate gradients in western Oregon and
Washington indicated by epiphytic macrolichens. Environmental Pollution 145:203-218.
Goulding, K. 2000. Nitrate leaching from arable and horticultural land. Soil Use Manage.
16:145-151.
Grant, C.A., S. Jia, K.R. Brown, and L.D. Bailey. 1996. Volatile losses of NH3 from surface-applied
urea and urea ammonium nitrate with and without the urease inhibitors NBPT or
ammonium thiosulphate. Can. J. Soil Sci. 76:417-419.
Hanafi, M.M, S.M. Eltaib, M.B. Ahmad, and S.R. Syed Omar. 2002. Evaluation of controlledrelease compound fertilizers in soil. Commun. Soil Sci. Plant Anal. 33:1139-1156.
Harper, L.A., V.R. Catchpoole, R. Davis, and K.L. Weir. 1983. Ammonia volatilization: Soil, plant
and microclimate effects on diurnal and seasonal fluctuations. Agron. J. 75:212-218.
Havelka, U.D., M.G. Boyle, and R.W. F. Hardy. 1982. Biological nitrogen fixation. p. 365-422. In
F.J. Stevenson (ed.) Nitrogen in Agricultural soils. ASA, CSSA, and SSSA, Madison, WI.
Honisch, M., C. Hellmeier, and K. Weiss. 2002. Response of surface and subsurface water
quality to land use changes. Geoderma 105:277-298.
Hopkins, B.G., C.J. Rosen, A.K. Shiffler, and T.W. Taysom. 2008. Enhanced efficiency fertilizers
for improved nutrient management: Potato (Solanum tuberosum). Online. Crop
Management doi: 10.1094/CM-2008-0317-01-RV.
IPCC. 1995. Radiative forcing of climate change and an evaluation of the IPCC IS92 emission
scenarios. p 337. In JT Houghton (ed.) Climate Change 1994. Published for the IPCC.
Cambridge University Press, Cambridge.
7
Isermann, K. 1994. Agriculture’s share in the emission of trace gases affecting the climate and
some cause-oriented proposals for sufficiently reducing this share. Environ. Pollut.
83:95-111.
Jones, C.A., R.T. Koenig, J.W. Ellsworth, B.D. Brown, and G.D. Jackson. 2007. Management of
urea fertilizer to minimize volatilization. Montana State University Extension Bulletin
173.
Jones, J.L. and R.J. Wagner. 1995. Water-quality assessment of the Central Columbia Plateau in
Washington and Idaho. p. 119. Analysis of available nutrient and pesticide data for
ground water, 1942-92, US Geological Survey Water-Resources Investigations Report 944258.
Keeney, D.R. 1982. Nitrogen management efficiency and minimum pollution. p. 605-649. In
F.J. Stevenson (ed.) Nitrogen in Agricultural Soils. ASA, CSSA, and SSSA, Madison, WI.
Kissel, D.E., M.L. Cabrera, and R. B. Ferguson. 1988. Reactions of ammonia and urea hydrolysis
products with soil. Soil Sci. Soc. Am. J. 52:1793-1796.
Kissel, D.E., M.L. Cabrera, N. Vaio, J.R. Craig, J.A. Rema, and L.A. Morris. 2009. Forest floor
composition and ammonia loss from urea in a loblolly pine plantation. Soil Sci. Soc. Am.
J. 73:630-637.
Lauer, D.A. 1985. Nitrogen uptake patterns of potatoes with high-frequency sprinkler-applied N
fertilizer. Agron. J. 77:193-197.
Lauer, D.A. 1986. Russet Burbank yield response to sprinkler-applied nitrogen fertilizer. Amer.
Potato J. 63:61-69.
Ledgard, S.F., J.W. Penno, and M.S. Sprosen. 1999. Nitrogen inputs and losses from
clover/grass pastures grazed by dairy cows, as affected by nitrogen fertilizer application.
J. Agric. Sci., Cambridge 132:215-225.
Liegel, E.A. and L.M. Walsh. 1976. Evaluation of sulfur-coated urea (SCU) applied to irrigated
potatoes and corn. Agron. J. 68:457-463.
Lightner, J.W., D.B. Mengel, and C.L. Rhyderd. 1990. Ammonia volatilization from nitrogen
fertilizer surface applied to orchardgrass sod. Soil Sci. Soc. Am. J. 54:1478-1482.
Lorenz, O.A., B.L. Weir, and J.C. Bishop. 1972. Effect of controlled-release nitrogen fertilizers on
yield and nitrogen absorption by potatoes, cantaloupes, and tomatoes. J. Amer. Soc.
Hort. Sci. 97:334-337.
Lorenz, O.A., B.L. Weir, and J.C. Bishop. 1974. Effect of sources of nitrogen on yield and
nitrogen absorption of potatoes. Amer. Potato J. 51:56-65.
Malhi, S.S., E. Oliver, G. Mayerle, G. Kruger, and K.S. Gill. 2003. Improving effectiveness of
seedrow-placed urea with urease inhibitor and polymer coating for Durum wheat and
canola. Commun. Soil Sci. Plant Anal. 34:1709-1727.
8
Martha Jr., G.B., M. Corsi, P.C.O. Trivelin, and M.C. Alves. 2004. Nitrogen recovery and loss in a
fertilized elephant grass pasture. Grass Forage Sci. 59:80-90.
Meisinger, J.J, J.S. Schepers, and W.R. Raun. 2008. Crop nitrogen requirement and fertilization.
p. 563-612. In J.S. Schepers and W.R. Raun (ed.) Nitrogen in Agricultural Systems.
49:563-612.
Mosier, A.R. 1998. Soil processes and global change. Biol. Fertil. Soils 27:221-229.
Mugusha, A.G., and D.J. Pluth. 1995. Ammonia loss following surface application of urea
fertilizer to undrained and drained forested minerotrophic peatland sites in central
Alberta, Canada. For. Ecol. Manage. 78:139-145.
Mulla, D.J. and J.S. Strock. 2008. Nitrogen transport process in soil. p. 361-400. In J.S. Schepers
and W.R. Raun (ed.) Nitrogen in Agricultural Systems. ASA, CSSA, and SSSA, Madison,
WI.
Nommik, H. and K. Wahtras. 1982. Retention and fixation of ammonium and ammonia in soils.
p. 123-171. In F.J. Stevenson (ed.) Nitrogen in Agricultural soils. ASA, CSSA, and SSSA,
Madison, WI.
Olson, R.A. and L.T. Kurtz. 1982. Crop nitrogen requirements, utilization, and fertilization. p.
567-604. In F.J. Stevenson (ed.) Nitrogen in Agricultural Soils. ASA, CSSA, and SSSA,
Madison, WI.
Olson-Rutz, K., C. Jones, and C.P. Dinkins. 2009. Enhanced efficiency fertilizers. Montana State
University Extension Bulletin 0188.
Pack, J.E., C.M. Hutchinson, and E.H. Simonne. 2006. Evaluation of controlled-release fertilizers
for Northeast Florida chip potato production. J. Plant Nutr. 29:1301-1313.
Pasda, G., R. Hähndel, and W. Zerulla. 2001. Effect of fertilizers with the new nitrification
inhibitor DMPP (3,4-dimethylpyrazole phosphate) on yield and quality of agricultural
and horticultural crops. Biol. Fertil. Soils 34:85-97.
Peralta, J.M., and C.O. Stockle. 2001. Dynamics of nitrate leaching under irrigated potato
rotation in Washington State: a long-term simulation study. Agric. Ecosyst. Environ.
88:23-34.
Pitchford, M.L., M.C. Green, R. Morris, C. Emery, R. Sakata, C. Swab, and P.T. Mairose. 2008.
Columbia River Gorge air quality study science summary report. Available at
http://www.deq.state.or.us/aq/gorgeair/docs/FinalScienceSummaryReport.pdf (verified
7 Dec., 2010). Oregon DEQ, Portland, OR.
Ruser, R., H. Flessa, R. Schilling, F. Beese, and J.C. Munch. 2001. Effect of crop-specific field
management and N fertilization on N2O emissions from a fine-loamy soil. Nutrient
Cycling in Agroecosystems 59:177-191.
9
Ruser, R., H. Flessa, R. Schilling, H. Steindl, and F. Beese. 1998. Soil compaction and fertilization
effects on nitrous oxide and methane fluxes in potato fields. Soil Sci. Soc. Am. J.
62:1587-1595.
Ryker, J.S. and J.L. Jones. 1995. Nitrate concentration in groundwater of the central Columbia
Plateau. US Department of Interior, US Geological Survey. Open-File Report 95-445.
Sanz-Cobena, A., T.H. Misselbrook, A. Arce, J.I. Mingot, J.A. Diez, and A. Vallejo. 2008. An
inhibitor of urease activity effectively reduces ammonia emissions from soil treated with
urea under Mediterranean conditions. Agric. Ecosyst. Environ. 126:243-249.
Schjoerring, J.K., S.G. Sommer, and M. Ferm. 1992. A simple passive sampler for measuring
ammonia emission in the field. Water Air Soil Pollut. 62:13-24.
Sharma, M., S. Kishore, S.N. Tripathi, and S.N. Behera. 2007. Role of atmospheric ammonia in
the formation of inorganic secondary particulate matter: A study at Kanpur, India. J.
Atmos. Chem. 58:1-17.
Shock, C.C., A.B. Pereira, and E.P. Eldredge. 2007. Irrigation best management practices for
potato. Amer. J. Potato Res. 84:29-37.
Shoji, S., J. Delgado, A. Mosier, and Y. Miura. 2001. Use of controlled release fertilizers and
nitrification inhibitors to increase nitrogen use efficiency and to conserve air and water
quality. Commun. Soil Sci. Plant Anal. 32:1051-1070.
Singh, B. and G.S. Sekhon. 1976. Some measures of reducing leaching loss of nitrates beyond
potential rooting zone I. Proper co-ordination of nitrogen splitting with water
management. Plant Soil 44:193-200.
Sommer, S.G. and A. K. Ersboll. 1996. Effect of air flow rate, lime amendments, and chemical
soil properties on the volatilization of ammonia from fertilizers applied to sandy soils.
Biol. Fertil. Soils 21:53-60.
Taysom, T.W., B.G. Hopkins, A.K. Shiffler, and S.C. Stephens. 2007. Polymer coated urea in
potato production. p. 169-175. Western Nutrient Management Conference. Vol 7. Salt
Lake City, UT.
Vaio, N., M. L. Cabrera, D.E. Kissel, J.A. Rema, J.F. Newsome, and V.H. Calvert III. 2008.
Ammonia volatilization from urea-based fertilizers applied to tall fescue pastures in
Georgia, USA. Soil Sci. Soc. Am. J. 72:1665-1671.
Venterea, R.T., D.E. Rolston, and Z.G. Cardon. 2005. Effects of soil moisture, physical, and
chemical characteristics on abiotic nitric oxide production. Nutr. Cycling
Agroecosystems 72:27-40.
Vos, J. 1994. Effects of dicyandiamide on potato performance. J. Agron. Crop Sci. 173:93-99.
10
Vos, J. 1999. Split nitrogen application in potato: effects on accumulation of nitrogen and dry
matter in the crop and on the soil nitrogen budget. J. of Agricultural Sci., Cambridge
133:263-274.
Waddell, J.T., S.C. Gupta, J.F. Moncrief, C.J. Rosen, and D.D. Steele. 1999. Irrigation and
nitrogen management effects on potato yield, tuber quality, and nitrogen uptake.
Agron. J. 91:991-997.
Waddell, J.T., S.C. Gupta, J.F. Moncrief, C.J. Rosen, and D.D. Steele. 2000. Irrigation- and
nitrogen-management impacts on nitrate leaching under potato. J. Environ. Qual.
29:251-261.
Westermann, D.T., G.E. Kleinkopf, and L.K. Porter. 1988. Nitrogen fertilizer efficiencies on
potatoes. Amer. Potato J. 65:337-386.
Wilson, M.L., C.J. Rosen, and J.F. Moncrief. 2009. Potato response to a polymer-coated urea on
an irrigated, coarse-textured soil. Agron. J. 101:897-905.
Zaman, M., M.L. Nguyen, J.D. Blennerhassett, and B.F. Quin. 2008. Reducing NH3, N2O, and NO3-N losses from a pasture soil with urease or nitrification inhibitors and elemental Samended nitrogenous fertilizers. Biol. Fertil. Soils 44:693-705.
Zaman, M., S. Saggar, J.D. Blennerhassett, and J. Singh. 2009. Effect of urease and nitrification
inhibitors on N transformation, gaseous emissions of ammonia and nitrous oxide,
pasture yield and N uptake in grazed pasture system. Soil Biol. Biochem. 41:1270-1280.
Zebarth, B.J. and C.J. Rosen. 2007. Research perspective on nitrogen BMP development for
potato. Amer. J. Potato Res. 84:3-18
Zhengping, W., O.V. Clemmput, P. Demeyer, and L. Baert. 1991. Effect of urease inhibitors on
urea hydrolysis and ammonia volatilization. Biol. Fertil. Soils 11:43-47.
Zvomuya, F., and C.J. Rosen. 2001. Evaluation of polyolefin-coated urea for potato production
on a sandy soil. HortScience 36:1057-1060.
Zvomuya, F., C.J. Rosen, M.P. Russelle, and S.C. Gupta. 2003. Nitrate leaching and nitrogen
recovery following application of polyolefin-coated urea to potato. J. Environ. Qual.
62:480-489.
11
EFFECT OF IRRIGATION RATE ON AMMONIA VOLATILIZATION
Jess C. Holcomb III, Donald A. Horneck, Dan M. Sullivan, and George H. Clough
Soil Science Society of America Journal
5585 Guilford Road
Madison, WI 53711
In Review
12
ABSTRACT
Sprinkler irrigation can limit loss from ammonia (NH3) volatilization when urea is surface
applied. This study was conducted to find the effective irrigation rate needed to limit loss from
volatilization with urea. A gradient of six irrigation rates (0.0, 1.25, 3.8, 7.6, 11.4, and 21.6-mm)
was used to find effective irrigation depth for urea. Ammonia was collected by the modified
passive flux method for 23 days after application (DAA). Cumulative NH3 loss ranged from 3.1 to
67.3 kg Nitrogen (N)/ha, with 7.6 mm reducing loss to 19.4 kg N/ha. During peak ammonia loss
from 2-8 DAA, the application of 11.4 mm irrigation was able to reduce loss to 0.5% of N
applied/day. To reduce total loss from NH3 by 90%, 14.6 mm of irrigation needed to be applied.
Decreased NH3 loss associated with higher irrigation rate led to increased wheat N
concentrations. The application of 14.6 mm of irrigation can successfully incorporate urea and
reduce loss from NH3 volatilization.
INTRODUCTION
Urea is an important source of N because of its high N content (46%), low cost, ease in
handling and its compatibility with other fertilizer materials (Harre and Bridges, 1988; Kissel et
al., 2009). In the presence of the enzyme urease with water, urea hydrolyzes according to the
reaction (Kissel et al., 1988):
urea + 2H2O +H+ urease 2NH4+ + HCO3further reacting as:
HCO3- + H+ CO2(g) + H2O.
Both reactions consume H+ and raise soil pH around reaction site. This increases the
ratio of ammonia to ammonium which promotes volatilization loss (Fenn and Hossner, 1985).
Reported ammonia volatilization losses from urea range from 15-40% of N applied (Lightner et
al., 1990; Sommer and Ersboll, 1996; Vaio et al., 2008; Kissel et al., 2009).
Agricultural activity is estimated to be responsible for 90% of anthropogenic NH3
emissions (Boyer et al., 2002), with the majority coming from livestock production and 12% from
N fertilizer application (Ferm, 1998). Ammonia volatilization represents an agronomic N loss as
well as an environmental pollutant. In the atmosphere the reaction of NH3 with NOX and SOX
13
creates particulate matter 2.5 μm aerosols that scatter light resulting in haze (Asman et al.,
1998; Ferm, 1998; Sharma et al., 2007). In the Columbia River Gorge in Oregon and Washington,
the deposition of inorganic N from 133 days in 2003-2004 ranged from 0.61 kg/ha to 0.81 kg/ha
with N sources originating from livestock operations and fertilizer applications in the Columbia
Basin (Fenn et al., 2007). Increased N deposition favors species that tolerate or thrive in a high
N environment while suppressing those adapted to low N (Fenn et al., 2003; Geiser and Neitlich,
2007).
Urea needs to be incorporated to a depth of 5 cm or more in soil to minimize ammonia
volatilization (Fenn and Miyamoto, 1981) with mechanical or irrigation incorporation being
suitable to minimize loss. Research on effective irrigation depth has varied from 5-75 mm to
minimize volatilization (Harper et al., 1983; Bouwmeester et al., 1985; Black et al., 1987;
Mugusha and Pluth, 1995). Vaio et al. (2008) reported loss occurring after 52 mm of rainfall on
a tall fescue pasture. Kissel et al. (2004) found rainfall had no effect on ammonia loss with rain
between 0 and 40 mm in a Loblolly pine plantation. These studies used either predetermined
irrigation rates and timing or recorded that volatilization ceased or continued after precipitation
events. No study compared a gradient of irrigation rates to determine irrigation depth required
to minimize volatilization loss. This has left effective irrigation requirements not established.
Typically, measurements of NH3 loss have been conducted in a laboratory by placing soil
and N fertilizer in a container and forcing air through an acid trap (Ernst and Massey, 1960;
Stumpe et al., 1984; Ferguson and Kissel, 1986; Whitehead and Raistick, 1990; Zhengping et al.,
1991; Sommer and Ersboll, 1996). It is difficult to relate laboratory conditions to field losses as
many parameters are controlled, however laboratory studies do provide valuable insight into
parameters affecting ammonia loss. Using polyvinyl chloride (pvc) inserted into the soil and
temporarily capping the system and recording NH3 loss by acid traps allowed field measurement
of ammonia loss (Keller and Mengel, 1986; Lightner et al.,1990). Using the same system but
suspending the cap to allow air movement allowed NH3 loss to be measured on a daily basis and
totaled for a study period (Oberle and Bundy, 1987; Grant et al., 1996; Martha Jr. et al., 2004).
Cabrera et al. (2001) constructed a chamber that automatically opened its lid when finished
testing; when the lid was closed, a pump simulated the current wind conditions outside the
chamber by forcing the air through an acid trap. These laboratory and field techniques prove
useful in measuring NH3, but they may not express NH3 loss under natural conditions as
14
enclosures alter air movement, precipitation, soil temperature, air temperature and/or solar
radiation inside the chambers (Martha Jr. et al., 2004).
Leuning et al. (1985) constructed an ammonia flux sampler that was placed at the center
of a plot and trapped ammonia at five heights with a sampler “shuttle” that pivoted into the
wind at each height. Schjoerring et al. (1992) used a four-mast system where the masts were
placed on the edge of the plot and measured NH3 flux at four heights with inexpensive glass
sampler tubes that allow frequent sampling. The advantage of these systems was not altering
the treatment area and measuring field scale NH3 volatilization loss. Both are expensive for
startup and sample analysis (Wood et al., 2000). Wood et al. (2000) reduced the cost by
combining the systems of using a single mast with glass samplers that rotated into the wind at
the center of a plot. This method has been used successfully to measure NH3 loss in field
conditions (Wood et al., 2000; Sullivan et al., 2003; Vaio et al., 2008; Holcomb III and Horneck
2009).
The objective of this study was to measure the effect of irrigation rate on NH3
volatilization from urea, account for the loss of N from NH3 loss, and determine the effective
irrigation rate needed to incorporate urea to minimize NH3 loss.
MATERIALS AND METHODS
This study was conducted in a center-pivot irrigated 50-ha wheat field in Umatilla
County near Echo, OR. The soil was classified as an Adkins fine sandy loam (coarse-loamy,
mixed, superactive, mesic Xeric Haplocalcids). The surface soil (0-30 cm) had an average pH of
6.5 (1:1 soil/deionized water). The field was watered 2 days before our study with 25.4-mm
irrigation to incorporate prior N application, raise the soil to field capacity, and even out surface
soil moisture.
The field was split into 18 wedges of 20o; each wedge contained a circular (30-m
diameter) plot with urea surface-applied at 112 kg N/ha and with each plot separated by at least
100 m to avoid contamination of NH3 between treatments. The pivot was programmed to
irrigate wedges with 0.0, 1.25, 3.8, 7.6, 11.4, and 21.6-mm corresponding to treatments, with
the treatments arranged in a randomized complete block design. A rain gauge was placed in
each treatment wedge in order to record irrigation rate. As this was the first irrigation of the
15
season, irrigation rates fluctuated due to inconsistent pressure in the irrigation lines and rates
reported are averages (Standard errors for irrigation rates are 0.00, 0.15, 0.19, 0.66, 0.59, and
3.29 for 0.0, 1.25, 3.8, 7.6, 11.4, and 21.6-mm irrigation, respectively). Immediately after
irrigation, measurement of ammonia volatilization loss was initiated using the modified passive
flux method (Wood et al, 2000; Vaio et al., 2008). This consists of a rotating mast placed at the
center of each circular plot. A tripod which did not interfere with the rotation of the mast was
placed on the mast in order to stabilize it during high wind events. Each mast was equipped
with a passive-flux sampler at five heights (0.45, 0.75, 1.50, 2.25, and 3.00 m; Leuning et al.,
1985). Each passive flux sampler consisted of a glass tube (0.7-cm i.d. by 20 cm long) with the
inside surface coated with 3% w/v oxalic acid in acetone to trap the NH3 in the air flowing
through the tube and an attached nozzle with a 1 mm hole to restrict incoming air flow. Four
identical background masts were placed in the field to measure ambient NH3, three on the
outside and one in the center. Background masts were place over 100-m from treatments to
protect against contamination. Most background NH3 levels were near zero during the study.
Ammonia flux samplers were replaced at 2, 3, 4, 5, 6, 7, 8, 10, 13 15, 17, and 24 days after
application (DAA) of fertilizer. Flux samplers were extracted by adding 2-mL deionized water
and shaken for 10-minutes. Extracts were analyzed colormetrically for NH4 (Sims et al., 1995).
Horizontal NH3 flux (Fx, μg N m-2 s-1) for each flux sampler was calculated by
Fx = (C*V)/(πr2KΔt)
[1]
where C is the concentration of NH4-N (μg N/ml) in deionized water used to extract sorbed NH4N, V is the volume of deionized water used for extraction (2mL), r is the radius of the hole in the
disc on the nozzle (0.0005 m), K is a correction factor (0.77), and Δt is the time at which the
sampler was exposed (s) (Schjoerring et al., 1992; Wood et al., 2000; Vaio et al., 2008). Net
horizontal flux for each sampler (Fx,p) was determined by subtracting horizontal flux from the
corresponding sampler height on the background mast (Fx,b). Net vertical flux (Fy, ug N m-2 s-1)
from each plot was estimated by integrating each horizontal flux with vertical distance for each
sampler accounted for:
Fy=(1/R)Σ(Fx,p-Fx,b)Δh
[2]
where R is the radius of the plot (15-m), and Δh (m) is the vertical distance corresponding to
each sampler.
16
An Adcon Telemetry (Klosterneuburg, Austria) weather station was placed at the study
area to measure air temperature, soil surface temperature, humidity, rainfall, wind speed, and
wind direction. Sentek Enviroscan (Stepney, Australia) moisture probes were placed at the 0.0,
3.8 and 11.4 mm irrigation rates in block 1 to measure soil moisture at 10.1, 20.3, 30.4, 50.8,
and 91.4 cm depths.
Soil samples were taken at 23 days after application (DAA) from depths of 0-2.5, 0-15.2,
and 0-30.4 cm. Soil samples were extracted with 2 M KCl (1:10 soil/KCl) and extracts were
analyzed colormetrically for NH4-N and NO3-N (Sims et al., 1995). The pH for each soil treatment
was analyzed using a 1:1 soil/water solution. Urease activity was determined for the 0-2.5 cm
depth only according to Torello and Wehner (1983). This consisted of 2, 2-g soil samples from
each treatment which were incubated for 5 hours in a phosphate buffer - urea solution; one
sample was inhibited by AgSO4 during the incubation. After incubation, both soils received KCl
and the uninhibited soil received AgSO4. Soils were then shaken for 1 hour. Solutions were
filtered through a Whatman No. 1 filter paper and the extract was analyzed colorimetrically for
ammonium (Sims et al., 1995). Net urease activity was calculated by subtracting the inhibited
sample from the uninhibited sample and expressed as μg NH4-N g-1 h-1.
Wheat samples were randomly sampled from each treatment (0.126 m2) at 23 DAA.
Above-ground dry matter was measured and total N was analyzed using the total N combustion
method (Gavlak et al., 2003) with an Elementar Vario Max CN analyzer (Hanau, Germany).
Ammonia loss from volatilization, soil ammonium and nitrate, soil pH, urease activity,
wheat dry matter, and wheat N concentration and uptake were subjected to an analysis of
variance and analyzed for linear and quadratic relationships with irrigation rate. Irrigation loss
rates between 2-8 DAA were analyzed with a linear regression (Statistix 9, 2008; SAS 9.1.2,
2004) and all means were separated with a LSD at a 0.05 probability level. Ammonia loss was
plotted vs irrigation rate, and fit to an exponential model (SigmaPlot, 2002).
17
RESULTS AND DISCUSSION
Environmental Conditions
Total precipitation at the study site was 9.6 mm with precipitation of 1.6, 0.6, 4.4, 1.2,
and 1.8-mm on 3, 12, 19, 20, and 24 DAA respectively. Relative humidity fluctuated from 22 to
97% with an average of 65%. Air temperature varied between -4.9oC and 19.7oC with an
average of 6.9oC. Soil temperature at 2.54 cm varied from 0.5oC to 17.9oC with an average of
7.8oC (Figure 2.1). Wind speeds varied from 0 to 12.2 m/s with an average of 2.4 m/s. Average
weather was calculated from measurements taken every 15 minutes.
Ammonia Volatilization Loss
Ammonia loss was measured for each treatment starting 2 DAA (Figure 2.2). Nitrogen
loss followed a linear trend between 2 DAA and 8 DAA when approximately 70% of treatment
total loss occurred. The 0.0 mm irrigation rate lost 7.41% of N applied per day which was not
different than the 6.63% N applied per day lost by the 1.25 mm irrigation rate. The 3.8 mm
irrigation rate lost 4.71% of N applied per day which differed from all other treatments (p
=0.05). The 7.6 mm irrigation rate also differed from all treatments with a loss of 1.89% of N
applied per day. The 11.4 mm and 21.6 mm irrigation rate were not different from each other
with losses of 0.59% and 0.15% of N applied per day, respectively. Ammonia loss starting at 8
DAA decreased and was not linear. The linear NH3 loss up to 8 DAA showed there was adequate
soil moisture to hydrolyze the urea, irrespective of irrigation rate. No irrigation rate was able to
totally prevent NH3 volatilization; however, irrigation was effective in minimizing the amount of
daily NH3 loss and therefore total NH3 lost.
The lowest cumulative loss of ammonia was associated with the highest irrigation rates
of 11.4 and 21.6 mm (Figure 2.2) with 5.5% and 2. 8% of N applied respectively. These were
lower than the 0.0 to 3.8 mm rates of irrigation (p = 0.05). The 7.6 mm irrigation rate lost
17.31% of N applied which was different from the 0.0 and 1.25 mm irrigation rates but not the
3.8, 11.4, or 21.6 rates (p = 0.05). The 0.00 mm irrigation rate lost the greatest amount of N as
ammonia, 60.06% of N applied, but this was not different from the 1.25 and 3.8 mm irrigation
18
rates with 53.44% and 38.73% respectively (p = 0.05). The substantial ammonia loss with low
irrigation reflects the failure of irrigation to move urea away from the granular site and into the
soil, increasing ammoniacal-N in soil solution and surrounding pH (Burch and Fox, 1989).
Ammonia loss from volatilization has been reported from 43-83% of N applied when urea was
broadcasted on moist soil (Carmona et al., 1990; Grant et al., 1996; Kissel et al., 2009).
The most NH3 was lost from treatments with low irrigation rates despite a low average
soil temperature (7.8oC). Near-freezing temperatures have been shown to allow ammonia
volatilization (Steenhuis et al., 1979), and can lead to large losses as NH3 can volatilize over a
longer period of time (Sommer and Olesen, 1991). Vaio et al. (2008) attributed loss over a
longer period for 68% of total NH3 loss (19%) from urea on tall fescue in the first month of a trial
when the average temperature was 10oC. Lightner et al. (1990) found similar losses of 30-40%
on orchard grass even though temperatures ranged from from 5 to 25oC.
Plotting irrigation rate by total N loss as NH3 (Figure 2.3) yields the following equation (R2 =
0.9193):
N Loss as NH3 (% N of applied) = 62.655e^ (-0.1559* irrigation rate (mm))
[3]
Figure 2.3 demonstrates that when water is applied there is an immediate reduction in
volatilization with increasing irrigation rate. Using the model to solve for 80% reduction in loss
results in a need for 10.3 mm of irrigation, a 90% reduction in loss needs 14.8 mm of irrigation,
and a 95% reduction needs 19.2 mm irrigation. This illustrates that as irrigation increases,
volatilization decreases but with a diminishing return particularly at irrigation rates above 14.8
mm. Black et al. (1987) found an irrigation rate of 16 mm was enough to reduce NH3 loss to 2%
which is similar to our 14.8 mm. Similar to this study, the irrigation was applied soon after
application to a ryegrass and white clover pasture. Irrigations of 12-mm and 10-mm in another
study were also found to reduce loss by over 50% (Marshall and Debell, 1980; Mundy, 1995).
Black et al. (1987) found that irrigation was not effective after 48 hours as hydrolysis had
already occurred. When Kissel et al. (2004) applied 24-mm rain immediately after application,
they found less than 1% loss, compared to 5% when irrigation was applied at day 7 and losses of
49% and 58% when precipitation occurred on day 16 and 30, respectively. Holcomb and
Horneck (2009) found similar results with losses of over 15% of N applied after 9-mm
precipitation 5 days after application on two Kentucky bluegrass fields. This demonstrates that
19
irrigation or rainfall is most efficient at reducing loss when applied prior to urea hydrolysis;
otherwise, ammonia volatilization loss still can be significant.
Soil and Plant Analyses
There was no difference in urease activity across treatments (p>0.05) and no trend with
irrigation rate (p>0.05) (Table 2.1). Urease activity at the study site, 7.13 to 10.51 μg NH4-N g-1
h-1, were comparable to the lower values reported from nine Kansas soils, 9 to 71 μg NH4-N g-1
h-1 (Sullivan and Havlin, 1992) and lower than one soil in Washington, 63.9 μg NH4-N g-1 h-1
(Proctor et al., 2010).
A visual increase in wheat vigor/growth was observed in plots receiving N compared to
area of the field that received no additional N. The 0.00 mm irrigation had less wheat dry
matter than the 3.8 mm rate (p<0.05). No differences in dry matter were measured between
the remaining treatments (Table 2.1). There was no relationship between dry-matter and
irrigation rate (p>0.05), most likely a result of collecting samples 23 DAA and slight differences in
stand. The wheat matured from Feekes 5 to Feekes 7 by 23 DAA. At Feekes 7, the amount of N
in the soil, even from the treatments that lost large amounts, the plant was not stressed for N.
Average N in 0-30.4 cm soil profile across treatments was 135 kg ha-1. Dry matter or grain
protein samples were not taken later in the season where supply effects may have been more
observable. A difference in plant N concentration was measured, irrigation rates of 11.4 and
21.6 mm had higher N concentrations than the 0.0 mm (p<0.05) (Table 2.1). There is also a
linear trend relating increased N concentration with increased irrigation rate
(y=39.642+0.4134x; p < 0.05). Wheat N uptake differences were minimal with only the 3.8 mm
irrigation having more N uptake than the 0.0 mm irrigation. Similar to the dry matter, there is
no trend between irrigation and N uptake (p >0.05). A linear trend existed between N uptake
and wheat dry matter (p<0.05) and there was no trend between wheat N concentration and N
uptake (p>0.05). This suggests that wheat N uptake is dependent on wheat dry-matter, not
wheat N concentration.
There were no differences in pH at any depth between treatments at (data not shown),
likely a result of pH samples taken 23 days after the application of urea. There may have been
differences in pH at the surface between treatments if samples had been taken earlier in the
20
experiment. Eighteen days following a urea application, Ferguson et al. (1984) measured soil pH
at or below original pH after an increase over 2 pH units the first 5 days after application. There
was a difference across all treatments between the 1 inch and 6 and 12 inch (p<0.05). This is
most likely from fertilizer applications that have been shown to decrease the surface pH of the
soil due to acidification (Olson and Kurtz, 1982).
Despite an average soil pH of 6.5 at 0-30 cm (pH 6 in upper 2.5 cm), large losses of
ammonia occurred at this site. Fenn and Hossner (1985) have shown that buffering capacity can
be more important than initial soil pH because pH increases markedly in response to alkaline
inputs when soil buffering capacity is low. A poorly buffered soil, such as the sandy loam at this
site, has the ability to rapidly increase pH temporarily resulting from a urea application
(Hargrove, 1988). Whitehead and Raistick (1990) found an increase in pH from 5.5 and 6.1 to
7.5 and 7.9 resulting in ammonia losses of 22% and 36%. Similarly, Mundy (1995) found a pH
increase over 2.5 pH units from 6.1 to over 8.5 after a urea application on moist soils. A
temporary increase in pH could explain the large losses from the field as well as the uniform pH
measured 23 days after application.
CONCLUSIONS
The use of a gradient of irrigation rates established an effective irrigation rate to
minimize volatilization. Ammonia volatilization loss from urea ranged from 3 to 67 kg N ha-1
depending on irrigation rate; irrigation reduced loss by 7 to 64 kg N ha-1 based on rate.
Increased irrigation rate decreased ammonia loss from volatilization. The decrease in
volatilization resulted in an increase in wheat N concentration. A reduction of 90% in NH3 loss
can be achieved by the application of 15 mm of irrigation, a savings of 61 kg N ha-1. Total NH3
loss from volatilization can be reduced by the addition of 8 mm irrigation and the addition of 11
mm irrigation can reduce the rate of ammonia loss during 2 – 8 DAA when loss from
volatilization is greatest. Further irrigation will result in minor decreases in ammonia
volatilization. High volatilization was measured with an average soil temperature of 7.8oC as
loss occurred over a longer period of time.
21
ACKNOWLEDGEMENTS
Agrotain International and the J.R. Simplot Company provided financial support for this
project. Madison Farms allowed the use of their field for our study. IRZ Consulting donated the
use of moisture probes and Syngenta donated the use of a weather station.
REFERENCES
Asman, W.A.H., M.A. Sutton, and J.K. Schjorring. 1998. Ammonia: emission, atmospheric
transport and deposition. New Phytologist 139:27-48.
Black, A.S., R.R. Sherlock, and N.P. Smith. 1987. Effect of timing of simulated rainfall on
ammonia volatilization from urea, applied to soil of varying moisture content. Journal of
Soil Science 38:679-687.
Bouwmeester, R.J.B., P.L.G. Vlek, and J.M. Stumpe. 1985. Effect of environmental factors on
ammonia volatilization from urea-fertilized soil. Soil. Sci. Soc. Am. J. 49:376-381.
Boyer, E.W., C.L. Goodale, N.A. Jaworski, and R.W. Howarth. 2002. Anthropogenic nitrogen
sources and relationships to riverine nitrogen export in the northeastern U.S.A.
Biogeochemistry 57/58:137-169.
Burch, J.A., and R.H.Fox. 1989. The effect of temperature and initial soil moisture content on
the volatilization of ammonia from surface applied urea. Soil Science 147:311-318.
Cabrera, M.L., D.E. Kissel, R.C. Davis, N.P. Qafoku, and W.I. Segars. 2001. Design and ammoniarecovery evaluation of a wind speed-sensitive chamber system. Soil Sci. Soc. Am. J.
65:1302-1306.
Carmona, G., C.B. Christianson, and B.H. Byrnes. 1990. Temperature and low concentration
effects of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) on ammonia
volatilization from urea. Soil Biol. Biochem. 22:933-937.
Ernst, J.W. and H.F. Massey. 1960. The effects of several factors on volatilization of ammonia
formed from urea in soil. Soil Sci. Soc. Proc. 24:87-90.
Fenn, M.E., J.S. Baron, E.B. Allen, H.M. Rueth, K.R. Nydick, L. Geiser, W.D. Dowman, J.O.
Sickman, T. Meixner, D.W. Johnson, and P. Neitlich. 2003. Ecological effects of nitrogen
deposition in the western United States. BioScience 53:404-420.
Fenn, M.E., L. Geiser, R. Bachman, T.J. Blubaugh, and A. Bytnerowicz. 2007. Atmospheric
deposition inputs and effects on lichen chemistry and indicator species in the Columbia
River Gorge, USA. Environmental Pollution 146:77-91.
22
Fenn, L.B., and L.R. Hossner. 1985. Ammonia volatilization from ammonium or ammoniumforming nitrogen fertilizers. Adv. Soil Sci. 1:123-169.
Fenn, L.B. and S. Miyamoto. 1981. Ammonia loss and associated reactions of urea in calcareous
soils. Soil Sci. Soc. Am. J. 45:537-540.
Ferguson, R.B., and D.E. Kissel. 1986. Effects of soil drying on ammonia volatilization from
surface-applied urea. Soil Sci. Soc. Am. J. 50:485-490.
Ferguson, R.B., D.E. Kissel, J.K. Koelliker, and W. Basel. 1984. Ammonia volatilization from
surface applied urea: Effect of hydrogen ion buffering capacity. Soil Sci. Soc. Am. J.
78:741-746.
Ferm, M. 1998. Atmospheric ammonia and ammonium transport in Europe and critical loads: a
review. Nutrient Cycling in Agroecosystems 51:5-17.
Gavlak R.G., D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2003a. Total nitrogen in
botanical materials. Soil, plant and water reference methods for the western region
2:146-147.
Geiser, L.H. and P.N. Neitlich. 2007. Air pollution and climate gradients in western Oregon and
Washington indicated by epiphytic macrolichens. Environmental Pollution 145:203-218.
Grant, C.A., S. Jia, K.R. Brown, and L.D. Bailey. 1996. Volatile losses of NH3 from surface-applied
urea and urea ammonium nitrate with and without the urease inhibitors NBPT or
ammonium thiosulphate. Can. J. Soil Sci. 76:417-419.
Hargrove, W.L. 1988. Soil, environmental, and management factors influencing ammonia
volatilization under field conditions. p. 17-36. In B.R. Bock and D.E. Kissel (ed.) Ammonia
volatilization from urea fertilizers. Bull. Y-206. National Fertilizer Development Center,
Tennessee Valley Authority, Muscle Shoals, Alabama.
Harper, L.A., V.R. Catchpoole, R. Davis, and K.L. Weir. 1983. Ammonia volatilization: Soil, plant
and microclimate effects on diurnal and seasonal fluctuations. Agron. J. 75:212-218.
Harre, E.A., and J.D. Bridges. 1988. Importance of urea fertilizers. p. 1-15. In B.R. Bock and D.E.
Kissel (ed.) Ammonia volatilization from urea fertilizers. Bull. Y-206. National Fertilizer
Development Center, Tennessee Valley Authority, Muscle Shoals, Alabama.
Holcomb III, J.C., and D.A. Horneck. 2009. Effect of Agrotain treated urea on ammonia
volatilization in Kentucky bluegrass in the Columbia Basin Oregon. Seed Production
Research at Oregon State USDA-ARS Cooperating 53-56.
Keller, G.D., and D.B. Mengel. 1986. Ammonia volatilization from nitrogen fertilizers surface
applied to no-till corn. Soil Sci. Soc. Am. J. 501:1060-1063.
Kissel, D.E., M.L. Cabrera, and R. B. Ferguson. 1988. Reactions of ammonia and urea hydrolysis
products with soil. Soil Sci. Soc. Am. J. 52:1793-1796.
23
Kissel, D.E., M.L. Cabrera, N.Vaio, J.R. Craig, J.A. Rema, and L.A. Morris. 2004. Rainfall timing
and ammonia loss from urea in a loblolly pine plantation. Soil Sci. Soc. Am. J 68:17441750
Kissel, D.E., M.L. Cabrera, N. Vaio, J.R. Craig, J.A. Rema, and L.A. Morris. 2009. Forest floor
composition and ammonia loss from urea in a loblolly pine plantation. Soil Sci. Soc. Am.
J. 73:630-637.
Leuning, R., J.R. Freney, O.T. Denmead, and J.R. Simpson. 1985. A sampler for measuring
atmospheric ammonia flux. Atmospheric Environment 19:1117-1124.
Lightner, J.W., D.B. Mengel, and C.L. Rhyderd. 1990. Ammonia volatilization from nitrogen
fertilizer surface applied to orchardgrass sod. Soil Sci. Soc. Am. J. 54:1478-1482.
Marshall, V.G., and D.S. DeBell. 1980. Comparison of four methods measuring volatilization
losses of nitrogen following urea fertilization of forest soils. Can. J. Soil Sci. 60:549-563.
Martha Jr., G.B., M. Corsi, P.C.O. Trivelin, and M.C. Alves. 2004. Nitrogen recovery and loss in a
fertilized elephant grass pasture. Grass and Forage Sci. 59:80-90.
Mugusha, A.G., and D.J. Pluth. 1995. Ammonia loss following surface application of urea
fertilizer to undrained and drained forested minerotrophic peatland sites in central
Alberta, Canada. For. Ecol. Manage. 78:139-145.
Mundy, G.N. 1995. Effect of initial soil water content and application of water on urea applied
to pasture. Aust. J. Agric. Res. 46:821-830.
Oberle, S.L., and L.G. Bundy. 1987. Ammonia volatilization from nitrogen fertilizers surface
applied to corn (Zea mays) and grass pasture (Dactylis glomerata). Biol. Fertil. Soils
4:185-192.
Olson, R.A., and L.T. Kurtz. 1982. Crop nitrogen requirements, utilization, and fertilization. p.
567-604. In F.J. Stevenson (ed.) Nitrogen in agricultural soils. ASA, CSSA, and SSSA,
Madison, WI.
Proctor, C., R. Koenig, and W. Johnston. 2010. Potential for ammonia volatilization from urea in
dryland Kentucky bluegrass seed production systems. Commun. Soil Sci. Plant Anal.
41:1-12.
SAS Institute Inc. 2004. SAS/STAT® 9.1 User’s Guide. Cary, NC: SAS Institute Inc.
Schjoerring, J.K., S.G. Sommer, and M. Ferm. 1992. A simple passive sampler for measuring
ammonia emission in the field. Water, Air, and Soil Pollution 62:13-24.
Sharma, M., S. Kishore, S.N. Tripathi, and S.N. Behera. 2007. Role of atmospheric ammonia in
the formation of inorganic secondary particulate matter: A study at Kanpur, India. J.
Atmos. Chem. 58:1-17.
24
SigmaPlot 2000/2001 for scientists. 2002. SigmaPlot 2000/2001 for scientists, Merrickville,
Ontario Canada.
Sims, G.K., T.R. Elsworth, and R.L. Mulvaney. 1995. Microscale determination of inorganic
nitrogen in water and soil extracts. Commun. Soil Sci. Plant Anal. 26:303-316.
Sommer, S.G. and A. K. Ersboll. 1996. Effect of air flow rate, lime amendments, and chemical
soil properties on the volatilization of ammonia from fertilizers applied to sandy soils.
Biol. Fertil. Soils 21:53-60.
Sommer, S.G., and J.E. Olesen. 1991. Effects of dry matter content and temperature on
ammonia loss from surface applied-cattle slurry. J. Environ. Qual. 20:679-683.
Statistix 9 Analytical Software. 2008. Statistix 9 User’s Manual, Analytical Software, Tallhassee,
FL.
Steenhuis, T.S., G.D. Bubenzer, and J.C. Converse. 1979. Ammonia volatilization of winter
spread manure. Trans. ASAE 22:152-157.
Stumpe, J.M., P.L.G. Vlek, and W.L. Lindsay. 1984. Ammonia volatilization from urea and urea
phosphates in calcareous soils. Soil Sci. Soc. Am. J. 48:921-927.
Sullivan, D.M., and J.L. Havlin. 1992. Soil and environmental effects on urease inhibition by
ammonium thiosulfate. Soil Sci. Soc. J. 56:950-956.
Sullivan, D.G., C.W. Wood, W.F. Owsley, M.L. Norfleet, B.H. Wood, J.N. Shaw, and J.F. Adams.
2003. Ammonia volatilization from a swine waste amended bermudagrass pasture.
Commun. Soil Sci. Plant Anal. 34:1499-1510.
Torello, W.A., and D.J. Wehner. 1983. Urease activity in a Kentucky bluegrass turf. Agronomy J.
75:654-656.
Vaio, N., M. L. Cabrera, D.E. Kissel, J.A. Rema, J.F. Newsome, and V.H. Calvert III. 2008.
Ammonia volatilization from urea-based fertilizers applied to tall fescue pastures in
Georgia, USA. Soil Sci. Soc. Am. J. 72:1665-1671.
Whitehead, D.C. and N. Raistrick. 1990. Ammonia volatilization from five nitrogen compounds
used as fertilizers following surface application to soils. J. of Soil Sci. 41:387-394.
Wood, C.W., S.B. Marshall, and M.L. Cabrera. 2000. Improved method for field-scale
measurement of ammonia volatilization. Commun. Soil Sci. Plant Anal. 31:581-590.
Zhengping, W., O.V. Clemmput, P. Demeyer, and L. Baert. 1991. Effect of urease inhibitors on
urea hydrolysis and ammonia volatilization. Biol. Fertil. Soils 11:43-47.
25
20
Air Temperature
2.54-cm Soil Temperature
a)
Temperature (oC)
15
10
5
0
-5
0
4
8
12
16
Days after application
20
24
14
b)
Wind Speed
Wind Speed (m/s)
12
10
8
6
4
2
0
0
4
8
12
16
Days after application
20
24
Figure 2.1. (a) Air temperature and soil temperature at 2.54-cm; and (b) wind speed measured
every 15 minutes during the study period from 9 March to 2 April 2010.
26
70
A
NH3-N loss (% N Applied)
60
A
50
0.0 mm Irrigation
40
AB
30
1.25 mm Irrigation
3.8 mm Irrigation
7.6 mm Irrigation
11.4 mm Irrigation
20
BC
21.6 mm Irrigation
10
C
C
0
25
20
15
10
5
0
Days after Application
Figure 2.2. Cumulative loss of NH3 during the period of 9 March to 2 April 2010 following
application of 112 kg urea-N ha-1 to winter wheat as affected by rate of irrigation. Irrigation
rates represent averages of irrigation applied as rates varied across plots.
27
NH3-N loss (% of N applied)
80
70
60
50
40
30
20
10
0
0
5
10
15
20
Irrigation Rate (mm)
25
30
Figure 2.3. Cumulative loss of NH3 during the period of 9 March to 2 April 2010 following
application of 112 kg urea-N ha-1 to winter wheat as affected by rate of irrigation application.
28
Table 2.1. Soil urease activity from 0-2.54 cm soil depth, wheat dry matter, wheat N
concentration, and wheat N uptake sampled 23 DAA.
Irrigation Rate
mm
0.0
1.25
3.8
7.6
11.4
21.6
LSD (0.05)
Linear
Quadratic
Urease Activity
μg NH4-N/(g h)
10.51 A †
10.01 A
9.37 A
7.13 A
8.66 A
7.70 A
1.81
NS
NS
Wheat Dry Matter
kg/ha
3403.3 B †
4398.0 AB
4478.3 A
3986.1 AB
3807.4 AB
3636.4 AB
474.2
NS
NS
Wheat N
g N/kg wheat
36.63 B †
41.00 AB
43.40 AB
43.73 AB
45.83 A
46.13 A
4.04
*
NS
Wheat N Uptake
kg N/ ha
124.7 B †
179.2 AB
193.6 A
174.7 AB
172.9 AB
169.3 AB
24.75
NS
NS
†Within a column, values followed by the same letter are not significantly different according to
LSD at P = 0.05.
NS signifies no significant relationship with irrigation rate in a linear or quadratic relationship at
p=0.05.
* signifies a significant relationship with irrigation rate in a linear or quadratic relationship at p =
0.05.
29
UREASE INHIBITORS EFFECT ON AMMONIA VOLATILIZATION FROM UREA
Jess C. Holcomb III, Donald A. Horneck, Dan M. Sullivan, and George H. Clough
Soil Science Society of America Journal
5585 Guilford Road
Madison, WI 53711
Publishing Date TBA
30
ABSTRACT
When urea cannot be incorporated, urease inhibitors may be used to limit N loss from
NH3 volatilization. The objectives of this study were to: (i) examine the effectiveness of urease
inhibitors in minimizing NH3 loss on grass seed and wheat; (ii) measure interaction between
urease inhibitors and differing irrigation rates; and (iii) measure urea hydrolysis with inhibitors.
Volatilization loss was measured from urea, ammonium sulfate, and urea coated with the
urease inhibitors using the modified passive flux method under differing irrigation rates. Urease
inhibitors used were stabilized N-(n-butyl) thiophosphoric triamide (Agrotain) and an organoacid complex containing malic acid and copolymers (OAC). In the grass seed study Agrotain
coated urea and ammonium sulfate reduced loss by 71.8% and 60.4% respectively compared to
urea. In the wheat study, urea and OAC lost 53.44% to 60.05% of N applied at the 0.00 and 1.25
mm irrigation rate while Agrotain lost 5.72% to 6.24% of N applied. The addition of 7.6 mm
irrigation reduced volatilization loss across N treatments to 17.31%, 8.11%, and 3.17% N applied
for urea, OAC and Agrotain, respectively. In the wheat study, urease activity was inhibited 23
days after application of fertilizer in all Agrotain plots. In the incubation study, Agrotain delayed
complete hydrolysis by 7 days at 26.7oC, 15 days at 16.6oC and 49 days at 4.4oC compared to
OAC and urea, which hydrolyzed at the same rate. Agrotain is an effective way to inhibit urea
hydrolysis and reduce N loss from NH3 volatilization when immediate incorporation is not
possible or feasible.
INTRODUCTION
Urea is a widely accepted N fertilization source as it has a high N content (46%), and is
low cost, easy to handle, and compatible with other fertilizer materials (Harre and Bridges,
1988; Kissel et al., 2009). Unlike other forms of N fertilizer, urea must be hydrolyzed before
plant use. Hydrolysis of urea follows the reaction according to Kissel et al. (1988):
urea + 2H2O +H+ urease 2NH4+ + HCO3further reacting as
HCO3- + H+ CO2(g) + H2O and NH4+NH3 + H+
31
The consumption of H+ in both reactions raises pH around the granular site (Zaman et
al., 2008). Increased pH results in higher ammonia concentration which increases loss (Kissel et
al., 1988). Ammonia loss associated with urea has been reported as high as 83% of N applied,
but more typical loss has ranged from 15% to 40% of N applied (Lightner et al., 1990; Grant et
al., 1996; Sommer and Ersboll, 1996; Ledgard, 1999; Martha Jr. et al., 2004; Vaio et al., 2008;
Kissel et al 2009).
Agriculture is responsible for an estimated 90% of anthropogenic ammonia emissions
(Boyer et al., 2002). With 12% resulting from fertilizer application and the remainder from
animal production (Ferm, 1998). Ammonia volatilization not only represents a loss in plant
available N, but also an environmental pollutant. Up to 75% of NH3 that is volatilized is
redeposited locally; however 25% can be transported long distances (Boyer et al., 2002), usually
as secondary aerosol particles (Schjoerring et al., 1992). An aerosol is created by the reaction of
NH3 with NOx and SOx which scatters light causing atmospheric haze (Ferm, 1998; Sharma et al.,
2007). Cumulative inorganic N deposition in the Columbia River Gorge ranged from 1.09 kg ha-1
to 1.71 kg ha-1 in 19 weeks in the winter of 2003-2004(Fenn et al., 2007). Nitrogen is speculated
to be originating in the Columbia Basin of Oregon and Washington from livestock operations
and fertilizer applications. Nitrogen deposition favors nitrophilic organisms and suppresses
organisms that are adapted to low N environments, altering native ecosystems far from the
emission sites (Fenn et al., 2003; Geiser and Neitlich, 2007). This is evident in the Columbia
River Gorge which has fewer lichen species that favor low N and two species of nitrophilic lichen
which probably are not native to the Pacific Northwest (Gieser and Neitlich, 2007).
Measuring NH3 loss has typically been conducted in a laboratory by placing soil and N
fertilizer in a container and forcing air through an acid trap (Ernst and Massey, 1960; Stumpe et
al., 1984; Ferguson and Kissel, 1986; Whitehead and Raistrick, 1990; Zhengping et al., 1991;
Sommer and Ersboll, 1996). Since parameters are controlled in laboratory conditions, losses are
hard to relate to the field. However, laboratory trials do provide valuable insight into ammonia
loss parameters. The use of polyvinyl chloride (pvc) pipe inserted into the soil, temporarily
capping the system and recording NH3 loss with acid traps enables relative loss analysis in the
field (Keller and Mengel, 1986; Lightner et al., 1990). Allowing air movement by suspending the
cap on this system allows daily collection of NH3 loss and can be totaled for a study period
(Oberle and Bundy, 1987; Grant et al., 1996; Martha Jr. et al., 2004). These laboratory and field
32
techniques have limitations as they alter the environment by affecting air and soil temperature,
precipitation, wind, and solar radiation and put into question the calculated loss compared to
what which may actually occur in the field (Martha Jr. et al., 2004).
Leuning et al.’s (1985) ammonia flux sampler allowed NH3 sampling at multiple heights
with shuttles collecting ammonia loss without altering the environment. Schjoerring et al.
(1992) used a similar method with four poles positioned at the edge of a circular plot with
inexpensive glass samplers, but this required a large number of analyses. Wood et al. (2000)
combined the two methods with one mast in the center with glass tube samplers which are
inexpensive and simple to set up. This method has been used several times to measure NH3 loss
in field conditions (Wood et al., 2000; Sullivan et al., 2003; Vaio et al., 2008; Holcomb III et al., In
Review).
To limit loss associated with NH3 volatilization, urea needs to be incorporated at least 5cm into the soil (Fenn and Miyamota, 1981). Urea can be incorporated to this depth
mechanically or with 14.8 mm irrigation (Holcomb III et al., In Review). Urease inhibitors may be
used to delay hydrolysis if urea cannot be incorporated after application. Agrotain International,
LCC (St. Louis, MO) markets a urease inhibitor, Agrotain, with stabilized N-(n-butyl)
thiophosphoric triamide (NBPT) that can be applied to both urea and urea ammonium nitrate
(UAN or Solution 32) and has been reported to reduce NH3 loss (Carmona et al., 1990;
Zhengping et al., 1991; Grant et al., 1996; Sanz-Cobena et al., 2008; Zaman et al., 2008; Zaman
et al., 2009). NBPT forms a tridentate ligand with urease (Manunza et al., 1999), which slows
the hydrolysis of urea. By slowing hydrolysis, H+ is not rapidly consumed which allows soil to
buffer pH without much change (Christianson et al., 1993; Blossfeld et al., 2009; Zaman et al.,
2009). This results in a more moderate pH and a lower concentration of NH4 in soil solution
which reduces chances for volatilization (Zaman et al., 2008). Although there has been research
on the use of Agrotain and other urease inhibitors, studies on a field scale are limited.
The objectives of this study were to: (i) determine the effectiveness of different urease
inhibitors for lowering ammonia volatilization without irrigation; (ii) determine the effect of
irrigation rate on urease inhibitors; and (iii) account for urea hydrolysis with urease inhibitors.
33
MATERIALS AND METHODS
Grass Seed Study
The grass seed study consisted of two center-pivot irrigated 50-ha burned Kentucky
bluegrass fields in Umatilla County near Echo, OR. The first field had a soil classified as a Quincy
loamy sand (Mixed, mesic Xeric Torripsamments) with a pH of 6.5 and the second field consisted
of two soils, one classified as an Adkins fine Sandy loam (coarse-loamy, mixed, superactive,
mesic Xeric Haplocalcids) and one a Quincy loamy sand with a field pH of 5.9. Treatments were
arranged in a randomized complete block design with three replications. Treatments included
urea, ammonium sulfate and urea coated with Agrotain (5.21 L Agrotain/Mg urea).
Each N treatment consisted of a circular (30 m diameter) plot with N fertilizer surface
applied at 112 kg N ha-1. Each plot was separated by at least 100 m to avoid contamination of
NH3 between treatments. Fields were pre-watered with 25.4 mm irrigation to incorporate prior
N applications and raise soil to field capacity. Loss from ammonia volatilization was measured
immediately after application using the modified passive flux method (Wood et al., 2000; Vaio et
al., 2008), which consisted of a rotating mast placed at the center of each plot. A tripod which
did not interfere with rotation of the mast was placed on the mast in order to add stabilization
during high winds. Each mast was equipped with a passive flux sampler at five heights (0.45,
0.75, 1.50, 2.25, and 3.00 m; Leuning et al., 1985). Each passive flux sampler consisted of a glass
tube (0.7 cm i.d. by 20 cm long) with the inside surface coated with 3% w/v oxalic acid in
acetone to trap the NH3 in the air flowing through the tube. A nozzle with a 1 mm hole to
restrict air flow was attached to the flux sampler. Identical background masts were placed
around the field to measure ambient NH3. Background masts were placed over 100 m from
treatments to protect against contamination. Most background NH3 levels were near zero. Flux
samplers were replaced 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 days after fertilizer application (DAA).
Samplers were extracted by adding 2 ml deionized water and shaken for 10 minutes with
extracts analyzed colorimetrically for NH4 (Sims et al., 1995).
Horizontal NH3 flux (Fx, μg N m-2 s-1) for each flux sampler was calculated by [1]:
Fx = (CV)/(πr2KΔt)
[1]
34
where C is the concentration of NH4-N (μg N/mL) in deionized water used to extract sorbed NH4N, V is the volume of deionized water used for extraction (2 mL), r is the radius of the hole in the
disc on the nozzle (0.0005 m), K is a correction factor (0.77), and Δt is the time during which the
sampler was exposed (s) (Schjoerring et al., 1992; Wood et al., 2000; Vaio et al., 2008). Net
horizontal flux for each sampler (Fx,p) was determined by subtracting horizontal flux from the
corresponding sampler height on the background mast (Fx,b). Net vertical flux (Fy, ug N m-2 s-1)
from each plot was estimated by integrating each horizontal flux with vertical distance for each
sampler accounted for [2]:
Fy=(1/R)Σ(Fx,p-Fx,b)Δh
[2]
where R is the radius of the plot (15 m), and Δh (m) is the vertical distance corresponding to
each sampler.
An Adcon Telemetry (Klosterneuburg, Austria) weather station was placed at the study
area to measure air temperature, soil surface temperature, humidity, rainfall, wind speed, and
wind direction with measurements taken every 15 minutes.
Wheat Study
The wheat study was conducted in a center pivot irrigated 50 ha wheat field in Umatilla
County near Echo, OR. The soil was classified as an Adkins fine sandy loam with an average pH
of 6.5 (0-30 cm). The field was arranged in a split-plot design with 20o irrigation wedges of
approximately 2.8 ha. Three N treatments, urea, urea coated with Agrotain (5.21 L
Agrotain/ton urea), and urea coated with an Organo-Acid Complex containing malic acid and
copolymers (OAC) were surface applied to circulare (30 m diameter) plots at 112 kg N ha-1
(Figure 3.1). Wedges received 0.0, 1.25, and 7.6 mm of overhead irrigation following treatment
application. A rain gauge was placed within each treatment wedge to record the amount of
irrigation applied.
Loss from ammonia volatilization was measured using the same method as the grass
seed study, except flux samplers were replaced 2, 3, 4, 5, 6, 7, 8, 10, 13 15, 17, and 24 DAA.
Along with the weather station in the field, Sentek Enviroscan (Stepney Australia) moisture
probes were placed in the 0.0, 3.8 and 11.4 mm irrigation rate plots (not replicated) in block 1 to
measure soil moisture at the 10.1, 20.3, 30.4, 50.8, and 91.4 cm depths.
35
Soil samples were taken from each treatment at depths of 0-2.5, 0-15.2, and 0-30.4 cm
at 23 DAA. Soil samples were extracted with 2 M KCl (1:10 soil/KCl) and extract analyzed
colormetrically for NH4-N and NO3-N (Sims et al., 1995). The pH for each soil sample was
analyzed in a 1:1 soil/water slurry (McLean, 1982). Urease activity was analyzed for the 0-2.5
cm depth soil samples according to Torello and Wehner (1983). Two 2-g soil samples from each
treatment were incubated for 5-hours in a phosphate buffer and urea solution, with one sample
inhibited by AgSO4 during the incubation. After incubation KCl was added to both soils and
AgSO4 was added to the uninhibited control soil, then shaken for 1 hour. Solutions were filtered
through a Whatman No. 1 filter paper and analyzed colorimetrically for NH4-N (Sims et al.,
1995). Net urease activity was calculated by subtracting the treatment value from the
uninhibited control value and expressed as μg NH4-N g-1 h-1.
Wheat plants were randomly sampled from within each treatment (0.126 m2) at 23
DAA. Above ground dry matter was measured and total N was analyzed using the total N
combustion method (Gavlak et al., 2003) with an Elementar Vario Max CN analyzer (Hanau,
Germany).
Incubation Study
Soil (Adkins coarse-loamy, mixed, superactive, mesic Xeric Haplocalcids, pH = 7.0) at
field capacity was collected from a winter wheat field at the Hermiston Agricultural Research
and Extension Center in Hermiston, OR to a depth of 30 cm. Soil was homogenized and
subsamples of 0.65 kg of soil (roughly 0.5 kg dry soil) were placed into gallon Ziploc™ Freezer
bags. Urea, Agrotain, OAC and a control were incubated at 4.4OC, 15.6 OC and 26.7OC. Each
treatment contained about 1.05 g N kg-1 soil (variation due to adding whole prills), applied to the
soil in Ziploc™ bags and thoroughly mixed. A drinking straw, to insure aerobic conditions, was
inserted into each bag which was then zipped shut around the straw. At 1, 3, 6, 13, 20, 28, 34,
48, 63, 76, and 104 DAA of N, bags were thoroughly remixed, then subsamples were collected (5
g soil for N analysis and 10 g soil for water content and pH). Gravimetric soil moisture was
determined by drying at 60OC. Soil pH was measured in a 1:1 dry soil/water slurry (McLean,
1982). Soil N was analyzed by adding 50 mL 2 M KCl solution to the 5 g wet soil sample and
shaking for 1 hour on an oscillating shaker. The solution was passed through Whatman No. 1
36
filter paper (Keeney and Nelson, 1982) and extracts were analyzed colorimetrically for NH4-N
(Sims et al., 1995).
Statistical Analyses
Ammonia loss and soil and plant response data were analyzed via analysis of variance
(SAS Institute Inc., 2004; Statistix 9, 2008). Daily loss rates for the grass seed and wheat trial
were analyzed via linear regression (Statistix 9, 2008) and means separated by LSD at a 0.05
probability level.
RESULTS AND DISCUSSION
Field studies were conducted on acid soils. The wheat field had a pH of 6.5 and the
grass seed fields had 6.5 and 5.9 pH. Despite low soil pH, loss of NH3 in all fields exceeded 15%
of N applied with the larger loss on the wheat field. Soil pH has been shown to be less
important than soil buffering capacity, as low buffered soils can have large pH swings (Fenn and
Hossner, 1985). Temporary pH increases from urea hydrolysis helps explain field NH3 loss.
Increased pH results in a higher ammonia concentration which increases loss. A temporary pH
increase explains why no pH differences were measured across treatments in the wheat study
after 23 DAA. Sandy soils have low pH buffering capacity allowing a rapid temporary pH
increase resulting from urea hydrolysis (Hargrove, 1988). A pH increase from 5.5 and 6.1 to 7.5
and 7.9 was found by Whitehead and Raistrick (1990) with 22-36% NH3 loss. A similar increase
of 2.5 pH units after a urea application on moist soils from 6.1 to 8.5 was found by Mundy
(1995).
Ammonia loss was measured despite low air and soil temperatures at all three locations.
The wheat study had an average soil temperature of 7.8oC while the grass seed study was
10.1oC. Sommer and Olesen (1991) found that NH3 loss can occurs at near freezing
temperatures from volatilization occurring over a longer period of time than at warmer
temperatures. Steenhuis et al. (1979) measured loss occurring at near freezing temperatures.
Loss of 19% urea applied was measured by Vaio et al. (2008) with an average air temperature of
10oC.
37
Grass Seed Study
Precipitation totaled 18.6 mm with rainfall of 0.4, 9.0, 4.4, and 4.8 mm on 4, 5, 6, and 15
DAA, respectively. Relative humidity fluctuated between 7% to 95% averaging 54%. Air
temperature varied between -5.2oC and 24.4oC averaging of 7.8oC (Figure 3.2). Soil temperature
at 2.54 cm varied from 0.9oC to 21.5oC averaging of 10.1oC. Wind speeds varied from 0 to 8.33
m/s averaging of 1.7 m s-1.
Since ammonia loss was not significantly different between fields (data not shown), the
results are averaged across both fields. Ammonia loss began immediately after application, and
cumulative loss increased until 10 DAA (Figure 3.3). After 10 DAA loss from treatments virtually
ceased. Percent of N applied lost averaged 15.4, 6.1, and 4.3% for urea, ammonium sulfate, and
Agrotain, respectively. Final cumulative N loss was similar for ammonium sulfate and Agrotain
(p<0.05). Ammonium sulfate represented a 60.4% reduction in N loss compared to urea and
Agrotain represented a 71.8% reduction. Although cumulative loss between Agrotain and
ammonium sulfate did not differ, average daily loss from 1 to 15 DAA was different (p=0.08).
Agrotain loss was 0.356 kg N ha-1day-1 (r2 = 0.973), while loss from ammonium sulfate was 0.444
kg N ha-1day-1 (r2=0.903). Unlike urea, ammonium sulfate does not hydrolyze so pH does not
increase temporarily. Without the pH increase from hydrolysis, NH4 would be the dominant
form thus decreasing loss (Fenn and Hossner, 1985). Zhengping et al. (1991) found a loss of
18.8% with urea and less than 3% using the active ingredient for Agrotain NBPT, a reduction of
84%. In that incubation study, however, the N was mixed into the soil, so N loss may have been
greater had it been left on the soil surface.
Ammonia loss increased after precipitation on Days 4, 5, and 6. All N sources increased
loss on 4 DAA after the first precipitation event (Figure 3.3). Prior to precipitation on 4 DAA,
prills were still visible for all N treatments. This suggested that there was not enough soil
moisture or relative humidity to completely dissolve the prills. Relative humidity for the first
four days averaged 18% with average air temperature of 12oC. The lack of water inhibited the
diffusion of urea to urease for hydrolysis (Ferguson and Kissel, 1986). Nitrogen fertilizers did not
completely dissolve even though the field was irrigated with 2.54 cm two days prior to N
application. The surface had dried enough to hinder urea dissolution and subsequent
hydrolysis. Soil moisture, humidity, and temperature were adequate at application to allow
38
some prill dissolution and hydrolysis as NH3 loss did occur prior to precipitation on 4 DAA. This
agrees with Stumpe et al. (1984) who reported that decreasing initial soil water content
decreased volatilization, as a result of delayed dilution and urea hydrolysis. Precipitation of 0.4
mm, on 4 DAA provided adequate water for hydrolysis but was inefficient for moving urea into
the soil resulting in increased NH3 loss, as also observed by Craig and Wollum II (1982). The 9
mm of precipitation 5 DAA should have slowed future volatilization as incorporation should
decrease NH3 loss. However, partial urea hydrolysis had already occurred prior to this event.
Because of its charge, NH4+ moves slower than urea through soil, so even with precipitation,
hydrolysis products remained close to the surface enabling further ammonia loss (Wagenet et
al., 1977). Zaman et al. (2009) found complete urea hydrolysis delayed by 1-2 weeks with
Agrotain. This helps explain the reduction in NH3 loss with Agrotain. Agrotain treated urea was
not hydrolyzed and it moved into the soil with the precipitation on 4, 5, and 6 DAA. With urea
incorporated, NH3 loss was minimal.
Wheat Study
Precipitation totaled 9.6 mm with rainfall of 1.6, 0.6, 4.4, 1.2, and 1.8 mm on 3, 12, 19,
20, and 24 DAA, respectively. Relative humidity fluctuated between 22% to 97% averaging 65%.
Air temperature varied between -4.9oC and 19.7oC averaging of 6.9oC. Soil temperature at 2.54
cm ranged from 0.5oC to 17.9oC averaging 7.8oC (Figure 3.4). Wind speeds varied from 0 to 12.2
m/s averaging 2.4 m/s.
Similar to the grass seed study, loss started soon after application with little loss after 10
DAA. Unlike the grass seed study, prills melted prior to the first sampling date at 2 DAA.
Precipitation of 1.6 mm on 3 DAA did not affect daily loss rates as they remained linear from 2-8
DAA. Daily loss rates from 2-8 DAA with 0.00 mm irrigation for urea and OAC did not differ from
each other at 8.30 and 8.36 kg N ha-1day-1, respectively while Agrotain’s daily loss rate at 0.54 kg
N ha-1day-1 was lower than urea and OAC. With 1.25 mm irrigation, daily N loss from 2-8 DAA
was again similar for urea and OAC at 7.43 and 8.05 kg N ha-1day-1, respectively and Agrotain’s
daily loss of 0.35 kg N ha-1day-1 was less than urea and OAC. Daily N loss rates from 2-8 DAA
with 7.6 mm irrigation was highest with urea (2.11 kg N ha-1day-1), intermediate with OAC (1.05
kg N ha-1day-1), and lowest with Agrotain (0.34 kg N ha-1day-1).
39
When comparing daily N loss from 2-8 DAA across irrigation rates, urea and OAC with
0.0 mm and 1.25 mm irrigation had the highest and similar rate of daily N loss. Agrotain did not
differ across irrigation rates and had the lowest daily N loss from 2-8 DAA. OAC with 7.6 mm
irrigation had higher daily N loss than Agrotain treatments but lower than urea with 7.6 mm
irrigation. Urea with 7.6 mm irrigation had lower daily N loss from 2-8 DAA than urea and OAC
with 0.0 mm and 1.25 mm irrigation. Agrotain reduced daily N loss from 2-8 DAA regardless of
irrigation rate. OAC reduced daily N loss rate only with 7.6 mm irrigation, with rates similar to
urea at 0.0 and 1.25 mm irrigation.
Nitrogen loss as NH3 from N treatments across irrigation rates and sampling dates
followed a similar trend, with the majority of loss occurring before 10 DAA (Figure 3.5). Final
cumulative NH3-N loss from N treatments across irrigation rates was greatest for urea and OAC
at 0.00 and 1.25 mm irrigation. All other treatments had lower final loss and did not differ from
each other but N treatment and irrigation interacted significantly (p<0.05). At 0.0 mm
irrigation, Agrotain’s final N loss was 5.72% of N applied, significantly less than 59.1% and 60.1%
for OAC and urea, respectively (Figure 3.6). There was no difference between urea and OAC.
Agrotain at 1.25 mm irrigation had a final cumulative N loss of 6.2% compared to 53.4% and
55.4% for urea and OAC, respectively, a reduction of 88.3% compared to urea. However, at 7.6
mm irrigation, Agrotain’s and OAC’s final cumulative loss did not differ at 3.17% versus 8.11%,
respectively. Both Agrotain and OAC had a lower N loss than urea at 17.31% of N applied.
Agrotain reduced final loss by 81.6% and OAC by 53.1% compared to urea. When N is at the soil
surface (0.00 mm irrigation) or near the surface (1.25 mm irrigation) Agrotain reduces N loss
from NH3 more effectively than OAC. Agrotain also had less loss than OAC at 7.6 mm irrigation
but it was not significant. The difference in volatilization loss between Agrotain and urea with
0.00 mm irrigation was similar to the findings of Carmona et al. (1990) who reported a reduction
of 82.6-95% using the active ingredient of Agrotain (NBPT) compared to urea with loss of 2.329.4% and 54%, respectively. However, this was conducted under laboratory conditions. Grant
et al. (1996) measured a reductions in volatilization loss of 85.2% and 93.9% when using the
active ingredient of Agrotain (NBPT) compared to urea (12.32% and 2.32% versus 83% and 38%,
respectively) in Canadian prairies.
There was no irrigation effect on soil urease activity at 0-2.5 cm soil depth (Table 3.1).
Urease activity differed significantly between products, ranging from 4.85 μg NH4-N g-1 h-1 for
40
Agrotain to 9.20 μg NH4-N g-1 h-1 for urea and 11.85 μg NH4-N g-1 h-1 for OAC. Why OAC
increased urease activity compared to urea is not known. Urease activity reduction with
Agrotain is a result of the urease inhibiting characteristic of its active ingredient, NBPT. Urease
activity ranged from 0.90 to -2.59 μg NH4-N g-1 h-1, which are comparable to the lower values
reported for Kansas soils 9-71 μg NH4-N g-1 h-1 (Sullivan and Havlin,1992) and a lower than a
Washington soil 63.9 μg NH4-N g-1 h-1 (Proctor et al., 2010).
There was a visible increase in wheat stand/vigor and color in fertilized plots compared
to the remainder of the field which received no additional N. Neither N treatments nor
irrigation rate affected wheat dry matter (Table 3.1). This is likely the result of the whole field
being fertilized one week prior to our treatment applications, collecting samples only 23 DAA,
and observable differences in the stand density. Wheat growth progressed from Feekes 5 at
application to Feekes 7 at 23 DAA. Wheat at Feekes 7 would not have been stressed for N, even
treatments where 60% of N was lost, since average soil N at 23 DAA from the 0-30.4 cm depth
was 118.8 kg N/ha across the field. Wheat protein at harvest may have differed but this was not
measured as part of our objectives. Wheat N concentration was not affected by N treatment or
irrigation but the interaction between N treatment and irrigation rate was significant at (Table
3.1). Increased irrigation rates led to increased wheat N concentration when urea and Agrotain
were applied. This is likely a result of urea losing upward of 60% N through volatilization at low
irrigation rates, however OAC would be expected to have a similar concentration as it lost a
similar amount of N. Although Agrotain lost less N through volatilization, Agrotain may still have
been inhibiting urease which would keep some of the N from being plant available. This may
explain the lack of N concentration increase in the plant. There was no difference between N
treatment, irrigation rate, or an interaction between N treatment and irrigation rate for wheat N
uptake (Table 3.1).
Soil pH was not affected by N treatment or irrigation rate (data not shown). The lack in
pH difference is a result of sample collection date (23 DAA). After 18 days following a urea
application Ferguson et al. (1984) measured soil pH at or below original pH after an increase
over 2 pH units the first 5 days after application. Agrotain would be expected to resist this
initial pH increase as Agrotain extends the hydrolysis period therefore allowing the soil to buffer
the H+ consumption. Zaman et al. (2009) measured slow hydrolysis of Agrotain, limiting
consumption of H+ and increased pH.
41
OAC had a larger fraction of pellets greater than 4 mm (data not shown) which may lead
to a larger loss of NH3 from the presence of a higher concentration of urea in a smaller area.
Incubation Study
At 4.4oC, urea and OAC were completely hydrolyzed at 13 DAA (Figure 3.7). Agrotain
delayed complete hydrolysis until 63 DAA. At 16.6oC urea and OAC were completely hydrolyzed
at 6 DAA while Agrotain was not completely hydrolyzed until 28 DAA. At 26.7oC OAC was
completely hydrolyzed by 6 DAA, while urea and Agrotain were completely hydrolyzed at 13 and
20 DAA, respectively. At all three temperatures urea and OAC followed similar rates of
hydrolysis suggesting that OAC has no urease inhibition properties. Although OAC is not an
effective urease inhibitor it reduced NH3 loss at 7.6 mm irrigation compared to urea. It is not
known why OAC decreased loss after incorporation with irrigation. Agrotain delayed complete
hydrolysis at each temperature compared to urea and OAC. NBPT is a known urease inhibitor
(Manunza et al., 1999). There was an effect of temperature on hydrolysis and an interaction
between temperature and N treatment (p<0.05). Increased incubation temperature for all
products led to increased hydrolysis rates (P<0.05), therefore increased rate of NH4 formation.
Although urea and OAC were both completely hydrolyzed by 13 DAA at all temperatures, there
were differences with hydrolysis prior to 13 DAA. Agrotain at lower temperatures led to a
longer delay in hydrolysis compared to higher temperatures. This may warrant examining
lowering rates of Agrotain when used at low temperatures to meet desired hydrolysis delays.
CONCLUSIONS
Agrotain reduced ammonia volatilization loss. Agrotain reduced N loss by 71.8% in the
grass seed study compared to urea, 4.3% versus 15.3% of N applied respectively. Ammonium
sulfate reduced loss to 6.07% of N applied in the grass seed study. In the wheat study, ammonia
loss from urea, OAC, and Agrotain ranged from 17.3-60.0%, 8.1-59.0%, and 3.1-6.2% depending
on irrigation rate, respectively. Agrotain reduced loss regardless of irrigation rate unlike urea
and OAC which relied on irrigation application to decrease volatilization. Agrotain reduced
urease activity in the irrigation study. During incubation, Agrotain delayed complete hydrolysis
42
by 49 days at 4.4oC, 15 days at 16.6oC, and 7 days at 26.7oC compared to urea. Urea and OAC
hydrolyzed at similar rates at all incubation temperatures. Agrotain is an effective urease
inhibitor and can reduce ammonia volatilization loss if urea cannot be incorporated.
ACKNOWLEDGEMENTS
Agrotain International and the J.R. Simplot Company provided financial support for this project.
Eagle Ranch and Madison Farms allowed the use of their fields for our study. IRZ Consulting
donated the use of moisture probes and Syngenta donated the use of a weather station.
REFERENCES
Blossfeld, S., B. Wade, C. Watson, R. Laughlin, and C. Krause. 2009. ‘N-sight’ technique: a visual
and quantitative analysis of urea hydrolysis and ammonia loss from soil. Available at
http://escholarship.org/uc/item/6jq4j315 (verified 21 Dec. 2010). UC Davis: The
Proceedings of the International Plant Nutrition Colloquium XVI, Davis, CA.
Boyer, E.W., C.L. Goodale, N.A. Jaworski, and R.W. Howarth. 2002. Anthropogenic nitrogen
sources and relationships to riverine nitrogen export in the northeastern U.S.A.
Biogeochemistry 57/58:137-169.
Carmona, G., C.B. Christianson, and B.H. Byrnes. 1990. Temperature and low concentration
effects of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) on ammonia
volatilization from urea. Soil Biol. Biochem. 22:933-937.
Christianson, C.B., W.E. Baethgen, G. Carmona, and R.G. Howard. 1993. Microsite reactions of
urea-nBTPT fertilizer on the soil surface. Soil Biol. Biochem. 25:1107-1117.
Craig, J.R., and A.G. Wollum, II. 1982. Ammonia volatilization and soil nitrogen changes after
urea and ammonium nitrate fertilization of Pinus taeda L. Soil Sci. Soc. Am. J. 46:409414.
Ernst, J.W. and H.F. Massey. 1960. The effects of several factors on volatilization of ammonia
formed from urea in soil. Soil Sci. Soc. Proc. 24:87-90.
Fenn, M.E., J.S. Baron, E.B. Allen, H.M. Rueth, K.R. Nydick, L. Geiser, W.D. Dowman, J.O.
Sickman, T. Meixner, D.W. Johnson, and P. Neitlich. 2003. Ecological effects of nitrogen
deposition in the western United States. BioScience 53: 404-420.
Fenn, M.E., L. Geiser, R. Bachman, T.J. Blubaugh, and A. Bytnerowicz. 2007. Atmospheric
deposition inputs and effects on lichen chemistry and indicator species in the Columbia
River Gorge, USA. Environmental Pollution 146:77-91.
43
Fenn, L.B., and L.R. Hossner. 1985. Ammonia volatilization from ammonium or ammoniumforming nitrogen fertilizers. Adv. Soil Sci. 1:123-169.
Fenn, L.B. and S. Miyamoto. 1981. Ammonia loss and associated reactions of urea in calcareous
soils. Soil Sci. Soc. Am. J. 45:537-540.
Ferguson, R.B., and D.E. Kissel. 1986. Effects of soil drying on ammonia volatilization from
surface-applied urea. Soil Sci. Soc. Am. J. 50:485-490.
Ferguson, R.B., D.E. Kissel, J.K. Koelliker, and W. Basel. 1984. Ammonia volatilization from
surface applied urea: Effect of hydrogen ion buffering capacity. Soil Sci. Soc. Am. J.
78:741-746.
Ferm, M. 1998. Atmospheric ammonia and ammonium transport in Europe and critical loads: a
review. Nutrient Cycling in Agroecosystems 51:5-17.
Gavlak R.G., D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2003a. Total nitrogen in
botanical materials. Soil, plant and water reference methods for the western region.
2:146-147.
Geiser, L.H. and P.N. Neitlich. 2007. Air pollution and climate gradients in western Oregon and
Washington indicated by epiphytic macrolichens. Environmental Pollution 145:203-218.
Grant, C.A., S. Jia, K.R. Brown, and L.D. Bailey. 1996. Volatile losses of NH3 from surface-applied
urea and urea ammonium nitrate with and without the urease inhibitors NBPT or
ammonium thiosulphate. Can. J. Soil Sci. 76:417-419.
Hargrove, W.L. 1988. Soil, environmental, and management factors influencing ammonia
volatilization under field conditions. p. 17-36. In B.R. Bock and D.E. Kissel (ed.) Ammonia
volatilization from urea fertilizers. Bull. Y-206. National Fertilizer Development Center,
Tennessee Valley Authority, Muscle Shoals, Alabama.
Harre, E.A., and J.D. Bridges. 1988. Importance of urea fertilizers. p. 1-15. In B.R. Bock and D.E.
Kissel (ed.) Ammonia volatilization from urea fertilizers. Bull. Y-206. National Fertilizer
Development Center, Tennessee Valley Authority, Muscle Shoals, Alabama.
Holcomb III, J.C., D. A. Horneck, D. M. Sullivan, and G.H. Clough. In Review. Effect of irrigation
rate on ammonia volatilization.
Keeney, D.R. and D.W. Nelson. 1982. Nitrogen—inorganic forms. p.643-698. In A.L. Page, R.H.
Miller, and D.R. Keeney (ed.) Methods of Soil Analysis. ASA, CSSA, and SSSA, Madison,
WI.
Keller, G.D., and D.B. Mengel. 1986. Ammonia volatilization from nitrogen fertilizers surface
applied to no-till corn. Soil Sci. Soc. Am. J. 501:1060-1063.
Kissel, D.E., M.L. Cabrera, and R. B. Ferguson. 1988. Reactions of ammonia and urea hydrolysis
products with soil. Soil Sci. Soc. Am. J. 52:1793-1796.
44
Kissel, D.E., M.L. Cabrera, N. Vaio, J.R. Craig, J.A. Rema, and L.A. Morris. 2009. Forest floor
composition and ammonia loss from urea in a loblolly pine plantation. Soil Sci. Soc. Am.
J. 73:630-637.
Ledgard, S.F., J.W. Penno, and M.S. Sprosen. 1999. Nitrogen inputs and losses from
clover/grass pastures grazed by dairy cows, as affected by nitrogen fertilizer application.
J. Agric. Sci., Cambridge 132:215-225.
Leuning, R., J.R. Freney, O.T. Denmead, and J.R. Simpson. 1985. A sampler for measuring
atmospheric ammonia flux. Atmospheric Environ. 19:1117-1124.
Lightner, J.W., D.B. Mengel, and C.L. Rhyderd. 1990. Ammonia volatilization from nitrogen
fertilizer surface applied to orchardgrass sod. Soil Sci. Soc. Am. J. 54:1478-1482.
Manunza, B., S. Deiana, M. Pintore, and C. Gessa. 1999. The binding mechanism of urea,
hydroxamic acid and N-(N-butyl)-phosphoric triamide to the urease active site. A
comparative molecular dynamics study. Soil Biol. Biochem. 31:789-796.
Martha Jr., G.B., M. Corsi, P.C.O. Trivelin, and M.C. Alves. 2004. Nitrogen recovery and loss in a
fertilized elephant grass pasture. Grass and Forage Sci. 59:80-90.
McLean., E.O. 1982. Soil pH and lime requirement. p. 199-224. In A.L. Page, R.H. Miller, and
D.R. Keeney (ed.) Methods of Soil Analysis. ASA, CSSA, and SSSA, Madison, WI.
Mundy, G.N. 1995. Effect of initial soil water content and application of water on urea applied
to pasture. Aust. J. Agric. Res. 46:821-830.
Oberle, S.L., and L.G. Bundy. 1987. Ammonia volatilization from nitrogen fertilizers surface
applied to corn (Zea mays) and grass pasture (Dactylis glomerata). Biol. Fertil. Soils
4:185-192.
Proctor, C., R. Koenig, and W. Johnston. 2010. Potential for ammonia volatilization from urea in
dryland Kentucky bluegrass seed production systems. Commun. Soil Sci. Plant Anal.
41:1-12.
Sanz-Cobena, A., T.H. Misselbrook, A. Arce, J.I. Mingot, J.A. Diez, and A. Vallejo. 2008. An
inhibitor of urease activity effectively reduces ammonia emissions from soil treated with
urea under Mediterranean conditions. Agric. Ecosyst. Environ. 126:243-249.
SAS Institute Inc. 2004. SAS/STAT® 9.1 User’s Guide. Cary, NC: SAS Institute Inc.
Schjoerring, J.K., S.G. Sommer, and M. Ferm. 1992. A simple passive sampler for measuring
ammonia emission in the field. Water Air Soil Poll. 62:13-24.
Sharma, M., S. Kishore, S.N. Tripathi, and S.N. Behera. 2007. Role of atmospheric ammonia in
the formation of inorganic secondary particulate matter: A study at Kanpur, India. J.
Atmos. Chem. 58:1-17.
45
Sims, G.K., T.R. Elsworth, and R.L. Mulvaney. 1995. Microscale determination of inorganic
nitrogen in water and soil extracts. Commun. Soil Sci. Plant Anal. 26:303-316.
Sommer, S.G., and A. K. Ersboll. 1996. Effect of air flow rate, lime amendments, and chemical
soil properties on the volatilization of ammonia from fertilizers applied to sandy soils.
Biol. Fertil. Soils 21:53-60.
Sommer, S.G., and J.E. Olesen. 1991. Effects of dry matter content and temperature on
ammonia loss from surface applied-cattle slurry. J. Environ. Qual. 20:679-683.
Statistix 9 Analytical Software. 2008. Statistix 9 User’s Manual, Analytical Software, Tallhassee,
FL.
Steenhuis, T.S., G.D. Bubenzer, and J.C. Converse. 1979. Ammonia volatilization of winter
spread manure. Trans. ASAE 22:152-157.
Stumpe, J.M., P.L.G. Vlek, and W.L. Lindsay. 1984. Ammonia volatilization from urea and urea
phosphates in calcareous soils. Soil Sci. Soc. Am. J. 48:921-927.
Sullivan, D.M., and J.L. Havlin. 1992. Soil and environmental effects on urease inhibition by
ammonium thiosulfate. Soil Sci. Soc. J. 56:950-956.
Sullivan, D.G., C.W. Wood, W.F. Owsley, M.L. Norfleet, B.H. Wood, J.N. Shaw, and J.F. Adams.
2003. Ammonia volatilization from a swine waste amended bermudagrass pasture.
Commun. Soil Sci. Plant Anal. 34:1499-1510.
Torello, W.A., and D.J. Wehner. 1983. Urease activity in a Kentucky bluegrass turf. Agron. J.
75:654-656.
Vaio, N., M. L. Cabrera, D.E. Kissel, J.A. Rema, J.F. Newsome, and V.H. Calvert III. 2008.
Ammonia volatilization from urea-based fertilizers applied to tall fescue pastures in
Georgia, USA. Soil Sci. Soc. Am. J. 72:1665-1671.
Wagenet, R.J., J.W. Biggar, and D.R. Nielsen. 1977. Tracing the transformations of urea fertilizer
during leaching. Soil Sci. Soc. Am. J. 41:896-902.
Whitehead, D.C., and N. Raistrick. 1990. Ammonia volatilization from five nitrogen compounds
used as fertilizers following surface application to soils. J. Soil Sci. 41:387-394.
Wood, C.W., S.B. Marshall, and M.L. Cabrera. 2000. Improved method for field-scale
measurement of ammonia volatilization. Commun. Soil Sci. Plant Anal. 31:581-590.
Zaman, M., M.L. Nguyen, J.D. Blennerhassett, and B.F. Quin. 2008. Reducing NH3, N2O, and NO3-N losses from a pasture soil with urease or nitrification inhibitors and elemental Samended nitrogenous fertilizers. Biol. Fertil. Soils44:693-705.
Zaman, M., S. Saggar, J.D. Blennerhassett, and J. Singh. 2009. Effect of urease and nitrification
inhibitors on N transformation, gaseous emissions of ammonia and nitrous oxide,
pasture yield and N uptake in grazed pasture system. Soil Biol. Biochem. 41:1270-1280.
46
Zhengping, W., O.V. Clemmput, P. Demeyer, and L. Baert. 1991. Effect of urease inhibitors on
urea hydrolysis and ammonia volatilization. Biol. Fertil. Soils 11:43-47.
47
Figure 3.1. Infrared photo of wheat field displaying layout of irrigation study. Irrigation rates
are randomly selected within each block. Within an irrigation rate, N treatment plots are the
bright red circles with a diameter of 30 meters (The “T” in Block 3 with arrows is pointing to N
treatments in the 0.00 mm irrigation rate). The “B” in Block 3 is the approximate location of a
background mast, background masts in Blocks 1 and 2 are beyond the scope of the image.
48
25
Air Temperature
2.5 cm Soil Temperatue
a)
Temperature (oC)
20
15
10
5
0
-5
0
2
4
6
8
10
12
14
16
Days after application
9
Wind Speed
b)
8
Wind Speed (m/s)
7
6
5
4
3
2
1
0
0
2
4
6
8
10
12
14
16
Days after application
Figure 3.2. (a) Air temperature and soil temperature at 2.54-cm, soil temperature data before 4
DAA was lost; and (b) wind speed measured at the grass seed fields. Data were measured every
15 minutes during the study period from 28 September to 13 October 2009.
49
18
Urea
16
Ammonium Sulfate
Agrotain
NH3-N loss (% of N applied)
14
12
10
8
6
4
2
0
16
14
12
10
8
6
4
2
0
Days after application
Figure 3.3. Cumulative loss of NH3 during the period of 28 September to 13 October 2009
following application of 112 kg N/ha to Kentucky bluegrass as affected by N source. Bars
represent standard error.
50
20
Air Temperature
2.54-cm Soil Temperature
a)
Temperature (oC)
15
10
5
0
-5
0
4
8
12
16
20
24
Days after application
14
b)
Wind Speed
12
Wind Speed (m/s)
10
8
6
4
2
0
0
4
8
12
16
20
24
Days after application
Figure 3.4. (a) Air temperature and soil temperature at 2.54-cm; and (b) wind speed measure at
the wheat field. Data were measured every 15 minutes during the study period from 9 March to
2 April 2010.
51
70
Urea + 0.0 mm Irrigation
A
A
A
A
N Loss as NH3 (% of N applied)
60
Urea + 1.25 mm Irrigation
Urea + 7.6 mm Irrigation
50
Agrotain + 0.0 mm Irrigation
40
Agrotain + 1.25 mm Irrigation
30
Agrotain + 7.6 mm Irrigation
20
B
10
B
B
B
B
0
0
5
10
15
20
Days after application
OAC + 0.0 mm Irrigation
OAC + 1.25 mm Irrigation
OAC + 7.6 mm Irrigation
25
Figure 3.5. Cumulative loss of NH3 during the period of 9 March to 2 April 2010 following
application of 112 kg N ha-1 to winter wheat as affected by N and irrigation rate treatments.
Treatments followed by the same letter are not significantly different according to LSD at P =
0.05.
52
0.00 mm Irrigation
70
A
A
N Loss as NH3 (% of N Applied)
60
1.25 mm Irrigation
70
60
A
A
50
40
40
40
30
30
30
20
20
20
10
10
0
B
0
0
5 10 15 20 25
Days After Application
Urea
Urea+ 7.6 mm
Irrigation
NBPT
+ 7.6 mm
Agrotain
Irrigation
OAC
OAC+ 7.6 mm
Irrigation
60
50
B
7.60 mm Irrigation
70
50
A
10
B
B
0
0
5 10 15 20 25
Days After Application
0
5 10 15 20 25
Days After Application
Figure 3.6. Cumulative loss of NH3 within irrigation rates for the period of 9 March to 2 April
2010 following application of 112 kg N ha-1 to winter wheat for urea, Agrotain, and OAC.
Treatments followed by the same letter are not significantly different according to LSD at P =
0.05.
53
160
Urea
Net NH4-N Produced (% of N
applied)
140
Agrotain
OAC
a)
120
100
80
60
40
20
0
0
10
20
Agrotain
OAC
30
40
50
60
70
160
Urea
b)
Net NH4-N Produced (% of N
applied)
140
120
100
80
60
40
20
0
0
10
20
30
40
50
60
70
Net NH4-N Produced (% of N
applied)
160
Urea
140
Agrotain
OAC
c)
120
100
80
60
40
20
0
0
10
20
30
40
Days after application
50
60
70
Figure 3.7. Net NH4-N from fertilizer, as affected by N treatment at incubation temperature (a)
4.4oC, (b) 16.6oC, and (c) 26.7oC. Bars represent standard error.
54
Table 3.1. Wheat response and soil urease activity (0-2.5 cm) as affected by N treatment and
irrigation rate. Wheat and soil samples were taken at 23 DAA.
N Treatment
Irrigation
Rate
Urease
Activity
-1 -1
Wheat
Dry
Matter
kg / ha
mm
µg NH4-N g h
Urea
0.00
10.51
3403.3
Agrotain
0.00
5.29
OAC
0.00
Urea
Wheat N
Concentration
Wheat N
Uptake
g N / kg wheat
kg N / ha
124.7
4499.0
36.63 C†
42.33 B
191.9
10.57
4253.0
42.30 B
179.9
1.25
10.01
4398.0
41.00 BC
179.2
Agrotain
1.25
4.70
3773.7
40.16 BC
151.1
OAC
1.25
12.02
3566.5
42.26 B
151.5
Urea
7.6
7.13
3986.1
43.73 AB
174.7
Agrotain
7.6
4.48
3820.4
47.33 A
183.2
OAC
Irrigation
7.6
12.94
NS
4309.9
NS
41.33 BC
NS
177.7
NS
N Treatment
*
NS
NS
NS
Interaction
NS
NS
*
NS
†Within a column, values followed by the same letter are not significantly different according to
LSD at P=0.05.
* signifies a significant relationship at p = 0.05.
NS signifies no significant relationship at p=0.05.
55
EFFECT OF SPECIALTY NITROGEN FERTILIZERS ON RUSSET BURBANK AND RUSSET NORKOTA
POTATO YIELD IN THE COLUMBIA BASIN
Jess Charles Holcomb III, Donald A. Horneck, Dan M. Sullivan, and George H. Clough
Styled according to Soil Science Society of America Journal
5585 Guilford Road
Madison, WI 53711
56
ABSTRACT
Enhanced efficiency nitrogen (N) fertilizers may limit N loss into the environment,
however they must also maintain or increase yield in order to be viable. This study was
conducted to: (i) examine whether these fertilizers could maintain or increase yield in Russet
Burbank and Norkota potatoes; (ii) whether petiole NO3 accurately reflects plant N
concentration with these products; and (iii) whether they released N in accordance to plant
demand. A three year field study was conducted at the Hermiston Agricultural Research and
Extension Center to compare yields with grower standard practice (GSP). An incubation study
was conducted with fertilizers at 4.4oC, 15.6oC, and 26.7oC for 104 days, measuring rate of NH4
and NO3 formation. No yield difference was measured between GSP and N treatments with
Russet Norkota. Russet Burbank yields were lower than GSP for two years and similar for one
year. Yields for N treatments were similar to 80% GSP suggesting that N availability is limited
with these products. Petiole NO3 cannot be used with some N treatments, as some inhibit NO3
formation and therefore NO3 uptake. All N products were affected by temperature in the
incubation study. Increased temperature led to increased NH4 and NO3 availability. No
difference was measured between Nutrisphere-N and urea for the formation of NH4 and NO3.
Nitamin and N-fusion only had 100% available N at 26.7oC after 104 days. Enhanced efficiency N
fertilizers cannot sustain or increase yields on a yearly basis on Russet Burbank and are not
economically viable as a result.
INTRODUCTION
In the western United States, irrigated potatoes (Solanum tuberosum) is a crop of major
economic importance, with production dominating several heavily productive areas (Taysom et
al., 2007). These are typically on sandy soils that are N limiting, so N must be added as potatoes
contain more N and K than any other nutrient (Errebhi et al., 1998; Westermann, 2005).
Applications of at least 340 kg N/ha are typical and usually represent one of the more expensive
parts of production (Lauer, 1985; Ojala et al., 1990). Nitrogen is often over-applied to ensure
against N deficiency and yield loss (Kleinkopf et al., 1981; Waddell et al., 1999). Typical N use
efficiency (NUE) ranges from 28% to 56% of N applied depending on environmental conditions
57
(Westermann et al., 1988; Joern and Vitosh, 1995; Errebhi et al., 1998). Low NUE results from
potatoes having a shallow rooting depth with up to 90% of their roots in the surface 23-38 cm of
soil (Asfary et al., 1983; Yamaguchi and Tanaka, 1990; Joern and Vitosh, 1995). The large
irrigation demand of potatoes combined with sandy soils results in NO3-N being leached below
the rooting zone (Singh and Sekhon, 1976; Prunty and Greenland, 1997; Shock et al., 2007). As a
result, the typical practice in the region is to add a small amount of N at preplant and then split
applications of N through fertigation based on petiole NO3-N concentration (Meyer and
Marcum, 1998; Zomuya and Rosen, 2001; Taysom et al., 2007). Split applications increase
nitrogen use efficiency (NUE) as less NO3 is available for leaching at any given moment and N
remains in the root zone for longer periods of time (Singh and Sekhon, 1976; Elkashif et al.,
1983; Lauer, 1985; Lauer, 1986; Westermann et al., 1988; Vos, 1999). This practice, however,
can be labor intensive and costly (Taysom et al. 2007).
Nitrogen management is critical for potatoes as deficient N can reduce canopy growth,
resulting in premature senescence, reduced yields, and less US #1’s (Taysom et al., 2007;
Zebarth and Rosen, 2007). Excessive N can delay tuber initiation and slow bulking in favor of
vegetative growth, reduce yield, and decrease tuber specific gravities (Lauer, 1985; Westermann
et al., 1985; Ojala et al., 1990; Biemond and Vos, 1992; Errebhi et al., 1998; Taysom et al., 2007).
Fluctuating N from low to high in-season can result in irregular growth leading to misshapen
tubers and internal damage (Taysom et al., 2007). Defects are important since processors pay
premiums for potatoes with good symmetry, free of defects and abnormalities, and higher
specific gravities (Zomuya and Rosen, 2001; Shock et al., 2007).
Loss of N affects environmental quality as well as agronomics. Loss of N into the
environment results from NO3 leaching, NH3 volatilization, and loss of N2O. Leaching represents
the majority of loss, followed by volatilization, and N2O loss is negligible (Zebarth and Rosen,
2007). Leaching of NO3 is the biggest concern in potato production as NO3 is easily lost on well
drained sandy soils (Jones and Wagner, 1995; Ryker and Jones, 1995). Loss from NO3 also is
important after harvest because potatoes leave large amounts of N in residue that is readily
mineralized which can leach, especially if the field is not followed by a crop (Goulding, 2000;
Peralta and Stockle, 2001; Honisch et al., 2002). Random surveys in the Columbia Basin show
that 30 to 33% of wells tested had NO3 levels above EPA standard of 10 ppm (Alva et al., 2002).
58
Ammonia volatilization loss can range from 15 to 40% N applied depending on field
conditions (Lightner et al., 1990; Grant et al., 1996; Sommer and Ersboll, 1996; Ledgard et al.,
1999; Martha Jr. et al., 2004; Vaio et al., 2008; Kissel et al., 2009). Although volatilization loss
can be large, most N applications on potatoes in the Columbia Basin are applied by fertigation
which should limit volatilization loss. Irrigation should move N into the soil where volatilization
risk is minimized, however this has not been verified. Nitrous oxide production is an
intermediate product formed in the denitrification process and increases with N applications
and saturated soils leading to anaerobic environments (Mosier, 1998; Zebarth and Rosen,
2007).The loss of N2O from soils is not agronomically important on aerated soils. Loss on most
crops is typically low, with maximums of 2% with most below 1% N applied, however this work
was not done on potatoes (Delgado and Mosier, 1996; Shoji et al., 2001). Research on potatoes
has demonstrated loss ranging from 2.77% up to 4.8% N applied as N2O during the growing
season (Ruser et al., 2001). This research was conduct on a silt loam soil which unlike sands are
aerated thus N2O loss may be less. Although loss is small, agriculture is estimated to account for
over 75% of anthropogenic N2O (Isermann, 1994; Ruser et al., 2001).
Enhanced Efficiency Fertilizer’s (EEF’s) are fertilizers that reduce loss to the environment
and/or increase nutrient availability compared to conventional fertilizers (Olson-Rutz et al.,
2009). Typically EEF’s either inhibit an N conversion pathway or gradually release N. For
example, the use of an inhibitor on the urease enzyme slows hydrolysis while reducing
volatilization loss. Another example, inhibiting nitrification leaves N as NH4 which is less
susceptible to leaching (Vos, 1994). The gradual release of N from slow release fertilizer is from
microbial breakdown releasing N (Olson-Rutz et al., 2009). Controlled release fertilizers (CRF’s)
have an active soluble coated membrane that acts as a diffusion barrier and releases N based on
water content or soil temperature (Hanafi et al., 2002; Taysom et al., 2007; Wilson et al., 2009).
Because of the ability to release N over time or keep N in a form less susceptible to loss, N
applications could be placed upfront without split applications or petiole testing. These
products carry a 10% to 30% premium over conventional forms of N which often makes them
impracticable based on economics (Pasda et al., 2001; Hopkins et al., 2008).
Enhanced Efficiency Fertilizers have been shown to reduce some environmental
consequences of N applications. Fluxes of N2O were reduced by 81%, 35%, and 35% by using
dicyandiamide (DCD), polyolefin-coated urea (POCU), or a CRF, respectively on barley (Delgado
59
and Mosier, 1996; Shoji et al., 2001). Dicyandiamide also kept N as NH4 by inhibiting the
conversion to NO3 and reducing leaching (Vos, 1994). Leaching of NO3 was reduced by 58% with
sulfur coated urea and 40% with polymer coated urea compared to urea alone (Waddell et al.,
2000; Zvomuya et al., 2003). The use of the urease inhibitor N-(n-butyl) thiophosphoric triamide
(NBPT) and Nitamin have reduced NH3 loss from 45-95% with NBPT and 26-68% with Nitamin
compared to urea (Carmona et al, 1990; Zhengping et al., 1991; Grant et al., 1996; Sanz-Cobena
et al., 2008; Vaio et al., 2008; Zaman et al., 2008; Zaman et al., 2009). Although EEF’s have been
reported to reduce loss to the environment, the ability to sustain or increase yields has been
mixed. Early work with sulfur coated urea and urea formaldehyde resulted in lower marketable
and total yield compared to NH4NO3 and (NH4)2SO4, as a result of N not meeting plant uptake
demand (Lorenz et al., 1972; Lorenz et al., 1974; Cox and Addiscott, 1976; Liegel and Walsh,
1976; Elkashif et al., 1983). Pack et al. (2006) found low N removal efficiencies as some CRF
pellets were unopened, had broken polymer shells, or released N too fast or slow. Recent work
with polymer coated urea (PCU), including ESN, and POCU have sustained or increased
marketable and total yield over urea (Zvomuya and Rosen, 2001; Zvomuya et al., 2003; Taysom
et al., 2007). Yields alsohave been maintained by several different CRF’s and DCD (Vos, 1994;
Shoji et al., 2001; Pack et al., 2006).
Measuring potato N sufficiency levels through petiole NO3 may not be valid with some
products as they either inhibit nitrification or the released N does not allow nitrification to occur
before plant uptake. Pasda et al. (2001) found DCD treated potatoes took up more NH4 than
NO3. Vos (1994) measured lower NO3 and higher NH4 in the petioles with DCD compared to
calcium-ammonium-nitrate with no yield reduction. Deficient petiole NO3 were measured in
mid to late season when PCU was incorporated at preplant with no yield decrease compared to
urea (Wilson et al., 2009).
The Pacific Northwest’s Columbia Basin is an intensely irrigated and managed system
that produces the highest yielding potatoes in the country: 78 Mg/ha compared to 38 Mg/ha
national average (Alva et al., 2002). Research on the effectiveness of new EEF’s is limited in this
region, so it is not known if these products can sustain or increase the already high yields, or if
they provide an advantage over the current N practices in the area. The objectives of this study
were to: (i) measure the ability of EEF’s to meet potato N need to sustain or increase yield and
quality; (ii) determine if petiole nitrate is an effective testing tool for plant N when using EEF’s;
60
and (iii) identify the N release rates of EEF’s and determine if they meet demand for the potato
crop.
MATERIALS AND METHODS
Potato Field Study
This study was conducted at the Hermiston Agricultural Research and Extension Center
in Hermiston, Oregon (Lat 45o 49’ 10”, Long 119o 17’ 00”, Elev. 607 ft) from 2007 to 2009. The
soil was an Adkins fine sandy loam (coarse-loamy, mixed, superactive, mesic Xeric Haplocalcids).
Seven different enhanced efficiency nitrogen fertilizers were used in the study, each had a
different mode of action to maximize plant uptake of N (Table 4.1). Treatments varied across
years to alter application rates and timing to find a method that could sustain or increase yields
(Table 4.2, Table 4.3, and Table 4.4). The study was set up in a randomized complete block
design with five replicates per treatment. Each plot was 7.62 m in length and consisted of 4
rows of potatoes, row spacing of 0.86 m with seed pieces planted every 0.22 m. Cut seed pieces
were bulk planted on 4/12/2007, 4/15/2008, and 4/20/2009. Pesticides were applied as needed
to control pests, diseases, and weeds according to standard commercial practices in the area.
Irrigation was applied through a center pivot irrigation system.
Petiole samples were collected on 56, 90, 101, 112, 128 days after planting (DAP) in
2007; 76, 83 DAP in 2008; and 49, 59, 95, 115 DAP in 2009. Ten petioles were taken from the
first fully expanded leaf (Porter and Sisson, 1993a), dried at 60oC and analyzed for extractable
nitrate (Gavlak et al., 2003) using a Thermo Orion nitrate ion selective electrode (Waltham, MA
USA).
Plants and tubers were collected on 60, 64, 78, 95, 113 DAP in 2009. Samples were
taken from 0.91 m of row, dried at 60oC, and ground on a Wiley Mill. Total N concentration was
analyzed using the combustion method (Gavlak et al., 2003b) with an Elementar Vario Max CN
analyzer (Hanau, Germany).
All potatoes were mechanically lifted and hand harvested at 169 DAP in 2007, 160 DAP
in 2008, and 154 DAP in 2009. Samples of 6.66 m were taken to compare yield from the center
two rows. Yield and grade were determined (culls, <113 g, US #2’s, 113-340 g, and > 340 g).
61
Samples were measured for specific gravity (SG) using the weight in air and weight in water
method (Hutchinson et al., 2003). Ten potatoes from the 113-340 g group were inspected for
internal defects.
Incubation Study
Soil at field capacity was collected from a winter wheat field at the Hermiston
Agricultural Research and Extension Center in Hermiston, OR (soil was an Adkins coarse-loamy,
mixed, superactive, mesic Xeric Haplocalcids, with pH 6.99) to a depth of 0.30 m. Soil was
homogenized and subsamples of 0.65 kg of soil (roughly 0.5 kg dry soil) were placed into gallon
Ziplock™ Freezer Bags. Seven treatments and a control were used for each temperature regime
with treatments consisting of urea, Agrotain, super-u, environmentally smart nitrogen (ESN),
Nutrisphere-N (NSN), Nitamin, and Nitamin N-Fusion. Each treatment had 1.05 g N kg-1 soil
applied. Nitrogen was applied to the soil in the Ziploc™ bags and thoroughly mixed. A drinking
straw was inserted into each bag which was then sealed around the straw. The straw insured
aerobic conditions. Samples were placed in incubators at 4.4OC, 15.6 OC, and 26.7OC. At 1, 3, 6,
13, 20, 28, 34, 48, 63, 76, and 104 DAA of N, bags were thoroughly remixed and sub sampled.
Sub samples consisted of 5 g soil for N analysis and 10 g soil for water content and pH. Soil
moisture was determined by drying at 60OC, measuring gravimetric soil content. Soil pH was
measured using a 1:1 soil/water solution on the dry soil (McLean, 1982). Soil N was analyzed by
adding 50 ml 2 M KCl solution to the 5 g wet soil sample and shaken for 1hour on an oscillating
shaker. The solution was passed through a Whatman No. 1 filter paper (Keeney and Nelson,
1982) and extracts were analyzed colorimetrically for ammonium (Sims et al., 1995).
At 104 days after N was applied urease activity was measured for all treatments
according to Torello and Wehner (1982). Two 2-g soil samples from each treatment were
incubated for 5-hours in a phosphate buffer-urea solution, with one sample inhibited by AgSO4
during the incubation. After incubation, both soils received KCl and the uninhibited soil received
AgSO4. Soils were then shaken for 1 hour. Solutions were filtered through a Whatman No. 1
filter paper and extract analyzed colorimetrically for ammonium (Sims et al., 1995). Net urease
62
activity was calculated by subtracting the inhibited sample from the uninhibited sample and
expressed as μg NH4-N g-1 h-1.
Statistical Analyses
All data were subjected to an analysis of variance (Statistix 9, 2008; SAS Institute Inc.,
2009) and means were separated using a LSD at 0.1 probability level for all potato data and a
0.05 probability level for the incubation data.
RESULTS AND DISCUSSION
Average air and soil temperature for months of production were similar between the
three years with average temperature increasing from lows below 10oC in March to mid to high
20oC in July and August (Table 4.5). Average monthly air and soil temperatures varied little
between years, with typical monthly temperatures within 1-2oC from year to year. Precipitation
for months of production varied from year to year, with total precipitation being the least in
2008 with 25.4 mm less precipitation than the high in 2009. However, the difference in
precipitation should not alter the outcome of the trial as irrigation was the primary supply of
water for the crop based on ET measurements.
Yields were greatest in 2007 (p<0.05). Yields in 2008 were lower than 2007 but higher
than in 2009, which had the lowest yields. This could be due to environmental factors; however,
weather data for all three years suggest that conditions were similar. There was no interaction
between year and treatments.
Russet Norkota
In 2007 there were no differences between GSP and N treatments for US #1’s, total
marketable yield, and total yield (Table 4.6). Applying 80% GSP yielded similarly to the 100%
GSP, suggesting that this variety will maintain yields at lower N inputs. Differences were
measured between treatments in size classes of 113-340 g and >340 g; however, these
differences were offset by lower values of smaller tubers. No differences were measured for
63
internal damages between GSP and any N treatment. There were also no differences in SG
between any N treatment. Petioles taken 56 DAP measured GSP with lower petiole nitrate than
all except 80% ESN at planting, 80% ESN at emergence, and 80% N-guard at emergence (Table
4.7). Sampling on 90 DAP 100% GSP had more nitrate than 100% N-guard at planting, 80% Nguard at planting, 80% ESN at emergence, and 80% GP-30 at emergence while 101 DAP there
were no differences between treatments. Petioles taken 112 DAP, 100% GSP had higher petiole
nitrate concentration than all other treatments. Petiole nitrate did not seem to affect Norkota
yield as all treatments yielded similarly despite varying nitrate levels.
In 2008, there were no differences between GSP and treatments within size class, US
#1’s, total marketable yield, and total yield (Table 4.8). The 80% GSP produced similar yields as
the 100% GSP, illustrating that Norkota N rates (340 kg ha-1) could be reduced and produce
similar yields. No differences were measured for internal defects. The 80% SU at emergence
plus had a lower SG and 80% NSN at emergence had a higher SG than the 100% GSP. However,
the 80% NSN at emergence’s SG was the same as the 80% GSP. Specific gravities does not have
an impact on Russet Norkota marketing, as it is a fresh market product. Petiole sampling 76
DAP resulted in no differences in NO3 concentrations between treatments. At 83 DAP, 80% and
100% ESN at planting, 80% and 100% NSN at emergence, and 80% N-guard at emergence had
higher petiole NO3 than 100% GSP and all treatments had higher petioles than 80% GSP (Table
4.9). With only two petiole samples during this year, interpreting these data is difficult;
however, differences in petiole NO3 concentration did not result in difference in yield.
The use of EEF’s did not affect yields from Russet Norkota. This cultivar showed little to
no response to the use of N products and it maintained yields at lower GSP N rates. Differences
in petiole nitrate levels did not affect total yield. This cultivar may not require the full GSP N
rate which may be the reason that no differences were measured between N treatments.
Although N treatments yielded similarly to the GSP, these products come at a premium price so
their use in this cropping system does not appear to be economically viable. The use of Russet
Norkota was dropped from the 2009 research as a result of no differences between GSP and N
treatments.
64
Russet Burbank
In 2007, there were no differences between treatments within the class size unders,
culls, and >340 g along with US #1’s (Table 4.10). There was a difference in US #2’s, where 100%
GSP out yielded more than all other treatments except 100% ESN at emergence. The 80% GSP
had more than all except 100% ESN at emergence, 100% N-guard at emergence and 100% ESN
at planting. The 80% GP-30 100 UAN was the only treatment that had a higher yield of 113-340
g range potatoes than the GSP. The 100% GSP had higher total marketable yield than all except
80% GSP and the 80% GSP had higher total marketable yield than all except 80% N-guard at
emergence and 80% GP-30 100 UAN. The 100% GSP had greater total yield than all treatments
except 80% GSP, with 80% GSP out-yielding all except 100% GP-30 100 UAN. There was no
treatment difference in internal defects and in SG with all treatments above the penalty
threshold of 1.076 (Pavek and Knowles, 2009). AT 56 DAP 100% GP-30 100 UAN and 80% GP-30
100 UAN had higher petiole nitrate concentration than both GSP rates (Table 4.11). All other
treatments were similar to the GSP treatments. Petiole nitrates did not differ at 90 DAP. At
101 DAP 100% GSP had higher nitrate concentration than all except 100% ESN at emergence,
with most treatments having similar nitrate levels to 80% GSP. At 112 DAP 100% GSP petioles
were higher in nitrate than all treatments except 100% ESN at emergence and 100% N-guard at
planting with 80% GSP having similar nitrate levels as 80% ESN at emergence, 100% N-guard at
emergence, 80% N-guard at emergence, 100% ESN at planting and 80% GP-30 100 UAN. The
last sample at 128 DAP measured no differences between treatments. The petiole data show
that most N treatments are not maintaining nitrate levels similar to 100% GSP but closer to 80%
GSP. This suggests that they are not releasing N according to plant needs and not meeting peak
demand. This lack of release resulted in lower yields in N treatments with yields comparable to
the 80% GSP.
In 2008, there were differences within potato class sizes except the >340 g (Table 4.12).
However, differences in class sizes were similar between GSP and N treatments with most not
differing from the 100% GSP. With US #1’s, 80% ESN at emergence plus 20% urea and 80% NSN
at emergence plus 20% later yielded similarly as the 100% GSP and all other treatments had
lower yields. All treatments except 100% SU at emergence were similar to the 80% GSP. The
80% SU at emergence was the only treatment that had similar yields as 100% GSP for total
65
marketable yield and total yield, with all other treatments having lower yields. All treatments
had similar total marketable yield as 80% GSP except 100% ESN at emergence which had lower.
All treatments had similar total yield as the 80% GSP. Similarities in yield between N treatments
and 80% GSP suggest that their entire N is not available to the crop, as most continue to have
lower yields than the 100% GSP. There was no difference in treatments for internal defects or
SG, with most treatments above the penalty threshold of 1.076 (Pavek and Knowles, 2009). On
76 DAP, petiole nitrate concentrations were similar between 100% GSP and all treatments 80%
GP-30 90 UAN at emergence. The 100% ESN at planting, 100% ESN at emergence, 80% ESN at
emergence plus 20% urea, 100% NSN at emergence, 80% NSN at emergence plus 20% later, 80%
NSN at emergence, 100% GP-30 90 UAN at emergence, and 80% SU at emergence with 70 urea
had similar nitrate levels as 80% GSP (Table 4.13). On 83 DAP, both GSP’s had similar petiole
nitrate concentrations and were lower than all other treatments. Only 100% ESN at planting,
80% ESN at planting, and 100% GP-30 90 UAN at emergence had similar nitrate as 100% GSP and
100% ESN at planting, 80% ESN at planting, 100% GP-30 90 UAN at emergence, and 80% GP-30
90 UAN at Emergence nitrate as 80% GSP. As these were the only petioles from this year, very
little can be suggested as these were taken early in the season and we do not know if nitrate
levels varied later in the season.
In 2009 there were two 100% GSP: 100% GSP at emergence and 100% GSP at planting.
There were differences within potato size classes for US 2’s and 113-340g however differences
between GSP and N treatments were minimal (Table 4.14). There was no difference between
treatments for >340 g, US 1’s, total marketable yield, and total yield. There were no differences
in specific gravity between treatments and GSP and no differences in internal damages.
Although no differences were measured in specific gravities, several treatments did have values
below the threshold of 1.076 which would result in a penalty at a processing plant (Pavek and
Knowles, 2009). These data shows that yields were maintained with all N treatments. However,
the 100% GSP yielded the same as 80% GSP suggesting that N levels were not as limiting as in
previous years. Although there were petiole nitrate differences between treatments, there was
no difference in petiole nitrate between GSP’s and N treatments at the 49 DAP (Table 4.15). At
59 DAP several treatments had higher and lower nitrate levels than the GSP. On 95 DAP ESN
180 Emerg, SU 330 Plant, and SU 260 Emerg had lower nitrate than both 100% GSP’s. The 80%
GSP had higher nitrate than SU 104 Emerg, 70 NF + 55 UAN, 88 NF + 152 UAN, 70 NF + 190 UAN,
66
and 88 NF + 242 UAN. On 115 DAP ESN 180 Emerg, SU 104 Emerg, 88 NF + 37 UAN, 70 NF 100
UAN, 88 NF 152 UAN, 70 NF + 190 UAN, and 88 NF + 242 UAN had lower nitrate than 100% GSP
at emergence. The 100% GSP at emergence was only higher than 70 NF 100 UAN and 88 NF +
242 UAN and lower than ESN 330 Emerg, ESN 290 Emerg, ESN 250 Emerg, ESN 210 Emerg, ESN
260 Emerg, and SU 260 Emerg. The 100% GSP at planting was lower than ESN 330 Plant, ESN
330 Emerg, ESN 290 Emerg, ESN 250 Emerg, ESN 210 Emerg, ESN 260 Emerg, SU 330 Plant, SU
260 Emerg, and 70 NF + 55 UAN. It does not appear that petiole nitrate reflected N in the plant
as differences between treatments did not result in yield differences.
Plant dry matter samples taken during 2009 were not affected by treatments when
sampled 64, 78, 95, and 113 DAP (data not shown). Only dry matter samples collected 60 DAP
had differences between treatments; however, N treatments did not differ from GSP. There
were no differences in potato dry matter at any point during the study. This is partly due to
inaccurate collection of potatoes at early sampling dates. Potato vine N uptake for sampling
periods only measured differences in three out of the five sampling periods, with minimal
difference between GSP and N treatments (data not shown). Tuber N uptake could not be
accurately accounted for as a result of inaccurate collection of potatoes during the sampling
periods.
At 60 DAP plant N concentration was similar with all treatments, but petiole NO3 varied
between products and GSP(Table 4.15 and Table 4.16). On 95 DAP there were differences for
both plant N concentration and petiole nitrate. There was no difference in N concentration
between GSP and the treatments except 70 NF + 55 UAN was lower than the GSP. Petiole data
for SU 104 Emerg, 70 NF + 55 UAN, 88 NF + 37 UAN, 70 NF 100 UAN, 88 NF 152 UAN, 70 NF +
190 UAN, and 88 NF + 242 UAN were all below the GSP. This difference in petiole nitrate may
prompt a grower to apply more N even though the N concentrations in the plants are similar.
Sampling 113 DAP there were differences between GSP and treatments for N concentration.
The 88 NF + 37 UAN, 70 NF 100 UAN, 88 NF 152 UAN, 70 NF + 190 UAN, and 88 NF + 242 UAN
had less N concentration than all GSP and several treatments had less than one GSP. These
treatments had similar nitrate as GSP when examining petiole nitrate. Comparing these
differences, petiole nitrate does not accurately reflect the N content in the plant with some N
treatments. This is likely a result of some N products keeping N in NH4 form or slowly releasing
N and not allowing nitrate to form before plant uptake. Vos (1994) found that the use of DCD,
67
which is in Super-U, posed problems with nitrate interpretation as DCD inhibits nitrate
formation. When inhibiting nitrate and supplying NH4 instead, nitrate sampling does not reflect
the N concentration in the plant as N in the plant is NH4. Whole plant samples and plant N only
were measured in 2009 when yields were similar across treatments, so differences between
plant matter and plant N did not result in different yields. Data from previous years when
treatment yields were lower than GSP would have given valuable information on how these
processes affect potato yield.
In both 2007 and 2009, 80% GSP yielded similarly to 100% GSP, while 2008 100% GSP
out-yielded 80% GSP. However, in 2008 and 2009 the 80% produced similar yields to most N
treatments and only in 2009 did N treatments produce similar yields to the 100% GSP. Nitrogen
treatments yielded similar to 80% GSP for two years which suggests that N availability may be a
problem with some of these products. There have been measured increases and maintained
yields with the use of ESN and DCD (Vos, 1994; Taysom et al., 2007; Wilson et al., 2009);
however, these were performed in regions outside the Columbia Basin. The intensively
managed, high yielding potato production in the Columbia Basin could be a reason these N
products are decreasing or maintaining yields. Current split N application practices supply
available N to the potato plant when it is needed. Maintaining yields with these N treatments is
economically unviable as they come with a premium, so a yield increase or a cost saving
attribute must be observed in order to make these practical for potato production in the
Columbia Basin.
Incubation Study
All products at 4.4oC slowed the release of N compared to urea except NSN (Figure 4.1).
NSN followed the same hydrolysis rate as urea through 100 DAA as well as the same NO3
formation. Urea and NSN had all N available by 13 DAA, either as NH4 or NO3. Agrotain and
Super U followed similar rates of NH4 formation with most N being present as NH4 by 63 DAA.
These products were able to slow urea hydrolysis, as both contain the urease inhibitor NBPT.
Both products had similar NO3 conversion rates. It would be expected that Super-U have lower
NO3 levels as it has the nitrification inhibitor DCD in its composition. Agrotain and Super-U had
all N available by 63 DAA. ESN and Nitamin had similar rates of NH4 formation although
68
different modes of action were used. ESN supplied 46% of its N by 20 DAA and then slowly
released the rest. ESN was the only product that showed large increases in NO3 formation,
exhibiting that it only regulates N release, it is not an inhibitor. ESN had all N available by the
end of the study on 104 DAA. Nitamin released about 48% of its N as NH4 by 13 DAA similar to
ESN, however its NO3 formation was lower throughout the study and only had NO3 formation
after 63 DAA. Nitamin also had only 60% of its total N available by the end of the study on 104
DAA. N-fusion released its N slowly with NH4 levels at 16% and NO3 levels at 8% by 104 DAA.
Final N available after 104 DAA was only 25%. At 40oF the use of Nitamin and N-fusion would
not be wise as the N released would not be able to meet plant need. The use of Agrotain,
Super-U, and ESN all released N slowly over time and had all N available at 104 DAA. Urea and
NSN behaved the same showing that NSN has no inhibiting capability.
At 15.6oC all products slowed release of N compared to urea except NSN (Figure 4.2).
NSN and urea had all their N as NH4 at 6 and 13 DAA respectively. The only difference was at 6
DAA when urea was 100% hydrolyzed and NSN was only 80%. Other than this all NH4 rates for
the two were similar throughout the study. At 20 DAA both NH4 levels began to decline as a
result of NO3 formation and NO3 formation for both products was similar for the trial. Urea and
NSN had similar N available for the entire study with all N available by 13 DAA. Agrotain and
Super-U both hydrolyzed at the same rate with 100% of their N available as NH4 by 28 DAA.
After 28 DAA Agrotain had more NO3 conversion and subsequent NH4 decline than Super-U as a
result of Super-U containing DCD. Both products had similar total N available throughout the
study, however the difference between the two was in the form of N, with Agrotain having more
N converting to NO3 than Super-U. ESN had 50% of its N as NH4 by 13 DAA and then after 20
DAA available NH4 declined with time. Available N continued to increase as NH4 was converted
to NO3 and by 104 DAA over 60% of total N in the form of NO3. Available N for ESN was 100% by
48 DAA. This exhibits that N from ESN is slowly released from the polymer and can be readily
hydrolyzed and then nitrified. Nitamin had the formation of 62% NH4 by 6 DAA, then NH4
declined with an increase in NO3 formation. Total N available was 73% at 104 DAA, with the
majority of N available in the first 20 DAA. Formation of NH4 for N-fusion was 24% by 20 DAA
and then slowly increased to 29% at 104 DAA. Formation of NO3 was low and increased after 20
DAA and remained around 15% from 50 to 104 DAA. By 104 DAA, 42% of total N was available.
This product seems to release N extremely slow and not meet N demands of the plant. Nitamin
69
would have a similar response on plant demand, as less than 80% of its N is available. Agrotain,
Super-U and ESN slowly release N and would have all N available by 48 DAA. Urea and NSN have
no slow release capabilities.
At 26.7oC, all products delayed available N compared to urea except NSN (Figure 4.3).
NSN and urea both had 100% hydrolysis by day 13 and both had NH4 decline after 20 DAA. Both
also had similar NO3 formation throughout the study except on the 104 DAA sampling period
when urea had less. NSN and urea also had all N available from 6 DAA onward. Agrotain and
Super-U followed similar hydrolysis rates with 100% N available as NH4 by 20 DAA. After this
time levels of NH4 declined as NO3 was formed. However, Super-U had less NO3 formation than
Agrotain as a result of DCD, as DCD is a nitrification inhibitor slowing conversion of NH4 to NO3
(Vos, 1994). Both products had 100% N available from 20 DAA onward. ESN had 32% N
available as NH4 at 13 DAA and then NH4 remained steady as NO3 conversion increased. By 48
DAA, ESN had all N available, close to 67% as NO3. Nitamin had 56% N available as NH4 by 6 DAA
then NH4 levels decreased as NO3 formed. By 104 DAA NO3 levels were 60% with total available
N about 100%. N –fusion had 23% N available as NH4 by 13 DAA, then slowly increased to 38%
by 104 DAA. Nitrate formation began at 20 DAA with final NO3 representing 60%. Total N
available from N-fusion after 104 DAA reached 100%. N-fusion and Nitamin exhibited slow
release with 100% N available after 104 DAA, which could stress the plant for N early in the
season. Agrotain, Super-U, and ESN all release N over time making it plant available. Urea and
NSN had no slow release capabilities.
At all temperatures NSN and urea performed similarly with no gradual release of N.
Agrotain and Super-U delayed the formation of NH4 as a result of NBPT. NBPT is a known urease
inhibitor therefore slowing the hydrolysis of urea (Manunza et al., 1999). After complete
hydrolysis, NO3 formation increased; however, Super-U was able to limit NO3 formation as it
contained DCD. ESN had initial N available as NH4 which was then converted to NO3, with NO3
levels increasing and NH4 levels staying consistent or declining. ESN was able to slowly release
urea and get N to the plant. Nitamin had an initial increase of N as NH4, since 30% of its N is urea
with the rest in a urea polymer form that slowly makes N available (Vaio et al., 2008). This
increase only reached 100% N available at 26.7oC showing that this product releases N too
slowly for plant demand at cooler temperatures. N-fusion was slow in releasing N, and slow in
formation in both NH4 and NO3. This product works too slowly to meet plant demands,
70
especially since potatoes can take up to 80% of N 20-60 days after emergence (Munoz et al.,
2005). Pack et al. (2006) found similar issues with controlled-release fertilizers as N release was
either too fast or too slow for plant demand. The lack of N availability from these products at
certain temperatures could be the reason for lower yields than the GSP in 2007 and 2008 and
comparable yields to the 80% GSP in 2007, 2008, and 2009.
It is believed that the rapid hydrolysis of urea, NSN, Agrotain, and Super-U along with
the high rates of N in this experiment may have reduced nitrification bacteria populations as a
result of increased NH3 levels. Ammonia could be smelled from certain bags during the
experiment. This problem may have resulted in a delay in NO3 formation. ESN had highest NO3
levels at all temperatures and is believed to not have affected nitrifying populations as it never
reached high NH4 levels like urea, NSN, Agrotain, and Super-U. No differences were measured in
urease activity between treatments (Table 6.20). This may be due to sampling at 104 DAA;
earlier sampling may have measured differences as Agrotain and Super-U have a known urease
inhibitor NBPT in their formulation. By 104 DAA, the NBPT already would have decomposed.
There was an effect of temperature on available N (p<0.05) and an interaction between
temperature and N treatment (p<0.05). This was measured for NH4 formation, NO3 formation,
and total available N for each treatment. Increased incubation temperature led to increased
hydrolysis rates and increased NH4 formation. This led to increased NO3 formation and an
increase in total available N. ESN is specifically designed to release N based on soil temperature
with its micro-thin polymer coating (Taysom et al., 2007; Wilson et al., 2009). Consequently, soil
temperature greatly affects N release. The effect of temperature on release rate from these N
products will affect N available to the plant, and will vary according to N treatment. This may
make it difficult to incorporate these products into a cropping system as N release is dependent
on environmental conditions, and environmental conditions are unpredictable. The GSP also
accounts for unpredictability as N is available when the plant demands it.
At all three temperatures, soil pH increased with all treatments (Figure 4.4). However,
all products increased soil pH faster than the control, likely a result from hydrolysis. At 4.4oC,
Agrotain and Super-U delayed peak pH until 13 DAA; at 15.6oC, Agrotain, Super-U, and ESN
delayed peak pH until 3 DAA. Agrotain, Super-U, ESN, and N-fusion all delayed peak pH until 6
DAA at 26.7oC. The delay in peak pH is due to slowing of urea hydrolysis. After increasing, the
71
pH declined for the rest of the study for treatments. Some variation between pH exists between
products after the peak; however, they follow no pattern between sampling dates.
CONCLUSIONS
Specialty N fertilizers maintained yield for Russet Norkota potatoes; however, a
reduction of GSP N also sustained yields. Although yield was maintained, the use of specialty N
fertilizers with Russet Norkota is still prohibitive due to the premium involved. Specialty N
fertilizers do not appear to produce a competitive yield at this time with grower standard
practice for Russet Burbank. Yields were below GSP for two out of three years of production,
with the third year only maintaining yields. The use of petiole nitrate sampling to measure plant
N cannot be used for some products as they inhibit nitrate conversion and therefore nitrate
uptake. During incubation the product NSN showed no gradual N release capability and
released N similar to urea. All other treatments gradually made N available; however, all were
affected by soil temperature. The dependence on soil temperature can delay available N from
some products and therefore not meet plant N demand.
REFERENCES
Alva, A.K., T. Hodges, R.A. Boydston, and H.P. Collins. 2002. Effects of irrigation and tillage
practices on yield of potato under high production conditions in the Pacific Northwest.
Commun. Soil Sci. Plant Anal. 33:1451-1460.
Asfary, A.F., A. Wild, and P.M. Harris. 1983. Growth, mineral nutrition and water use by potato
crops. J. Agric. Sci., Camb. 100:87-101.
Biemond, H. and J. Vos. 1992. Effects of nitrogen on the development and growth of the potato
plant. 2. The partitioning of dry matter, nitrogen and nitrate. Ann. Bot. 70:37-45.
Carmona, G., C.B. Christianson, and B.H. Byrnes. 1990. Temperature and low concentration
effects of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) on ammonia
volatilization from urea. Soil Biol. Biochem. 22:933-937.
Cox, D., and T.M. Addiscott. 1976. Sulphur-coated urea as a fertilizer for potatoes. J. Sci. Food
Agric. 27:1015-1020.
72
Delgado, J.A. and A.R. Mosier. 1996. Mitigation alternatives to decrease nitrous oxides
emissions and urea-nitrogen loss and their effect on methane flux. J. Environ. Qual.
25:1105-1111.
Elkashif, M.E., S.J. Locascio, and D.R. Hensel. 1983. Isobutylidene diurea and sulfur-coated urea
as N sources for potatoes. J. Amer. Soc. Hort. Sci. 108:523-526.
Errebhi, M., C.J. Rosen, S.C. Gupta, and D.E. Birong. 1998. Potato yield response and nitrate
leaching as influenced by nitrogen management. Agron. J. 90:10-15.
Gavlak R.G., D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2003a. Total nitrogen in
botanical materials. Soil, Plant and Water Reference Methods for the Western Region.
2:146-147.
Gavlak R.G., D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2003b. Extractable potassium,
nitrate, ammonium, ortho-phosphate, and chloride of botanical materials. Soil, Plant
and Water Reference Methods for the Western Region. 2:150-152.
Goulding, K. 2000. Nitrate leaching from arable and horticultural land. Soil use and
management 16:145-151.
Grant, C.A., S. Jia, K.R. Brown, and L.D. Bailey. 1996. Volatile losses of NH3 from surface-applied
urea and urea ammonium nitrate with and without the urease inhibitors NBPT or
ammonium thiosulphate. Can. J. Soil Sci. 76:417-419.
Hanafi, M.M, S.M. Eltaib, M.B. Ahmad, and S.R. Syed Omar. 2002. Evaluation of controlledrelease compound fertilizers in soil. Commun. Soil Sci. Plant Anal. 33:1139-1156.
Honisch, M., C. Hellmeier, and K. Weiss. 2002. Response of surface and subsurface water
quality to land use changes. Geoderma 105:277-298.
Hopkins, B.G., C.J. Rosen, A.K. Shiffler, and T.W. Taysom. 2008. Enhanced efficiency fertilizers
for improved nutrient management: Potato (Solanum tubersum). Online. Crop
Management doi: 10.1094/CM-2008-0317-01-RV.
Hutchinson, C., E. Simonne, P. Solano, J. Meldrum, and P. Livingston-Way. 2003. Testing of
controlled release fertilizer programs for seep irrigated Irish potato production. J. Plant
Nutrition 26:1709-1723.
Isermann, K. 1994. Agriculture’s share in the emission of trace gases affecting the climate and
some cause-oriented proposals for sufficiently reducing this share. Environ. Pollut.
83:95-111.
Joern, B.C. and M.L. Vitosh. 1995. Influence of applied nitrogen on potato Part II: Recovery and
partitioning of applied nitrogen. Amer. Potato J. 72:73-84.
73
Jones, J.L. and R.J. Wagner. 1995. Water-quality assessment of the Central Columbia Plateau in
Washington and Idaho. p. 119. Analysis of available nutrient and pesticide data for
ground water, 1942-92, US Geological Survey Water-Resources Investigations Report944258.
Keeney, D.R. and D.W. Nelson. 1982. Nitrogen—inorganic forms. p.643-698. In A.L. Page, R.H.
Miller, and D.R. Keeney (ed.) Methods of soil analysis. ASA, CSSA, and SSSA, Madison,
WI.
Kissel, D.E., M.L. Cabrera, N. Vaio, J.R. Craig, J.A. Rema, and L.A. Morris. 2009. Forest floor
composition and ammonia loss from urea in a loblolly pine plantation. Soil Sci. Soc. Am.
J. 73:630-637.
Kleinkopf, G.E., D.T. Westermann, and R.B. Dwelle. 1981. Dry matter production and nitrogen
utilization by six potato cultivars. Agron. J. 73:799-802.
Lauer, D.A. 1985. Nitrogen uptake patterns of potatoes with high-frequency sprinkler-applied N
fertilizer. Agron. J. 77:193-197.
Lauer, D.A. 1986. Russet Burbank yield response to sprinkler-applied nitrogen fertilizer. Amer.
Potato J. 63:61-69.
Ledgard, S.F., J.W. Penno, and M.S. Sprosen. 1999. Nitrogen inputs and losses from
clover/grass pastures grazed by dairy cows, as affected by nitrogen fertilizer application.
J. Agric. Sci., Cambridge 132:215-225.
Liegel, E.A. and L.M. Walsh. 1976. Evaluation of sulfur-coated urea (SCU) applied to irrigated
potatoes and corn. Agron. J. 68:457-463.
Lightner, J.W., D.B. Mengel, and C.L. Rhyderd. 1990. Ammonia volatilization from nitrogen
fertilizer surface applied to orchardgrass sod. Soil Sci. Soc. Am. J. 54:1478-1482.
Lorenz, O.A., B.L. Weir, and J.C. Bishop. 1972. Effect of controlled-release nitrogen fertilizers on
yield and nitrogen absorption by potatoes, cantaloupes, and tomatoes. J. Amer. Soc.
Hort. Sci. 97:334-337.
Lorenz, O.A., B.L. Weir, and J.C. Bishop. 1974. Effect of sources of nitrogen on yield and
nitrogen absorption of potatoes. Amer. Potato J. 51:56-65.
Manunza, B., S. Deiana, M. Pintore, and C. Gessa. 1999. The binding mechanism of urea,
hydroxamic acid and N-(N-butyl)-phosphoric triamide to the urease active site. A
comparative molecular dynamics study. Soil Biol. and Biochem. 31:789-796.
Martha Jr., G.B., M. Corsi, P.C.O. Trivelin, and M.C. Alves. 2004. Nitrogen recovery and loss in a
fertilized elephant grass pasture. Grass Forage Sci. 59:80-90.
McLean., E.O. 1982. Soil pH and lime requirement. p. 199-224. In A.L. Page, R.H. Miller, and
D.R. Keeney (ed.) Methods of soil analysis. ASA, CSSA, and SSSA, Madison, WI.
74
Meyer, R.D., and D.B. Marcum. 1998. Potato yield, nitrogen, and soil nitrogen response to
water and nitrogen. Agron. J. 90:420-429.
Mosier, A.R. 1998. Soil processes and global change. Biol. Fertil. Soils 27:221-229.
Munoz, F., R.S. Mylavarapu, and C.M. Hutchinson. 2005. Environmentally responsible potato
production systems: A review. J. Plant Nutrition 28:1287-1309.
Ojala, J.C., J.C. Stark, and G.E. Kleinkopf. 1990. Influence of irrigation and nitrogen management
on potato yield and quality. Amer. Potato J. 67:29-43.
Olson-Rutz, K., C. Jones, and C.P. Dinkins. 2009. Enhanced efficiency fertilizers. Montana State
University Extension Bulletin 0188.
Pack, J.E., C.M. Hutchinson, and E.H. Simonne. 2006. Evaluation of controlled-release fertilizers
for Northeast Florida chip potato production. J. Plant Nutr. 29:1301-1313.
Pasda, G., R. Hähndel, and W. Zerulla. 2001. Effect of fertilizers with the new nitrification
inhibitor DMPP (3,4-dimethylpyrazole phosphate) on yield and quality of agricultural
and horticultural crops. Biol. Fertil. Soils 34:85-97.
Pavek, M.J. and N.R. Knowles. 2009. Process Value-Methods. p 15. 2009 potato cultivar yield
and postharvest quality evaluations. Washington State University, Pullman, WA.
Peralta, J.M., and C.O. Stockle. 2001. Dynamics of nitrate leaching under irrigated potato
rotation in Washington state: a long-term simulation study. Agriculture, Ecosystems
and Environment 88:23-34.
Porter, G.A. and J.A. Sisson. 1993. Yield, market quality and petiole nitrate concentration of nonirrigated Russet Burbank and Shepody potatoes in response to sidedressed nitrogen.
Amer. Potato J. 70:101-116.
Prunty, L., and R. Greenland. 1997. Nitrate leaching using two potato-corn N-fertilizer plans on
sandy soil. Agric. Ecosyst. Environ. 65:1-13.
Ruser, R., H. Flessa, R. Schilling, F. Beese, and J.C. Munch. 2001. Effect of crop-specific field
management and N fertilization on N2O emissions from a fine-loamy soil. Nutrient
Cycling in Agroecosystems 59:177-191.
Ryker, J.S. and J.L. Jones. 1995. Nitrate concentration in groundwater of the central Columbia
Plateau. US Department of Interior, US Geological Survey. Open-File Report 95-445.
Sanz-Cobena, A., T.H. Misselbrook, A. Arce, J.I. Mingot, J.A. Diez, and A. Vallejo. 2008. An
inhibitor of urease activity effectively reduces ammonia emissions from soil treated with
urea under Mediterranean conditions. Agric. Ecosyst. Environ. 126:243-249.
SAS Institute Inc. 2004. SAS/STAT® 9.1 User’s Guide. Cary, NC: SAS Institute Inc.
Shock, C.C., A.B. Pereira, and E.P. Eldredge. 2007. Irrigation best management practices for
potato. Amer. J. of Potato Res. 84:29-37.
75
Shoji, S., J. Delgado, A. Mosier, and Y. Miura. 2001. Use of controlled release fertilizers and
nitrification inhibitors to increase nitrogen use efficiency and to conserve air and water
quality. Commun. Soil Sci. Plant Anal. 32:1051-1070.
Sims, G.K., T.R. Elsworth, and R.L. Mulvaney. 1995. Microscale determination of inorganic
nitrogen in water and soil extracts. Commun. Soil Sci. Plant Anal. 26:303-316.
Singh, B. and G.S. Sekhon. 1976. Some measures of reducing leaching loss of nitrates beyond
potential rooting zone I. Proper co-ordination of nitrogen splitting with water
management. Plant Soil 44:193-200.
Sommer, S.G. and A. K. Ersboll. 1996. Effect of air flow rate, lime amendments, and chemical
soil properties on the volatilization of ammonia from fertilizers applied to sandy soils.
Biol. Fertil. Soils 21:53-60.
Statistix 9 Analytical Software. 2008. Statistix 9 User’s Manual, Analytical Software, Tallhassee,
FL.
Taysom, T.W., B.G. Hopkins, A.K. Shiffler, and S.C. Stephens. 2007. Polymer coated urea in
potato production. p. 169-175. Western Nutrient Management Conference. Vol 7. Salt
Lake City, UT.
Torello, W.A., and D.J. Wehner. 1983. Urease activity in a Kentucky bluegrass turf. Agronomy J.
75:654-656.
Vaio, N., M. L. Cabrera, D.E. Kissel, J.A. Rema, J.F. Newsome, and V.H. Calvert III. 2008.
Ammonia volatilization from urea-based fertilizers applied to tall fescue pastures in
Georgia, USA. Soil Sci. Soc. Am. J. 72:1665-1671.
Vos, J. 1994. Effects of dicyandiamide on potato performance. J. Agron. Crop Sci. 173:93-99.
Vos, J. 1999. Split nitrogen application in potato: effects on accumulation of nitrogen and dry
matter in the crop and on the soil nitrogen budget. J. Agric. Sci., Cambridge 133:263274.
Waddell, J.T., S.C. Gupta, J.F. Moncrief, C.J. Rosen, and D.D. Steele. 1999. Irrigation and
nitrogen management effects on potato yield, tuber quality, and nitrogen uptake.
Agron. J. 91:991-997.
Waddell, J.T., S.C. Gupta, J.F. Moncrief, C.J. Rosen, and D.D. Steele. 2000. Irrigation- and
nitrogen-management impacts on nitrate leaching under potato. J. Environ. Qual.
29:251-261.
Westermann, D.T. 2005. Nutritional requirements of potatoes. Amer. J. of Potato Res. 82:301307.
Westermann, D.T. and G.E. Kleinkopf. 1985. Nitrogen requirements of potatoes. Agron. J.
77:616-621.
76
Westermann, D.T., G.E. Kleinkopf, and L.K. Porter. 1988. Nitrogen fertilizer efficiencies on
potatoes. Amer. Potato. J. 65:337-386.
Wilson, M.L., C.J. Rosen, and J.F. Moncrief. 2009. Potato response to a polymer-coated urea on
an irrigated, coarse-textured soil. Agron. J. 101:897-905.
Yamaguchi, J., and A. Tanaka. 1990. Quantitative observation on the root system of various
crops growing in the field. Soil Sci. Plant Nutr. 36:483-493.
Zaman, M., M.L. Nguyen, J.D. Blennerhassett, and B.F. Quin. 2008. Reducing NH3, N2O, and NO3-N losses from a pasture soil with urease or nitrification inhibitors and elemental Samended nitrogenous fertilizers. Biol. Fertil. Soils 44:693-705.
Zaman, M., S. Saggar, J.D. Blennerhassett, and J. Singh. 2009. Effect of urease and nitrification
inhibitors on N transformation, gaseous emissions of ammonia and nitrous oxide,
pasture yield and N uptake in grazed pasture system. Soil Biol. Biochem. 41:1270-1280.
Zebarth, B.J. and C.J. Rosen. 2007. Research perspective on nitrogen BMP development for
potato. Amer. J. Potato Res. 84:3-18
Zhengping, W., O.V. Clemmput, P. Demeyer, and L. Baert. 1991. Effect of urease inhibitors on
urea hydrolysis and ammonia volatilization. Biol. Fertil. Soils 11:43-47.
Zvomuya, F., and C.J. Rosen. 2001. Evaluation of polyolefin-coated urea for potato production
on a sandy soil. HortScience 36:1057-1060.
Zvomuya, F., C.J. Rosen, M.P. Russelle, and S.C. Gupta. 2003. Nitrate leaching and nitrogen
recovery following application of polyolefin-coated urea to potato. J. Environ. Qual.
62:480-489.
77
Urea
Agrotain
Super-u
NSN
a)
Available NH4 (% N applied)
100
80
60
40
20
0
0
20
Urea
40
60
80
100
ESN
b)
Available NH4 (% N applied)
100
80
60
40
20
0
0
20
Urea
Nitamin
40
60
80
100
N-fusion
c)
Available NH4 (% N applied)
100
80
60
40
20
0
0
20
40
60
80
100
Figure 4.1. Available NH4 at 4.4oC from (a) urease and nitrification inhibitors, (b) polymer coated
urea, and (c) slow release N in incubation as affected by N treatment. Values are the average of
the replications.
78
Urea
Available NH4 (% N applied)
120
Agrotain
Super-u
NSN
a)
100
80
60
40
20
0
0
Available NH4 (% N applied)
120
20
Urea
40
60
80
100
ESN
b)
100
80
60
40
20
0
0
Urea
120
Available NH4 (% N applied)
20
Nitamin
40
60
80
100
N-fusion
c)
100
80
60
40
20
0
0
20
40
60
80
100
Figure 4.2. Available NH4 at 15.6oC from (a) urease and nitrification inhibitors, (b) polymer
coated urea, and (c) slow release N in incubation as affected by N treatment. Values are the
average of the replications.
79
Urea
Agrotain
Super-u
NSN
Available NH4 (% N applied)
120
100
a)
80
60
40
20
0
0
Urea
120
Available NH4 (% N applied)
20
40
60
80
100
ESN
100
b)
80
60
40
20
0
0
20
Urea
Nitamin
40
60
80
100
N-fusion
Available NH4 (% N applied)
120
c)
100
80
60
40
20
0
0
20
40
60
80
100
Figure 4.3. Available NH4 at 26.7oC from (a) urease and nitrification inhibitors, (b) polymer
coated urea, and (c) slow release N in incubation as affected by N treatment. Values are the
average of the replications.
80
Control
8.4
Urea
Agrotain
Super-U
NSN
ESN
Nitamin
N-Fusion
a)
8.2
pH
8
7.8
7.6
7.4
7.2
7
0
20
40
60
80
100
8.5
b)
8
pH
7.5
7
6.5
6
5.5
0
20
40
60
80
100
8.5
c)
8
pH
7.5
7
6.5
6
5.5
5
0
20
40
60
Days after application
80
100
Figure 4.4. Soil pH at (a) 4.4oC, (b) 15.6oC, and (c) 26.7oC in incubation as affected by N
treatment. Values are the average of the replications.
81
Table 4.1. Modes of action for enhanced efficiency nitrogen fertilizers.
Product
Agrotain
Super-U
Nutrisphere-N (NSN)
Environmentally Smart N (ESN)
Nitamin
N-Fusion
Mode of Action
Urease Inhibitor
Urease and Nitrification Inhibitor
Urease Inhibitor
Polymer Coated Urea
Slow Release N (Microbial Breakdown of urea polymers)
Slow Release N (Microbial Breakdown of urea polymers)
Table 4.2. Nitrogen treatments for Russet Norkota and Russet Burbank for 2007, listing N source, N rates (kg ha-1), and application timing.
Unless noted, N rates represent N treatment product. All plots received 22 kg N/ha preplant.
N Source
Russet Norkota
100% ESN at planting
80% ESN at planting
100% N-guard at planting
80% N-guard at planting
80 % ESN at emergence
80% N-guard at emergence
100% GP-30
80% GP-30
100% GSP
N at Planting
80% GP-30 100 UAN
100% GSP
80% GSP
Other N
392
313
392
313
392
392
112 UAN
112 UAN
80% GSP
Russet Burbank
100% ESN at emergence
80% ESN at emergence
100% N-guard at emergence
80% N-guard at emergence
100 % ESN at planting
100% N-guard at planting
100% GP-30 100 UAN
N at Emergence
112 Urea
70x4
50x4
269 Urea
89 Urea
201 Urea
392
313
392
313
313
313
112
140x2
112
112 Urea
112x2
269 Urea
89 Urea
201 Urea
Notes
All at Emergence
All at Emergence
All at Emergence
All at Emergence
All at Planting
All at Planting
Applied for 4 weeks starting at Emergence
Applied for 4 weeks starting at Emergence
Other 240 kg N-urea split 5 times in growing
season
Other 180 kg N-urea split 5 times in growing
season
All at Planting
All at Planting
All at Planting
All at Planting
All at Emergence
All at Emergence
Applied for 2 weeks starting at Emergence
Applied for 2 weeks starting at Emergence
Other 240 kg N-urea split 5 times in growing
season
Other 180 kg N-urea split 5 times in growing
season
82
Table 4.3. Nitrogen treatments for Russet Norkota and Russet Burbank for 2008, listing N source, N rates (kg ha-1), and application timing.
Unless noted, N rates represent N treatment product. All plots received 22 kg N/ha preplant.
N Source
Russet Norkota
100% ESN at planting
80 % ESN at planting
80% ESN at emergence
100% NSN at emergence
80% NSN at emergence
80% N-guard at emergence
100% GP-30 90 UAN
80% GP-30 90 UAN
100% N standard
80% N standard
100 % SU at emergence
80% SU at emergence 70 urea
80% SU at emergence
Russet Burbank
100 % ESN at planting
100% ESN at emergence
80% ESN at emergence plus
100% NSN at emergence
80% NSN at emergence plus
20% later
80% NSN at emergence
100% GP-30 90 uan at
80% GP 30 90 uan at
100% N standard
80% N standard
100 % SU at emergence
80% SU at emergence plus
80% SU at emergence
Planting
Emergence
336
269
Other
67 Urea
269
336
269
269
100 UAN
100 UAN
100 Urea
89 Urea
336
269
269
392
313
67
67x4
38x4
212 Urea
156 Urea
67
78 Urea
313
392
313
313
100 UAN
100 UAN
100 Urea
89 Urea
392
313
313
78
67x4
39x4
269 Urea
201 Urea
78
Notes
All at Planting
All at Planting
All at Emergence
All at Emergence
Other Applied June 26
All at Emergence
Other Applied for 4 weeks starting after Emergence
Other Applied for 4 weeks starting after Emergence
Other 212 kg N-urea split 5 times during growing season
Other 156 kg N-urea split 4 times during growing season
All at Emergence
Other Applied June 19
All at Emergence
All at Planting
All at Planting
All at Emergence
All at Emergence
Other Applied June 26
All at Emergence
Other Applied for 4 weeks starting at emergence
Other Applied for 4 weeks starting at emergence
Other 269 kg N-urea split 7 times during growing season
Other 201 kg N-urea split 6 times during growing season
All at Emergence
Other Applied on June 1
All at Emergence
83
Table 4.4. Nitrogen treatments for Russet Burbank for 2009, listing N source, N rates (kg ha-1), and application timing. Unless noted, N rates
represent N treatment product. All plots received 22 kg N/ha preplant.
Nitrogen Source
ESN 330 Plant
ESN 330 Emerg
ESN 290 Emerg
ESN 250 Emerg
ESN 210 Emerg
ESN 260 Emerg
ESN 180 Emerg
GSP 350 Emerg
GSP 280 Emerg
GSP 350 Plant
SU 330 Plant
SU 260 Emerg
SU 104 Emerg
70 NF +55 UAN
88 NF + 37 UAN
70 NF 100 UAN
88 NF 152 UAN
70 NF +190 UAN
88 NF + 242 UAN
Planting
369
Emergence
0
369
325
280
235
291
244
100 Urea
100 Urea
118 Urea
369
Other
44 Urea
89 Urea
134 Urea
89 Urea
246 Urea
190 Urea
251 Urea
Notes
All at Planting
All at Emergence
All at Emergence
All at Emergence
All at Emergence
All at Emergence
All at Emergence
Other 246 kg N-urea split 5 times during growing season
Other 190 kg N-urea split 4 times during growing season
Other 251 kg N-urea split 5 times during growing season
291
123 Agrotain, 127 Urea
118
78 NF, 61 UAN
98 NF, 41 UAN
100 NF
151 UAN
229 UAN
78 NF, 112 UAN
98 NF, 271 UAN
78 NF, 212 UAN
98 NF, 271 UAN
Other, urea split 2 times, Agrotain split 3 times (5
separate applications)
Other 151 kg N-UAN split 3 times during growing season
Other 229 kg N-UAN split 5 times during growing season
Other all at tuberization
Other all at tuberization
Other 4 equal applications starting at emergence
Other 4 equal applications starting at emergence
84
Table 4.5. Mean monthly air temperature, soil temperature, and total precipitation for years 2007-2009.
o
o
----------Air Temp C-----------
--------Soil Temp C------------
-------Precipitation mm--------
2007
2008
2009
2007
2008
2009
2007
2008
2009
March
9.17
6.58
5.86
8.83
8.00
7.07
12.19
16.26
25.40
April
11.51
9.38
10.82
14.03
11.42
12.13
11.94
2.79
12.95
May
16.47
16.26
16.47
18.05
17.78
17.26
10.16
10.16
26.67
June
19.58
18.83
20.56
20.92
20.73
23.43
24.13
12.95
3.05
July
25.63
23.99
25.24
24.61
24.59
27.17
0.51
0.00
1.27
August
22.19
22.22
23.61
23.18
23.27
26.32
1.27
5.33
2.03
September
17.68
17.39
18.85
20.62
20.62
23.28
6.35
0.76
2.29
Average (total)
17.48
16.40
17.35
18.61
18.07
19.52
(66.55)
(48.26)
(73.66)
85
Table 4.6. Yield, potato class, specific gravity, and internal damage for Russet Norkota in 2007 as affected by N treatment. Values followed
by the same letter are not significantly different at the 0.1 probability level.
Treatment
100% ESN at planting
80% ESN at planting
100% N-guard at planting
80% N-guard at planting
80 % ESN at emergence
80% N-guard at emergence
100% GP-30
80% GP-30
100% N standard
80% N standard
Significance
LSD (0.1)
<113 g
Culls
2’s
113-340 g
> 340 g
US No 1
Total
Total
Mrktbl
yield
---------------------------------------------------Mg/ha-----------------------------------------7.6
0.0 B
0.9
65.7 ABC
27.6 BCD 93.5
94.6
102.4
8.3
0.0 B
1.3
65.5 ABC
20.8 D
86.3
87.7
96.4
6.9
0.9 A
1.1
51.1 E
39.2 A
90.3
91.7
99.5
7.6
0.0 B
1.3
54.9 DE
33.8 AB
88.8
90.3
98.2
7.6
0.0 B
1.3
67.7 AB
20.8 D
88.5
90.1
98.0
7.2
0.0 B
1.3
60.3 CD
30.3 BC
90.6
91.9
99.3
7.8
0.2 B
7.6
57.8 D
33.0 AB
91.0
98.6
106.9
9.4
0.0 B
1.6
50.7 E
39.5 A
90.3
91.9
101.5
7.8
0.0 B
1.3
61.4 BCD
35.0 AB
96.4
97.7
106.1
7.8
1.1 A
1.8
69.3 A
22.2 CD
91.5
93.5
102.6
NS
*
NS
*
*
NS
NS
NS
2.0
0.4
4.9
6.5
8.5
8.3
8.1
7.6
Specific
Gravity
1.0679
1.0691
1.0703
1.0712
1.0684
1.0705
1.0689
1.0684
1.0673
1.0676
NS
2.0
Total
Internals
%
12.5
7.5
10
2.5
7.5
0
20
15
7.5
10
NS
0.4
*Significance at the 0.1 probability level
86
87
Table 4.7. Petiole nitrate levels for Russet Norkota in 2007 as affected by N treatment and
sampling date (DAP). Values followed by the same letter are not significantly different at the 0.1
probability level.
Treatment
100% ESN at planting
80% ESN at planting
100% N-guard at planting
80% N-guard at planting
80 % ESN at emergence
80% N-guard at emergence
100% GP-30
80% GP 30
100% N standard
80% N standard
Significance
LSD (0.1)
Sample Dates
56
90
101 112
---------------------------g NO3-N/kg-------------------25.6 CD
16.1
AB
17.1 18.1 BC
23.2 E
16.6
AB
8.5
19.4 B
26.5 BC
12.2
B
9.5
14.2 BC
28.1 AB
12.4
B
10.8 12.8 C
23.5 E
12.3
B
8.3
14.3 BC
24.7 CDE 15.3
AB
11.4 15.3 BC
28.9 A
20.4
A
14.7 17.8 BC
27.8 AB
14.0
B
12.2 18.9 BC
24.5 DE
20.9
A
15.3 27.2 A
24.3 DE
11.1
B
13.2 16.1 BC
*
*
NS
*
1.9
5.6
6.9
6.6
*Significance at the 0.1 probability level
Table 4.8. Yield, potato class, and specific gravity for Russet Norkota in 2008 as affected by N treatment. Values followed by the same letter
are not significantly different at the 0.1 probability level.
Treatment
100% ESN at planting
80 % ESN at planting
80% ESN at emergence
100% NSN at emergence
80% NSN at emergence
80% N-guard at emergence
100% GP-30 90 UAN at emergence
80% GP-30 90 UAN at emergence
100% N standard
80% N standard
100 % SU at emergence
80% SU at emergence with 70 urea
80% SU at emergence
Significance
LSD
<113 g
Culls
2’s
113-340 g
> 340 g
US No 1
Total
Total
Mrktbl yield
-----------------------------------------Mg/ha--------------------------------------------------4.7
0.0
4.7
59.0
13.0
72.0
76.7
81.8
5.2
0.2
3.4
60.1
8.1
68.1
71.5
77.1
6.3
0.2
3.1
58.5
13.0
71.5
74.6
81.1
5.6
0.0
4.9
56.5
17.0
73.3
77.3
83.8
5.6
0.0
4.5
59.4
16.6
76.0
80.3
85.9
4.7
0.4
6.5
59.9
13.2
72.9
79.4
84.7
6.5
0.0
4.0
62.5
9.4
72.0
76.0
82.5
5.4
0.0
4.5
61.6
9.2
70.8
75.5
80.9
5.4
0.2
4.9
62.5
13.5
75.8
80.9
86.8
4.0
0.0
3.6
60.1
13.2
73.3
76.9
81.1
5.2
0.0
4.3
62.3
10.5
72.9
76.9
82.0
7.2
0.9
4.9
51.3
11.4
62.5
67.5
75.5
4.0
0.0
3.1
58.3
10.5
68.8
72.0
76.0
NS
NS
NS
NS
NS
NS
NS
NS
1.6
0.7
2.0
7.4
7.8
8.7
8.7
8.7
Specific
Gravity
1.0712 AB
1.0698 ABCD
1.0676 DE
1.0688 CD
1.0718 A
1.0706 ABC
1.0694 BCD
1.0702 ABC
1.0694 BCD
1.0714 AB
1.0698 ABCD
1.0656 E
1.0698 ABCD
*
0.002
*Significance at the 0.1 probability level
88
89
Table 4.9. Petiole nitrate levels for Russet Norkota in 2008 as affected by N treatment and
sampling date (DAP). Values followed by the same letter are not significantly different at the 0.1
probability level.
Treatment
Sample Dates
76
83
-----g NO3-N/kg----100% ESN at planting
26.0
25.3 AB
80 % ESN at planting
24.6
26.4 A
80% ESN at emergence
23.8
23.1 BC
100% NSN at emergence
25.0
26.7 A
80% NSN at emergence plus 20% later
24.7
25.1 AB
80% N-guard at emergence
22.2
24.9 AB
100% GP-30 90 UAN at emergence
23.8
24.4 ABC
80% GP-30 90 UAN at emergence
23.0
23.4 BC
100% N standard
24.8
22.3 C
80% N standard
21.7
18.2
100 % SU at emergence
27.6
24.5 ABC
80% SU at emergence with 70 urea
27.1
23.5 BC
80% SU at emergence
25.8
24.2 ABC
Significance
NS
*
LSD (0.1)
3.3
2.3
*Significance at the 0.1 probability level
D
Table 4.10. Yield, potato class, specific gravity, and internal damage for Russet Burbank in 2007 as affected by N treatment. Values followed
by the same letter are not significantly different at the 0.1 probability level.
Treatment
100% ESN at emergence
80% ESN at emergence
100% N-guard at emergence
80% N-guard at emergence
100 % ESN at planting
100% N-guard at planting
100% GP-30 100 UAN
80% GP-30 100 UAN
100% N standard
80% N standard
Significance
LSD (0.1)
<113 g
Culls
2’s
113-340 g
> 340 g
US
Total
Total
No 1 Mrktbl
yield
---------------------------------------------------Mg/ha------------------------------------------------11.2
2.5
29.6 ABC
36.5 D
16.6
53.1
82.9 C
96.8 C
10.5
0.7
23.1 CDE
43.3 BCD
15.7
59.0
82.0 C
93.5 C
11.4
1.1
24.4 BCD
39.5 BCD
20.6
60.1
84.7 C
97.5 C
6.9
0.2
13.7 E
47.3 B
31.2
78.7
92.6 BC
100.0 C
10.1
0.7
25.6 BCD
37.9 CD
24.0
61.9
87.7 C
98.6 C
7.6
0.2
17.3 DE
40.8 BCD
28.7
69.5
87.0 C
94.8 C
8.1
1.1
19.5 CDE
46.2 BC
30.5
76.7
96.2 BC
105.6 BC
10.5
0.7
15.5 DE
57.8 A
18.2
76.2
91.7 BC
103.1 C
8.3
0.7
38.1 A
39.0 BCD
34.1
73.3
111.4 A
120.6 A
10.1
0.9
34.5 AB
41.0 BCD
30.0
71.1
105.6 AB
116.8 AB
NS
NS
*
*
NS
NS
*
*
3.4
1.8
10.3
8.7
13.7
16.8
14.1
13.0
Specific
Gravity
1.0768
1.0817
1.0801
1.0835
1.0805
1.0868
1.081
1.0832
1.0774
1.0793
NS
0.0063
Total
Internals
%
20
8
4
4
2
8
8
4
10
12
NS
12
*Significance at the 0.1 probability level
90
91
Table 4.11. Petiole nitrate levels for Russet Burbank in 2007 as affected by N treatment and
sampling date (DAP). Values followed by the same letter are not significantly different at the 0.1
probability level.
Treatment
Sample Dates
56
90
101
112
128
--------------------------------g NO3-N/kg------------------------------100% ESN at emergence
80% ESN at emergence
22.1
22.0
C
C
26.8
23.3
24.9
22.6
AB
BCDE
23.4
20.8
AB
BC
14.7
10.9
100% N-guard at emergence
80% N-guard at emergence
23.0
22.1
C
C
21.6
17.7
22.8
16.8
BCD
F
13.8
16.6
D
CD
11.2
12.0
100 % ESN at planting
22.4
C
26.3
24.2
BC
21.0
BC
13.0
100% N-guard at planting
100% GP-30 100 uan at planting
23.4
25.1
BC
AB
22.9
21.1
23.1
20.1
BCD
DEF
25.4
21.5
AB
B
13.4
12.8
80% GP 30 100 uan at planting
100% N standard
26.2
22.9
A
C
23.6
25.1
19.5
27.7
EF
A
20.8
27.4
BC
A
12.3
15.9
80% N standard
Significance
21.9
*
C
22.0
NS
21.4
*
CDE
16.6
*
CD
14.2
NS
LSD 0.1
1.8
5.3
3.2
*Significance at the 0.1 probability level
4.6
4.6
Table 4.12. Yield, potato class, specific gravity, and internal damage for Russet Burbank in 2008 as affected by N treatment. Values followed
by the same letter are not significantly different at the 0.1 probability level.
Treatment
100 % ESN at planting
100% ESN at emergence
80% ESN at emergence plus
20% urea
100% NSN at emergence
80% NSN at emergence plus
20% later
80% NSN at emergence
100% GP-30 90 uan at
emergence
80% GP 30 90 uan at
emergence
100% N standard
80% N standard
100 % SU at emergence
80% SU at emergence and
80% SU at emergence
Significance
LSD (0.1)
Total
Total
Mrktbl
yield
------------------------------------------------------Mg/ha-----------------------------------------------7.8
1.1
12.3 C
39.5 BCDE 18.8
58.3 BCDE 70.4 DE
79.6 CD
9.4
0.2
11.4 C
40.1 BCD
15.0
55.1 DEF
66.6 E
76.2 D
7.8
0.4
12.1 C
44.2 AB
22.4
66.6 AB
78.7 BCD 87.2 BC
1.074
1.072
1.092
Total
Internals
%
32
42
32
8.3
6.5
0.0
0.4
14.3 BC
15.0 BC
35.0 CDE
41.5 ABC
24.7
24.2
59.6 BCDE
65.7 ABC
73.8 CDE
80.7 BC
82.3 CD
87.9 BC
1.071
1.077
28
28
5.6
7.8
1.3
0.2
13.2 C
17.0 ABC
48.6 A
39.9 BCD
14.1
16.8
62.8CD
56.7 CDEF
76.0 CDE
73.5 CDE
82.9 CD
81.8 CD
1.08
1.082
26
26
8.1
0.2
15.5 BC
34.3 CDE
22.6
57.2 CDE
72.6 CDE
81.1 CD
1.078
36
7.4
6.7
0.2
1.1
16.4 ABC
14.6 ABC
46.2 AB
40.8 BCD
27.8
20.4
74.2 A
61.2 BCDE
90.6 A
77.6 BCD
1.088
1.087
48
42
7.6
7.6
6.7
NS
3.1
1.3
0.9
0.2
NS
1.1
22.2 A
19.5 AB
22.9 A
*
6.1
32.1 E
34.1 DE
39.9 BCDE
*
7.4
15.7
19.1
24.2
NS
9.2
47.7 F
53.1 EF
63.9 BCD
*
9.0
69.9 DE
72.4 CDE
86.8 AB
*
15.2
98.2 A
85.4
BCD
79.1 CD
80.9 CD
93.9 AB
*
9.6
1.091
1.082
1.079
NS
0.0161
40
26
38
NS
19
<113 g
Culls
2’s
113-340 g
> 340 g
US No 1
Specific
Gravity
*Significance at the 0.1 probability level
92
93
Table 4.13. Petiole nitrate levels for Russet Burbank in 2008 as affected by N treatment and
sampling date (DAP). Values followed by the same letter are not significantly different at the 0.1
probability level.
Treatment
100 % ESN at planting
100% ESN at emergence
80% ESN at emergence plus 20% urea
100% NSN at emergence
80% NSN at emergence plus 20% later
80% NSN at emergence
100% GP-30 90 uan at emergence,
80% GP 30 90 uan at emergence planting
100% N standard
80% N standard
100 % SU at emergence
80% SU at emergence and
80% SU at emergence
Significance
LSD (0.1)
*Significance at the 0.1 probability level
Sample Date
76
83
------------g NO3-N/kg---------22.6 ABC
19.7 CD
23.0 ABC
19.3 CDE
22.7 ABC
25.4 AB
23.6 AB
22.9 ABC
19.6 C
25.5 A
19.8 C
22.5 ABC
24.1 AB
21.4 ABCD
13.9 D
15.1 E
23.3 ABC
23.2 ABC
21.0 BC
17.4 DE
25.0 A
21.0 BCD
24.5 AB
21.4 ABCD
25.1 A
25.3 AB
*
*
3.7
4.4
Table 4.14. Yield, potato class, specific gravity, and internal damage for Russet Burbank in 2009 as affected by N treatment. Values followed
by the same letter are not significantly different at the 0.1 probability level.
Treatment
ESN 330 Plant
ESN 330 Emerg
ESN 290 Emerg
ESN 250 Emerg
ESN 210 Emerg
ESN 260 Emerg
ESN 180 Emerg
GSP 350 Emerg
GSP 280 Emerg
GSP 350 Plant
SU 330 Plant
SU 260 Emerg
SU 104 Emerg
70 NF +55 UAN
88 NF + 37 UAN
70 NF 100 UAN
88 NF 152 UAN
70 NF +190 UAN
88 NF + 242 UAN
Significance
LSD (0.1)
<113 g
Culls
2’s
113-340 g
> 340 g
US No 1's
Total Mrkble
Total
Yield
--------------------------------------------------------Mg/ha------------------------------------------------------------------7.8
0.4
9.2 A
44.2 EFG
16.1
60.3
69.7
78.2
5.8
0.4
6.9 ABCDE
46.4 DEFG 15.5
61.9
69.0
75.5
5.8
0.0
8.7 AB
40.6
G
21.1
61.9
70.6
76.7
5.6
0.0
4.7 DEF
41.2
G
15.9
57.4
62.1
68.1
7.2
0.2
5.2 CDEF
43.3
FG
15.5
59.0
64.1
72.0
7.4
0.0
4.0 EF
49.8 BCDE
10.8
60.8
65.0
72.6
6.9
0.7
4.3 EF
41.7
G
15.7
57.4
61.9
69.7
6.7
0.0
8.5 ABC
43.0
FG
17.5
60.8
69.3
76.2
7.4
0.4
3.8 EF
49.5 BCDE
13.5
63.2
67.0
75.1
6.9
4.0
5.6 BCDEF
44.8 EFG
13.7
58.7
64.3
75.5
7.2
0.4
5.8 ABCDEF 44.4 EFG
16.4
61.0
67.0
74.9
5.6
0.2
3.8 EF
45.5 DEFG 12.1
57.6
61.6
67.7
7.8
0.4
8.1 ABCD
52.9 ABC
12.1
65.2
73.3
81.8
9.0
0.2
4.9 DEF
55.6 AB
11.0
66.6
71.5
80.9
7.4
0.0
6.7 ABCDEF 51.6 ABCD
13.2
64.8
71.7
79.4
8.3
0.4
3.4
F
48.6 CDEF
6.3
54.9
58.5
67.5
8.1
0.2
4.7 DEF
49.5 BCDE
14.1
63.9
68.8
77.3
8.3
0.2
4.7 DEF
48.9 CDEF
11.7
60.8
65.5
74.0
6.7
0.0
4.0 EF
57.2 A
14.1
71.3
75.3
82.3
NS
NS
*
*
NS
NS
NS
NS
1.8
2.0
3.4
6.1
6.5
9.0
9.0
8.7
Specific
Gravity
1.0753
1.0775
1.0759
1.0741
1.0772
1.0793
1.0785
1.0648
1.0794
1.0769
1.0698
1.0776
1.0769
1.0790
1.0516
1.0760
1.0755
1.0838
1.0823
NS
0.0144
AB
AB
AB
AB
AB
A
AB
BC
A
AB
AB
AB
AB
AB
C
AB
AB
A
A
Total
Internals
%
14
6
8
8
6
6
4
8
8
10
8
14
4
12
4
26
4
10
4
NS
10.8
*Significance at the 0.1 probability level
94
95
Table 4.15. Petiole nitrate levels for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP). Values followed by the same letter are not significantly different at the 0.1
probability level.
Treatments
Sample Dates
49
59
95
115
------------------------------------------g NO3-N/kg--------------------------------------ESN 330 Plant
18.9 ABC
20.0 AB
7.1 CDE
12.8 ABCD
ESN 330 Emerg
19.1 AB
18.5 ABCD
15.1 A
15.4 AB
ESN 290 Emerg
19.5 A
18.1 ABCD
12.9 AB
15.2 ABC
ESN 250 Emerg
18.8 ABC
19.5 ABC
13.6 AB
16.6 A
ESN 210 Emerg
19.0 AB
19.9 AB
14.8 AB
13.7 ABC
ESN 260 Emerg
16.7 CDEFG
15.4 CDEF
14.0 AB
13.6 ABC
ESN 180 Emerg
18.1 ABCD
19.4 ABC
7.9 CD
11.2 CDEF
GSP 350 Emerg
17.5 ABCDEF
14.5
12.2 AB
14.3 ABC
GSP 280 Emerg
17.7 ABCDE
16.0 BCDE
10.9 BC
8.8
DEFG
GSP 350 Plant
17.1 BCDEF
11.6
13.7 AB
7.6
FGH
SU 330 Plant
19.2 AB
20.6 A
7.7 CD
12.7 ABCD
SU 260 Emerg
17.9 ABCD
19.7 ABC
7.5 CD
15.4 AB
SU 104 Emerg
16.8 CDEFG
8.7
HI
4.1
DEFG
7.6
DEF
12.2 BCDE
DEFG
EFGH
FGH
70 NF +55 UAN
15.6
EFG
11.8
EFGH
5.8
88 NF + 37 UAN
16.4
DEFG
11.4
FGH
7.1 CDE
8.3
EFG
70 NF 100 UAN
17.2 BCDEF
16.6 ABCD
3.4
EFG
3.9
H
88 NF 152 UAN
16.3
16.8 ABCD
5.3
DEFG
5.6
GH
DEFG
70 NF +190 UAN
14.8
G
6.3
I
1.6
G
5.0
GH
88 NF + 242 UAN
15.5
FG
10.2
GHI
3.1
FG
3.9
H
Significance
*
*
*
*
LSD (0.1)
2.1
4.4
3.9
4.1
*Significance at the 0.1 probability level
96
Table 4.16. Potato plant N concentration (%) for Russet Burbank in 2009 as affected by N
treatment and sampling date (DAP). Values followed by the same letter are not significantly
different at the 0.1 probability level.
Treatment
Sample Dates
59
64
78
95
115
-------------------------------------------------%--------------------------------------------ESN 330 Plant
2.85
4.38
3.93 ABCD
3.44 AB
2.52
ESN 330 Emerg
2.80
3.85
4.10 ABC
3.28 AB
3.13 A
ESN 290 Emerg
3.39
4.26
3.91 ABCD
3.41 AB
2.99 ABCD
ESN 250 Emerg
3.74
4.29
4.29 A
3.19 ABC
3.05 AB
ESN 210 Emerg
3.71
4.37
3.90 ABCDE
3.29 AB
2.80 BCDEF
ESN 260 Emerg
3.38
4.18
3.69 CDEFG
3.13 ABC
2.62
EFGH
ESN 180 Emerg
3.10
4.20
4.02 ABC
3.08 BC
2.53
FGHI
GSP 350 Emerg
2.98
4.27
4.06 ABC
3.36 AB
3.04 ABC
GSP 280 Emerg
2.95
4.48
3.82 BCDEF
3.18 ABC
2.72
GSP 350 Plant
2.59
4.45
3.87 ABCDE
3.12 ABC
2.79 BCDEFG
SU 330 Plant
3.11
4.42
4.26 AB
3.49 A
2.76 CDEFGH
SU 260 Emerg
2.51
4.01
3.86 ABCDE
3.40 AB
2.50
SU 104 Emerg
2.81
4.77
3.83 BCDEF
3.11 ABC
2.87 ABCDE
70 NF +55 UAN
3.10
3.29
3.50
DEFGH
3.33 AB
2.64
EFGH
88 NF + 37 UAN
2.91
4.02
3.44
EFGH
2.86 C
2.29
IJ
70 NF 100 UAN
2.39
4.57
3.40
FGH
2.38
2.11
JK
88 NF 152 UAN
2.99
4.24
3.36
GH
2.40
D
1.93
K
70 NF +190 UAN
2.66
4.33
3.20
H
2.39
D
1.87
K
88 NF + 242 UAN
3.01
4.13
3.22
H
2.30
D
1.99
K
Significance
NS
NS
*
*
*
LSD (0.1)
0.85
0.45
0.37
0.28
0.73
*Significance at the 0.1 probability level
D
GHI
DEFGH
HI
97
GENERAL CONCLUSIONS
Jess Charles Holcomb III
98
The use of enhanced efficiency nitrogen (N) fertilizers and cultivation practices were
able to reduce loss of N into the environment. Agrotain-treated urea reduced NH3 loss by 71.8%
over urea in grass seed. Across irrigation rates of 0.0 and 1.25-mm, N loss was 5.7 to 6.2% of N
applied for Agrotain compared to urea and OAC with loss of 53.4 to 60.0% of N applied. Only at
7.6 mm of irrigation did loss decline for urea and OAC with 17.3 and 8.1%, respectively.
Agrotain at 7.6 mm irrigation lost 3.17% of N applied. Agrotain also was inhibiting urease after
23 days after application compared to urea and OAC. Organo acid complex did not reduce NH3
loss unless it was incorporated into the soil. Although the use of Agrotain reduced N loss,
enhanced efficiency fertilizers are not the sole options. The use of ammonium sulfate reduced
NH3 loss by 60.4% of N applied compared to urea. Irrigation also reduced loss and incorporated
urea; an application of 14.6 mm reduced NH3 loss by 90% compared to no irrigation.
The reduction in N loss measured in the NH3 volatilization studies did not translate to
increased yield in potato trials. Enhanced efficiency N products maintained yield in only one
year of the study, with reduced yield for two years with Russet Burbank. Products typically
produced yields similar to the 80% N treatments, suggesting N was not being released according
to plant uptake. These products were able to maintain yields for two years with Russet Norkota.
However, all treatments in the Russet Norkota study maintained yields; even the 80% N
treatments suggested that N was not limiting. These products also make nitrate petiole
sampling obsolete, as nitrate does not accurately reflect plant N levels. Since these products do
not consistently maintain yield and are more expensive, they cannot be incorporated into
production systems in the Columbia Basin at this time. The use of cultural practices, such as
split applications of N, continue to produce maximum yields as well as reduce N loss compared
to applying N all at once. Further work with these products needs to be done in order to link the
reduction in environmental N loss to increased yields or lower N rates. Yield data from the nonirrigated and irrigated NH3 loss studies may have provided valuable insight into whether a
reduction in N loss did result in greater yield.
The N release rates from enhanced efficiency products exhibited how they reduce N loss
and how it may be affecting yield. All products tested, excluding NSN and OAC, were able to
delay N release compared to urea. Delay was affected by temperature, with lower
temperatures leading to a longer delay period. The delay in N release protects it from loss, as
less N is susceptible. It also allows more time for incorporation, further reducing loss. However,
99
delayed N can stress the plant, as adequate N is not available. Nitrogen release from these
products must meet N uptake demands for the crop in order to be successful. This may be a
problem since all products increased delay with cooler temperatures, so environmental
conditions will affect available N on a yearly basis.
Growers have multiple tools to use to reduce N loss into the environment. When
applying N, applying irrigation or a non-urea N source can be used reduce N volatilization. If
these are not available, the use of a urease inhibitor such as Agrotain may be used to reduce
loss. However, the reduction obtained with the use of products needs to result in an increased
yield or a reduction in N rate to make them viable. This may be heavily dependent on the crop
and cropping system used, as evident with the lack in yield increase in the potato study. Further
work needs to be done to determine into which cropping systems these products can be
successfully incorporated.
100
BIBLIOGRAPHY
Allison, F.E. 1955. The enigma of soil nitrogen balance sheets. Adv. Agron. 7:213-250.
Alva, A.K., T. Hodges, R.A. Boydston, and H.P. Collins. 2002. Effects of irrigation and tillage
practices on yield of potato under high production conditions in the Pacific Northwest.
Commun. Soil Sci. Plant Anal. 33:1451-1460.
Asfary, A.F., A. Wild, and P.M. Harris. 1983. Growth, mineral nutrition and water use by potato
crops. J. Agric. Sci., Camb. 100:87-101.
Asman, W.A.H., M.A. Sutton, and J.K. Schjorring. 1998. Ammonia: emission, atmospheric
transport and deposition. New Phytologist 139:27-48.
Biemond, H. and J. Vos. 1992. Effects of nitrogen on the development and growth of the potato
plant. 2. The partitioning of dry matter, nitrogen and nitrate. Ann. Bot. 70:37-45.
Black, A.S., R.R. Sherlock, and N.P. Smith. 1987. Effect of timing of simulated rainfall on
ammonia volatilization from urea, applied to soil of varying moisture content. J. Soil Sci.
38:679-687.
Blossfeld, S., B. Wade, C. Watson, R. Laughlin, and C. Krause. 2009. ‘N-sight’ technique: a visual
and quantitative analysis of urea hydrolysis and ammonia loss from soil. Available at
http://escholarship.org/uc/item/6jq4j315 (verified 21 Dec. 2010). UC Davis: The
Proceedings of the International Plant Nutrition Colloquium XVI, Davis, CA.
Bouwmeester, R.J.B., P.L.G. Vlek, and J.M. Stumpe. 1985. Effect of environmental factors on
ammonia volatilization from urea-fertilized soil. Soil. Sci. Soc. Am. J. 49:376-381.
Boyer, E.W., C.L. Goodale, N.A. Jaworski, and R.W. Howarth. 2002. Anthropogenic nitrogen
sources and relationships to riverine nitrogen export in the northeastern U.S.A.
Biogeochemistry 57/58:137-169.
Burch, J.A., and R.H. Fox. 1989. The effect of temperature and initial soil moisture content on
the volatilization of ammonia from surface applied urea. Soil Science 147:311-318.
Cabrera, M.L., D.E. Kissel, R.C. Davis, N.P. Qafoku, and W.I. Segars. 2001. Design and ammoniarecovery evaluation of a wind speed-sensitive chamber system. Soil Sci. Soc. Am. J.
65:1302-1306.
Carmona, G., C.B. Christianson, and B.H. Byrnes. 1990. Temperature and low concentration
effects of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) on ammonia
volatilization from urea. Soil Biol. Biochem. 22:933-937.
Christianson, C.B., W.E. Baethgen, G. Carmona, and R.G. Howard. 1993. Microsite reactions of
urea-nBTPT fertilizer on the soil surface. Soil Biol. Biochem. 25:1107-1117.
101
Cox, D., and T.M. Addiscott. 1976. Sulphur-coated urea as a fertilizer for potatoes. J. Sci. Food
Agric. 27:1015-1020.
Craig, J.R., and A.G. Wollum, II. 1982. Ammonia volatilization and soil nitrogen changes after
urea and ammonium nitrate fertilization of Pinus taeda L. Soil Sci. Soc. Am. J. 46:409414.
Delgado, J.A. and A.R. Mosier. 1996. Mitigation alternatives to decrease nitrous oxides
emissions and urea-nitrogen loss and their effect on methane flux. J. Environ. Qual.
25:1105-1111.
Elkashif, M.E., S.J. Locascio, and D.R. Hensel. 1983. Isobutylidene diurea and sulfur-coated urea
as N sources for potatoes. J. Amer. Soc. Hort. Sci. 108:523-526.
Ernst, J.W. and H.F. Massey. 1960. The effects of several factors on volatilization of ammonia
formed from urea in soil. Soil Sci. Soc. Proc. 24:87-90.
Errebhi, M., C.J. Rosen, S.C. Gupta, and D.E. Birong. 1998. Potato yield response and nitrate
leaching as influenced by nitrogen management. Agron. J. 90:10-15.
Fenn, M.E., J.S. Baron, E.B. Allen, H.M. Rueth, K.R. Nydick, L. Geiser, W.D. Dowman, J.O.
Sickman, T. Meixner, D.W. Johnson, and P. Neitlich. 2003. Ecological effects of nitrogen
deposition in the western United States. BioScience 53: 404-420.
Fenn, M.E., L. Geiser, R. Bachman, T.J. Blubaugh, and A. Bytnerowicz. 2007. Atmospheric
deposition inputs and effects on lichen chemistry and indicator species in the Columbia
River Gorge, USA. Environmental Pollution 146:77-91.
Fenn, L.B., and L.R. Hossner. 1985. Ammonia volatilization from ammonium or ammoniumforming nitrogen fertilizers. Adv. Soil Sci. 1:123-169.
Fenn, L.B. and S. Miyamoto. 1981. Ammonia loss and associated reactions of urea in calcareous
soils. Soil Sci. Soc. Am. J. 45:537-540.
Ferguson, R.B., and D.E. Kissel. 1986. Effects of soil drying on ammonia volatilization from
surface-applied urea. Soil Sci. Soc. Am. J. 50:485-490.
Ferguson, R.B., D.E. Kissel, J.K. Koelliker, and W. Basel. 1984. Ammonia volatilization from
surface applied urea: Effect of hydrogen ion buffering capacity. Soil Sci. Soc. Am. J.
78:741-746.
Ferm, M. 1998. Atmospheric ammonia and ammonium transport in Europe and critical loads: a
review. Nutrient Cycling in Agroecosystems 51:5-17.
Gavlak R.G., D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2003a. Total nitrogen in
botanical materials. Soil, plant and water reference methods for the western region.
2:146-147.
102
Gavlak R.G., D.A. Horneck, R.O. Miller, and J. Kotuby-Amacher. 2003b. Extractable potassium,
nitrate, ammonium, ortho-phosphate, and chloride of botanical materials. Soil, plant
and water reference methods for the western region. 150-152.
Geiser, L.H., and P.N. Neitlich. 2007. Air pollution and climate gradients in western Oregon and
Washington indicated by epiphytic macrolichens. Environ. Pollut. 145:203-218.
Goulding, K. 2000. Nitrate leaching from arable and horticultural land. Soil use and
management 16:145-151.
Grant, C.A., S. Jia, K.R. Brown, and L.D. Bailey. 1996. Volatile losses of NH3 from surface-applied
urea and urea ammonium nitrate with and without the urease inhibitors NBPT or
ammonium thiosulphate. Can. J. Soil Sci. 76:417-419.
Hanafi, M.M, S.M. Eltaib, M.B. Ahmad, and S.R. Syed Omar. 2002. Evaluation of controlledrelease compound fertilizers in soil. Commun. Soil Sci. Plant Anal. 33:1139-1156.
Hargrove, W.L. 1988. Soil, environmental, and management factors influencing ammonia
volatilization under field conditions. p. 17-36. In B.R. Bock and D.E. Kissel (ed.) Ammonia
volatilization from urea fertilizers. Bull. Y-206. National Fertilizer Development Center,
Tennessee Valley Authority, Muscle Shoals, Alabama.
Harper, L.A., V.R. Catchpoole, R. Davis, and K.L. Weir. 1983. Ammonia volatilization: Soil, plant
and microclimate effects on diurnal and seasonal fluctuations. Agron. J. 75:212-218.
Harre, E.A., and J.D. Bridges. 1988. Importance of urea fertilizers. p. 1-15. In B.R. Bock and D.E.
Kissel (ed.) Ammonia volatilization from urea fertilizers. Bull. Y-206. National Fertilizer
Development Center, Tennessee Valley Authority, Muscle Shoals, Alabama.
Havelka, U.D., M.G. Boyle, and R.W. F. Hardy. 1982. Biological nitrogen fixation. p. 365-422. In
F.J. Stevenson (ed.) Nitrogen in Agricultural soils. ASA, CSSA, and SSSA, Madison, WI.
Holcomb III, J.C., and D.A. Horneck. 2009. Effect of Agrotain treated urea on ammonia
volatilization in Kentucky bluegrass in the Columbia Basin Oregon. Seed Production
Research at Oregon State USDA-ARS Cooperating 53-56.
Holcomb III, J.C., D. A. Horneck, D. M. Sullivan, and G.H. Clough. In Review. Effect of irrigation
rate on ammonia volatilization.
Honisch, M., C. Hellmeier, and K. Weiss. 2002. Response of surface and subsurface water
quality to land use changes. Geoderma 105:277-298.
Hopkins, B.G., C.J. Rosen, A.K. Shiffler, and T.W. Taysom. 2008. Enhanced efficiency fertilizers
for improved nutrient management: Potato (Solanum tubersum). Online. Crop
Management doi: 10.1094/CM-2008-0317-01-RV.
Hutchinson, C., E. Simonne, P. Solano, J. Meldrum, and P. Livingston-Way. 2003. Testing of
controlled release fertilizer programs for seep irrigated Irish potato production. J. Plant
Nutr. 26:1709-1723.
103
IPCC. 1995. Radiative forcing of climate change and an evaluation of the IPCC IS92 emission
scenarios. In Houghton JT (ed) Climate Change 1994. Published for the IPCC. Cambridge
University Press, Cambridge, pp 337.
Isermann, K. 1994. Agriculture’s share in the emission of trace gases affecting the climate and
some cause-oriented proposals for sufficiently reducing this share. Environ. Pollut.
83:95-111.
Joern, B.C. and M.L. Vitosh. 1995. Influence of applied nitrogen on potato Part II: Recovery and
partitioning of applied nitrogen. Amer. Potato J. 72:73-84.
Jones, C.A., R.T. Koenig, J.W. Ellsworth, B.D. Brown, and G.D. Jackson. 2007. Management of
urea fertilizer to minimize volatilization. Montana State University Extension Bulletin
173.
Jones, J.L. and R.J. Wagner. 1995. Water-quality assessment of the Central Columbia Plateau in
Washington and Idaho. p. 119. Analysis of available nutrient and pesticide data for
ground water, 1942-92, US Geological Survey Water-Resources Investigations Report 944258.
Keeney, D.R. 1982. Nitrogen management efficiency and minimum pollution. p. 605-649. In
F.J. Stevenson (ed.) Nitrogen in Agricultural soils. ASA, CSSA, and SSSA, Madison, WI.
Keeney, D.R. and D.W. Nelson. 1982. Nitrogen—inorganic forms. p.643-698. In A.L. Page, R.H.
Miller, and D.R. Keeney (ed.) Methods of soil analysis. ASA, CSSA, and SSSA, Madison,
WI.
Keller, G.D., and D.B. Mengel. 1986. Ammonia volatilization from nitrogen fertilizers surface
applied to no-till corn. Soil Sci. Soc. Am. J. 501:1060-1063.
Kissel, D.E., M.L. Cabrera, and R. B. Ferguson. 1988. Reactions of ammonia and urea hydrolysis
products with soil. Soil Sci. Soc. Am. J. 52:1793-1796.
Kissel, D.E., M.L. Cabrera, N.Vaio, J.R. Craig, J.A. Rema, and L.A. Morris. 2004. Rainfall timing
and ammonia loss from urea in a loblolly pine plantation. Soil Sci. Soc. Am. J 68:17441750.
Kissel, D.E., M.L. Cabrera, N. Vaio, J.R. Craig, J.A. Rema, and L.A. Morris. 2009. Forest floor
composition and ammonia loss from urea in a loblolly pine plantation. Soil Sci. Soc. Am.
J. 73:630-637.
Kleinkopf, G.E., D.T. Westermann, and R.B. Dwelle. 1981. Dry matter production and nitrogen
utilization by six potato cultivars. Agron. J. 73:799-802.
Lauer, D.A. 1985. Nitrogen uptake patterns of potatoes with high-frequency sprinkler-applied N
fertilizer. Agron. J. 77:193-197.
Lauer, D.A. 1986. Russet Burbank yield response to sprinkler-applied nitrogen fertilizer. Amer.
Potato J. 63:61-69.
104
Ledgard, S.F., J.W. Penno, and M.S. Sprosen. 1999. Nitrogen inputs and losses from
clover/grass pastures grazed by dairy cows, as affected by nitrogen fertilizer application.
J. Agric. Sci., Cambridge 132:215-225.
Leuning, R., J.R. Freney, O.T. Denmead, and J.R. Simpson. 1985. A sampler for measuring
atmospheric ammonia flux. Atmos. Environ. 19:1117-1124.
Liegel, E.A. and L.M. Walsh. 1976. Evaluation of sulfur-coated urea (SCU) applied to irrigated
potatoes and corn. Agron. J. 68:457-463.
Lightner, J.W., D.B. Mengel, and C.L. Rhyderd. 1990. Ammonia volatilization from nitrogen
fertilizer surface applied to orchardgrass sod. Soil Sci. Soc. Am. J. 54:1478-1482.
Lorenz, O.A., B.L. Weir, and J.C. Bishop. 1972. Effect of controlled-release nitrogen fertilizers on
yield and nitrogen absorption by potatoes, cantaloupes, and tomatoes. J. Amer. Soc.
Hort. Sci. 97:334-337.
Lorenz, O.A., B.L. Weir, and J.C. Bishop. 1974. Effect of sources of nitrogen on yield and
nitrogen absorption of potatoes. Amer. Potato J. 51:56-65.
Malhi, S.S., E. Oliver, G. Mayerle, G. Kruger, and K.S. Gill. 2003. Improving effectiveness of
seedrow-placed urea with urease inhibitor and polymer coating for Durum wheat and
canola. Commun. Soil Sci. Plant Anal. 34:1709-1727.
Manunza, B., S. Deiana, M. Pintore, and C. Gessa. 1999. The binding mechanism of urea,
hydroxamic acid and N-(N-butyl)-phosphoric triamide to the urease active site. A
comparative molecular dynamics study. Soil Biology and Biochemistry 31:789-796.
Marshall, V.G., and D.S. DeBell. 1980. Comparison of four methods measuring volatilization
losses of nitrogen following urea fertilization of forest soils. Can. J. Soil Sci. 60:549-563.
Martha Jr., G.B., M. Corsi, P.C.O. Trivelin, and M.C. Alves. 2004. Nitrogen recovery and loss in a
fertilized elephant grass pasture. Grass and Forage Sci. 59:80-90.
McLean., E.O. 1982. Soil pH and lime requirement. p. 199-224. In A.L. Page, R.H. Miller, and
D.R. Keeney (ed.) Methods of soil analysis. ASA, CSSA, and SSSA, Madison, WI.
Meisinger, J.J, J.S. Schepers, and W.R. Raun. 2008. Crop nitrogen requirement and fertilization.
p. 563-612. In J.S. Schepers and W.R. Raun (ed.) Nitrogen in Agricultural systems. 49;
563-612.
Meyer, R.D., and D.B. Marcum. 1998. Potato yield, nitrogen, and soil nitrogen response to
water and nitrogen. Agron. J. 90:420-429.
Mosier, A.R. 1998. Soil processes and global change. Biol. Fertil. Soils 27:221-229.
Mugusha, A.G., and D.J. Pluth. 1995. Ammonia loss following surface application of urea
fertilizer to undrained and drained forested minerotrophic peatland sites in central
Alberta, Canada. For. Ecol. Manage. 78:139-145.
105
Mulla, D.J. and J.S. Strock. 2008. Nitrogen transport process in soil. p. 361-400. In J.S. Schepers
and W.R. Raun (ed.) Nitrogen in Agricultural systems. ASA, CSSA, and SSSA, Madison,
WI.
Mundy, G.N. 1995. Effect of initial soil water content and application of water on urea applied
to pasture. Aust. J. Agric. Res. 46:821-830.
Munoz, F., R.S. Mylavarapu, and C.M. Hutchinson. 2005. Environmentally responsible potato
production systems: A review. J. Plant Nutr. 28:1287-1309.
Nommik, H. and K. Wahtras. 1982. Retention and fixation of ammonium and ammonia in soils.
p. 123-171. In F.J. Stevenson (ed.) Nitrogen in Agricultural soils. ASA, CSSA, and SSSA,
Madison, WI.
Oberle, S.L., and L.G. Bundy. 1987. Ammonia volatilization from nitrogen fertilizers surface
applied to corn (Zea mays) and grass pasture (Dactylis glomerata). Biol. Fertil. Soils
4:185-192.
Ojala, J.C., J.C. Stark, and G.E. Kleinkopf. 1990. Influence of irrigation and nitrogen management
on potato yield and quality. Amer. Potato J. 67:29-43.
Olson, R.A. and L.T. Kurtz. 1982. Crop nitrogen requirements, utilization, and fertilization. p.
567-604. In F.J. Stevenson (ed.) Nitrogen in Agricultural soils. ASA, CSSA, and SSSA,
Madison, WI.
Olson-Rutz, K., C. Jones, and C.P. Dinkins. 2009. Enhanced efficiency fertilizers. Montana State
University Extension Bulletin 0188.
Pack, J.E., C.M. Hutchinson, and E.H. Simonne. 2006. Evaluation of controlled-release fertilizers
for Northeast Florida chip potato production. J. Plant Nut. 29:1301-1313.
Pasda, G., R. Hähndel, and W. Zerulla. 2001. Effect of fertilizers with the new nitrification
inhibitor DMPP (3,4-dimethylpyrazole phosphate) on yield and quality of agricultural
and horticultural crops. Biol. Fertil. Soils 34:85-97.
Pavek, M.J. and N.R. Knowles. 2009. Process Value-Methods. p 15. 2009 potato cultivar yield
and postharvest quality evaluations. Washington State University, Pullman, WA.
Peralta, J.M., and C.O. Stockle. 2001. Dynamics of nitrate leaching under irrigated potato
rotation in Washington state: a long-term simulation study. Agriculture, Ecosystems
and Environment 88:23-34.
Pitchford, M.L., M.C. Green, R. Morris, C. Emery, R. Sakata, C. Swab, and P.T. Mairose. 2008.
Columbia River Gorge air quality study science summary report. Available at
http://www.deq.state.or.us/aq/gorgeair/docs/FinalScienceSummaryReport.pdf (verified
7 Dec., 2010). Oregon DEQ, Portland, OR.
106
Porter, G.A. and J.A. Sisson. 1993. Yield, market quality and petiole nitrate concentration of nonirrigated Russet Burbank and Shepody potatoes in response to sidedressed nitrogen.
Amer. Potato J. 70:101-116.
Proctor, C., R. Koenig, and W. Johnston. 2010. Potential for ammonia volatilization from urea in
dryland Kentucky bluegrass seed production systems. Commun. Soil Sci. Plant Anal.
41:1-12.
Prunty, L., and R. Greenland. 1997. Nitrate leaching using two potato-corn N-fertilizer plans on
sandy soil. Agric. Ecosystems Environ. 65:1-13.
Ruser, R., H. Flessa, R. Schilling, F. Beese, and J.C. Munch. 2001. Effect of crop-specific field
management and N fertilization on N2O emissions from a fine-loamy soil. Nutrient
Cycling in Agroecosystems 59:177-191.
Ruser, R., H. Flessa, R. Schilling, H. Steindl, and F. Beese. 1998. Soil compaction and fertilization
effects on nitrous oxide and methane fluxes in potato fields. Soil Sci. Soc. Am. J.
62:1587-1595.
Ryker, J.S. and J.L. Jones. 1995. Nitrate concentration in groundwater of the central Columbia
Plateau. US Department of Interior, US Geological Survey. Open-File Report 95-445.
Sanz-Cobena, A., T.H. Misselbrook, A. Arce, J.I. Mingot, J.A. Diez, and A. Vallejo. 2008. An
inhibitor of urease activity effectively reduces ammonia emissions from soil treated with
urea under Mediterranean conditions. Agriculture, Ecosystems and Environment
126:243-249.
SAS Institute Inc. 2004. SAS/STAT® 9.1 User’s Guide. Cary, NC: SAS Institute Inc.
Schjoerring, J.K., S.G. Sommer, and M. Ferm. 1992. A simple passive sampler for measuring
ammonia emission in the field. Water, Air, and Soil Pollution 62:13-24.
Sharma, M., S. Kishore, S.N. Tripathi, and S.N. Behera. 2007. Role of atmospheric ammonia in
the formation of inorganic secondary particulate matter: A study at Kanpur, India. J.
Atmos. Chem. 58:1-17.
Shock, C.C., A.B. Pereira, and E.P. Eldredge. 2007. Irrigation best management practices for
potato. Amer. J. of Potato Res. 84:29-37.
Shoji, S., J. Delgado, A. Mosier, and Y. Miura. 2001. Use of controlled release fertilizers and
nitrification inhibitors to increase nitrogen use efficiency and to conserve air and water
quality. Commun. Soil Sci. Plant Anal. 32:1051-1070.
SigmaPlot 2000/2001 for scientists. 2002. SigmaPlot 2000/2001 for scientists, Merrickville,
Ontario Canada.
Sims, G.K., T.R. Elsworth, and R.L. Mulvaney. 1995. Microscale determination of inorganic
nitrogen in water and soil extracts. Commun. Soil Sci. Plant Anal. 26:303-316.
107
Singh, B. and G.S. Sekhon. 1976. Some measures of reducing leaching loss of nitrates beyond
potential rooting zone I. Proper co-ordination of nitrogen splitting with water
management. Plant and Soil 44:193-200.
Sommer, S.G. and A. K. Ersboll. 1996. Effect of air flow rate, lime amendments, and chemical
soil properties on the volatilization of ammonia from fertilizers applied to sandy soils.
Biol. Fertil. Soils 21:53-60.
Sommer, S.G., and J.E. Olesen. 1991. Effects of dry matter content and temperature on
ammonia loss from surface applied-cattle slurry. J. Environ. Qual. 20:679-683.
Statistix 9 Analytical Software. 2008. Statistix 9 User’s Manual, Analytical Software, Tallhassee,
FL.
Steenhuis, T.S., G.D. Bubenzer, and J.C. Converse. 1979. Ammonia volatilization of winter
spread manure. Trans. ASAE 22:152-157.
Stumpe, J.M., P.L.G. Vlek, and W.L. Lindsay. 1984. Ammonia volatilization from urea and urea
phosphates in calcareous soils. Soil Sci. Soc. Am. J. 48:921-927.
Sullivan, D.M., and J.L. Havlin. 1992. Soil and environmental effects on urease inhibition by
ammonium thiosulfate. Soil Sci. Soc. J. 56:950-956.
Sullivan, D.G., C.W. Wood, W.F. Owsley, M.L. Norfleet, B.H. Wood, J.N. Shaw, and J.F. Adams.
2003. Ammonia volatilization from a swine waste amended bermudagrass pasture.
Commun. Soil Sci. Plant Anal. 34:1499-1510.
Taysom, T.W., B.G. Hopkins, A.K. Shiffler, and S.C. Stephens. 2007. Polymer coated urea in
potato production. p. 169-175. Western Nutrient Management Conference. Vol 7. Salt
Lake City, UT.
Torello, W.A., and D.J. Wehner. 1983. Urease activity in a Kentucky bluegrass turf. Agron. J.
75:654-656.
Vaio, N., M. L. Cabrera, D.E. Kissel, J.A. Rema, J.F. Newsome, and V.H. Calvert III. 2008.
Ammonia volatilization from urea-based fertilizers applied to tall fescue pastures in
Georgia, USA. Soil Sci. Soc. Am. J. 72:1665-1671.
Venterea, R.T., D.E. Rolston, and Z.G. Cardon. 2005. Effects of soil moisture, physical, and
chemical characteristics on abiotic nitric oxide production. Nutrient Cycling in
Agroecosystems 72:27-40.
Vos, J. 1994. Effects of dicyandiamide on potato performance. J. Agron. Crop Sci. 173:93-99.
Vos, J. 1999. Split nitrogen application in potato: effects on accumulation of nitrogen and dry
matter in the crop and on the soil nitrogen budget. J. of Agricultural Sci., Cambridge
133:263-274.
108
Waddell, J.T., S.C. Gupta, J.F. Moncrief, C.J. Rosen, and D.D. Steele. 1999. Irrigation and
nitrogen management effects on potato yield, tuber quality, and nitrogen uptake.
Agron. J. 91:991-997.
Waddell, J.T., S.C. Gupta, J.F. Moncrief, C.J. Rosen, and D.D. Steele. 2000. Irrigation- and
nitrogen-management impacts on nitrate leaching under potato. J. Environ. Qual.
29:251-261.
Wagenet, R.J., J.W. Biggar, and D.R. Nielsen. 1977. Tracing the transformations of urea fertilizer
during leaching. Soil Sci. Soc. Am. J. 41:896-902.
Westermann, D.T. 2005. Nutritional requirements of potatoes. Amer. J. Potato Res. 82:301307.
Westermann, D.T. and G.E. Kleinkopf. 1985. Nitrogen requirements of potatoes. Agron. J.
77:616-621.
Westermann, D.T., G.E. Kleinkopf, and L.K. Porter. 1988. Nitrogen fertilizer efficiencies on
potatoes. Amer. Potato. J. 65:337-386.
Whitehead, D.C., and N. Raistrick. 1990. Ammonia volatilization from five nitrogen compounds
used as fertilizers following surface application to soils. J. Soil Sci. 41:387-394.
Wilson, M.L., C.J. Rosen, and J.F. Moncrief. 2009. Potato response to a polymer-coated urea on
an irrigated, coarse-textured soil. Agron. J. 101:897-905.
Wood, C.W., S.B. Marshall, and M.L. Cabrera. 2000. Improved method for field-scale
measurement of ammonia volatilization. Commun. Soil Sci. Plant Anal. 31:581-590.
Yamaguchi, J., and A. Tanaka. 1990. Quantitative observation on the root system of various
crops growing in the field. Soil Sci. Plant Nutr. 36:483-493.
Zaman, M., M.L. Nguyen, J.D. Blennerhassett, and B.F. Quin. 2008. Reducing NH3, N2O, and NO3-N losses from a pasture soil with urease or nitrification inhibitors and elemental Samended nitrogenous fertilizers. Biol. Fertil. Soils 44:693-705.
Zaman, M., S. Saggar, J.D. Blennerhassett, and J. Singh. 2009. Effect of urease and nitrification
inhibitors on N transformation, gaseous emissions of ammonia and nitrous oxide,
pasture yield and N uptake in grazed pasture system. Soil Biol. Biochem. 41:1270-1280.
Zebarth, B.J. and C.J. Rosen. 2007. Research perspective on nitrogen BMP development for
potato. Amer. J. Potato Res. 84:3-18
Zhengping, W., O.V. Clemmput, P. Demeyer, and L. Baert. 1991. Effect of urease inhibitors on
urea hydrolysis and ammonia volatilization. Biol. Fertil. Soils 11:43-47.
Zvomuya, F., and C.J. Rosen. 2001. Evaluation of polyolefin-coated urea for potato production
on a sandy soil. HortScience 36:1057-1060.
109
Zvomuya, F., C.J. Rosen, M.P. Russelle, and S.C. Gupta. 2003. Nitrate leaching and nitrogen
recovery following application of polyolefin-coated urea to potato. J. Environ. Qual.
62:480-489.
110
APPENDICES
111
2
Oxalic Acid
1.8
A
A
Water
1.6
Absorbance
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0
3
6
9
12
15
Concentration (ppm NH4-N)
Figure 6.1. Absorbance from ammonium as affected by using ammonium standards in deionized water and in 0.013835 M oxalic acid. Trend lines followed by same letter are not
significantly different according to p=0.05.
Absorbance
Absorbance
112
0.2
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0.2
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
a)
A
A
A
A
A
A
A
A
A
A
A
A
A
A
b)
A
A
A
A
A
A
Figure 6.2. Absorbance from ammonia samplers tested (a) with 1 drop (4 drops NH4OH/1 L
deionized water (DI)) and (b) 3 drops (4 drops NH4OH/1 L DI) as affected by the frequency of
shaking with DI water. A shake represents water moving from one side of the tube to the other,
continuous shaking represents rapid movement of water from ones side of tube to the other.
Columns followed by same letter are not significantly different according to LSD p=0.05.
113
3.5
KCl
3
A
A
Water
A
A
Concentration (ppm NH4-N)
2.5
2
B
1.5
C
B
C
1
0.5
0
11 Drop
3 Cleaner
Drop NH
NH3
Cleaner
4 Drops
Drop NH
3 Cleaner
NH3
Cleaner
2 mL NH3
NH3 Cleaner
Cleaner
11 Drop
4OH
Drop NH
NH4OH
Figure 6.3. Concentration from ammonia samplers tested with 1 drop, 2 drops, and 2 mL of NH3
cleaner and 1 drop (4 drops NH4OH/1 L deionized water (DI)) as affected by the extraction with
deionized water or KCl solution. Columns followed by same letter are not significantly different
according to LSD p=0.05.
114
0.09
0.08
0.07
Abosrbance
0.06
0.05
0.04
0.03
0.02
0.01
0
NH
NH4
Free Water
Water in
in Burned
Burned Tube
Tube
4-Free
NH4-Free
Water
NH4
Free Water
Figure 6.4. Absorbance of NH4-free water compared to NH4-free water shaken in a burned tube,
tube was burned at 450oC for 16 hours.
115
2.5
Ammonium
Nitrate
A
2
Absorbance
B
1.5
1
0.5
0
0
2
4
6
8
10
12
14
16
Concentration (ppm NH4-N)
Figure 6.5. Absorbance from ammonium standards as affected from the standards being
ammonium or nitrate decomposed in Devarda’s alloy to ammonium. Trend lines followed by
same letter are not significantly different according to p=0.05.
116
2
1.8
A
A
1.6
A
A
1 Hour
2 Hour
3 Hour
4 Hour
5 Hour
24 Hour
1.4
B
Absorbance
1.2
C
1
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
Concentration (ppm NH4-N)
12
14
16
Figure 6.6. Absorbance from ammonium standards from nitrate decomposition in Devarda’s
alloy as affected by the length of time decomposition was allowed in Devarda’s alloy. Trend
lines followed by same letter are not significantly different according to p=0.05.
117
2.5
KCl
Water
A
A
2
Absorbance
1.5
1
0.5
0
0
3
6
9
12
15
Concentration (ppm NH4-N)
Figure 6.7. Absorbance from ammonium as affected by using ammonium standards in deionized
water and in 2 M KCl solution. Trend lines followed by same letter are not significantly different
according to p=0.05.
Urea
Background
Agrotain
Background
Urea
Background
Agrotain
120
N loss as NH3 (% N applied)
100
80
60
40
20
0
0
5
10
15
20
25
30
Days after application
Figure 6.8. Cumulative loss of NH3 during the period of 29 July to 24 August 2009 following application of 112 kg N/ha to wheat stubble as
affected by N source of urea and Agrotain coated urea. Background represents NH3 flux between treatment plots.
118
119
7
6
Nitrogen Loss (kg/ha/12 hrs)
5
4
3
2
1
Aug 3; PM
Aug 3; AM
Aug 2; PM
Aug 2; AM
Aug 1; PM
Aug 1; AM
Jul 31; PM
Jul 31; AM
Jul 30; PM
0
Figure 6.9. Average diurnal nitrogen loss as ammonia across treatments on wheat stubble after
application of 112 kg N/ha.
120
100
Urea
90
Agrotain
80
N loss as NH3 (% of N applied)
70
60
50
40
30
20
10
0
0
4
8
Days after application
12
16
Figure 6.10. Cumulative loss of NH3 during the period of 23 October to 9 November 2009
following application of 112 kg N/ha to unburned grass seed field as affected by N source of
urea vs. Agrotain-coated urea. Bars represent standard error.
121
30
A
Grass Burn (% of plot burned)
25
20
15
10
5
B
0
Urea
Agrotain
Figure 6.11. Percent of plots burned after the application of 112 kg N/ha to unburned grass
seed field as affect by N source of urea and Agrotain-coated urea. Columns followed by same
letter are not significantly different according to LSD p=0.05.
122
10.1 cm
Soil moisture (mm
water/100mm soil)
0.25
20.3 cm
30.4 cm
50.8 cm
91.4 cm
a)
0.2
0.15
0.1
0.05
0
24
20
16
12
8
4
0
Days After Application
0.25
Soil moisture (mm
water/100mm soil)
b)
0.2
0.15
0.1
0.05
0
24
20
16
12
8
4
0
Days After Application
Soil moisture (mm
water/100mm soil)
0.25
c)
0.2
0.15
0.1
0.05
0
0
4
8
Days After12
Application 16
20
24
Figure 6.12. Soil moisture at varying depths for irrigation rates (a) 0.0 mm, (b) 3.8 mm, and (c)
11.4 mm. Moisture probe at irrigation rate 0.0 mm (a) was removed 17 DAA.
123
Urea
Agrotain
Super-u
NSN
ESN
Nitamin
N-fusion
60
Available NO3 (% N applied)
a)
50
40
30
20
10
0
0
20
40
60
80
100
160
b)
Available N (% N applied)
140
120
100
80
60
40
20
0
0
20
40
60
Days after application
80
100
Figure 6.13. Available (a) NO3 and (b) total N (NH4 + NO3) at 4.4oC in incubation as affected by N
treatment.
124
Urea
Agrotain
Super-u
NSN
ESN
Nitamin
N-fusion
70
Available NO3 (% N applied)
a)
60
50
40
30
20
10
0
0
20
40
60
80
100
160
b)
Available N (% N applied)
140
120
100
80
60
40
20
0
0
20
40
60
Days after application
80
100
Figure 6.14. Available (a) NO3 and (b) total N (NH4 + NO3) at 15.6oC in incubation as affected by
N treatment.
125
Urea
Agrotain
Super-u
NSN
ESN
Nitamin
N-fusion
Available NO3 (% N applied)
100
a)
90
80
70
60
50
40
30
20
10
0
0
20
40
60
80
100
b)
140
Available N (% N applied)
120
100
80
60
40
20
0
0
20
40Days after application
60
80
100
Figure 6.15. Available (a) NO3 and (b) total N (NH4 + NO3) at 26.7oC in incubation as affected by
N treatment.
126
90
80
70
Urea
% Fertilizer
60
NSN
50
40
30
20
10
0
>4
2.38 - 4
2 - 2.38
Size (mm)
0.841 - 2
0.595 - 0.841
Figure 6.16. Size of fertilizer prills based on product. Agrotain is coated urea, so it would have
the same percentages as urea.
127
Table 6.1. Linear regression for absorbance from N standards with concentrations ranging from
0 to 15 ppm NH4-N as affected by time of color determination.
R
2
Time
Intercept
Slope
Hours
Absorbance
Absorbance/ppm NH4-N
0
0.05403
B†
0.10942
B†
0.9989
0.5
0.07128
A
0.11808
A
0.9987
1
0.0716
A
0.11802
A
0.9987
2
0.07055
A
0.1178
A
0.9987
3
0.07144
A
0.11736
A
0.9986
† Within a column, values followed by the same letter are not significantly different according to
LSD at P = 0.05.
128
Table 6.2. Ammonium levels measured after nitrate decomposition as affected by the initial
rate of nitrate added to Devarda’s alloy.
Added NO3-N to
Devarda’s Alloy
ppm NO3-N
25
100
200
400
800
1000
Average
Measured
NH4-N
ppm NH4-N
27.13
23.14
25.83
25.48
18.57
15.36
22.58
129
Table 6.3. Average 12-hour weather data for diurnal wheat stubble data. No precipitation
occurred.
Date
2009
7/30; PM
7/31; AM
7/31; PM
8/1; AM
8/1; PM
8/2; AM
8/2; PM
8/3; AM
8/3; PM
Air
Temp
O
C
33.8
24.2
35.3
25.1
37.7
27.8
34.9
27.2
32.9
2 Inch Soil
Temp
O
C
31.9
27.1
32.4
27.3
33.1
28.7
33.7
28.9
33.0
Wind
Speed
m/s
2.3
1.2
2.1
1.4
1.7
1.5
1.6
2.6
3.6
Rel.
Hum.
%
21.8
45.6
21.3
40.3
20.1
39.4
18.1
36.5
18.8
130
Table 6.4. Average ppm nitrogen (N) as ammonia for the sampling period before (Aug 6), during
(Aug 7), and after (Aug 10) a smoke event. Samplers refer to height of ammonia collection.
Height of
samplers
m
3.00
2.25
1.50
0.75
0.50
Total
Before
Aug 6
ppm N
2.68
1.13
1.79
2.64
5.24
13.49
SMOKE
Aug 7
ppm N
1.94
2.20
2.96
6.45
10.97
24.51
After
Aug 10
ppm N
0.92
1.05
0.96
1.47
2.43
6.85
131
Table 6.5. Cumulative loss of NH3 from plots during 1 hour on 20 November 2009 resulting from
the application of waste water to an alfalfa field through irrigation.
Plot
N loss as NH3
kg N/ha
1
0.034
2
0.031
3
0.070
132
Table 6.6. Soil N present as NH4 and NO3 at varying soil depth after the application of 112 kg N
as urea/ha as affected by irrigation rate.
Irrigation Rate
Soil Depth
-------0-2.5 cm-----
-----0-15.2 cm -----
-----0-30.4 cm -------
mm
NH4
NH4
NH4
0
33.7
10.9 B
34.9
27.4
97.4
26.5
1.25
42.0
13.3 B
33.0
17.3
157.7
20.0
3.8
24.7
17.1 AB
46.4
24.7
107.3
20.5
7.6
18.8
19.8 AB
11.0
38.0
102.3
30.8
11.4
15.6
25.7 A
18.5
28.5
65.0
31.1
21.6
9.6
22.9 A
14.2
45.5
24.2
43.3
Significance
NS
*
NS
NS
NS
NS
NO3
NO3
NO3
------------------------------------kg N/ha----------------------------------------
† Within a column, values followed by the same letter are not significantly different according to
LSD at P = 0.05.
133
Table 6.7. Soil pH at varying soil depths after the application of 112 kg N ha-1 as urea as affected
by irrigation rate.
Irrigation Rate
mm
0.0
0.1
0.25
0.5
0.75
1.0
Significance
Soil Depth
0-2.5 cm 0-15.2 cm 0-30.4 cm
--------------------pH-----------------5.85
6.32
6.51
5.85
6.36
6.20
5.88
6.13
6.29
6.04
6.07
6.51
5.72
6.24
6.50
5.88
6.25
6.27
NS
NS
NS
134
Table 6.8. Accountable N at varying soil depth after the application of 112 kg N ha-1 as urea as
affected by irrigation rate; accountable N = wheat N uptake + soil N corresponding to soil depth.
Irrigation Rate
Soil Depth
0-2.5 cm
0-15.2 cm
0-30.4 cm
mm
------------------------------------kg N/ha-----------------------------------
0
169.5
187.2
248.7
1.25
234.5
229.6
357.0
3.8
235.5
264.8
321.5
7.6
213.4
223.8
307.9
11.4
214.4
220.0
269.2
21.6
201.9
229.1
236.9
Significance
NS
NS
NS
135
Table 6.9. Soil pH at varying soil depths after the application of 112 kg N/ha as affected by
irrigation rate and N source.
N Source
Urea
Agrotain
OAC
Urea
Agrotain
OAC
Urea
Agrotain
OAC
N Source
Irrigation Rate
Treatment*N Source
Irrigation
Rate
mm
0.00
0.00
0.00
1.25
1.25
1.25
7.6
7.6
7.6
Soil Depth
0-2.5
0-15.2
0-30.4
cm
cm
cm
---------------------pH-----------------5.85
6.32
6.51
6.42
6.30
6.87
6.09
6.33
6.39
5.85
6.36
6.20
6.04
6.08
6.41
5.94
6.12
6.40
6.04
6.07
6.51
5.92
6.19
6.55
6.08
5.98
6.61
NS
NS
NS
NS
NS
NS
NS
NS
NS
136
Table 6.10. Soil N present as NH4 and NO3 at varying soil depth after the application of 112 kg
N/ha as affected by irrigation rate and N-source.
N-Source
Irrigation Rate
Soil Depth
mm
-0-2.5 cmNH4 NO3
Urea
0.00
------------------------kg N/ha----------------------33.7 10.9
34.9 27.4 97.4
26.5
Agrotain
0.00
53.7
13.6
93.1
24.8
60.4
23.7
OAC
Urea
0.00
1.25
22.2
42.0
17.3
13.3
43.9
33.0
18.8
17.3
89.9
157.7
12.7
20.0
Agrotain
OAC
1.25
1.25
45.7
26.8
14.6
20.8
53.4
40.9
15.4
7.2
124.7
92.6
16.2
9.7
Urea
7.6
18.8
19.8
11.0
38.0
102.3
30.8
Agrotain
OAC
Irrigation
N-Source
7.6
7.6
20.8
9.5
*
*
25.3
28.3
*
*
46.4
40.0
*
*
22.5
29.0
NS
NS
52.9
88.9
*
NS
39.3
22.7
NS
NS
NS
NS
NS
NS
NS
NS
Irrigation*N Source
-0-15.2 cmNH4
NO3
-0-30.4 cmNH4
NO3
137
Table 6.11. Accountable N at varying soil depth after the application of 112 kg N/ha as affected
by irrigation rate and N Source; accountable N = wheat N uptake + soil N corresponding to soil
depth.
N-Source
Irrigation Rate
Soil Depth
0-2.5 cm
0-15.2 cm
0-30.4 cm
mm
---------------kg N/ha-----------------
Urea
0
113.8
131.5
193.1
Agrotain
0
161.9
212.6
178.8
OAC
0
105.9
129.1
169.1
Urea
1.25
147.9
143.0
270.4
Agrotain
1.25
158.4
167.0
239.0
OAC
1.25
93.4
93.9
148.1
Urea
7.6
102.6
113.0
197.1
Agrotain
7.6
108.4
131.2
154.5
OAC
7.6
113.9
145.1
187.7
Irrigation
NS
NS
NS
N-Source
NS
NS
NS
Irrigation*N Source
NS
NS
NS
138
Table 6.12. Urease activity 104 days after application of N fertilizer as affected by N source and
incubation temperature.
N-Source
o
Temperature ( C)
4.4
15.6
26.7
--------μg NH4-N/(g h)-------Control
0.72
1.83
1.32
Urea
0.29
0.85
1.75
Agrotain
1.16
0.56
0.12
Super-U
0.31
0.43
1.75
NSN
0.74
1.85
0.41
ESN
0
1.71
0.27
Nitamin
0.21
0.48
0.99
N-fusion
0.48
0.54
1.28
Treatment
NS
NS
NS
Temp
NS
NS
NS
Temp*Treat
NS
NS
NS
139
Table 6.13. Potato vine mass for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP).
Treatment
Sample Date
60
64
78
95
113
------------------------------Mg/ha------------------------------ESN 330 Plant
5.51
4.39
4.77
4.48
1.79
ESN 330 Emerg
7.69
3.74
4.95
4.73
2.35
ESN 290 Emerg
5.96
4.55
4.42
4.93
3.21
ESN 250 Emerg
6.14
3.74
5.63
6.05
3.12
ESN 210 Emerg
7.17
3.59
4.73
5.38
3.09
ESN 260 Emerg
6.61
4.06
4.19
5.56
2.31
ESN 180 Emerg
7.31
4.60
5.45
5.47
2.44
GSP 350 Emerg
5.25
4.26
4.84
6.48
2.73
GSP 280 Emerg
7.26
4.42
5.22
5.60
2.91
GSP 350 Plant
4.69
2.87
5.65
4.51
2.26
SU 330 Plant
6.19
3.92
4.69
6.23
2.49
SU 260 Emerg
4.55
4.42
4.75
5.02
2.47
SU 104 Emerg
6.75
3.12
5.02
5.58
2.20
70 NF +55 UAN
4.01
4.21
4.80
6.37
2.62
88 NF + 37 UAN
5.96
5.18
4.55
5.25
1.37
70 NF 100 UAN
4.57
4.55
4.30
4.35
1.97
88 NF 152 UAN
6.86
4.93
4.71
4.10
2.58
70 NF +190 UAN
6.14
4.15
5.25
4.37
1.88
88 NF + 242 UAN
8.63
4.55
4.55
3.83
1.59
Significance
NS
NS
NS
NS
NS
140
Table 6.14. Potato mass for Russet Burbank in 2009 as affected by N treatment and sampling
date (DAP).
Treatment
ESN 330 Plant
ESN 330 Emerg
ESN 290 Emerg
ESN 250 Emerg
ESN 210 Emerg
ESN 260 Emerg
ESN 180 Emerg
GSP 350 Emerg
GSP 280 Emerg
GSP 350 Plant
SU 330 Plant
SU 260 Emerg
SU 104 Emerg
70 NF +55 UAN
88 NF + 37 UAN
70 NF 100 UAN
88 NF 152 UAN
70 NF +190 UAN
88 NF + 242 UAN
Significance
Sample Date
78
95
113
-------------Mg/ha-----------0.16
1.84
3.56
1.23
3.43
3.90
0.45
2.00
5.25
1.14
2.51
5.42
1.39
1.79
4.39
1.48
8.32
4.91
1.05
2.60
5.69
0.94
1.97
4.35
1.35
1.43
4.24
0.63
2.08
4.53
0.47
3.07
4.75
1.10
1.86
5.74
0.99
2.73
4.77
0.54
3.03
4.98
1.05
3.27
4.69
1.23
1.93
5.96
1.48
3.03
7.26
1.39
3.41
4.51
1.01
2.62
4.84
NS
NS
NS
141
Table 6.15. Potato plant N uptake for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP). Values followed by the same letter are not significantly different at the 0.1
probability level.
Treatment
ESN 330 Plant
ESN 330 Emerg
ESN 290 Emerg
ESN 250 Emerg
ESN 210 Emerg
ESN 260 Emerg
ESN 180 Emerg
GSP 350 Emerg
GSP 280 Emerg
GSP 350 Plant
SU 330 Plant
SU 260 Emerg
SU 104 Emerg
70 NF +55 UAN
88 NF + 37 UAN
70 NF 100 UAN
88 NF 152 UAN
70 NF +190 UAN
88 NF + 242 UAN
Significance
Sample Date
60
64
78
95
113
------------------------lbs N/acre--------------------------------308.7 384.0 373.7
304.1 BCD
91.9 CDE
428.2 286.5 406.4
312.2 ABC
147.7 ABC
410.2 382.9 354.2
343.4 AB
192.7 A
471.2 322.4 486.2
392.0 AB
193.9 A
544.7 309.8 380.6
353.2 AB
177.3 AB
464.5 337.2 307.3
350.1 AB
125.9 BCD
466.9 232.2 437.4
350.6 AB
123.5 BCDE
309.8 360.2 391.6
432.4 A
170.1 AB
419.6 396.1 402.6
365.6 AB
160.7 AB
235.2 257.6 437.8
286.2 BCD
129.1 BCD
373.5 328.0 405.1
431.3 A
139.4 ABC
221.3 340.3 372.1
339.3 AB
121.2 BCDE
379.7 297.0 383.6
349.7 AB
123.2 BCDE
250.4 270.8 339.2
434.8 A
144.8 ABC
365.6 398.6 321.2
299.2 BCD
64.3 E
209.2 417.9 287.4
208.6 CD
86.9 CDE
455.3 406.2 316.8
195.7 CD
97.2 CDE
345.0 322.6 337.2
211.2 CD
73.0 DE
552.4 380.9 301.7
180.2 D
63.2 E
NS
NS
NS
*
*
*Significance at the 0.1 probability level
142
Table 6.16. Potato N concentration (%) for Russet Burbank in 2009 as affected by N treatment
and sampling date (DAP). Values followed by the same letter are not significantly different at
the 0.1 probability level.
Treatment
ESN 330 Plant
ESN 330 Emerg
ESN 290 Emerg
ESN 250 Emerg
ESN 210 Emerg
ESN 260 Emerg
ESN 180 Emerg
GSP 350 Emerg
GSP 280 Emerg
GSP 350 Plant
SU 330 Plant
SU 260 Emerg
SU 104 Emerg
70 NF +55 UAN
88 NF + 37 UAN
70 NF 100 UAN
88 NF 152 UAN
70 NF +190 UAN
88 NF + 242 UAN
Treatment
Sample Date
78
95
113
-------------------% N------------------1.5785
1.532
1.524
1.528
1.602
1.552
1.6415
1.504
1.424
1.74
1.53
1.484
1.87
1.56
1.424
1.6265
1.524
1.38
1.572
1.566
1.436
1.674
1.618
1.594
1.508
1.542
1.5
1.566
1.594
1.402
1.676
1.542
1.552
1.752
1.58
1.428
1.564
1.588
1.48
1.516
1.6167
1.456
1.484
1.416
1.454
1.666
1.51
1.35
1.6
1.466
1.346
1.51
1.422
1.32
1.48
1.434
1.456
NS
NS
NS
*Significance at the 0.1 probability level
143
Table 6.17. Potato N uptake for Russet Burbank in 2009 as affected by N treatment and
sampling date (DAP). Values followed by the same letter are not significantly different at the 0.1
probability level.
Treatment
ESN 330 Plant
ESN 330 Emerg
ESN 290 Emerg
ESN 250 Emerg
ESN 210 Emerg
ESN 260 Emerg
ESN 180 Emerg
GSP 350 Emerg
GSP 280 Emerg
GSP 350 Plant
SU 330 Plant
SU 260 Emerg
SU 104 Emerg
70 NF +55 UAN
88 NF + 37 UAN
70 NF 100 UAN
88 NF 152 UAN
70 NF +190 UAN
88 NF + 242 UAN
Treatment
Sample Date
78
95
113
-------------Mg/ha------------5.8
55.6
114.8
38.1
111.9
118.1
15.7
59.9
156.7
40.1
74.9
165.2
51.3
54.7
124.9
49.5
244.1
135.2
34.3
76.7
163.0
31.6
59.9
137.9
41.9
44.2
125.8
21.1
64.3
130.7
15.5
91.9
145.7
36.5
58.1
157.8
32.1
88.3
138.1
17.5
70.4
144.1
25.3
93.9
140.1
41.5
60.3
159.6
48.6
88.1
185.4
41.5
92.4
113.2
28.7
74.0
139.7
NS
NS
NS
*Significance at the 0.1 probability level
144
Table 6.18. Linear regression for NH3 loss from 2 DAA to 8 DAA following application of 112 kg
urea-N/ha to Winter Wheat as affected by rate of irrigation application.
Irrigation Rate
Slope
R2
-1
mm
% N applied day
0.0
7.41 A†
0.6305
1.25
6.64 A
0.7673
3.8
4.71 B
0.9542
7.6
1.89 C
0.7068
11.4
0.59 D
0.3613
21.6
0.15 D
0.0334
† Within a column, values followed by the same letter are not significantly different according to
LSD at P = 0.05.
145
Table 6.19. Linear regression for NH3 loss from 2 DAA to 8 DAA following application of 112 kg
urea-N/ha to Winter Wheat as affected by N treatment and rate of irrigation application.
N
Irrigation
Treatment rate
mm
Daily N loss as NH3
Significant Difference
R2
% N applied kg N ha-1day-1 Within
Across
-1
day
Irrigation Irrigation
Urea
0.00
7.41
8.30
A†
a‡
0.6305
Agrotain
0.00
0.49
0.54
B
d
0.4903
OAC
0.00
7.46
8.36
A
a
0.8334
Urea
1.25
6.64
7.43
A
a
0.7673
Agrotain
1.25
0.32
0.35
B
d
0.6568
OAC
1.25
7.20
8.05
A
a
0.8073
Urea
7.60
1.89
2.11
A
b
0.7068
Agrotain
7.60
0.18
0.35
C
d
0.1269
OAC
7.60
0.94
1.05
B
c
0.8755
† Within a column and irrigation rate, daily loss values followed by the same letter are not
significantly different according to LSD at P = 0.05.
‡Within a column, daily loss values followed by the same letter are not significantly different
according to LSD at P=0.05.
146
Table 6.20. Soil urease activity in incubation as affected by N treatment and temperature.
N-Source
Control
Urea
Agrotain
Super-U
NSN
ESN
Nitamin
N-Fusion
Control
Urea
Agrotain
Super-U
NSN
ESN
Nitamin
N-Fusion
Control
Urea
Agrotain
Super-U
NSN
ESN
Nitamin
N-Fusion
N-Source
Temperature
Interaction
Temperature (oC)
4.4
4.4
4.4
4.4
4.4
4.4
4.4
4.4
15.6
15.6
15.6
15.6
15.6
15.6
15.6
15.6
26.7
26.7
26.7
26.7
26.7
26.7
26.7
26.7
Urease Activity
3.60
1.45
5.80
1.55
3.70
0.00
1.05
2.40
9.15
4.25
2.80
2.15
9.25
8.55
2.40
2.70
6.60
8.75
0.60
8.75
2.05
1.35
4.95
8.40
NS
NS
NS
Table 6.21. Available NH4 at 4.4oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
91.0 A
91.0 A
94.8 A
78.7 A
89.8 A
NH4
Urea
15.0 A
37.2 A
64.3 A
Agrotain
4.0 C
5.8 C
10.3
Super-U
3.0 CD
4.9 C
8.3
NSN
13.9 A
33.7 A
60.4 B
ESN
2.4
7.1 C
20.2
Nitamin
6.8 B
N-Fusion
0.0
Standard
Error
0.5
D
E
95.6 A
E
E
D
95.6 A
96.3 A
18.9
D
25.1 C
33.9 C
41.7 C
59.0 B
84.4 A
81.1 A
93.4 A
15.6
D
19.8 C
26.4
30.5
48.6 C
72.7 B
74.8 A
84.6 A
98.5 A
101.0 A
101.4 A
95.8 A
93.0 A
91.8 A
81.1 A
92.0 A
36.5 C
46.6 B
51.5 B
52.8 B
55.8 B
54.2 C
48.6 B
48.6 B
D
D
20.5 B
40.0 C
48.8 B
51.4 B
54.2 B
55.8 B
54.6 BC
52.2 C
43.9 B
38.3 C
0.0
2.4
3.5
5.5
8.5
9.8
11.5
14.6
16.7 C
16.5
5.0
4.6
1.8
D
1.7
F
3.1
E
2.7
D
2.7
E
2.5
E
2.9
D
5.2
D
D
147
Table 6.22. Available NO3 at 4.4oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
40.6 AB
3.6 B
18.1 AB
27.9 B
17.2 B
NO3
Urea
0.0 A
0.0 B
Agrotain
0.0 A
0.6 AB
0.0 B
0.1 B
0.0 A
2.3 B
10.0 C
14.0 A
16.0 ABC
28.6 B
21.8 B
Super-U
0.0 A
3.5 A
0.0 B
0.0 B
0.0 A
2.9 B
8.5 C
2.7 B
27.8 A
25.2 B
16.4 B
NSN
0.0 A
0.2 B
2.0 A
7.5 A
9.0 A
14.2 A
51.2 A
9.4 AB
20.9 A
25.7 B
16.9 B
ESN
0.3 A
0.4 B
1.7 A
3.0 AB
1.7 A
2.6 B
21.3 BC
7.9 AB
11.0 ABC
41.2 A
46.6 A
0.4 AB
2.8 AB
7.0 A
8.9 AB
Nitamin
0.0 A
0.0 B
0.0 B
0.0 B
0.0 A
0.5 B
0.5 C
0.0 B
0.9 BC
14.2 C
21.2 B
N-Fusion
0.0 A
0.0 B
0.0 B
0.0 B
0.0 A
0.0 B
1.1 C
0.0 B
0.0 C
0.0
8.6 C
Standard
Error
0.1
1.4
0.7
2.7
5.3
4.6
11.8
4.7
8.0
2.6
D
2.8
148
Table 6.23. Total N (NH4 + NO3) at 4.4oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
93.3 A
112.9 A
106.6 A
107.1 AB
Total N (NH4 + NO3)
Urea
15.0 A
36.9 A
64.5 A
96.9 A
101.3 A
105.2 A
131.7 A
Agrotain
4.0 C
6.3 C
9.5
D
18.5 C
22.7 C
35.3 C
51.7 BC
72.7 B
100.4 A
109.7 A
115.2 A
Super-U
3.0 CD
8.4 C
7.8
D
14.9 C
17.4 CD
28.8 C
39.0 CD
51.0
D
100.6 A
100.0 AB
101.1 BC
NSN
13.9 A
33.9 A
62.0 A
105.3 A
107.2 A
115.7 A
147.1 A
102.5 A
112.8 A
106.8 A
109.0 AB
ESN
2.7
7.4 C
21.6 C
39.3 B
46.7 B
53.2 B
74.1 B
63.8 BC
65.2 B
89.9 B
95.3 C
D
Nitamin
6.8 B
N-Fusion
0.0
Standard
Error
0.5
E
20.3 B
38.7 B
46.5 B
47.4 B
53.8 B
55.5 BC
52.3 CD
52.3 B
58.1 C
59.5
D
0.0
1.1
1.2 D
1.2
5.6 D
10.8
8.0
13.0 C
12.4
25.2
E
6.2
8.0
6.4
13.2
10.0
5.5
2.4
D
1.7
E
D
D
5.8
E
D
4.9
149
Table 6.24. Available NH4 at 15.6oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
97.2 A
61.2 C
56.5 B
52.3 B
45.4 B
NH4
Urea
26.1 A
86.90 A
Agrotain
4.8
D
11.1 CD
16.9 C
38.0
D
79.3 B
107.3 A
104.6 A
81.4 B
60.9 B
54.4 B
46.1 B
Super-U
3.7
D
8.3 CD
14.0 C
34.1
D
75.7 B
108.1 A
103.9 A
99.5 A
83.4 A
72.4 A
71.4 A
NSN
22.8 B
77.1 A
77.0 AB
104.0 A
106.7 A
104.3 A
97.8 A
62.7 C
56.2 B
52.9 B
45.2 B
ESN
3.9
18.5 C
35.2 C
50.7 C
55.0 C
45.7 B
48.0 B
49.6
D
49.4 C
48.0 C
39.4 C
Nitamin
13.5 C
54.2 B
62.3 B
59.7 B
57.3 C
41.5 B
39.7 C
39.1
E
42.1
D
42.6
D
43.8 B
N-Fusion
0.0
6.3
12.2 C
19.5
22.9 C
20.3
22.2
F
25.6
E
27.3
E
29.4
Standard
Error
1.0
11.2
2.4
24.0
D
3.6
3.1
3.7
D
E
5.1
D
96.7 A
103.8 A
E
106.9 A
104.2 A
D
2.4
2.6
1.4
D
1.2
150
Table 6.25. Available NO3 at 15.6oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
39.3 C
39.9 AB
60.1 A
45.1 C
NO3
Urea
0.0 A
0.0 C
5.1 B
0.1 A
2.0 B
5.6 BC
6.7 BC
Agrotain
0.0 A
0.0 C
1.0 B
0.0 A
9.3 B
19.6 A
42.3 A
32.0 C
41.1 A
54.2 AB
51.5 BC
Super-U
0.0 A
0.0 C
0.0 B
3.3 A
12.1 AB
12.9 ABC
7.6 BC
5.1
28.5 C
54.1 AB
29.4
NSN
0.2 A
11.5 A
36.2 A
1.3 A
10.6 AB
6.2 BC
16.3 BC
61.3 A
40.5 A
49.2 BC
53.9 B
ESN
0.0 A
3.4 B
1.6 B
1.4 A
26.4 A
24.9 A
31.2 AB
50.4 B
46.2 A
42.3 C
62.5 A
Nitamin
0.0 A
0.2 C
0.0 B
0.0 A
9.4 AB
16.9 AB
13.6 BC
36.3 C
30.1 BC
32.1
D
29.4
D
N-Fusion
0.0 A
0.0 C
0.0 B
0.0 A
0.0 B
3.3 C
1.7 C
13.4
15.3
13.9
E
13.5
E
Standard
Error
0.1
1.0
10.1
1.9
7.9
5.5
11.9
3.7
E
D
4.6
D
4.2
D
3.7
151
Table 6.26. Total N (NH4 + NO3) at 15.6oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
100.6 C
96.56 B
112.5 B
90.6 B
Total N (NH4 + NO3)
Urea
26.1 A
86.6 A
Agrotain
4.8
D
10.9 CD
17.9
D
Super-U
3.7
D
8.0
12.8
D
NSN
23.0 B
88.6 A
113.3 A
ESN
3.9
21.9 C
36.4 C
D
D
101.8 A
103.0 A
106.2 AB
109.1 B
101.7 BC
36.9 C
87.2 BC
127.0 A
146.9 A
113.4 B
102.0 B
108.7 B
97.6 A
36.6 C
86.4 BC
121.0 AB
110.2 B
102.9 C
111.9 A
126.5 A
100.8 A
104.9 A
116.4 A
110.6 B
114.2 B
124.0 A
96.7 B
95.3 C
99.1 A
52.1 B
81.5 BC
70.6 C
79.3 CD
100.0 C
95.6 B
97.2 C
101.9 A
Nitamin
13.5 C
54.3 B
61.0 B
58.3 B
66.7 C
58.4 C
53.4
D
75.4
D
72.2 C
74.8
D
73.2 C
N-Fusion
0.0
6.0
10.9
18.1
20.0
25.2
20.4
E
35.6
E
40.9
41.3
E
42.9
Standard
Error
1.0
E
5.2
D
6.4
D
3.2
D
11.6
D
7.6
D
13.4
3.5
3.0
D
4.3
D
3.2
152
Table 6.27. Available NH4 at 26.7oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
86.2 AB
69.6 B
56.9 B
44.8 CD
40.8 CD
41.1 BC
37.1 CD
NH4
Urea
21.4 A
34.3 B
89.3 B
99.7 A
109.7 A
Agrotain
4.0
D
5.3
D
12.4
E
74.9 B
105.8 A
73.0 B
62.5 B
55.4 B
44.5 CD
39.6
Super-U
2.9
DE
5.4
D
11.5
E
73.5 B
109.9 A
98.5 A
87.4 A
71.9 A
70.8 A
66.3 A
65.7 A
NSN
18.4 B
48.0 A
98.2 A
103.6 A
104.1 A
92.4 A
72.1 B
59.0 B
51.5 B
45.5 BC
43.7 B
ESN
1.4
4.2
22.9
32.2
34.5 B
35.0 C
36.0 C
36.0
40.1
36.4
34.4
53.5 C
39.0 B
38.0 C
39.9 C
43.0 C
46.5 BC
45.9 B
23.9
21.2 C
25.6 C
27.0 C
32.2
35.3
33.9
4.9
6.3
6.4
1.8
EF
Nitamin
9.0 C
N-Fusion
0.0
Standard
Error
0.8
F
D
D
27.6 C
56.3 C
0.0
6.24
1.1
E
2.0
F
4.4
D
D
D
D
2.4
DE
E
2.3
D
DE
D
40.1 BC
E
38.7 CD
2.2
153
Table 6.28. Available NO3 at 26.7oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
36.6 AB
58.1 AB
60.3 A
63.0 A
49.7
NO3
Urea
0.0 A
8.4 A
12.8 A
0.2 C
2.3 A
22.0 AB
D
Agrotain
0.0 A
0.0 C
0.0 B
3.5 BC
0.2 A
35.3 A
41.7 AB
43.6 BC
47.5 AB
50.4 AB
80.4 AB
Super-U
0.0 A
0.0 C
0.0 B
0.0 C
0.0 A
4.4 B
23.7 B
34.4 C
29.4 BCD
41.5 B
71.3 ABC
NSN
0.1 A
2.1 B
0.0 B
1.4 BC
2.5 A
11.5 B
34.2 AB
45.8 BC
36.0 BC
49.9 AB
75.4 ABC
ESN
0.0 A
0.0 C
0.0 B
16.5 A
3.1 A
39.2 A
52.9 A
67.1 A
64.3 A
63.6 A
86.9 A
Nitamin
0.0 A
0.0 C
0.0 B
4.8 B
8.1 A
22.5 AB
24.6 B
32.8 C
25.7 CD
34.3 B
59.8 CD
N-Fusion
0.0 A
0.0 C
0.0 B
0.0 C
4.3 A
21.0 AB
24.3 B
34.2 C
16.7
38.2 B
66.5 BCD
Standard
Error
0.1
0.4
1.0
1.9
4.9
9.8
11.3
7.4
8.4
9.3
9.4
D
154
Table 6.29. Total N (NH4 + NO3) at 26.7oC in incubation as affected by N treatment. Values followed by the same letter are not significantly
different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
Total N (NH4 + NO3)
Urea
21.4 A
Agrotain
4.01
D
5.2
D
11.0
D
Super-U
2.9
DE
5.2
D
10.2
DE
NSN
18.6 B
50.1 A
97.3 A
ESN
1.4
4.0
21.9 C
42.7 B
EF
Nitamin
9.0 C
N-Fusion
0.0
Standard
Error
0.8
F
D
102.1 A
99.3 A
108.8 A
105.9 A
106.2 A
115.0 A
105.2 A
103.8 A
90.8 C
77.8 B
102.6 A
108.4 A
104.2 A
99.1 A
92.1 A
90.1 ABC
117.6 AB
71.5 B
106.5 A
101.7 A
111.1 A
106.3 A
100.3 A
107.8 A
137.1 A
104.4 A
104.9 A
102.4 A
106.4 A
104.9 A
87.6 AB
95.5 AB
119.2 AB
48.8 C
35.9 BC
74.3 B
88.9 AB
103.2 A
104.4 A
100.1 AB
121.3 AB
27.4 C
54.9 B
58.4 C
43.8 B
60.6 BC
64.5 BC
75.8 B
72.3 B
80.3 BC
99.9 BC
0.0
4.9
21.9
23.8 C
46.6 C
51.4 C
66.5 B
52.1 C
72.2 C
105.2 BC
8.1
12.2
11.6
8.8
8.9
10.0
10.7
1.2
E
2.7
E
4.9
D
155
Table 6.30. Soil pH at 4.4oCin incubation as affected by N treatment. Values followed by a like letter at not significantly different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
F
7.70 C
8.30 A
28
34
48
63
76
104
7.94 A
7.81 C
7.61
7.59 C
7.45 C
7.69
7.72 CD
7.51
7.41 CD
7.88 B
7.59 C
7.56 B
pH
Control
7.01
Urea
7.79 AB
8.15 A
7.92 BC
7.72 C
7.68
Agrotain
7.30
D
7.61 CD
7.80
D
8.06 AB
8.21 B
Super-U
7.28
DE
7.58
7.67
NSN
7.84 A
ESN
7.19
Nitamin
N-Fusion
Standard
Error
F
7.09
E
8.24 A
D
7.67
E
8.15 B
7.34
E
7.86 B
D
7.98 A
DE
E
8.12 AB
8.20 B
8.18 B
7.97 AB
7.86 B
7.47
E
7.36
7.89 BC
7.75 C
7.72
7.67
E
7.33
E
7.70
7.74 C
7.44
E
7.39 CD
7.74 BC
7.94 B
8.12 A
8.13 C
8.02
D
7.66
D
7.91 B
8.06 A
7.71 B
7.59 B
7.70 BC
8.03 A
8.10 A
8.11 AB
8.09 C
8.06
D
7.73 C
7.99 A
8.07 A
7.79 A
7.72 A
7.60 C
7.78 B
7.85 CD
8.05 B
8.19 B
8.11 C
7.84 B
7.98 A
8.06 A
7.57 CD
7.29
0.04
0.07
0.03
0.03
0.02
0.01
0.01
0.02
0.05
0.03
0.02
D
7.91 A
D
8.01 A
E
D
7.28
D
D
E
156
Table 6.31. Soil pH at 15.6oCin incubation as affected by N treatment. Values followed by a like letter at not significantly different at p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
8.18 A
34
48
8.03 A
7.70
63
76
104
7.34 AB
7.38 A
pH
Control
6.95
Urea
7.95 A
7.89 BC
Agrotain
7.37 C
Super-U
NSN
D
7.22
D
7.36
D
7.57
D
8.32 A
7.53 C
7.57
D
7.70
7.82 C
7.89 B
8.11 A
7.29 C
7.88 BC
7.89 B
8.12 A
7.93 A
7.91 BC
7.50 C
7.61
ESN
7.30 C
7.94 AB
8.03 A
7.96 C
8.05 C
7.93 C
Nitamin
7.92 A
8.03 A
7.95 AB
7.92 C
7.96
N-Fusion
Standard
Error
7.59 B
7.96 AB
7.95 AB
8.05 B
0.04
0.05
0.03
0.02
E
8.03 C
8.07 C
D
D
7.72
D
7.56
E
7.39
E
7.88 A
8.07 A
7.49 A
6.70 C
7.62
D
7.45
DE
7.75 BCD
8.04 A
7.55 A
6.49 C
7.64
D
7.47
D
7.72 CD
7.88 BC
7.44 AB
7.36 A
7.42
DE
7.84 AB
8.00 AB
7.51 A
6.56 C
7.69 C
7.67
D
7.39
E
6.87 C
5.68
8.01 B
7.80 B
7.42
E
7.53
E
7.07 BC
7.02 B
8.16 B
8.06 B
7.87 B
7.81 ABC
7.82 CD
7.34 AB
7.25 A
0.02
0.02
0.03
0.05
0.06
0.18
0.10
7.62
F
D
7.50
F
D
157
Table 6.32. Soil pH at 26.7oC in incubation as affected by N treatment. Values followed by a like letter at not significantly different at
p=0.05.
Treatment
Days After Application
1
3
6
13
20
28
34
48
63
76
104
pH
Control
7.00
Urea
7.97 A
Agrotain
7.26
D
7.62 C
7.85 BC
Super-U
7.21
DE
7.55 C
7.77 CD
NSN
7.98 A
8.14 A
7.74
ESN
7.12
7.61 C
7.80 CD
Nitamin
7.77 B
8.10 A
8.05 A
7.92 A
N-Fusion
Standard
Error
7.61 C
7.80 B
7.91 B
8.00 A
0.04
0.06
0.04
0.09
0.12
F
7.11
D
8.16 A
E
7.25
E
7.54 B
8.27 A
8.10 A
7.99 A
7.65 AB
7.51 A
7.29 A
6.93 A
7.82 CD
7.84 A
7.90 BC
7.90 AB
7.81 AB
7.33 ABC
6.45 B
6.15 B
5.73 CD
7.91 A
7.78 CD
7.82 BC
7.75 AB
7.06 C
6.54 B
5.94 B
5.54
7.93 A
7.81 BCD
7.65 CD
7.56 B
7.81 A
7.15 A
6.84 A
6.78 A
7.87 A
7.95 BC
7.91 AB
7.77 AB
7.50 ABC
7.28 A
6.22 B
5.87 C
7.34 C
7.58
7.13
E
6.83
6.26
6.13 B
5.76 B
5.34
8.05 AB
7.55
D
7.24 C
7.37 ABC
7.18 A
6.99 A
6.50 B
7.85 BC
7.60 CD
7.28 C
7.21 BC
7.59 A
6.83 A
6.36 B
0.11
0.12
0.23
0.21
0.22
0.09
D
D
D
D
DE
E
158