Methods to Improve Nutrient Use Efficiency in Rice
6R‐2/Room 4Tuesday 11:10‐11:56
Wednesday 10:10‐10:56
Timothy W. Walker, Ph. D.Associate Agronomist
662‐822‐2291
Nitrogen Use Efficiency
NUE = Grain yield (lb/acre)Nitrogen applied (lb/acre)
Nitrogen Use Efficiency
Yield
Genetics
Variety Selection Breeding
Management
Agronomic Pest
Nitrogen Use Efficiency
N Rate
Decrease N Rate
Account for Soil Supply
N‐ST*R (U of A)
Rate Response
Account for Plant Need
Chlorophyll Plant Area BoardSensor‐based
Maintain N Rate
Prevent Loss
Ammonia
Agrotain Water
Nitrate
Water Nitrification Inhibitors
Nitrogen Use EfficiencyMaintain N
Rate
Prevent Loss
Ammonia
Agrotain Water
Nitrate
Water Nitrification Inhibitors
Urea’s Reaction ProducesNH3 Gas
2 NH3 ammonia gas on soil surfaceor in flood
- H2O & CO2
CO(NH2)2 (NH4)2CO3 2 NH4+ + 2 OH-
urea urease (pH ~ alkaline) ammonium salt in soil
Note: Urea’s reaction in soil initially is alkaline and increases soil pH causing ammonia volatilization loss if not incorporated in soil quickly.
Slide borrowed from R. Norman
Ammonia Volatilization of Urea Applied to a Conventional Tilled and a Stale-Seedbed Silt loam soil (RREC, 2001)
[N source LSD0.05 = 3.1% of applied N]
0
5
10
15
20
25
30
35
0 5 10 15 20 25
Time (days)
Vola
tiliz
atio
n (%
of a
pplie
d N
)
Ammonia VolatilizationEnds at ~10 Days
↓Stale-Seedbed
Conventional Till
Griggs etal., 2007; SSSAJ
Slide borrowed from R. Norman
Ammonia Volatilization of 15N-labeled Urea and Ammonium Sulfate From a Perry Clay Soil14 Days before Flooding (SEREC, 2000)
0
5
10
15
20
25
30
0 2 4 6 8 10 12 14 16 18 20 22
Time (days)
Vol
atili
zatio
n (%
of a
pplie
d N
)
Ammonium Sulfate Urea
Urea
Ammonium Sulfate
Ammonia Volatilization Losses(Clay soil)
Flood
Griggs et al., 2007; SSSAJ
Slide borrowed from R. Norman
Rice Research Station – fertility and Agronomy Project
i
e-h d-h
a
a-d a-da-e a-c
y = 520.4x + 6697.5
5000
5500
6000
6500
7000
7500
8000
8500
9000
9500
10 DPF 7 DPF 4 DPF 1 DPF
Yie
ld (l
b/A
)
Application time (Days Prior to Flooding)
UreaAgrotain-UreaLinear (Urea)
581 lbs7 %
1238 lbs15 %
Rice Research Station – fertility and Agronomy Project
0
5
10
15
20
25
3 6 9 12 15 18 21
NH4‐N lo
ss (%
of t
otal
applied)
Time (days)
UreaAS‐UreaASSuper‐UAgrotain‐Urea
Rice Research Station – fertility and Agronomy Project
(Urease inhibitor only) (Urease and nitrification inhibitors)
a-d a-da-e a-c
c-gb-f b-f
a-c
5000
5500
6000
6500
7000
7500
8000
8500
9000
10 DPF 7 DPF 4 DPF 1 DPF
Yie
ld (l
b/A
)
Application time (Days Prior to Flooding)
Agrotain-UreaSuper-U
Ammonia Volatilization
0
2
4
6
8
10
12
0 5 10 15 20
% of a
pplied
Days
NH3 Volatilization Loss
urea
ams
agrotain
Data from Tunica clay. Dillon and Walker, unpublished
Urea vs Agrotain
LSD = 7Source x Timing (P = 0.0024)
8224
8566
8269
8599
7806
8361
8500 8452
7400
7600
7800
8000
8200
8400
8600
8800
10 7 4 1
lb/acre
AgrotainUrea
LSD = 453
Urea vs Agrotain
LSD = 7Source x Timing (P = 0.0024)
7420
7818
7586
7155
7860
7710
6800
7000
7200
7400
7600
7800
8000
10 7 2
AgrotainUrea
LSD = 361
Agrotain vs Super U
LSD = 7Source x Timing (P = 0.0024)
8224
8566
8269
8599
8056
8488
8113
8331
7700
7800
7900
8000
8100
8200
8300
8400
8500
8600
8700
10 7 4 1
AgrotainSuper U
LSD = 453
Testing the Mechanism – Product Evaluation
• Agrotain is the only ureaseinhibitor recommended in Arkansas.
• Other products unproven to inhibit NH3 loss include– Nutrisphere– N‐Zone– Extend– Upgrade
Lab EvaluationUpgrade
05
1015202530354045
0 5 10 15
Cumulative NH3Loss
(% of a
pplied N‐fe
rtilizer)
Time (days)
Urea Agrotain‐Urea Upgrade‐Urea
Source: Norman and Roberts (unpublished data)
Lab EvaluationN‐Zone
08
16243240485664
0 5 10 15
Cumulative NH3Loss
(% of a
pplied N‐fe
rtilizer)
Time (days)
Urea Agrotain‐Urea N‐Zone‐Urea
Source: Norman and Roberts (unpublished data)
Lab EvaluationNutrisphere
08
16243240485664
0 5 10 15
Cumulative NH3Loss
(% of a
pplied N‐fe
rtilizer)
Time (days)
Urea Agrotain+Urea Nutrisphere+Urea Ammonium Sulfate
Source: Franzen et al. (2011, in press) J. Plant Nutr.0.25% Nutrisphere added
Lab EvaluationExtend
05
1015202530354045
0 5 10 15
Cumulative NH3Loss
(% of a
pplied N‐fe
rtilizer)
Time (days)
Urea Agrotain‐Urea Extend‐Urea
Source: Norman and Roberts (unpublished data)
Nitrification/Denitrification
2NH4+ + 3O2 2NO2‐ + 2H2O + 4H+Nitrosomonas
2NO2‐ + O2 2NO3‐Nitrobacter
NO3‐ + H2O NO, N2O, N2 (gases)Permanent Flood
Nitrogen Stabilizers
113
131137
164
100
110
120
130
140
150
160
170
180
10 DBF 2 DBF
bu/ac 60120
Urea Conversion to NO3‐
Time (days)
0 3 6 9 12 15 18 21 24 27
NH
4 rem
aini
ng (%
of i
nitia
l)
0102030405060708090
100110
DulaneyF13SF14WalkerCircleHLADavis
Urea Conversion to NO3‐
Soil A K T1/2 R2
‐‐‐‐‐‐‐‐‐‐%‐‐‐‐‐‐‐‐‐‐ ‐‐‐‐‐‐‐‐‐d‐1‐‐‐‐‐‐‐‐‐ ‐‐‐‐‐d‐‐‐‐‐ ‐‐Unit less‐‐
LA 106.3244 (8.6832) 0.1046 (0.0187) 6.6 0.945
F13S 98.1749 (5.0216) 0.0840 (0.0095) 8.3 0.971
Dulaney 92.3076 (8.0813) 0.0708 (0.0139) 9.8 0.910
Davis 101.8352 (7.4631) 0.1353 (0.0218) 5.1 0.961
CircleH 103.3625 (7.8772) 0.1447 (0.0242) 4.8 0.960
F14 105.0458 (7.1418) 0.1573 (0.0236) 4.4 0.970
Walker 96.3323 (5.5211) 0.1672 (0.0212) 4.1 0.977
Nitrification Rate of UreaNitrification of Urea in two Soils
Days0 5 10 15 20 25 30 35
% u
rea-
N a
s N
O3-
N
0
20
40
60
80
100
120
Calhoun soilDewitt soil
Unpublished data: Golden et al. (2009)Slide borrowed from R. Norman
Grain Yield
LSD = 7Source x Timing (P = 0.0024)8218
8071 8041 8069
8235
7467
7642
7858
7994
7000
7200
7400
7600
7800
8000
8200
8400
43% Urea ENTEC Super U Agrotain
2DBF10DBF
LSD = 421
Data collected at DREC2010
Sharkey clay soil
Nitrification InhibitorNutrisphere
05
101520253035404550
Soil Inorganic N (p
pm)
NO3‐N NH4‐N
Source: Franzen et al. (2011, in press) J. Plant Nutr.90 lb urea‐N/acre; LSD0.05 (8.4 ppm for NO3 and 4.5 ppm for NH4)Data from Hazelton, North Dakota)
Sensor‐based
1NUE Fixed = 35%NUE Sensor = 38%
$ Fixed = $447$ Sensor = $446
Commercially Available Active Sensors
Photo courtesty of B. Tubana
Rice Info on the Webwww.rice.msstate.edu
Special Thanks
• Dr. Dustin Harrell• Dr. Brenda Tubana• Mr. Kevin Dillon• Mr. Paxton Fitts• Dr. Rick Norman• Dr. Nathan Slaton• Dr. Bobby Golden• Dr. Trent Roberts
Special Thanks
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