IFDC
Evaluation of Boron as Urease Inhibitor
Upendra Singh, Job Fugice, Wendie Bible,
Rick Austin and Joaquin Sanabria
International Fertilizer Development Center (IFDC)
Muscle Shoals, Alabama, USA
ASA-CSSA-SSA, Annual Meetings, Nov 6, Tampa, FL
1
Background


IFDC
Improving the efficiency
of production resourceuse is critical
Mineral fertilizers
(N fertilizers)
continue to play an
important role
Available freshwater decline
Arable land area shrinking.
Marine harvests dwindling.
Poor efficiency in plant uptake of
nutrients applied.
Agricultural research worldwide
decline.
2
CO2 Equivalent Emission from Urea

Total CO2 equivalent emission from urea production
and application = 3.53 kg CO2 equivalent/kg urea
(production = 1.71 and application = 1.82)

Total urea consumption (2011) = 59 million
tons(FAOSTAT, 2012)

Total CO2 equivalent emission = 208 million tons

Low N Use Efficiency (30%40% recovery): economic
and environment concern
Air
(78% Nitrogen)
Ammonia
Energy and Feedstock
(Natural Gas)
IFDC
Urea
Energy (Natural Gas)
and Carbon Dioxide
3
Urease Activity
urease, 2H2O


(NH4)2CO3
IFDC
2NH3 + CO2 + H2O
Most soils’ urease activity is too high  rapid hydrolysis
- NH3 volatilization loss
- Seed/seedling damage
- Accumulation of nitrite (toxic concentration)
- N2O-NOX conversion
- Air pollution
- Re-deposition  eutrophication of lakes and streams
On average, 20%-33% of applied urea-N is lost through
volatilization
4
Improving Efficiency of Urea
IFDC
Reduce Urea Hydrolysis
 Urea Aldehydes – reduced solubility and/or reduced release
ureaforms, isobutylidene diurea, Nitamin, NFusion
 Coated Urea – slow and controlled-released urea
S-coated, polymer-coated, ESN

Urea used in association with inhibitors of urease activity
NBTPT, CHPT, Agrotain, etc
Placement of Urea
 Urea Deep Placement (UDP)
Rice PFPN with conventional urea = 38 kg grain/kg N
Rice PFPN for UDP = 80 kg grain/kg N
5
Goals of Incorporating B in Urea

Evidence of reduced volatilization loss

Essential nutrient for plant growth

Use urea as delivery system

Also, improve physical properties of urea
IFDC
6
Objectives
IFDC
Overall Objective:
Improve the efficiency of urea by reducing
ammonia volatilization using boron as urease
inhibitor
Specific Objectives:
• Evaluate effectiveness of B in reducing volatilization
loss under flooded and upland soil conditions
• Evaluate effectiveness of B delivery technology
(seed core vs compacted and pelletized)
• Evaluate the longevity of B-treated urea
7
Methodology for Incorporating Boron



IFDC
Utilize urea as “delivery system” for
micronutrients/inhibitors
Compaction and pelletization of B with urea
Core technology using urea fluid bed granulation
process
• Process begins with a small “core” of
urea
• Urea core replaced with micronutrient
core
• Requires little capital or process change
• Allows for customization (products,
rates) – B, Fe, Zn, Iodine, Selenium, etc.
8
Centralized Core Production
IFDC
Cores make up ~5% of urea granule
Centralized production of cores ensure quality
9
Experiment Outline Summary
IFDC

Five experiments with a range of N sources were conducted under
upland and flooded conditions

Soils Used: Sumter (clay, pH 7.8), Crowley (silt loam, pH 6.8), Greenville
(loam, pH 6.1), Hiwassee (clay loam, pH 5.4)

N Rate: 200 kg N ha-1

Products Evaluated:
- Borax (Na2B4O7•5H2O)
- Boric Acid (H3BO3)
- NBTPT
- CHPT
- Commercial: Agrotain, AgrotainPlus,
SuperU, ESN (polymer-coated)

Watering
tube
Applied as 0.5%-2% B with urea, 0.4%
NBTPT or CHPT, recommended rate
of commercial inhibitors
10
Experiment Setup
IFDC
Initially setup in greenhouse (Experiments 1-3)
11
IFDC
Results

Effectiveness of B compacted and pelletized with urea in reducing
ammonia volatilization under upland soil conditions

Soil Used: Sumter
Daily Ammonia Volatilization Loss
Cummulative Ammonia Volatilization Loss
350
70
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
N Loss (mg N)
50
40
300
Cummulative N Loss (mg N)
60
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
30
20
250
200
150
100
50
10
0
0
0
2
4
6
8
10
Days
12
14
16
18
0
2
4
6
8
10
12
14
16
18
Days
12
IFDC
Results

Effectiveness of B compacted and pelletized with urea in reducing
ammonia volatilization under upland soil conditions

Soil Used: Hiwassee
100
Daily NH 3 Volatilization
60
Cummulative N Loss (mg N)
Urea
0.25% Borax
0.5% Borax
1% Borax
2% Borax
0.4% NBTPT
Check
80
N Loss (mg N)
Cummulative NH 3 Volatilization
400
40
20
0
300
200
Urea
0.25% borax
0.5% borax
1% borax
2% borax
NBTPT
Check
100
0
0
2
4
6
8
10
Days
12
14
16
18
0
2
4
6
8
10
12
14
16
18
Days
13
IFDC
Results

Effectiveness of B compacted and pelletized with urea in reducing
ammonia volatilization under flooded soil conditions

Soil Used: Sumter
Cummulative Ammonia Volatilization Loss
Daily Ammonia Volatilization Loss
70
600
N Loss (mg N)
50
40
30
20
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
500
Cummulative N Loss (mg N)
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
60
400
300
200
100
10
0
0
0
5
10
15
Days
20
25
0
5
10
15
20
25
Days
14
IFDC
Ammonia Volatilization Loss Using 1-Year-Old Product
Treatment
Description
Cumulative Ammonia Volatilization Loss (mg NH3-N pot-1)
Upland Sumter Soil
Flooded Sumter Soil
Duration
Duration
Duration
Duration
(1-5 days)
(1-15 days)
(1-5 days)
(1-22 days)
Urea
249 A
357 A
258 A
609 A
0.25% Borax
225 AB
327 AB
215 B
574 BC
0.5% Borax
235 AB
352 AB
220 B
584 AB
1% Borax
218 B
326 AB
223 B
579 B
2% Borax
219 B
346 AB
216 B
573 BC
0.5% Boric Acid
212 B
316 B
197 B
550 C
0.4% NBTPT
98 C
256 C
161 C
567 BC
LSD (5%)
24
31
25
41
15
IFDC
Results

Comparing effectiveness of one-year-old with freshly prepared Btreated urea in reducing ammonia volatilization under upland soil
conditions

Soil Used: Sumter
180
500
160
120
Cummulative N Loss (mg N)
140
N Loss (mg N)
Cummulative NH3 Volatilization for Products
Prepared in 2008 and 2009
Daily Ammonia Volatilization For Products
Prepared in 2008 and 2009
Urea
1% Borax (2008)
1% Borax (2009)
0.5% Boric Acid (2008)
0.5% Boric Acid (2009)
NBTPT (2008)
NBTPT (2009)
Check
100
80
60
40
400
300
Urea
1% Borax (2008)
1% Borax (2009)
0.5% Boric Acid (2008)
0.5% Boric Acid (2009)
NBTPT (2008)
NBTPT (2009)
Check
200
100
20
0
0
0
2
4
6
8
Days
10
12
14
0
2
4
6
8
10
12
14
Days
16
IFDC
Results

Effectiveness of B compacted and pelletized with urea
compared with seed-core B with urea in reducing ammonia
volatilization under upland soil conditions

Soil Used: Greenville
100
400
Cummulative Ammonia Volatilization Loss
Cummulative Ammonia-N Loss (mg N)
Ammonia Volatilization (mg N)
Daily Ammonia Volatilization
Loss
80
60
40
20
0
Urea
Agrotain
AgrotainPlusDCD
0.6% Boric acid-seedcore
0.5% Boric acid-compact
Check
300
200
100
0
0
2
4
6
8
10
12
Days After N Fertilizer Application
14
16
0
2
4
6
8
10
12
14
16
Days After N Fertilizer Application
17
IFDC
Results

Comparing the effectiveness of B compacted and pelletized
with the seed core technology under upland soil conditions

Soil Used: Crowley
300
Cummulative Ammonia Volatilization, Oct 2013
Cummulative N Loss (mg N)
250
100
Daily Ammonia-N Volatilization Loss, Oct 2013
Daily N Loss (mg N)
80
60
200
150
100
50
40
0
0
2
4
6
8
10
12
14
16
18
20
Days After N Application
20
0
0
2
4
6
8
10
12
Days After N Application
14
16
18
20
Check
Urea
0.5% Boric Acid Compact
0.5% Boric Acid +S Seed
0.5% Boric Acid + S + PPDA Seed
0.5% Boric Acid + S + DCD Seed
ESN
Agrotain Ultra
Super U
18
Summary
IFDC

B-treated urea had 13%-28% less NH3 volatilization loss than
urea and was effective under both upland and flooded soil
conditions

Seed-core or compacted B with urea both resulted in
similar reduction in NH3 volatilization loss

NBTPT (Agrotain) had 34%-91% less NH3 volatilization loss
than urea

For NBTPT, NH3 volatilization loss dropped from 61% less
(fresh) to 23% less (year old) compared to urea; B remained
at 19%
19
Concluding Remarks
IFDC

Urea can be used as a delivery mechanism for applying B or
any other micronutrient(s)

B delivery mechanism could be seed-core or compacted B
with urea: both mechanisms are equally effective

B-treated urea could be stored for at least one year without
losing its effectiveness

Benefits of B with urea: better distribution of B
(micronutrient), application of essential element, reduction
in NH3 volatilization loss, improves physical properties of
urea
20
IFDC
Daily Ammonia Volatilization Loss
70
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
60
N Loss (mg N)
50
40
30
20
10
0
0
2
4
6
8
10
12
14
16
18
Days
21
IFDC
Cummulative Ammonia Volatilization Loss
350
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
Cummulative N Loss (mg N)
300
250
200
150
100
50
0
0
2
4
6
8
10
12
14
16
18
Days
22
IFDC
100
Daily NH 3 Volatilization
Urea
0.25% Borax
0.5% Borax
1% Borax
2% Borax
0.4% NBTPT
Check
N Loss (mg N)
80
60
40
20
0
0
2
4
6
8
10
12
14
16
18
Days
23
IFDC
Cummulative NH 3 Volatilization
Cummulative N Loss (mg N)
400
300
200
Urea
0.25% borax
0.5% borax
1% borax
2% borax
NBTPT
Check
100
0
0
2
4
6
8
10
12
14
16
18
Days
24
IFDC
Daily Ammonia Volatilization Loss
70
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
60
N Loss (mg N)
50
40
30
20
10
0
0
5
10
15
20
25
Days
25
IFDC
Cummulative Ammonia Volatilization Loss
600
Urea
0.5% Borax
1% Borax
2% Borax
0.5% Boric Acid
0.4% NBTPT
0.4% CHPT
Cummulative N Loss (mg N)
500
400
300
200
100
0
0
5
10
15
20
25
Days
26
IFDC
180
Daily Ammonia Volatilization For Products
Prepared in 2008 and 2009
160
N Loss (mg N)
140
120
Urea
1% Borax (2008)
1% Borax (2009)
0.5% Boric Acid (2008)
0.5% Boric Acid (2009)
NBTPT (2008)
NBTPT (2009)
Check
100
80
60
40
20
0
0
2
4
6
8
10
12
14
Days
27
IFDC
Cummulative N Loss (mg N)
500
Cummulative NH3 Volatilization for Products
Prepared in 2008 and 2009
400
300
Urea
1% Borax (2008)
1% Borax (2009)
0.5% Boric Acid (2008)
0.5% Boric Acid (2009)
NBTPT (2008)
NBTPT (2009)
Check
200
100
0
0
2
4
6
8
10
12
14
Days
28
IFDC
100
Ammonia Volatilization (mg N)
Daily Ammonia Volatilization
Loss
80
60
40
20
0
0
2
4
6
8
10
12
14
16
Days After N Fertilizer Application
29
IFDC
400
Cummulative Ammonia-N Loss (mg N)
Cummulative Ammonia Volatilization Loss
Urea
Agrotain
AgrotainPlusDCD
0.6% Boric acid-seedcore
0.5% Boric acid-compact
Check
300
200
100
0
0
2
4
6
8
10
12
14
16
Days After N Fertilizer Application
30
IFDC
100
Daily Ammonia-N Volatilization Loss, Oct 2013
Daily N Loss (mg N)
80
60
40
20
0
0
2
4
6
8
10
12
14
16
18
20
Days After N Application
31
IFDC
300
Cummulative Ammonia Volatilization, Oct 2013
Cummulative N Loss (mg N)
250
200
150
100
50
0
0
2
4
6
8
10
12
14
16
18
20
Days After N Application
Check
Urea
0.5% Boric Acid
0.5% Boric Acid
0.5% Boric Acid
0.5% Boric Acid
ESN
Agrotain Ultra
Super U
Compact
+S Seed
+ S + PPDA Seed
+ S + DCD Seed
32