The document discusses how applying urea fertilizer with nitrification and urease inhibitors as well as growth accelerators can increase crop yields while reducing nitrous oxide emissions. A study was conducted in Pakistan applying different combinations of urea, nitropyrene inhibitor, nBTPT inhibitor and GA-K growth accelerator to maize. It found that combining all inputs led to the highest yields, nitrogen uptake, and lowest nitrous oxide emissions. The use of inhibitors was shown to slow the release of nitrogen, keeping it available longer for plant uptake and reducing losses.

2. BY
MUHAMMAD KAMIL SARDAR ALI
DR. KHADIM DAWAR

3.  Worldwide the twin effects of rising human population and climate
change is putting enormous pressure on dwindling land and water
resources to produce enough food to meet its requirement.
 Experts predict that by 2020, agricultural production in Asia will be
severely affected by climate change and drought, which is
characterized by low water levels as a result of the lack of monsoon
rains; these phenomena will in turn have devastating effects on food
security.
 Cereals-based cropping system Nitrogen (N) is a key factor for
sustainable agriculture, and the predominant form of that chemical
fertilizers is Urea.

4.  In Pakistan, urea commonly applied N fertilizer to enhance crop
yield and high economic return.
 However, urea has not being used for productive purposes in many
cropping systems compared to other N fertilizers, and its deficiency
constitutes one of the major yield limiting factors for cereal
production.
 Besides the economic significance for the farmers, losses may have
negative ecological impact on atmospheric quality. Large
percentage of the applied fertilizer N is essentially lost in the form:
• NH3 Volatilisation
• NO3
-
Leaching
• N2O and NO emission
• Excessive application rates
• Substantial water input

5.  Sources are: Fossil fuel, Fertilizer, Live stock and wastes.
 The concentration of N2O has increased by 16% since 1750.
 Atmospheric concentration of N2O is much smaller than carbon dioxide (CO2), its
global warming potential is 296 times greater than CO2.
 Average time in troposphere 114-120 yr.
 Contributes about 6% of the overall global warming effect.
 Contribution from agricultural sector is about 16%

6.  Use of non-Urea N sources for surface application
 Use of naturally occurring ‘Biostimulators’ for
enhancing the growth of agricultural and
horticultural crops. The activity of biostimulators to
promote plant growth is often attributed to their
ability to directly or indirectly provide mineral
nutrients (mostly N, but also P, S and other macro-
and micro-nutrients) to plants. Alternatively,
biostimulators are postulated to increase the plant’s
ability to assimilate these mineral nutrients,
including gibberellins, auxins and cytokinins.

7.  Applying urea with Urease inhibitors (UI)
Use of urease activity inhibitors, is a biochemical method which retards the
hydrolysis of urea by inhibiting the urease enzyme (released by many bacteria
and some plants) in the soil and limit the proportion of microsites where the
enzyme is inhibited.
The important products include phenyl phosphorodiamidate (PPD), hydroquinone
(HQ), N-(n-butyl) thiophosphorictriamide (NBPT), phenyl mercuric acetate (PMA),
catechol.
 Applying urea with Nitrification Inhibitors (NI)
NI inhibits nitrification via suppressing growth of ammonia oxidizers. Inhibit
nitrification by interfering with the ammonia monooxygenase (AMO) enzyme
which catalyzes ammonia oxidation. In soil, discrete groups of nitrifying bacteria
(Nitrosomonos) are known to be involved in ammonia oxidation.
Important products are 3,4-dimethyl-1H-pyrazoliumdihydrogen (DMPP),
dicyandiamide (DCD), thiosulphate, neem, karanjin, Nitrapyrine

8.  The objectives of this research was to compare and assess N losses
of nitrous oxide emissions and bioavailability of urea applied with N
process inhibitors under different soil types and irrigation
conditions.
 To investigate the effect of applying urea with nitropyrene alone, or
a combination of both nBTPT and nitropyrene and PGRs on plant
productivity in hot climate conditions in Pakistan.

9.  The experiment was conducted at University of Agriculture
Peshawar research farm.
 Maize was sown during June, 2015.
 Randomize Complete Block Design (RCBD) was used having four
replications. Each plot had of minimum size of 3 m x 3 m (9m2 area).
 Full recommended dose of phosphorus at 90 kg P2O5 ha-1
in the form
of single superphosphate, potash at 60 kg K2O ha-1
in the form of
potassium sulphate was applied at time of sowing.
 N fertilizer with or without N-inhibitors, Urease Inhibitors and GA-K
salt was applied in 2 split applications at different growth stages.

10.  T1
Control
 T2
Urea only @ 200 kg N ha-1
 T3
Urea with Nitropyrene (200 g ha-1
) @ 200 kg N ha-1
 T4
Urea with nBTPT (3 Litre Tonne-1
) @ 200 kg N ha-1
 T5
Urea with GA-K-salt (60 g ha-1
) @ 200 kg N ha-1
 T6
Urea with Nitropyrene +nBTPT + GA-K salt @ 200 kg N ha-1

11.  Nitrous oxide (N2O) measurement and analysis
 Soil mineral N determination
 Soil pH and EC
 Soil Organic Matter
 Soil Texture
 Moisture content
 Total N in soil, plant and grain samples

12.  Plant height
 Number of leaves plant-1
 Number of grains ear-1
 Thousand grains weight (g)
 Biological yield
 Grain yield
 Stover yield (kg ha-1
)
 Plant samples were analyzing for total N determination

14. Property Units Concentration
Sand % 14.22
Silt % 76.68
Clay % 9.10
Textural class - Silt loam
pH (1:5) - 7.23
Electrical conductivity(EC) d Sm-1
0.174
Lime % 17.3
Organic matter content % 0.9
Total nitrogen content % 0.23
Bulk density gm cm-3
1.35

18. Treatment
Plant Height
(cm)
Number of
Leaves plant-1
Number of
grains ear-1
Thousand
grain wt (gm)
Control 162.77c 10.5e 270d 196.48b
Urea 176.65bc 11d 326.75cd 265.00a
Urea + Nitropyrene 178.63b 11.15cd 361.25bc 278.91a
Urea + nBTPT 181.22ab 11.45bc 375.25abc 288.73a
Urea + GA-K-salt 190.35ab 11.55ab 408ab 294.50a
Urea + Nitropyrene +
nBTPT + GA-K salt
194.65a 11.925a 430.25a 319.18a
LSD (0.05) 14.220 0.392 58.85 67.15

19. Treatment Biological yield
(kg ha-1
)
Total Increase
(kg ha-1
)
% Increase by
Inhibitors, GA-K
Control 6744.444c -- --
Urea 8730.556b -- --
Urea + Nitropyrene 9472.222b 741.66 7.83
Urea + nBTPT 10050ab 1319.45 13.13
Urea + GA-K-salt 10208.33ab 1477.78 14.48
Urea + Nitropyrene +
nBTPT + GA-K salt
11619.44a 2888.90 24.87
LSD (0.05) 1908.8

20. Treatment Grain yield
(kg ha-1
)
Total Increase
(kg ha-1
)
% Increase by
Inhibitors, GA-K
Control 2297.22c -- --
Urea 3519.44b -- --
Urea + Nitropyrene 3797.22b 277.78 7.32
Urea + nBTPT 4061.11b 541.67 13.34
Urea + GA-K-salt 4327.77ab 808.34 18.68
Urea + Nitropyrene +
nBTPT + GA-K salt
4963.89a 1444.45 29.10
LSD (0.05) 846.76

21. Treatment Stover yield
(kg ha-1
)
Total Increase
(kg ha-1
)
% Increase by
Inhibitors, GA-K
Control 4447.22c -- --
Urea 5211.113bc -- --
Urea + Nitropyrene 5675abc 463.8867 8.17
Urea + nBTPT 5988.89ab 777.7744 12.99
Urea + GA-K-salt 6130.56ab 919.4428 15.00
Urea + Nitropyrene +
nBTPT + GA-K salt
6905.56a 1694.444 24.54
LSD (0.05) 1469.6

22. Treatment
Total Nitrogen
Uptake
(kg ha-1
)
Total Increase
( kg ha-1
)
% Increase by
Inhibitors, GA-K
Control 57.81103e -- --
Urea 87.96837d -- --
Urea + Nitropyrene 103.9065c 15.93815 15.34
Urea + nBTPT 111.6099bc 23.64151 21.18
Urea + GA-K-salt 118.5496ab 30.58122 25.80
Urea + Nitropyrene +
nBTPT + GA-K salt
130.095a 42.12661 32.38
LSD (0.05) 13.32

25.  Combined application of GA-K+urease + nitrification inhibitors was
superior to inhibitors alone and urea in increasing the yield and yield
components of maize.
 Both inhibitors increased N uptake compared with non-inhibitor treated
urea. And reduce leaching because plants absorb more of the applied
nutrient (less N available to leach).
 Coated urea slowly released NH4 and NO3 ions as compared to non
coated Urea treatments revealed that Inhibitors play a vital role in
releasing N and also keeping it in more available form for plants.

26.  Mean values for total herbage produced by treatments
receiving GA-K co-applied with controlled release urea
fertilizer were mostly high.
 Further, this research shows that the chemical
stabilization of Urea fertilizers, through inhibitors may
increase yields N use efficiency and reduce N2O in this
agricultural system.

27.  Thus, the use of N inhibitors with urea and GA-
K is recommended for increasing crop
production and restrict N2O emission on a
calcareous alkaline soil.
 However, economics of the use of inhibitors
and PGRs must be worked out carefully before
it is recommended.