This slide about NItrogen Use Efficiency through management and Use of coated fertilizer

1. NITROGEN USE EFFICIENCY (NUE)
MANAGEMENT, COATED FERTILIZERS
AND INHIBITORS
Presented By
BIJAYA KHADKA
Agriculture and Forestry University (AFU)
Rampur, Chitwan

2. Nitrogen Use Efficiency (NUE) is the fraction of applied
nitrogen removed from the field by the crop.
NUE = Nitrogen removed from field in crop product (kg/ha) x100
Fertilizer N applied (kg/ha)
Nitrogen Use Efficiency (NUE)
Soil
N-Fertilizer

3. •NUE is very low ranging from 30-50%.
•However, conversion of N inputs to products for
arable crops can be 60-70% or even more (Kitchen
and Goulding, 2001).
•The main reason for low NUE is that nitrogen is lost
from soil in different forms at different stages
(Prasad1998).

4. Nitrogen Loss Mechanisms
1. Ammonium volatilization
2. Nitrate leaching
3. Denitrification
3. Erosion/ Runoff

6. Methods To Improve Nitrogen Efficiency
Proper management of soil, crop and fertilizer is the key to
enhance NUE.
• N-Fertilizer management (type, amount & timing of
application)
• Crop and soil management (soil drainage, good soil
structure etc.)
• Manure management (e.g. timing and application method)
• Modification of N fertilizers (CRF/SRF, urease and
nitrification inhibitors)

7. Crop Management
•Sward management (age, species, nutrient balance,
soil and plant analysis)
•The development of crop plants with improved
nitrogen assimilation.
•Identify genes that can increase NUE by crop plants,
which may reduce the rate of N application to crops.
(Genetic engineering for NUE).

8. Soil Management
• Soil factors that influencing losses are pH, texture,
structure, topography and drainage.
• Improved drainage so, soil is not so wet and prone to
denitrification and leaching losses.
• liming of acid soils (Bhat et al. 2010) and application of
gypsum on sodic soils (Abrol et al. 1988) can considerably
enhance NUE.
• Destruction of soil texture due to puddling in rice may
lower NUE in wheat in the rice-wheat cropping system
(Aulakh et al. 1992).

9. Fertilizer Management
• Fertilizer source, rate and time of application is
important management factor.
• Avoid application at the time of heavy rainfall.
• Use NH4
+-N instead of NO3-N based fertilizers under
wet conditions (Paddy field).
• Foliar application of N in flooded rice fields where soil
application is not possible.
• Deep placement of Urea to avoid volatilization.
• Spilt application of N in crop grown under irrigation.

10. Modification of N Fertilizers
A) Slow Release Fertilizers or Controlled Release
Fertilizers (SRF/CRF)
B) Urea Super Granules
C) Urease and Nitrification inhibitors

11. Slow Release Fertilizers (SRF)
• SRF products reduce the rate of N release to the soil
solution compared to urea or other inorganic sources.
• Fertilizer material that would supply N continuously but
slowly over an extended period
• Two general categories:
1. Uncoated, slow release
2. Coated, slow release

12. Uncoated Slow Release Fertilizer
Name
Base
Compound
Common Name N
content
(%)
Inhibition
duration
(weeks)
Urea
Formaldehyde
Ureaforms
Methylene
urea
Methylol urea
Nitroform, Folocorn,
Hydrolene, Resi-
grow
35-40 10-30
Isobutylidene
diurea
Isobutyliden
e urea
IBDU 31 10-16
Triazone Triazone /
Urea
N-Sure, Nitamin,
Trisert, Formmlene
28-33 6-10
Contylidene
diurea
Urea /
Contylidene
CDU, Triabon 34 6-12

13. Coated Slow Release Fertilizers
• Sulfur-coated urea (SCU)
– Coating with sulfur reduces solubility of urea
in water
– Releases N through oxidation of S coating.
– Used for turf fertilization
• Polymer-coated (or Poly-coated) urea (PCU)
– Urea is coated with organic polymer or resin.
– Polymer thickness controls the N release rate.
– Water moves in through coating to dissolve urea.
– N diffuses out through porous polymer membrane.

14. • Neem or ‘nimin’ coated urea (NCU)
–Primarily based on the nitrification inhibiting
properties of neem (Thomas and Prasad 1983)
– Although some slow release property was provided by
the carbon in the neem cake

15. Advantages of SRF
 Reducing split application in sand soils/ potato (Wilson
et.al., 2009)
Greater utilization of N in corn, barley and potato (Shoji
et.al.,2001)
 Reducing N leaching loss on sandy soil (Pack et. al., 2006)
PCU increase corn yield in low-lying areas (subject to
denitrification losses) (Noellsch et. al., 2009)

16. Urea Super Granule (USG)
•Super granules are conventional soluble fertilizers
formulated in a compacted form, with a relatively
small surface-to-volume ratio.
•Slow or relatively slow release of nutrients into the
soil solution.
•Particularly in tropical and subtropical regions.
•In tropical regions, their preferred use is in irrigated
rice.

17. Urease Inhibitors
•Inhibit the hydrolysis of urea by reducing the activity of
enzyme urease.
•Reducing the rate of conversion of urea to NH4
+
(NH2) 2 CO+H2O (NH4)2 CO3 2NH3 + H2O+CO2
Urease
Hydrolysis
Volatilization

18. Urease Inhibitor Products
•N-(n-butyl) triophosphoric triamide (NBPT)
– Agrotain ®(Agrotain, Inc., LLC, Corydon, KY)
– Urease enzyme inhibitor
– Fertilizer additive that increases the
efficiency of Urea/UAN fertilizer
•Thiosulfate
•Hydroquinone
•Thiophosphosphoryl triamides

19. Nitrification Inhibitors
• Inhibit nitrification process by direct toxicity to Nitrosomonas
bacteria.
• Delay conversion of NH4
+ to NO3
-
• Thereby reduce the loss of NO3 by leaching and denitrification.
NH4
+ NO2
- NO3
-
Denitrification
Leaching loss
Plant uptake
Nitrobacter
Nitrosomonas

20. Nitrification Inhibitor Products
• Nitrapyrin or N-serve [2-chloro-6-(trichloromethyl)-piridine)]
– N-Serve® (Dow AgroSciences LLC, Indianapolis, IN)
only labeled for corn, sorghum, and wheat.
• Dicyandiamide (DCD)
• SuperU® (Agrotain)
– contatins Agrotain and DCD

21. Results of adding a urease and
nitrification inhibitor to Nitrogen
Minimize losses from:
• Immobilization
• Volatilization
• Leaching
• Denitrification
Enhances ammonium (NH4
+ ) nutrition.