Nitrogen fertilizers, classification, manufacturing, fate in soil

1. Nitrogen Fertilizers
16 and 17 Fertilizer Definition
Classification of N fertilizers
Manufacturing process
Properties of important fertilizers
Fate or reactions of N- fertilizers in soils.
MARKS: 06
Dr AB Jadhav,
Assistant professor
Soil Science and Agril. Chemistry,
Agriculture College, Pune

3. Nutrient Efficiency Cause of low efficiency
Nitrogen 30-50 %
Immobilization, volatilization,
denitrification, Leaching
Phosphorus 15-20% Fixation in soils Al – P, Fe – P, Ca – P
Potassium 70-80% Fixation in clay - lattices
Sulphur 8-10% Immobilization, Leaching with water
Micro nutrients (Zn,
Fe, Cu, Mn, B)
1-2% Fixation in soils
Major Concerns In Indian Agriculture
Declining Nutrient Use Efficiency

9. Classification of Fertilizer

18. UREA [CO(NH)2]2
First time an organic compound synthesized from inorganic compound by
Friedrich Wohler (1828)
Manufacturing of Urea
Commercially urea is manufactured by chemical reaction of liquid NH3 with CO2
in a reactor maintained at temp. range of 180 to 2000C and pressure 200-350 kg
cm2
2 NH3 + CO2 ======== ======== NH4COONH2 (Ammonium carbonate)
NH4COONH2 (Ammonium carbonate) ============== [CO(NH)2]2 (urea) + H2O
180-200 0C
200-350 kg cm2
2500C
Decomposition
Equivalent acidity: The amount of lime (CaCO3) required for neutralizing the acidity caused
by 100 kg urea (Urea has 80 equivalent acidity)
Biuret:
It a chemical compound with the chemical formula H2NCNHCNH2. It is the result of
condensation of two molecules of urea and is a problematic impurity in urea-based
fertilizers. This white solid is soluble in hot water. The term "biuret" also describes a family of
organic compounds with the functional group - (HN-CO-)2N-.

19. Properties of
Urea
First isolated from urine
by Rouelle (1773)
Organic fertilizer
contains 46% N in
amide corm
Hygroscopic nature,
free flowing, does
not forms lumps or
aggregates Acid forming fertilizer
(equivalent acidity is
80) but less acidic than
ammonium sulphate
Melting point of urea
132.70C. When heated
at this temp.it
decomposes and
liberated NH3,
Maximum
permissible biuret
value for urea is 1.5%
for soil application
and for foliar 0.5%
Highly water soluble
and prone to leaching
loss through rain or
excess rainfall.
Available in crystalline
form, prilled form (2-4
mm) Urea super
granule (USG) of
10-11 mm
UREA [CO(NH)2]2

20. Properties of
NH4SO4
Low analysis
fertilizer due to
less than 20.5%
N
Acid forming
fertilizer
(equivalent acidity
is 107),
Suitable for
alkaline
soil/neutral soil
It also contains
23.7% S
Free flowing,
crystalline
White
crystalline, free
flowing and least
hygroscopic
It should not be
mixed with lime
because of loss of
NH3 via
volatilization
Widely used in S
deficient soils
Ammonium Sulphate (NH4SO4: 20.5 % N)

21. Manufacturing of NH4SO4
This fertilizer comes from by-product of steel industry. This was
first produced in India at Jamshedpur, Jharkhand in 1933 as a by-
product of steel industry.
During burning of coke and coal, large amount of coke-oven
gases are released which are rich in NH3 are liberated this
liberated gas pass through dilute H2SO4 and ammonium sulphate
is formed.
2NH3 + H2SO4 ======= NH4SO4

22. Another way for the manufacturing of NH4SO4 is direct reaction
between anhydrous NH3 and H2SO4 this process is not cost effective
due to high cost of H2SO4
Ammonium Sulphate Manufacturing
Caprolactam Process
By-product of synthetic fiber
(nylon industry)
Large amount of NH3 released
during nylon production.
This NH3 is reacted with H2SO4
and (NH4)2SO4 is produced
Followed by Gujrat State
Fertilizer Corporation GSFC
Gypsum Process
First (NH4)2CO3 is prepared by
reacting NH3+CO2
Gypsum is reacted with NH4CO3
and ammonium sulphate is
produced
2NH3 + CO2==== (NH4)2CO3
(NH4)2CO3 + CaSO4==== (NH4)2SO4

23. Ammonium
Nitrate
(NH4NO3)
Not produced in
India,
Poor physical
properties,
Contains 34% N
(half in NH4 and
half is in NO3)
Highly water
soluble hence
prone to loss
On storage it
forms cakes and
lumps becomes
hygroscopic
Difficult to apply
uniformly in the
field
Crystal changes
upon storage
and its very
explosive in
nature
Ammonium Nitrate (NH4NO3:34% N)

24. Ammonium Nitrate Manufacturing
Ostwald Process
NH3 + 5 O2 === 4NO + 6H2O
2NO + O2 ==2NO2
4NO2 + O2 + 2H2O=== 4 HNO3
HNO3 + NH3 === NH4NO3

25. Properties of
CaNH4NO3
NH4NO3 is mixed
with limestone
(CaCO3) to
produce CAN
Contains 25% Neutral fertilizer
known as “Kisan
Khad”
Hazardous effects
of NH4NO3
lowered by
addition of CaCO3
Acidifying effect
of NH4 is
buffered by Ca
Soluble in water,
suitable for top
dressing,
resistant to
leaching
Application of
NH4NO3 or CAN
in low land
paddy losses of
NO3 are more
Calcium Ammonium Nitrate (CaNH4NO3: 34% N)

26. Reaction of N-fertilizers in Soil

35. Thank you