1. N ITROGEN F ERTILIZERS

2. T YPES O F N ITROGEN
F ERTILIZERS
 Organic nitrogen – This is found in decaying animals
and plant materials. They are slow-acting but they
supply nitrogen for a longer period.
 Inorganic nitrogen – This can be either ammonium or
nitrate. In the form of ammonium, it bonds tightly
with the soil particles, so it moves through the soil to
plants more slowly. In the form of nitrate, plants can
quickly and easily absorb nitrogen, but it leaches, or is
washed, from the soil quickly.

3. I NORGANIC
 Nitrate fertilizers (NO3- ): Nitrogen present in these fertilizers
are in nitrate form, NO3 - which are rapidly dissociated to
release NO3-ions and readily absorbed by the plants. They are
alkaline in their residual effect in soil.
 Ammonium fertilizers (NH4+): Ammonium fertilizers are soluble
in water and, as such, absorbed on the soil colloids and thus
protected from being washed away by run off or by leaching.
The absorbed ammonium ions on soil collections are
transformed to nitrate slowly and taken up by most of the
crops. They are acidic in their residual effect in soil.
 Nitrate and Ammonium fertilizers (Nitrate, NO3- and
ammonium, NH4+ ): These fertilizers contain nitrogen in both
nitrate (NO3- ) and ammonium forms (NH4+ ). They are soluble
in water and suitable for most of the crops and soils. They are
acidic in its residual effect.

4. O RGANIC
 Amide Fertilizers (Amine, NH2 or amide, CN2): These
fertilizers contains nitrogen in organic compounds as
amide—NH2 or ---- CN 2 , not directly available to
plants, as such , but quickly converted by soil
microbes to ammonia cal and nitrate form and then
utilized.
 Slow release nitrogenous fertilizers: These are newly
developed fertilizers which release nitrogen in soil
very slowly so that it may be available to the plants
for longer period of time. Use of these materials
result in better utilization of applied nitrogen by the
growing crop plants and reduce losses.

5. N ITROGEN CYCLE

6. P ROCESS OF THE
E XTRACTION OF N ITROGEN
Nitrogen may be prepared from air by passing the air through a solution
of caustic soda to remove carbon dioxide.
2 NaOH + CO2 ==> Na2CO3 + H2O
Then the gas stream is passed over heated copper turnings which
removes the oxygen.
Cu + O2 ==> 2 CuO
However, when nitrogen is prepared by this method, the gas is somewhat
impure due to the presence of traces of the inert Nobel
Gases, which are also present in the atmosphere.
Nitrogen may also be prepared by the decomposition of compounds
containing nitrogen. For example, nitrogen gas is liberated on
heating a dilute solution of ammonium nitrite.
NH4NO2 ==> N2 + 2 H2O

7. A DVANTAGES O F N ITROGEN
F ERTILIZERS
 • Works immediately
Inorganic fertilizers are usually given as a “rescue treatment” to plants
that are malnourished, unhealthy or even dying. Inorganic fertilizers are
appropriate in this situation because the nutrients needed by the plants
are readily available. In comparison, using an organic fertilizer would
mean that the plant has to wait until the components of the organic
fertilizer have been broken down first into its primary nutrients. By
then, the plant could be dead already.
 • Affordable
You do not have to spend much on buying an inorganic fertilizer because it
is relatively cheap. Of course, it is not as cost-effective when compared
to using compost. Yet, for the convenience that it gives you when it
comes to caring for your plants, an inorganic fertilizer is a very good deal
already.

8. D ISADVANTAGES O F
N ITROGEN F ERTILIZERS
 • Accumulation of toxic wastes
Inorganic fertilizers are not entirely composed of the nutrients needed by the
plants. It also contains salts and other compounds. These are not absorbed
by the plants so they are left behind in the soil and build up over time. When
found in large amounts in the soils, these compounds can alter the chemistry
of the soil that makes it less ideal for planting. Often times, the soil needs to
be neutralized using other substances to return it to a normal state that is
suitable for planting. Furthermore, these toxic compounds may also get
washed away when you water your plants and seep into groundwater. It has
been reported that the toxic wastes from fertilizers contaminating the water
we drink is bad for the health.
 • Too much is not a good thing
Fertilizers are good sources of nutrients for plants. However, too much of it can
also be harmful to the plants. Applying the fertilizer directly to the plants may
burn the delicate plant structures such as the roots. This could affect the
over-all development of the plant.

9. B ENEFITS
 Fertilizers are used to maintain the correct level of
nitrogen in the soil, ensuring strong, green plants with
a healthy growth rate. Nitrogen fertilizers can be used
on a wide range of flora, from the household garden
to commercial crops. They are currently used in one-
third of the world's total crop production, including
species such as maize, barley and soybean. Nitrogen
fertilizers are also extensively used on commercial
lawns, including a large proportion of the world's golf
courses.