Fertilizers enhance crop fertility and production.

1. What are Fertilizer?
Substances that are added to soil to increase their fertility are called Fertilizer.
 Manure:
“A manure is an organic material used to fertilize land and its usually consists of
faces and urine of domestic livestock.”
 Types:
 Natural Fertilizer:
like leaves, cow dung, bone meal compost etc. are used to
make up the deficiency of nitrogen, Phosphorus, and potassium in soils these
substances are called Natural Fertilizer.

2.  Artificial Fertilizer:
The Fertilizer which are manufactured to provide nitrogen,
potassium and phosphorus to Plant.
Nutrients in the Fertilizer:
Primary Nutrients:
“Such nutrients which are required in a very large amount for the growth
of the plant.”
Examples:
“Nitrogen, Potassium and Phosphorus the quantity required.”
Quantity:
5kg to 200kg per acre.

3.  Micro Nutrients:
“Such nutrients which are required in a very small amount for
the growth of the plants.”
Examples:
Iron, Zinc, Copper, manganese, boron and molybdenum
Quantity:
6g to 200g per acre.
 Secondary Nutrients:
 They are secondary nutrients because plants
require them in smaller quantities than Primary Nutrients and larger than
micro Nutrients.
 Examples:
 Calcium, magnesium, sodium and Sulphur.

4.  Need for Fertilizer:
After repeated cultivation, a stage is however reached when the soil
become less productive, if supply of the above nutrients is not provided. Thus, in
order to make up this deficiency certain elements in the form of their compound
have to added to soil to make it reproductive. These substances are known as
fertilizer.
“Thus Fertilizer are those substances which must be added to the soil

5. It is important to note that a deficiency of any nutrient
will lead to a poor yield so that the distinction between
primary, secondary and micro- only refers to the
amounts taken up by the crop and does not in any way
mean that some are less important than others and can
be ignored; they are all important and each needs to be
balanced one against the other.

8. Requirments
1. The substance must be soluble in water.
2. It should be stable.
3. It should be cheap.
4. It should maintain the pH of the soil in the vicinity
5. of 7 to 8.
6. It should not be a poison for plant.
7. By rain or water, it should be converted into a form,
8. which the plant can assimilate easily.

9. Fertilizers; merits
❖ They are easy to transport, store, and apply.
❖ They are specific in nature.
❖ They are water soluble and can easily dissolve in the soil.
❖ They have a rapid effect on the crops.
❖ They increase the crop yield and provide enough food to feed the large population.
❖ They are predictable and reliable.
Fertilizers; demerits
❖ They are expensive.
❖ The ingredients in the fertilizers are toxic to the skin and respiratory system.
❖ Excessive use of fertilizers damages the plants and reduces soil fertility.
❖ Leaching occurs and the fertilizers reach the rivers causing eutrophication.
❖ Long term use reduces the microbial activity and disturbs the pH of the soil

10. Precautions
Therefore, before adding fertilizer, farmers send a soil sample to
a laboratory for baseline testing. By testing their soil, farmers
know which nutrients-and how much-to apply to the soil.
If too little is added, crops will not produce as much as they
should. If too much is added, or at the wrong time, excess
nutrient will run off the fields and pollute streams and ground
water.
farmers must be careful to use the right amount, at the right
time, to avoid potential negative effects to theenvironment

11. Replace The Nutrients
 Fertilizers replace the nutrients that crops remove from the soil.
 Mineral fertilizers are used to supplement the soil's nutrient stocks.

12. Develop Tolerance Against Pests
 Less dependent on Insecticides and
Herbicides.
 K decreases the susceptibility of host
plants
 High N supply decreases in the
severity of the infection
 Si creates a physical barrier which can
restrict fungal hyphae penetration