3. Improvement In Food Resources
Fertilizers are the sources of plant nutrients manufactured commercially from chemicals. They are inorganic or organic compounds containing necessary plant nutrients such as nitrogen, phosphorus and potassium.
The chemical substance which can be used as a fertilizer must have the following characteristics :
It must be soluble in water.
It should be easily assimilated by plants.
It should be fairly stable.
It should not be injurious to plants.
It should not disturb pH of the soil.
It should be cheap.
Fertilizers are classified according to the element (N, P or K) which they supply to the soil.
(i) Nitrogeneous fertilizers
(ii) Phosphatic fertilizers
(iii) Potash fertilizers
(iv) NPK fertilizers