Manures are not able to supply the required quantities of the essential plant nutrients to the soil. So they are to be supplemented with chemical fertilizers. Fertilizers are chemical compounds, which are applied to the soil to increase the supply of one or more of the essential nutrients such as nitrogen, phosphorus or potash. Fertilizers are generally inorganic materials and contain these elements in the form of soluble chemical compounds. Fertilizers are usually classified according to the particular plant nutrient, which forms their principal constituent. Chemical fertilizers may be classified into the following types:

1. Nitrogenous fertilizers

2. Phosphatic fertilizers

3. Potassic fertilizers


4. Compound fertilizers

5. Mixed fertilizers