Fertilizers

• Fertilizers may be defined as industrially manufactured chemicals containing plant nutrients more than in organic manures which are able to release nutrients immediately just after application.
• They have definite chemical composition with higher analytical value and capable of supplying plant nutrients in available form.

Classification of fertilizers

1. On the basis of primary nutrient content mainly fertilizers are classified in two groups, which are:

a) Straight fertilizers

• Fertilizers that contain only one primary nutrient are referred to straight fertilizers e.g. ammonium sulphate, urea etc (they supply nitrogen only).b) Multi-nutrient fertilizers
• Those fertilizers that contain two to three primary nutrients are called multi-nutrients fertilizers.
• Binary fertilizers contain two major nutrients e.g. potassium nitrate (13%N and 44% K2O) and they are also called incomplete fertilizer (having lack of any 3 major nutrient elements) and ternary fertilizers contain three major nutrients
• Eg. complete fertilizer (15:15:15%) NP and K respectively.
• Multi nutrient fertilizers are more beneficial than straight fertilizer because multi nutrient fertilizers are easy of handling, transport, storage and application with high fertilizer efficiency.
• These fertilizers are usually produced in granular form.

2. Fertilizers are also classified as high analytic and low analytic fertilizers.

• High analytic fertilizers containing more than 25% of major plant nutrients e.g. urea (46%N) and low analytic fertilizers containing less than 25% of the major plant nutrients e.g. single super phosphate (16% P2O5), sodium nitrate (16%N) etc.

3. Fertilizer can also be classified based on physical form, which are: a) Solid and b) Liquid form

• Most of the fertilizers are in solid form.
• They are in several form viz. powder (SSP), crystals (A/S), prills (urea, DAP), super granules (urea supergranules).
• Liquid fertilizers are of two types: a) Clear liquid fertilizers: When the nitrogenous, phosphatic and potassic and other fertilizers are completely dissolved in water these are called clear liquid fertilizer.

b) Suspension liquid fertilizers:

• Those fertilizers in which some of the fertilizer materials are suspended as fine particles.