2. • Fertilizers are the substances, which are added to the soil
to make up and provide the elements necessary for the
growth of plants.
• These may include
naturally occurring inorganic
naturally occurring organic substances
such substances prepared synthetically.
4. 1.BASED ON THE COMPOSITION
• 1.Straight fertilizers - single nutrient
E.g., Urea contains only Nitrogen (N) @ 46 %
Single Super Phosphate (SSP) contains only Phosphorus (P) @
16 %.
• 2. Complex fertilizers: contain two or three primary plant
nutrients of which two primary nutrients are in chemical
combination.
These fertilisers are usually produced in granular form.
eg. Diammonium phosphate, nitrophosphates and ammonium
phosphate.
3. Mixed fertilizers: are physical mixtures of straight fertilisers.
They contain two or three primary plant nutrients.
5. Complete vs. Incomplete
• Complete has all three primary nutrients-nitrogen
phosphorous & potassium
–Examples: 10-10-10, 15-30-15, 20-5-20
• Incomplete DOES NOT have all three primary nutrients
–Examples: 20-0-0, 0-20-0, 12-0-44
8. • Liquid fertilizers: e.g, anhydrous ammonia (which is
actually transported as a fluid and injected into soil in
gaseous form), nitrogen (N) solutions (usually made from
a mixture of urea and ammonium nitrate), ammonium
polyphosphate and triazones
9. • Acid forming fertilizer :Acid forming fertilizer is one
capable of increasing acidity of the soil which is derived
principally from the nitrification of ammonium salts by
soil bacteria.
e.g., All ammonium N fertilizers (except ammonium
nitrate with lime) have a gradual acidforming effect.
That's because the conversion of ammonium (NH.) to
nitrate (NO3) releases acid-forming hydrogen ions (H+).
The same applies to urea and most NP and NPX
fertilizers.
3. BASED ON ITS EFFECT ON CHANGING SOIL pH
10. • Base Fertilizer : Base fertilizers is one capable decreasing
the acidity of the soil.
e.g., Nitrate N fertilizers that have their nitrate combined
with a strong base have a slightly basic effect (i.e. calcium
nitrate, potassium nitrate, sodium nitrate).
• Neutral fertilizer: Neutral fertilizer is one that is guranted
to leave neither an acidic nor basic residue in soil.
e.g,., The straight P or K fertilizers have no effect on soil
pH. Examples: potassium chloride, potassium sulfate, and
the superphosphates.
11.
12.
13. D. Micronutrient Fertilizers
• There are seven essential micronutrients required by
plants.
• These are iron, manganese, zinc, copper, chlorine, boron
and molybdenum
• E.g, lron fertilizers: Ferrous sulphate
