PROPERTIES AND IDENTIFICATION OF FERTILIZERS
Characteristics Nitrogenous Fertilizers
- Highly soluble in water.
- Highly mobile in the soil hence it is applied as a top dress.
- Easily leached because of the high solubility hence does not have residual effect on the soil.
- Has scorching effect on young crops during wet seasons.
- Easy to volatilize during hot season.
- They have a tendency to cake under moist conditions.
- They are hygroscopic hence should be stored in dry conditions.
Sulphate of Ammonia (NH4) 2 SO4-
- white crystals,
- Has acidic effect,
- Contains 20% N.
Ammonium Sulphate Nitrate [(NH4), SO4+ NH4 NO;]
Colour: granules which appear yellow orange,
- Less acidic,
- Contains 26% N.
Calcium Ammonium Nitrate (CAN)
Colour: greyish granules,
Neutral in nature, contains 21 % N.
Colour: small whitish granules
Easily leached or volatilized,
Contains 45- 46%N.
- Has low solubility and immobile.
- Has a high residual effect hence benefit the next season’s crop.
- Easy to store because they are not hygroscopic.
- Appearance: whitish, creamy white granules,
- Contains 20-21 % P, O5
Appearance: dark greyish granules,
Contains 40-42% P205
Appearance: small greyish granules,
Contain 44-48% P205
- Has moderate scorching effect.
- Moderately soluble in water.
- Most Kenyan soils have sufficient potassium.
Marinate of Potash (KCI)
- Contain 60 – 62% K10
- Slightly hygroscopic.
- Appearance amorphous white.
Sulphate of Potash (50% K10)
Compound or Mixed Fertilizers
These are fertilizers which supply 2 or more of the macronutrients.
- Mono ammonium phosphate.
- Di-ammonium phosphate
- 20:20:20, 23:23:23
Advantages of application of compound fertilizers
- Saves time and money.
- Mixture gives improved storage properties and better handling.
Disadvantages of compound fertilizers application
- Mixing may not be thorough.
- Incompatibility of the individual fertilizers.