Fertilizer is any material of natural or synthetic origin added to the soil to supply one or more plant nutrients.
CLASSIFICATION OF FERTILIZER
- Straight fertilizers
Straight fertilizers are those which supply only one primary plant nutrient, namely nitrogen or phosphorus or potassium, e.g. Urea, ammonium sulphate, potassium chloride and potassium sulphate.
- Complex fertilizers
Complex fertilizers contain two or three primary plant nutrients of which two primary nutrients are in chemical combination. These fertilizers are usually produced in granular form e.g. Diammonium phosphate, nitrophosphates and ammonium phosphate.
3. Mixed fertilizers:
Physical mixtures are straight fertilizers. They contain two or three primary plant nutrients. Mixed fertilizers are made by thoroughly mixing the ingredients either mechanically or manually.
Fertilizers can also be classified based on physical form
|Solid fertilizers are in several forms:||Liquid fertilizers|
|Powder (single superphosphate)
Crystals (ammonium sulphate)
Prills (urea, diammonium phosphate, superphosphate),
Granules (Holland granules)
Supergranules (urea supergranules)
Briquettes (urea briquettes).
|Liquid form fertilizers are applied with irrigation water or for application.
Ease of handling, less labour requirement and possibility of mixing with herbicides has made the liquid fertilizers more acceptable to farmers.
TYPES OF FERTILIZERS
- Nitrogenous fertilizers:
More than 80 per cent of the fertilizers used in this country are made up of nitrogenous fertilizers, particularly urea.
The nitrogenous fertilizers can be further classified into:
|Ammonical Fertilizers||Nitrate Fertilizers||Ammoniacal and
|Ammonium sulphate||Sodium Nitrate||Ammonium Nitrate||Urea|
|Ammonium chloride||Calcium Nitrate||Calcium Ammonium Nitrate||Calcium Cynamide|
|Anhydrous ammonia||Potassium Nitrate||Ammonium Sulphate Nitrate|
- Ammonical fertilizers
Ammoniacal fertilizers contain the nutrient nitrogen in the form of ammonium or ammonia.
Except rice, all crops absorb nitrogen in nitrate form. These fertilizers are resistant to leaching loss, as the ammonium ions get readily absorbed on the colloidal complex of the soil.
- Ammonium sulphate [(NH4)2 SO4]
It is a white salt completely soluble in water containing 20.6 per cent of nitrogen and 24.0 per cent of sulphur. It is used advantageously in rice and jute cultivation.
It is easy to handle and it stores well under dry conditions. But during rainy season, it sometimes forms lumps. It can be applied before sowing, at the time of sowing or as a top-dressing to the growing crop.
- Ammonium chloride (NH4Cl)
It is a white salt contains 26.0 per cent of nitrogen. It is usually not recommended for tomato, tobacco and such other crops as may be injured by chlorine.
- Nitrate Fertilizers
Nitrate fertilizers contain the nitrogen in the form of NO3. These ions are easily lost by leaching because of the greater mobility of nitrate ions in the soil.Continuous use of these fertilizers may reduce the soil acidity as these nitrogenous fertilizers are basic in their residual effect on soils.
- Potassium nitrate (KNO3)
The purified salt contains 13.0 per cent nitrogen and 36.4 per cent potassium. The nitrogen of the potassium nitrate has the same properties and value as that of the sodium nitrate.
- Calcium nitrate [Ca (NO3)2]
It is a white crystalline hygroscopic solid soluble in water containing 15.5 per cent nitrogen and 19.5 per cent calcium. The calcium is useful for maintaining a desirable soil pH.
- Ammoniacal and nitrate fertilizers
These fertilizers contain nitrogen in both ammonium and nitrate forms. The nitrates are useful for rapid utilization by crops and the ammonical is gradually available.
- Calcium ammonium nitrate (CAN)
Calcium ammonium nitrate is a fine free-flowing, light brown or grey granular fertilizer, containing 26 per cent of nitrogen.It is almost neutral and can be safely applied even to acid soils. 50% of its total nitrogen is in the ammoniacal form and another 50% is in nitrate form.
- Ammonium nitrate (NH4NO3)
Contain 35 per cent nitrogen half as nitrate nitrogen and half in the ammonium form. In the ammonium form, it cannot be easily leached from the soil.This fertilizer is quick-acting, but highly hygroscopic and not fit fo storage.
- Ammonium sulphate nitrate [(NH4)2SO4 NH4NO3]
It contains 26 per cent nitrogen, three fourths of it in the ammoniacal form and the rest (6.5 per cent) as nitrate nitrogen.It is a mixture of ammonium nitrate and ammonium sulphate.It is readily converted to ammoniacal and nitrate forms in the soil.
- Amide fertilizers
Amide fertilizers are readily soluble in water and easily decomposable in the soil.
- Urea [CO (NH2)2]
It is the most concentrated solid nitrogenous fertilizer, containing 46 per cent nitrogen.It is a white crystalline substance readily soluble in water.
- Calcium cyanamide (CaCN2)
Calcium cyanamide or nitrolime contains 20.6 per cent of nitrogen. It is a greyish white powdery material that decomposed in moist soil giving rise to ammonia.
Phosphatic fertilizers are chemical substances that contain the nutrient phosphorus in absorbable form (Phosphate anions) or that yield after conversion in the soil.
- Super phosphate [Ca (H2PO4)2)
It contains 16 Per cent P2O5 in available form. It is a grey ash like powder with good keeping or storage qualities. Phosphatic fertilizer hardly moves in the soil and hence they are placed in the, root zone.
- Triple super phosphate
The concentrated super phosphate is called as Triple super phosphate and it contains 46 per cent P2O5. It can be applied before or at sowing or transplanting.
There are a limited number of fertilizer materials that can be used to supply K when needed.
Common fertilizer sources of K
|Potassium chloride KCl||60% K2O|
|Potassium-magnesium sulfate K2SO4-2MgSO4||20% K2O|
|Potassium nitrate KNO3||44% K2O|
|Potassium sulfate K2SO4||50 %K2O|
Potassium chloride (KCI)
Potassium chloride or muriate of potash is a white or red, crystal containing 60.0 per cent K2O.It is completely soluble in water and therefore readily available to the crops.
It is not lost from the soil, as it is absorbed on the colloidal surfaces.It can be applied at sowing or before or after sowing.
Potassium sulphate (K2SO4)
Potassium sulphate or sulphate of potash is a white salt and contains 48 per cent K2O.
It is soluble in water and therefore readily available to the crop.It does not produce any acidity or alkalinity in the soil.
The importance of fertilization of crops with micro-nutrients is increasing mainly because of greater removal from the soil, intensive liming of soil, intensive drainage of soil, higher use of nitrogenous, phosphatic and potassic fertilizers etc. There are seven essential micronutrients required by plants. These are iron, manganese, zinc, copper, chlorine, boron and molybdenum.
- lron fertilizers
These are generally water soluble substances, predominantly sprayed as foliar nutrients on the crops. Plants absorb iron in the form of Fe2+.
|It is a water soluble fertilizer containing 20 % Fe|
|Fe – Chelates
|Suitable for application as foliar nutrients|
- Manganese fertilizers
The manganese (Mn) fertilizers are as follows:
( MnSO4 7H2O)
|It is the well-known water soluble Mn fertilizer.
It is pink salt containing 24 % Mn.
It dissolves in water and is suitable for foliar application.
|Mn – chelates (Mn – DTA)||It contains 13 % Mn.
It plays an important role in the crop fertilization.
- Copper Fertilizers
Copper sulphate (CuSO4 5H2O) – 25 % Cu
Copper sulphate (CuSO4 H2O) – 36 % C
- Boron Fertilizers
|Borax (Na2B4O 10H2O)||It contains 11 % B
It is water soluble white salt
It can be applied as a soil dressing or foliar application
|Boric acid (H3BO3)||It contains 18 % B
It is a white crystalline powder
It is applied as a foliar nutrient
- Zinc fertilizers
Zinc (Zn) fertilizers play an important role in Zn deficient
|It is water soluble whitish salt containing 23 % Zn.
It is applied as foliar nutrient. Its acidic action causes corrosion damage to plants
| Zinc oxide
|It contains 70 % Zn.
It is slightly soluble in water
It is used as slow acting foliar nutrient
- Molybdenum Fertilizers
|Molybdate||It contain 40% Mo|
|Ammonium [(NH4)6Mo7O24.4H2O]||Molybdate||It contain 54% Mo|
Secondary major-nutrient fertilizers
- Magnesium fertilizers
These are chemical substances containing the nutrient magnesium in the form of magnesium cations (Mg2+).
- Magnesium Sulphate (MgSO4)
The utilization rate of magnesium fertilizers decreases with increasing potassium supplies.
- Calcium fertilizers
These are the chemical substances containing the nutrient calcium in absorbable calcium cations (‘Ca2+) form. The raw material of calcium fertilizers is lime found in nature.
- Calcium Chloride (CaCl26H2O)
It contains at least 15 per cent calcium. It is highly water soluble and can, therefore, be dissolved for application as a foliar nutrient.
Find out how many bad sod DAP, Urea and Potash will be needed. Requirement of nitrogen is 64 kg/acre, phosphorous 46kg/acre and potash 30kg/acre.
We known; DAP have 46% phosphorous and 16% nitrogen, urea contains 46% nitrogen and MOP contains 60% K.
23 kg phosphorous comes from = 1 bag of DAP
1 kg phosphorous comes from = 1/23 bag of DAP
46 kg phosphorous comes from = 1/23 × 46 = 2 bags DAP
So, 2 bags of DAP require to fulfill phosphorus status of wheat acre.
We known; DAP contains 18% Nitrogen, so
1 bag of DAP gives = 9 kg Nitrogen
2 bags of DAP give = 18 kg Nitrogen
Remaining Nitrogen = 64-18 = 46 kg
We known, Urea contains 46% Nitrogen
23 kg nitrogen comes from = 1 bag of Urea
1 kg nitrogen comes from = 1/23 bag of Urea
46 kg nitrogen comes from = 1/23 × 46 = 2 bags Urea
So, 2 bags of Urea require fulfilling nitrogen status of wheat acre.
One bag of MOP contains 60% of K2O
60 kg potash comes from = 1 bag of MOP
1 kg potash comes from = 1/60 bag of MOP
60 kg nitrogen comes from = 1/60 × 60 = 1 bags of MOP
So, 1 bags of MOP require fulfilling potash status of wheat acre.
2 bags of DAP, Urea and 1 bag of MOP is require for one acre of wheat.
Authors: Ansa Rebi, Komal Javed , Sehrish Kiran