The following points highlight the five important types of fertilizers. The types are: 1. Nitrogenous Fertilizers 2. Phosphatic Fertilizers 3. Potassic Fertilizers 4. Mixed Fertilizers 5. Bio-Fertilizers.
Fertilizer Type # 1. Nitrogenous Fertilizers:
i. Ammonium Sulphate:
Ammonium sulphate [(NH4)2 SO4] was most widely used nitrogenous fertilizer in our country. It is a white crystalline salt and contains 20.5-21.0 percent ammoniacal nitrogen. It is quick acting fertilizer with good storage quality. Ammonium sulphate can be applied at sowing time as a basal dressing and as top dressing i.e. during growing period of the crop.
It should not be applied along with seeds. It is suitable fertilizer for all crop and for a wide variety of soil. Ammonium sulphate physiologically is acidic in nature having acid equivalent 110 i.e. 110 kg Calcium carbonate is required to neutralize the acidity produced by application of 20.0 kg nitrogen as Ammonium sulphate.
ii. Urea:
Urea (CO(NH2)2) is one of the most popular nitrogenous fertilizer containing nitrogen in amide form. It is a white crystalline product soluble in water and has a tendency of being caking. It is highly concentrated nitrogenous fertilizer containing 44.0-46.0 percent organic nitrogen. It is very soluble in water and therefore subject to rapid leaching.
When applied at sowing time, it should not be allowed to come in contact with seed. Urea can be applied as basal dressing, top dressing and foliar spray. It is a suitable fertilizer for application to all crops and soil when the soil is moist. Physiologically Urea id acidic fertilizer and its acid equivalent (a.e) is 80.
iii. Ammonium Chloride:
Ammonium chloride (NH4Cl) is a white crystalline substance and contains 26.0 percent ammoniacal nitrogen. It is much soluble in water than Ammonium sulphate. In India, it is largely used for industrial purposes. Its behavibour is same as Ammonium sulphate.
iv. Sodium Nitrate:
Sodium nitrate (NaNO3) is a white crystalline substance and very hygroscopic in nature. It contains 16.0 percent nitrogen. It is not suitable fertilizer for water logged condition, because large portion of fertilizer is lost by leaching. It is good fertilizer for the crop such as Wheat (Triticum sp). Maize (Zea mays), Barley (Hordeum vulgare L), Cotton (Gossypium sp), Sugarcane (Saccharum officinarumL) etc. It is physiologically basic in nature and its basic equivalent is 27.
v. Ammonium Nitrate:
Ammonium nitrate (NH4 NO3) is also a nitrogenous fertilizer. It is a white crystalline salt, very soluble in water and hygroscopic in nature. It contains 33.0-35.0 percent nitrogen, out of which half as nitrate nitrogen and half in ammonium for. It is also an acid forming fertilizer.
vi. Ammonium Sulphate Nitrate:
Ammonium sulphate nitrate ((NH4)2SO4 + NH4NO3) is a mixture of Ammonium nitrate and Ammonium sulphate. It is available in white crystalline form or as granular for of a dirty white color. It contains 26.0 percent nitrogen, three fourth being in ammoniacal form and the rest (i.e. 6.5 percent) in nitrate form. It is soluble in water and is readily available to crops.
It can be applied before sowing of seed or transplanting of seedlings at sowing time as basal dressing or as top dressing. It is useful for all crops and is suitable for application to all types of soils. It also produces acidity in soil, but to a much less extent (about half) than Ammonium sulphate.
vii. Calcium Cyanamide:
Calcium cyanamide (CaCN2) is a dark grey powdered substance. It is not hygroscopic and therefore easy to store. It is poisonous substance. So care should be taken during handling. It contains 20.0-21.0 percent nitrogen. It is a basic fertilizer and its basicity is 57.
Fertilizer Type # 2. Phosphatic Fertilizers:
i. Superphosphate:
Super phosphate is most widely used phosphatic fertilizer in India. It is a grey ash like powder with good keeping quality. lt is manufactured largely by treating ground phosphate rock with almost an equal quantity by weight of Sulphuric acid.
The fertilizer is manufactured in three grades as follows:
(a) Single Superphosphate – The single super phosphate contains 16.0-20.0 percent P2O5. It is manufactured by treating ground phosphate rock with sulphuric acid (H2SO4).
(b) Double super phosphate – The double Super phosphate contains 30.0-35 percent P2O4.lt is manufactured by treating ground phosphate rock with Phosphoric acid (H3PO4).
(c) Triple super phosphate – The triple super phosphate contains 45.0-50.0 percent P2O5.
It is manufactured by treating ground phosphate rock with sulphuric acid (H2SO4).
The whole of P2Os of Super phosphate is in water soluble form and it is readily available for nutrition of plants. Although Super phosphate readily dissolve in water, it does not wash out from the soil. It is suitable for all crops and can be applied to all soils except acid soil. In acid soil, it is immediately converted into insoluble phosphate due to precipitation as iron and aluminium phosphate. It should be applied before or at the time of sowing seed or planting of seedlings.
ii. Bone Meal:
Bone meal is both phosphatic manure and fertilizer. It contains a small quantity of nitrogen.
It is available in two forms as follows:
(a) Raw bone meal – The raw bone meal contains 3.0-4.0 percent nitrogen and 20.0- 25.0 percent P2O5.
(b) Steamed bone meat – The Steamed bone meal contains 1.0-2.0 percent nitrogen and 25.0-30.0 percent P2O5.
Bone meal having particles not large than 3/32 inch in size is considered suitable for use as fertilizer. Bone meal may be applied to the soil either at sowing time or just before it. It is most suitable fertilizer for acid soil and is considered a safe manure for all crops.
Fertilizer Type # 3. Potassic Fertilizers:
i. Muriate of Potash or Potassium Chloride:
Muriate of potash or Potassium chloride is a white or reddish to white crystalline or powdered material. It contains 50.0-60.0 percent Potassium (K2O), the whole of which is readily available to plants. It is soluble in water, but it is not lost from the soil as it absorbed in the soil particles readily. It can be applied at sowing time or prior to sowing. Now-a-days, it is being applied as top dressing.
ii. Potassium Sulphate or Sulphate of Potash:
Potassium sulphate or Sulphate of Potash is also a potassic fertilizer. It is made by treating Potassium chloride with Magnesium sulphate. It contains 48.0-52.0 percent Potassium (K2O). It dissolve readily in water and becomes available to the plant almost immediately after application. It can be applied at any time upto sowing of seeds. It is considered better than Muriate of Potash for crops like Potato (Solanum tuberosum L).Tobacco (Nicotiana sp) and fruit trees.
Fertilizer Type # 4. Mixed Fertilizer:
Mixed fertilizer is one which contains two or three fertilizers and is available in the market in a particular grade (e.g. Grade-1:8:8:8). The fertilizer grade refers to minimum guarantee of plant nutrient content in terms of total nitrogen, available P2O5 and water soluble K2O. The mixed fertilizer can be made by adopting the following formula –
Calculation = a x (b/c)
Where, a = Amount of nutrient in mixed fertilizer.
B = Amount of mixed fertilizer to be prepared.
C = Amount Of the nutrient in the ingredient.
Example – Preparation of fertilizer mixture of 1000 kg having grade 5:5:10.
Ans:
If the mixed fertilizer so prepared is used immediately after preparation, no filler is added.
N.B – Filler is the “make weight materials” added to the mixed fertilizer of fertilizer material. It is added to make the difference between the weights of the added ingredients required to supply the nutrient in a ton of given analysis.
One fertilizer cannot be mixed with other fertilizer because uneven mixing of incompatible fertilizer leads to a loss of some of the fertilizer nutrients in the form of gas, convert soluble nutrients into insoluble ones or produce caking.
Certain fundamental principles are to be followed in mixing fertilizer as follows:
(a) Ammonium sulphate, Ammonium chloride and other ammoniacal fertilizers and nitrogenous organic manures should not be mixed with lime.
(b) Calcium cyanamide, Basic slag, quick lime, slaked lime should not be mixed with fertilizers containing nitrogen in ammoniacal form.
(c) Urea should not be mixed with Superphosphate and Super phosphate should not be mixed with lime or calcium carbonate or wood ashes.
(d) Sodium nitrate or Potassium nitrate should not be mixed with Superphosphate.
(e) Ammonium sulphate nitrate should not be mixed with lime.
Fertilizer and its Relation of Plant Nutrient:
Fertilizer Type # 5. Bio-Fertilizer:
The term ‘Bio-fertilizer’ itself denotes that, it is a ‘Live Fertilizer’.
A bio-fertilizer (also bio-fertilizer) is a substance which contains living microorganisms which, when applied to seed, plant surfaces, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Bio-fertilizers are organisms that enrich the nutrient quality of soil.
(1) Bio-fertilizer is eco-friendly organic agro-input and more cost-effective than chemical fertilizers.
(2) Bio-fertilizers add nutrients through the natural processes of nitrogen fixation.
(3) Bio-fertilizer adds nutrients through solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances.
(4) Bio-fertilizers can be expected to reduce the use of chemical fertilizers and pesticides. Bio-Fertilizers are supplement to Chemical Fertilizers.
(5) Bio-Fertilizers are cheap and can reduce the cost of cultivation.
(6) Bio-fertilizers improve soil properties i.e. porosity and water holding capacity of soil and sustain soil fertility.
(7) Bio-Fertilizers will help solve such problems as increased salinity of the soil and chemical run-offs from the agricultural fields.
Blue green algae belonging to a general cyanobacteria genus, Nostoc or Anabaena or Tolypothrix or Aulosira, fix atmospheric nitrogen and are used as inoculations for paddy (Oryza sativa L) crop grown both under upland and low-land conditions. Anabaena in association with water fern Azolla contributes nitrogen up to 60 kg/ha/season and also enriches soils with organic matter.