Uses And Benefits of Fertilizers…
Plants need nutrients to grow. These nutrients are absorbed from the soil by the plant’s root system. Fertilizers provide the most important nutrients that plants need for proper growth and development. When nutrients are not replaced in the adequate quantity and form, soil productivity will decrease with each harvest.
What Are Fertilizers?
Fertilizers are chemical products supplied to crops to increase their capacity and productivity. Farmers often use it to increase crop yields. Fertilizers contain essential nutrients that plants need, such as nitrogen, potassium, and phosphorus. By applying fertilizers to your farmland, you’re also increasing the water holding capacity soil fertility.
Type of fertilizers
These are two main types of fertilizers;
1. Organic Fertilizers.
2. Inorganic Fertilizers.
1. Organic fertilizers (OF)
Organic fertilizers are natural fertilizers obtained from plants and animals. They enrich the soil with carbon compounds needed for plant activities. Organic fertilizers increase the soil’s organic matter content, promote the reproduction and activities of microorganisms and alter the physical and chemical properties of the soil.
Organic fertilizers can be obtained from the following products:
– Agricultural waste: straw, bean manure, cotton manure, rice bran, biogas residues, mushroom residues, etc.
– Animal waste: slaughterhouse waste, fish market waste, urine, and feces from chickens, pigs, cattle, sheep, ducks, geese, goats, etc.
– Household waste: food waste, plant bones, roots and leaves, etc.
– Industrial waste: still grain residues, vinegar residues, sugar residues, etc.
– Minerals: humic acid, bentonite, dolomite, etc.
– Sludge: river sludge, dam sludge, sewage sludge, municipal sludge, etc.
2. Inorganic fertilizers
Inorganic fertilizers are chemical fertilizers that contain nutrients necessary for the growth of crops produced by chemical methods.
Inorganic fertilizers are divided into 5 different categories;
1. Nitrogenous Fertilizers
2. Phosphate Fertilizers
3. Potassium Fertilizers
4. Compound Fertilizers
5. Complete Fertilizers (NPK)
1. Nitrogenous Fertilizers:
Nitrogen fertilizers contain nitrogen necessary for crop growth. Nitrogen is the main component of chlorophyll, which maintains balance during photosynthesis. It is also part of plant amino acids and forms proteins. Nitrogen fertilizers improve the yield and quality of agricultural products.
These nitrogenous fertilizers are divided into four groups namely; nitrate, ammonia and ammonium salts, chemical compounds containing nitrogen in the amide form, and plant and animal byproducts.
There are seven categories of nitrogenous fertilizers, which are;
(i) Sodium Nitrate:
The refined product contains about 16% nitrogen in the form of nitrates, which can be supplied directly to crops. For this reason, it is used as a source of nitrogen, especially in seedlings and vegetables, which require readily available nitrogen to grow quickly.
Sodium nitrate is easily soluble in water and is quickly leached from the soil. It is especially useful for acidic soils. Its continued use on a large scale in the soil can cause flocculation and poor physical condition in areas with little rain.
(ii) Ammonium sulfate:
It is a white crystalline salt containing 20-21% ammoniacal nitrogen. It is very suitable for crops in wet areas such as rice and jute. Ammonium sulfate is easy to handle and can be stored well under dry conditions.
It is also suitable for wheat, cotton, sugar cane, potato and many other crops grown in different soils. Its continuous use increases soil acidity and reduces yield. Its application in acidic soil significantly increased the yield of tea plantations. It is recommended to use this fertilizer together with bulk organic fertilizers to avoid its harmful effects.
Ammonium sulfate can be applied before planting, during planting, or as a cover for growing crops. It should not be used during germination, as in its concentrated form it will have a very detrimental effect on germination.
(iii) Ammonium Nitrate:
Ammonium nitrate is a white crystalline salt that contains 33% to 35% nitrogen, 50% nitrate nitrogen and 50% ammonium. In the form of ammonium, it is not easily leached from the ground. It starts fast, strongly hygroscopic and cannot be stored. Under certain circumstances it is explosive, so it must be handled with care.
If you continue to use this fertilizer on your farmland, it will acidify the soil. This is why about 40% limestone or dolomite is usually mixed with Ammonium Nitrate because the presence of lime makes it suitable for acidic soils.
(iv) Ammonium Sulphate Nitrate:
It is a mixture of ammonium sulfate and ammonium nitrate. It is available in the form of white crystals or off-white granules. It contains 26% nitrogen, three-quarters are in the form of ammonia and the rest is nitrogen nitrate.
It is very soluble in water and has a very fast and non-explosive effect. It is suitable for all plants. Slightly acidify the soil. It can be used before, during or as a top-dressing, but it is not suitable for seeds.
(v) Ammonium Chloride:
It is a very crystalline compound in good physical condition. Contains 26% ammonia nitrogen. It is widely used for rice. Its effect is similar to that of ammonium sulfate. Not recommended for certain types of crops, such as tomatoes, tobacco, etc., as it can be damaged by chlorine.
Urea is a white crystalline organic compound. It is a highly concentrated nitrogen fertilizer that contains 45% to 46% organic nitrogen. It is highly hygroscopic and cannot be stored well in wet areas. To overcome this problem, it is also formed into particles covered with an inert, non-hygroscopic material.
It is very soluble in water and leaches quickly from the soil. It works very fast and will quickly convert to ammonia when used. It is used during planting or as a top-dressing, but never during germination. It is suitable for most crops and can be applied to all types of soil.
(vii) Calcium Ammonium Nitrate:
It is a fine-grained compound with a light brown or gray colour. It is made from ammonium nitrate and ground limestone. It is almost neutral and can even be used on acidic soils. Its nitrogen content ranges from 25% to 28%. Of the total nitrogen, 50% is retained as ammonia, and the remaining 50% is retained as nitrate.
2. Phosphate Fertilizers:
The main nutrient in a phosphorus fertilizer is phosphorus. The efficiency of fertilizer depends upon effective phosphorus content, methods of fertilizing, properties of soil and crop strains. Phosphorus found in the protoplasm of the cell plays an important role in cell growth and proliferation. The phosphorus fertilizer is beneficial for the growth of roots of the plants.
Phosphate fertilizers are classified as natural phosphates, treated phosphates, by-product phosphates and chemical phosphates.
3. Potassium Fertilizers:
These are applied only to those soils that are deficient in potash.
Potassic fertilizers are used as:
(a) muriate of potash (potassium chloride)
(b) sulphate of potash (potassium sulphate).
(a) Muriate of Potash (MOP):
It is a gray crystalline material containing 50 to 63 percent of potash (K2O), the whole of which is available to the crops. It remains absorbed on the colloidal surfaces and is not leached out from the soil. It is applied at sowing time or before sowing.
(ii) Sulphate of Potash:
It is more costly as it is prepared by treating potassium chloride with magnesium sulphate. It contains 48 to 52 percent K2O. It dissolves readily in water and becomes available to the crops almost immediately after application. It can be applied at any time up to sowing. In certain crops like tobacco, chillies, potato and fruit-tree it is considered better than muriate of potash.
4. Compound Fertilizers:
These fertilizers contain two or three plant nutrients simultaneously. When both nitrogen and phosphorus are deficient in the soil, a compound fertilizer, e.g., amorphous, can be used. It contains 16 percent nitrogen and 20 percent P2O5. Two different fertilizers can be mixed in the correct proportion to produce the compound fertilizer.
5. Complete Fertilizer (NPK):
Compound fertilizers are not always well adapted to different kinds of soils. For that reason mixed fertilizers containing two or more materials in suitable proportions are used according to the needs of different soils. Mixtures usually fulfill the nutrient deficiencies in a more balanced manner and require less labour to apply than different fertilizers used separately.
These mixtures containing all the three principal nutrients (N, P and K) are called complete fertilizers as most soils usually remain deficient in these three elements. A special mixture for different crops are also produced by the manufacturers.
In some cases insecticides, fungicides and weed-killers, such as DDT, BHC and mercury or copper salts and 2, 4-D are mixed into the complete fertilizers. The component fertilizers must be compatible to ensure mutual reaction. Uneven mixing must be avoided. Bone-meal, muriate of potash and sulphate of potash can be mixed with all fertilizers.
Advantages of Fertilizers;
- They have a rapid effect on the crops.
- They are easy to transport, store, and apply.
- For supplying a specific nutrient we can select a specific fertilizer due to its nutrient-specific nature.
- They are predictable and reliable.
- They are water-soluble and can easily dissolve in the soil. Hence, they are easily absorbed by the plants.
- They increase the crop yield and provide enough food to feed the large population.
Disadvantages of Fertilizers;
- They can be expensive.
- Long-term use reduces the microbial activity and disturbs the pH of the soil.
- The ingredients in the fertilizers are toxic to the skin and respiratory system.
- Excessive use of fertilizers damages the plants and reduces soil fertility.
- Leaching occurs and the fertilizers reach the rivers causing eutrophication.
Uses of Fertilizers;
- They are used to providing additional nutrients to the plants.
- They are added to improve the yield of the crops.
- Fertilizers are added to potted plants to replace the lost nutrients.
- Nitrogen-rich fertilizers are used for the greening of lawns.
- Organic fertilizers improve the texture and fertility of the soil.
- Gardeners use fertilizers to address certain needs of the plants such as nutritional needs.
Importance of Fertilizers;
It is very difficult to meet the demands of the increasing population with such fewer resources. Loss of soil fertility, pests, and lack of nutrients has resulted in a decrease in agricultural production. This has increased the importance of fertilizers in agriculture.
Fertilizers can be important to the plants in the following ways:
1. Fertilizers increase plants’ tolerance towards pests. This has reduced their reliance on insecticides and herbicides, thereby, producing healthier crops. Consequently, diseases have reduced, providing aesthetic value to the crops.
2. Fertilizers improve the water-holding capacity of the plants and increase root depth.
3. The potassium content present in the fertilizers strengthens the straws and stalks of the plants.
4. The phosphorus present in the fertilizers helps in the faster development of roots and formation of seeds in the plants.
5. Nitrogen in the fertilizers enhances the growth of the plants which can be characterized by the green colour of the plants.
Since the chemical fertilizers adversely affect soil fertility, biofertilizers were brought into use. These are substances that contain living or latent cells, and even micro-organisms. They provide the soil with the necessary nutrients and microbes for the growth of the plants.
They help the soil retain its fertility. They are environment-friendly and destroy pathogenic components responsible for causing disease in plants. Acetobacter and Rhizobium are two of such widely used biofertilizers.