What are Fertilizers?
A fertilizer is anything that is applied to plant tissues or soil to provide nutrients. The fertilizers can come in two forms that are natural and man-made. Nitrogen, Phosphorus and potassium are the main macronutrients that are present in fertilizers. There are different ranges and forms of fertilizers that the farmers use such as dry form, and pelletized form.
Component of Fertilizer
Fertilizers help plants grow faster. This goal can be achieved in two ways. The first is through the use of nutrient-rich additives. The second mechanism by which certain fertilizers work is to improve the soil's efficacy by altering water retention and aeration.
Three Main Macronutrients-
Nitrogen (N): Leaf growth
Phosphorus (P): Development of roots, flowers, seeds, fruit;
Potassium (K): Strong stem growth, movement of water in plants, promotion of flowering and fruiting;
Three Secondary Macronutrients: calcium (Ca), magnesium (Mg), and sulfur (S);
Micronutrients: copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), boron (B). Of occasional significance are silicon (Si), cobalt (Co), and vanadium (V).
The elements are used to classify the nutrients required for good plant life, but they are not utilized as fertilizers. Instead, fertilizers are made up of compounds containing these elements. The macronutrients are ingested in greater amounts and are found in plant tissue in amounts ranging from 0.15 % to 6.0 % dry matter (0 % moisture). Hydrogen, oxygen, carbon, and nitrogen are the four primary elements found in plants. Water and carbon dioxide are abundant sources of carbon, hydrogen, and oxygen.
Even though nitrogen makes up the majority of the atmosphere, it is in a form that plants cannot use. Because nitrogen is found in proteins, DNA, and other components, it is the most important fertilizer (e.g., chlorophyll). Nitrogen must be made available in a "fixed" form to be nutrient to plants. Only a few microorganisms and their host plants (most notably legumes) can fix nitrogen (N2) in the atmosphere by converting it to ammonia. Phosphate is essential for the creation of DNA, ATP (the cell's principal energy carrier), and some lipids.
Types of Fertilizer
Fertilizers are categorised in a number of ways. They're categorised as "straight fertilizers" if they just give one nutrient (e.g., K, P, or N). Multinutrient fertilizers (also known as "complex fertilizers") include two or more nutrients, such as nitrogen and phosphorus. Fertilizers are also classed as inorganic (which is the subject of the majority of this article) or organic (which is the subject of the remainder of this article). Except for ureas, inorganic fertilizers do not contain carbon-containing compounds. Organic fertilizers are often made up of (recycled) plant or animal debris. Because of the multiple chemical processes necessary for their synthesis, inorganic fertilizers are sometimes referred to as synthetic fertilizers.
Following are the Different Types of Fertilizers Used Today-
Single Nutrient Fertilizers: Ammonia or its solutions are the most used nitrogen-based direct fertilizers. NH4NO3 (ammonium nitrate) is also commonly utilised. Urea is another common nitrogen source, with the advantage of being solid and non-explosive, as opposed to ammonia and ammonium nitrate, respectively. Calcium ammonium nitrate (Ca(NO3)2 • NH4 • 10H2O) has just a small share of the nitrogen fertilizer market.
Superphosphates are the most common straight phosphate fertilizers. SSP is made up of 14–18 % P2O5, this time in the form of Ca(H2PO4)2, as well as phosphogypsum (CaSO4 • 2H2O). TSP is normally made up of 44–48 % P2O5 and no gypsum. Muriate of potash is the most common potassium-based straight fertilizer (MOP). Muriate of potash is commonly sold as a 0-0-60 or 0-0-62 fertilizer and contains 95–99 % KCl.
One of the first and most commonly utilised nitrogen (N) fertilizers for crop productivity was ammonium sulphate ((NH4)2 SO4). It's becoming less common, but it's especially useful when both nitrogen (N) and sulphur (S) are needed. Its high solubility allows it to be used in a variety of agricultural applications.
Multinutrient Fertilizers: These fertilizers are widely used. They are made up of two or more nutrients.
Binary Fertilizers-
Plants receive both nitrogen and phosphorus from major two-component fertilizers. NP fertilizers are what they're called. Monoammonium phosphate (MAP fertilizer) and diammonium phosphate (DAP fertilizer) are the two most used NP fertilizers. NH4H2PO4 is the active component in MAP. (NH4)2HPO4 is the active component in DAP. Water solubility is about 85% for MAP and DAP fertilizers.NPK Fertilizers-
NPK fertilizers are made up of three parts: nitrogen, phosphorus, and potassium. NPK fertilizers are divided into two categories: compound and mixes. Blended NPK fertilizers are physical combinations of single nutritional components, whereas compound NPK fertilizers contain chemically bonded constituents.
The NPK rating system is a way of describing how much nitrogen, phosphorus, and potassium are in a fertilizer. NPK ratings are three digits separated by dashes that describe the chemical content of fertilizers (e.g., 10-10-10 or 16-4-8) The first value shows the product's nitrogen content; the second, P2O5; and the third, K2O. Although fertilizers do not include P2O5 or K2O, the system is a common abbreviation for the quantity of phosphate (P) or potassium (K) in a fertilizer.
Micronutrients: Micronutrients are absorbed in lesser amounts and are found in plant tissue in parts-per-million (ppm) concentrations ranging from 0.15 to 400 ppm (less than 0.04 percent dry matter). These elements are frequently required for enzymes that are necessary for plant metabolism. These elements have a significantly greater impact than their weight % because they enable catalysts (enzymes). Boron, zinc, molybdenum, iron, and manganese are examples of micronutrients. These elements are delivered in the form of water-soluble salts. At moderate soil pH and phosphate concentrations, iron transforms to insoluble (bio-unavailable) compounds, posing special challenges.
Production of Various Fertilizers
Nitrogen Fertilizers: The Haber-Bosch process produces ammonia (NH3), which is used to make nitrogen fertilizers. The hydrogen (CH4) is commonly supplied by natural gas (CH4), and the nitrogen (N2) is obtained from the air in this energy-intensive process. All other nitrogen fertilizers, such as anhydrous ammonium nitrate (NH4NO3) and urea (CO(NH2)2), need this ammonia as a feedstock.
The Atacama desert in Chile also has deposits of sodium nitrate (NaNO3) (Chilean saltpetre), which was one of the first nitrogen-rich fertilisers employed around 1830. Fertilizer is still mined from it. The Ostwald technique also produces nitrates from ammonia.
Phosphate Fertilizers: Phosphate fertilizers are made from phosphate rock, which comprises the minerals fluorapatite Ca5(PO4)3F (CFA) and hydroxyapatite Ca5(PO4)3OH, which contain phosphorus. Treatment with sulfuric (H2SO4) or phosphoric acids converts these minerals into water-soluble phosphate salts (H3PO4). This application is the driving force behind the large-scale manufacture of sulfuric acid. The nitro phosphate process, also known as the Odda process, involves dissolving phosphate rock containing up to 20% phosphorus (P) in nitric acid (HNO3) to produce a combination of phosphoric acid (H3PO4) and calcium nitrate (Ca(NO3)2). This mixture can be used with potassium fertilizer to provide a compound fertilizer that contains the three macronutrients N, P, and K in easily soluble form.
Potassium Fertilizers: Potash is a mixture of potassium minerals that are used to generate potassium fertilizers (chemical symbol: K). Because potash is water-soluble, the primary effort in extracting this nutrient from the ore entails several purification stages, such as removing sodium chloride (NaCl) (common salt). Potash is sometimes referred to as K2O for the sake of simplicity when discussing potassium content. Potassium chloride, potassium sulphate, potassium carbonate, and potassium nitrate are the most common potash fertilizers.
What are Biofertilizers?
A biofertilizer is a material that contains living microorganisms that colonise the rhizosphere or interior of the plant when applied to seeds, plant surfaces, or soil and encourage development by increasing the supply or availability of primary nutrients to the host plant. Biofertilizers supply nutrients to plants through natural processes such as nitrogen fixation, phosphorus solubilization, and the creation of growth-promoting chemicals. Biofertilizers use microorganisms to restore the soil's natural nutrient cycle and increase soil organic matter.
Healthy plants can be developed with the application of biofertilizers while also improving the soil's sustainability and health. Biofertilizers will likely minimise the need for synthetic fertilisers and pesticides, but they will not be able to completely replace them. Plant-growth promoting rhizobacteria is a favoured scientific word for these beneficial bacteria because they serve multiple roles (PGPR).
Importance of Fertilizers
Fertilizers replenish the nutrients lost by crops in the soil. Crop yields and agricultural output would be dramatically lowered if fertilizers were not used. Mineral fertilizers are used to enhance the soil's nutrition pool with minerals that are easily absorbed and utilized by plants.
As a result, we must replace what we take out in order to meet human nutritional demands in the crops and meat we eat. The objective is to strike the appropriate balance and maintain a level of nutrients in soils that will support our crops without using excessive amounts of fertilizer.
Every year and after every crop, these reserves are depleted, and we must replenish them with fertilizers.
Simply Said, Fertilizer is Used to:
Provide nutrients that are not found in the soil.
Replace nutrients that were removed during harvest.
To improve the quality of your food and increase your yield, balance the nutrients.
Conclusion
Fertilizers are of great importance in farming. They act as food for plants. They are mainly responsible for providing the nutrient supplies to the plants they are not able to receive from the environment. Fertilizers are rich in nutrients that are helpful for plants. We should use more mineral fertilizers. The objective is to strike the appropriate balance and maintain a level of nutrients in soils that will support our crops without using excessive amounts of fertiliser. Every year and after every crop, these reserves are depleted, and we must replenish them with fertilisers.
FAQs on Fertilizers
1. What is a fertilizer and what is its main purpose in agriculture?
A fertilizer is any natural or synthetic substance applied to soil or plant tissues to supply one or more essential nutrients for plant growth. The primary purpose of fertilizers is to replenish nutrients that are depleted from the soil during harvesting, ensuring that subsequent crops have the necessary elements for healthy development and high yields.
2. What are the three main macronutrients provided by fertilizers and what are their functions?
The three main macronutrients, often referred to as N-P-K, are essential for plant health. Their primary functions are:
- Nitrogen (N): Promotes vigorous leaf and stem growth, giving plants a lush, green appearance.
- Phosphorus (P): Crucial for the development of strong roots, flowers, seeds, and fruit.
- Potassium (K): Supports overall plant health, including strong stem growth, efficient water movement, and resistance to disease.
3. What are the main types of fertilizers used in farming?
Fertilizers can be broadly categorised based on their composition and origin. The main types include:
- Straight Fertilizers: These provide a single primary nutrient, such as Urea (Nitrogen), Superphosphate (Phosphorus), or Muriate of Potash (Potassium).
- Complex/Multinutrient Fertilizers: These supply two or more essential nutrients chemically bonded together, like DAP (Diammonium Phosphate) which provides both N and P.
- Organic Fertilizers: Derived from natural sources like plant or animal matter, examples include compost, manure, and bone meal.
- Biofertilizers: These contain living microorganisms that enhance nutrient availability for plants through natural processes like nitrogen fixation.
4. What is the key difference between a chemical fertilizer and a biofertilizer?
The key difference lies in their composition and mechanism. A chemical fertilizer is a synthetic substance that directly provides a concentrated dose of specific nutrients like N, P, and K to the soil. In contrast, a biofertilizer is a substance containing living microorganisms that enrich the soil's nutrient quality by fixing atmospheric nitrogen, solubilizing phosphorus, and stimulating plant growth through natural biological processes.
5. How does the NPK rating on a fertilizer bag help a farmer make a decision?
The NPK rating (e.g., 10-10-10 or 16-4-8) provides a standardised way to understand the nutrient content of a fertilizer. The three numbers represent the percentage by weight of Nitrogen (N), Phosphorus (as P₂O₅), and Potassium (as K₂O), respectively. This rating allows a farmer to choose the precise nutrient blend required for a specific crop at a particular growth stage, addressing specific soil deficiencies and optimising agricultural output.
6. What are some common examples of nitrogen, phosphorus, and potassium fertilizers?
Some common examples of single-nutrient (straight) fertilizers include:
- Nitrogen (N) Fertilizers: Urea, Ammonium Nitrate, and Ammonium Sulphate.
- Phosphorus (P) Fertilizers: Single Superphosphate (SSP) and Triple Superphosphate (TSP).
- Potassium (K) Fertilizers: Muriate of Potash (Potassium Chloride).
7. Why is it necessary to replenish soil nutrients with fertilizers after each harvest?
Crops absorb essential nutrients from the soil to grow and produce grains, fruits, and vegetables. When these crops are harvested and removed from the field, the nutrients they contain are also removed permanently from the local ecosystem. This continuous depletion would leave the soil infertile over time. Fertilizers are necessary to restore this nutrient balance, ensuring the soil remains productive for future planting and maintaining consistent agricultural yields.
8. What is the difference between macronutrients and micronutrients in the context of plant growth?
The difference between macronutrients and micronutrients is based on the quantity required by the plant, not their importance. Macronutrients (like Nitrogen, Phosphorus, Potassium, Calcium) are needed in large quantities for building plant structures and for major physiological processes. In contrast, micronutrients (like Iron, Manganese, Zinc, Copper) are required in very small, trace amounts but are equally critical, often acting as cofactors for essential enzymatic reactions.
9. What are the potential environmental concerns associated with the overuse of chemical fertilizers?
While essential for food production, the overuse of chemical fertilizers can lead to significant environmental issues. Excess nitrogen and phosphorus that are not absorbed by plants can wash into nearby water bodies, a process called eutrophication. This causes harmful algal blooms that deplete oxygen in the water, killing fish and other aquatic life. Additionally, improper use can lead to soil degradation and the release of greenhouse gases like nitrous oxide.
