Agriculture Fertilizers

Currently, food security is a major concern as the world population is increasing. Therefore, fertilizer has become very important to agriculture for feeding the growing population. Fertilizers are those materials which help in supplying nutrients to the soil resulting in increasing the crop yield. It also compensates for plant extracts and losses in soil crop systems through methods like leaching, volatilization etc. It also helps in improving and maintaining soil fertility. Fertilisers (inorganic, organic and bio fertilizers) have different ways of functioning to release nutrients to the soil and have their benefits and limitations concerni crop growth and soil fertility. Therefore, proper nutrient management (balancing soil nutrient inputs with crop requirement) and fertilizers management (producing maximum nutrient-based crops at peak harvest time) must be taken to ensure an improved and safe environment.

What are Fertilizers?

Fertilizers are nutrient-rich substances that are added to the soil to increase soil fertility, resulting in better and high yields, if they are added to the required amount of soil

A simple example of applying fertilizer to soil is Urea hydrolysis.

$\mathrm{CO(NH_2)_2 + H_2 O + Urease \rightarrow 2NH_3 + CO_2}$

Here, Urea, $\mathrm{CO(NH_2)_2}$ the most common fertilizer, when applied on moist soil and reacts with naturally occurring substance (urease) produced by soil. It leads to the formation of $\mathrm{NH_3}$ and $\mathrm{CO_2}$, both these substances help in increasing soil fertility and plant growth. The three Important macronutrients needed by plants in large quantities are

• Nitrogen(N)

• Phosphorus(P)

• Potash(K)

Other macronutrients are sulphur (S), calcium (Ca) and magnesium (Mg), which are also needed by plants but in smaller amounts

Types of Fertilizers

Fertilizer is the composition of a single or multiple chemical compounds or nutrients, depending on the composite composition and different methods of releasing nutrients, fertilizer is divided into the following categories.

• Inorganic fertilizer (Chemical Fertilizers)− These fertilizers are mainly constituted of chemical substances such as urea, ammonium nitrate, potassium chloride etc. These fertilizers are non-biodegradable. These fertilizers are also called artificial or synthesized fertilizers. It is further divided into two types.

  • Macronutrients Fertilizers − There are mainly six elements that play an important role in the growth of the plants. In the first category, primary macronutrients containing nitrogen, phosphorus, and potassium are very essential for accelerating and proper growth of any plant. Another category is secondary macronutrients containing calcium, sulphur, and magnesium, which are also equally essential for plants.

  • Micronutrients Fertilizers− Though these fertilizers serve less but cater to essential needs of the plants, so this fertilizer is intended to provide small amounts of nutrients such as copper, zinc, boron, iron, and chlorine etc.

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• Organic Fertilizers − These fertilizers are produced using naturally occurring substances such as sewage, guano, slurry, manure, worm castings etc, and are easily biodegradable. These naturally occurring substances are then decomposed or broken down into smaller and soluble particles by the action of a large number of bacteria. Hence these soluble particles or fertilizers are then taken by the roots, resulting in increasing soil quality and crop yield.

• Bio−Fertilizers − Biofertilizers are those substances that produce nutrients consisting of nitrogen and phosphate solubilizing bacteria. Example− Azotobacter, Pseudomonas etc. These bacteria or microorganisms enrich the nutrient quality of the soil. Also, plant−aiding microorganisms such as PGPR (plant growth−promoting rhizobacteria) and AMF (arbuscular mycorrhizal fungi), interface with plant roots helping in enhancing growth, mineral nutrition, disease resistance and drought tolerance.

Application of fertilizers

Humans never failed in being masterminds. Investing crores of rupees and lots of energy in building dams has several advantages.

• It helps in improving the crop yield and replenishing the lost nutrients in the soil.

• Nitrogen present in fertilizers has less capacity to acidify soils. So nitrogen−based fertilizers should be used maximum to produce healthy crops.

• Even using smaller quantities of chemical fertilizers provide an adequate amount of nutrients to the soil and results in a higher yield.

• Using biofertilizers majorly help in non producing the unwanted crops where dual crops are growing.

• They are used for planting all kinds of crops.

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Benefits of Fertilizers

Besides ensuring increased crop production, fertilizer shows many other benefits.

Using Inorganic fertilizer (Chemical Fertilizers)	Using Organic Fertilizers	Using Biofertilizers
It is easier to handle and use.	Helpful in mobilising the soil nutrients and making them reach the plants in equal and balanced quantities.	It ensures soil enrichment.
Due to the presence of soluble salts, it dissolves easily in soil and has an instant effect on crops.	It is useful for restoring soil stress by maintaining its moisture content.	Microorganisms present in these fertilizers convert complex organic substances into simpler or nutrient-rich substances that are easily available for plants.
Only a small amount of these fertilizers produce a large amount of productivity.	It is environmentally friendly.	It naturally increases nitrogen and phosphorus content in soil through processes like nitrogen fixation and solubilizing phosphorus, making soil more naturally rich in nutrients.
Fertilizers like gypsum, when added to soil, allow water to move into the soil and make the crop grow well.	These fertilizers are an abundant source of soil microbes which in turn produce a healthy crop and help fight against insect attacks.	These fertilizers produce hormones like amino acids, vitamins etc which enhance the root growth of plants
Using fertilizers such as lime helps in maintaining the balanced pH of the soil, as its application reduces the effect of acid on the soil	It has a less toxic effect on the plants

List of Chemical Fertilizers

Here, a list of chemical fertilizers (and their formulae) are categorised −.

Nitrogenous Fertilizers	Phosphatic Fertilizers	Potassic Fertilizers
Urea, $\mathrm{((NH)_2)_2}$	Rock Phosphate	Muriate of Potash, KCl
Ammonium Sulphate $\mathrm{((NH)_4)_2 SO_4}$	Phosphoric Acid, $\mathrm{H_3 PO_4}$	Sulphate of Potash, $\mathrm{K_2 SO_4}$
Ammonium Nitrate, $\mathrm{NH_4 NH_3}$	Super Phosphates	Potassium metaphosphate, $\mathrm{KO_3 P}$
Sodium Nitrate, $\mathrm{NaNO_3}$	Diammonium Phosphate, $\mathrm{((NH)_4)_2 HPO_4}$	Potassium Nitrate, $\mathrm{KNO_3}$
Potassium Nitrate, $\mathrm{KNO_3}$
Calcium Ammonium Nitrate, $\mathrm{Ca((NO)_3)_2 NH_4 NO_3}$

Conclusion

Agricultural sector is the main source of our food supply. The use of fertilizer has become important to meet our daily food requirements. Fertilizers are nutrient-rich substances that are added to the soil to boost soil fertility, which in return, increases plant growth and crop yields. The important chemical elements present in fertilizers such as nitrogen (N), phosphorus (P) and potash (K), are majorly responsible for the high yield of plants. Different fertilizers serve various purposes for the soil, such as soil conditioning, resistance to disease and insect attacks, the release of growth-promoting hormones and so on, which again helps in increasing the yield. Adding the right amount of fertilizers to the soil ensures a healthy and high yield food crop. Hence, in all the ways fertilizers help in fulfilling our daily food needs.

FAQs

Q1. How fertilizer is important for feeding the world.

Fertilizers contain nutrient-rich substances and their addition to the soil increases soil fertility, hence helping in increasing crop yield. The rapid increase in crop yield helps in meeting the food needs of the growing population.

Q2. Does adding organic fertilizer to the soil improve soil health and crop quality?

Organic fertilizers are produced by substances like slurry, seaweeds, manure etc. These substances are converted from complex compounds to simpler compounds by the action of microorganisms. These simpler or nutrient-rich compounds are easily soluble in the soil, therefore, helping in improving soil quality and increasing crop yields.

Q3. Does fertilizers affect human health?

Among all fertilizers, chemical fertilizers can affect human health as some heavy metals such as lead, mercury etc are present in it, which affects the kidneys, liver and lungs of human beings.

Q4. Which fertilizer is largely used in agriculture and why?

Catering to a high population, it is necessary to produce food at a faster rate. This would only be possible with chemical or inorganic fertilizers. Chemical fertilizers are mostly used to produce maximum yield. As it contains macronutrients and micronutrients which serve an ample amount of nutrients to the soil to increase crop yield.

Q5. Why does excessive use of fertilizers burn plants?

Fertilizers contain nutrients in the form of salts. These salts easily dissolve in water but excessive use of salts remains undissolved in the water. This undissolved salt remains in the soil making plants unable to absorb water and other nutrients. Hence it causes great upset to soil structure, therefore resulting in the burning of plants.