Biofertilizers: Definition, Types, Components, Importance, Advantages

Edited By Irshad Anwar | Updated on Aug 20, 2025 06:11 PM IST

Biofertilizers are organic fertilizers containing beneficial microorganisms that enhance plant growth by increasing the availability of essential nutrients like nitrogen and phosphorus. These eco-friendly alternatives help in restoring soil fertility naturally without causing long-term harm. They do not harm soil health. By enriching the soil with natural nutrients and improving water retention, biofertilizers play a vital role in microbes in human welfare.

This Story also Contains

Components of Biofertilizers
Types of Biofertilizers
Importance of Biofertilizers
Pros and Cons of using Biofertilizers
Types of Questions Asked from Biofertilizers
Tips, Tricks, and Strategies for Biofertilizers
MCQs on Biofertilizers
Frequently Asked Questions (FAQs)

Biofertilizers

These biological agents are especially important in sustainable agriculture, where maintaining soil health and reducing chemical input is a priority. They also contribute to reducing the environmental impact caused by excessive use of synthetic inputs. As a result, biofertilizers are becoming an essential component of agricultural fertilizers, supporting both crop yield and ecological balance.

Components of Biofertilizers

Biofertilizers are products that contain living microorganisms that can enhance the growth and productivity of plants. The microorganisms in biofertilizers provide nutrients to plants, increase soil fertility, and promote soil health. The main components of biofertilizers are:

Components	Explanation
Bacteria	Commonly used as microorganisms in biofertilizers some of the basic examples are Rhizobium azotobacter and Azospirillum.
Fungi	One of the common microorganisms used to enhance the nutrient absorption rate of the soil. It also helps in controlling plant diseases. Some of the common examples are Mycorrhizal fungi.
Algae	Microorganisms are used to control the photosynthesis of the plant which helps in fixing the atmospheric nitrogen.
Organic Matter	The organic matter includes compost and vermicompost which is essential for providing important nutrients to the plant. Also helps in improving the soil structure and fertility.
Enzymes	Provides important proteins which help in breaking down organic matter.
Vitamins and Growth Hormones	The vitamins and growth hormones like auxins and cytokinins are responsible for promoting plant growth and development.

Types of Biofertilizers

The primary categories of biofertilizers are as follows:

Type of Biofertilizers	Explanation
Symbiotic nitrogen-fixing bacteria	These microorganisms are responsible for forming symbiotic relationships with plants. Examples Rhizobium
Loose Association of nitrogen-fixing bacteria	These bacteria are associated loosely with the plant root system without forming a tight bond. It is also known as rhizosphere association and forms an associated mutualism with the plant. Example: Azospirillum

Importance of Biofertilizers

Some Basic importance of Biofertilizers are discussed below:

Biofertilizers enhance plant growth and soil quality.
They prevent the spread of diseases.
They are economical and environmentally favourable.
As natural fertilizers, biofertilizers shield the ecosystem from contaminants.
They remove a lot of dangerous elements from the soil that can wreak havoc on plants.
Even in semi-arid environments, biofertilizers are successful.

Pros and Cons of using Biofertilizers

Biofertilizers have both pros and cons. Some of the important ones are discussed below:

Pros of Biofertilizers	Cons of Biofertilizers
These are made using natural sources and they do not harm the involvement of plants, animals and humans in any way.	Bio fertilizers work slowly and textiles show the results.
They can be easily produced at a low cost which reduces the need for expensive fertilizers and pesticides.	The bio-fertilizers also have shorter shelf life which requires specific storage conditions to maintain the effectiveness of the biofertilizer.
It contains microorganisms that can fix atmospheric nitrogen, increase soil fertility and also give important nutrients to the soil.	It requires strict quality control in order to ensure a good result. Poor quality of biofertilizer can lead to bad results.
One of the major cons of biofertilizers is they reduce the risk of harmful chemicals going into the soil and waterways. This reduces the various types of pollution of the environment.	Different types of biofertilizers have unique application needs which require proper use of biofertilizers in order to increase the performance.
It increases plant growth and productivity which leads to improved crop yield and quality.

Types of Questions Asked from Biofertilizers

During exam preparation, different types of questions about the Biofertilizers are asked. The table below contains the different patterns of questions asked in different exams.

Exam Type	Types of Questions Asked	Weightage
CBSE	Characteristics of biofertilizers (definition, components, and functions). Types of microorganisms used in biofertilizers (bacteria, fungi, algae). Mechanisms of action of biofertilizers (how they enhance plant growth). Advantages and disadvantages of using biofertilizers. Applications of biofertilizers in sustainable agriculture.	4%
NEET	Symbiotic and associative nitrogen-fixing bacteria in biofertilizers (e.g., Rhizobium, Azospirillum). The role of mycorrhizal fungi in nutrient absorption. Comparison between biofertilizers and chemical fertilizers. The impact of biofertilizers on soil health and crop yield. Specific requirements for the effective application of biofertilizers.	2%
Paramedical	The environmental impact of using biofertilizers. Biofertilizers' role in promoting sustainable agricultural practices. Potential challenges in the production and application of biofertilizers. Research trends and advancements in biofertilizer technology. The relationship between biofertilizers and organic farming.	3%

Tips, Tricks, and Strategies for Biofertilizers

It takes effort to remember everything in a single go. We made the entire problem easy. Some of the tricks regarding Biofertilizers are given below which you can use to memorise the important points.

Components of Biofertilizers

"BFAEO: Bacteria, Fungi, Algae, Enzymes, Organic matter"

B: Bacteria (e.g., Rhizobium, Azospirillum) help fix nitrogen and improve soil fertility.
F: Fungi (e.g., mycorrhizal fungi, Trichoderma) enhance nutrient absorption and control diseases.
A: Algae (e.g., blue-green algae) can fix atmospheric nitrogen and improve soil health.
E: Enzymes assist in breaking down organic matter, making nutrients more available to plants.
O: Organic matter (e.g., compost) enriches the soil and supports microbial activity.

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Types of Biofertilizers

"SLA: Symbiotic, Loose Association, Algae"

S: Symbiotic Nitrogen-Fixing Bacteria (e.g., Rhizobium) form relationships with plants to fix nitrogen.
L: Loose Association of Nitrogen-Fixing Bacteria (e.g., Azospirillum) live near roots, aiding in nutrient uptake.
A: Algal Biofertilizers utilize blue-green algae to enhance soil fertility and provide nutrients.

Advantages of Biofertilizers

"CIEE: Cost-effective, Improved fertility, Eco-friendly, Enhanced yield"

C: Cost-effective alternatives to chemical fertilizers.
I: Improves soil fertility by enhancing nutrient availability.
E: Eco-friendly as they are made from natural sources and reduce pollution.
E: Enhances yield and improves crop quality.

Disadvantages of Biofertilizers

"SLQC: Slow action, Limited shelf-life, Quality control, Specific requirements"

S: Slow action compared to chemical fertilizers; may take longer to see results.
L: Limited shelf-life and specific storage conditions are required for effectiveness.
Q: Quality control is essential; poor quality can lead to ineffective results.
C: Specific requirements for applications may limit their usability in some scenarios.

MCQs on Biofertilizers

Q1. For soya bean cultivation, which of the following is used as a biofertilizer?

Nostoc
Azospirillum
Rhizobium
Azotobacter

Correct answer: 3) Rhizobium

Explanation:

Biofertilizers: It is a substance containing living microorganisms. When applied to seeds, plant surfaces, or soil, these bacteria colonize the rhizosphere or interior of the plant, promoting growth by increasing the supply or availability of primary nutrients to the host plant. Biofertilizers supplement nutrients through natural nitrogen fixation processes. Examples: Rhizobium, Azotobacter, Blue-green algae, Azospirillum.

Because a biofertilizer is technically alive, it can symbiotically bond with plant roots. Microorganisms involved could easily and safely convert complex organic material into simple compounds that can be easily taken up by plants. The function of microorganisms is long-lasting, which improves soil fertility. It preserves the soil as a natural habitat.

Rhizobium: Rhizobium has commensal relationships with leguminous legumes such as soybeans. Symbiosis is defined as "living together." (G. syn = together, bios = existence. All interactions in which two species truly exist together without consideration for advantage or harm to the participants are considered symbiotic. Plants cannot absorb air nitrogen directly; instead, they require it in liquid forms. Rhizobium is a bacteria that can transform atmospheric nitrogen into a soluble state. However, Rhizobium cannot produce its sustenance. As a result, it resides in the roots of gram, peas, moong, beans, and other legumes and gives nitrogen to them. The majority of legumes (dals) are derived from leguminous vegetation. In exchange, the bacteria receive sustenance and protection from the vegetation.

Nostoc: Some blue-green phytoplankton are capable of nitrogen-fixing. Nitrogen is fixed in blue-green algae by specialized cells known as heterocysts. They transform nitrogen from the atmosphere into nitrogenous molecules such as amino acids and nitrates. These nutrients make the earth more fertile. As a result of nitrogen fixation, blue-green phytoplankton enhance soil productivity. Examples of blue-green algae that fix nitrogen are Nostoc.

Azotobacter: It is a nitrogen-fixing free-living bacterium that is widely used in wheat, rice, cotton, and sugarcane crops.

Azospirillum: Azospirillum is an aerobic-associated symbiotic nitrogen-fixing organism that develops a symbiotic association with the roots of grasses. It is used in the production of sorghum and pearl millet.

Hence, the correct answer is option 3) Rhizobium.

Q2. In order to supplement the cattle's nutritional needs, especially that of milking bovines, which bio-fertilizer is used?

Azotobacter
Azospirillum
Rhizobium
Azolla

Correct answer: 4) Azolla

Explanation:

Azolla: Azolla is also known as mosquito ferns or aquatic ferns. Their form is extremely reduced and specialized, resembling duckweed or some mosses rather than the typical fern. In addition to being used as animal feed, human food, medicine, and a water purifier, it can also be used as animal feed. As a bio-fertilizer, it improves soil fertility and boosts crop yields.

Azotobacter: Cysts are the resting stages of free-living diazotrophic bacteria. Most of the time, it is found in neutral to alkaline soils, in aquatic environments, and on plants. Several metabolic functions are available to it, including the ability to fix atmospheric nitrogen by converting it to ammonia.

Azospirillum: One of the most studied plant growth-promoting bacteria (PGPB) is Azospirillum. This is a common model for plant-bacterial interactions. There are at least 22 species of Azospirillum, with Azospirillum brasilense being the most widely known

Rhizobium: Rhizobium is a genus of bacteria that produces root nodules on plants. Legumes live in symbiosis with these bacteria

Hence, the correct answer is option 4) Azolla.

Q3. An organism used as a biofertilizer for raising soyabean crops is

Azotobacter
Azospirillum
Rhizobium
Nostoc

Correct answer: 3) Rhizobium

Explanation:

Rhizobium is a significant bio-fertilizer that is also used for symbiotic nitrogen fixation with leguminous plants. Symbiosis leads to an increase in nitrogen levels in the soil, which is one of the key factors in the general fixation of nitrogen. Application of Rhizobium inoculums to crops is an agronomic activity that is currently undertaken to provide a sufficient supply of nitrogen for the growth of healthy plants and agricultural productivity in a sustainable way.

Hence the correct answer is Option 3) Rhizobium.

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Frequently Asked Questions (FAQs)

Q1. What is a biofertilizer with an example?
Biofertilizers are substances containing living microorganisms that enhance plant growth by increasing nutrient availability. Example: Rhizobium for nitrogen fixation in legumes.

Q2. What are the benefits of biofertilizers?
Biofertilizers improve soil fertility, promote sustainable agriculture, reduce the need for chemical fertilizers, and enhance plant growth naturally.

Q3. Is cow dung a biofertilizer?
Cow dung is not a biofertilizer itself, but it can support microbial growth and act as an organic fertilizer when decomposed properly.

Q4. What are the main sources of biofertilizers?
The main sources include bacteria like Rhizobium, Azotobacter, cyanobacteria like Anabaena, and fungi like Mycorrhiza.

Q5. Is NPK a biofertilizer?
No, NPK (Nitrogen, Phosphorus, Potassium) is a chemical fertilizer, not a biofertilizer.

Frequently Asked Questions (FAQs)

1. What are certain examples for biofertilizers?

Rhizobium, Azotobacter, Azospirillum, and blue-green algae (BGA) are examples for biofertilizers.

2. Benefits of Vermicompost on plants?

Vegetable farming and kitchen gardening have been transformed by vermicompost. Among all the fertilizers, it has produced the finest results in organic farming. Whether cultivated in containers or on raised beds, vermicompost can be used as a major fertilizer to grow a variety of fruiting, subterranean, and leafy vegetables.

3. Who can use biofertilizers?

These fertilizers can be applied to a variety of crops, including horticultural crops, vegetables, fruit trees, forest trees, medicinal, herbal, and decorative plants, as well as legumes, cash crops, cereal crops, fodder crops, oil seed crops, and horticultural crops.

4. What are the limitations of biofertilizers?

Biofertilizers work in conjunction with chemical fertilizers; they do not replace them. Only 20 to 30 percent more crops are produced as a result of using biofertilizers. Like chemical fertilizers, they do not significantly boost productivity. For particular crops, specific fertilizers are.

5. What precautions are used while using Biofertilizers?

Packets of biofertilizer must be kept in a cool, dry place away from heat and sunshine. The proper biofertilizer combinations must be employed. Rhizobium should only be used for the designated crop because it is crop-specific.

6. How do nitrogen-fixing bacteria in biofertilizers benefit plants?

Nitrogen-fixing bacteria, such as Rhizobium and Azotobacter, convert atmospheric nitrogen into a form that plants can use. They form symbiotic relationships with plant roots, particularly in legumes, where they live in root nodules. This process, called biological nitrogen fixation, provides plants with essential nitrogen for growth without the need for chemical fertilizers.

7. How do phosphate-solubilizing microorganisms improve soil fertility?

Phosphate-solubilizing microorganisms, such as certain bacteria and fungi, secrete organic acids that convert insoluble phosphates in the soil into soluble forms. This process increases the availability of phosphorus to plants, which is crucial for root development, energy transfer, and overall plant growth.

8. How do mycorrhizal fungi contribute to plant nutrition?

Mycorrhizal fungi form symbiotic associations with plant roots, extending the root system's reach. They help plants absorb water and nutrients, particularly phosphorus, from a larger soil volume. In exchange, the fungi receive carbohydrates from the plant. This mutualistic relationship enhances plant growth, stress tolerance, and soil structure.

9. What are biofertilizers and how do they differ from chemical fertilizers?

Biofertilizers are living microorganisms that enhance plant nutrition and growth when applied to seeds, plant surfaces, or soil. Unlike chemical fertilizers, which directly provide nutrients, biofertilizers work by increasing the availability of nutrients already present in the soil or by fixing atmospheric nitrogen. They are environmentally friendly and promote sustainable agriculture.

10. What is the difference between carrier-based and liquid biofertilizers?

Carrier-based biofertilizers use solid materials like peat or lignite to support microbial growth, while liquid biofertilizers contain suspended microorganisms in a nutrient-rich broth. Liquid formulations often have a longer shelf life, are easier to apply, and provide more uniform distribution. However, carrier-based formulations may offer better protection to microorganisms in harsh conditions.