Biofertilisers: An Overview

Introduction

Biofertilizers are essential for the biosphere’s nutrient cycle. Moreover, it is the critical route on which plants rely for nutrients. They contain microorganisms’ living or latent cells. These substances are essential for enhancing the nutrients of the host plants. In addition, they are also more reasonable in terms of price than chemical fertilisers.

Over the past, farmers used chemical fertilisers to increase their crop production. But, it led to the overuse of chemical fertilisers, which resulted in pollution and depletion of the soil’s minerals. Thus, farmers switched to organic farming, which includes using Biofertilizers.

Definition of Biofertilizers

 Biofertilizers are substances containing living microorganisms. When applied to plants via the surface or soil, it colonises its interior or the rhizosphere. Using these substances means using microbes in place of chemicals to enhance the soil’s nutrition. As they do not cause harm to the environment, they are a vital part of organic farming.

These substances promote growth in the plants by boosting the supply of vital nutrients to the host plant. They enhance the soil’s nutrient composition via nitrogen fixation and solubilization of mineral ions. Moreover, these substances are known for accelerating the soil’s microbial processes, which boosts the availability of nutrients in a form that plants can assimilate quickly. In simpler terms, it restores the soil’s natural nutrient cycle and builds soil organic matter.

Classification of Biofertilizers

The different biofertilizers are essential for helping the plants grow at different phases during development. The important biofertilizers classification are:

Nitrogen Fixing Biofertilizers

These fertilisers boost the nitrogen level of the soil. Moreover, it also fixes the soil’s atmospheric nitrogen and ensures it is available to the plant. Rhizobium is an essential nitrogen-fixing biofertilizer. Other examples of this type are nostoc, azospirillum, azotobacter and more.

Phosphate Biofertilizers

There are two kinds of phosphate Biofertilizers. One is Phosphorus Solubilizing Biofertilizers and the other is Phosphorus Mobilising Biofertilizers. The former works to solubilise insoluble phosphate, releasing insoluble phosphorus in the soil, secreting organic acids  and lowering the pH to dissolve the soil’s bound phosphates. Its examples include species of Aspergillus, Pseudomonas, etc.

The Phosphorus Mobilising Biofertilizers transfer phosphorus from the soil to its root cortex. It stimulates the metabolic processes of the soil, ensures the root system is absorbing the nutrients and penetrates the root’s cortical cells. The examples include Arbuscular Mycorrhiza (AM fungi).

Biofertilizers for Micro-nutrients

These substances help in degrading silicates and aluminium silicates in the soil. Also, they assist in silicate weathering. Silicate and Zinc solubilizers are the bacterial species and the Bacillus sp. is an example.

Plant Growth Promoting Rhizobacteria (PGPRs)

These substances serve as a biofertilizer as well as a biopesticide. It promotes the growth in plants by enhancing nutrient availability, producing phytohormones and suppressing plant diseases.

Compost Biofertilizers

These refer to the animal dung that helps in enriching the soil with microorganisms. It is an eco-friendly organic fertiliser consisting of phosphate, nitrogen, solubilizing bacteria and several types of decomposing fungi. The microorganisms break down the organic matter such as cattle waste, dead plants, etc.

Liquid Biofertilizers

These substances consist of agriculturally valuable microorganisms. They help fix the atmospheric nitrogen, solubilize the insoluble phosphates and make them available for the plant. Moreover, they also have a long shelf life and are more tolerant to varying temperatures; thus, they remain free from contamination. As it is easy to produce and apply, it significantly decreases the use of chemical fertilisers.

Examples of Biofertilizers

There are many biofertilizer examples that we must be aware of. The most important ones are Rhizobium, Phosphate Solubilizing Bacteria, Azotobacter, Mycorrhiza and Azospirillum. These five are incorporated in India’s Fertiliser Control Order (FCO) 1985.

Blue-Green Algae (BGA) is a traditional fertiliser that includes Nostoc, Tolypothrix, Anabaena, etc., which is perfect for paddy crops. For leguminous crops like pulses, farmers use Rhizobiuminoculant. On the other hand, for crops such as wheat, maize, potato, cotton, other vegetable crops and  Azotobacter comes into use.

Use of Biofertilizers

There are various uses of biofertilizers that benefit the plants and soil greatly. The most important uses are:

Treatment of Soil: It is used for treating the soil. To do it, these substances are mixed along with compost fertilisers. They are kept like that overnight and then the next day, they spread the mixture on the soil in the area where the seeds will be sown.

Seedling Root Dip: This process is used explicitly for rice crops typically. They plant the seedlings in the bed of water for around 8 to 10 hours.

Treatment of Seeds: This method creates a mixture of nitrogen and phosphorus fertilisers. After that, they dip the seeds into the mixture. Then they dry the seeds and sow them as soon as possible for great results.

Conclusion

All in all, biofertilizers are great for enhancing the availability of plant nutrients. Also, they help maintain the fertility of the soil over a prolonged period. Most importantly, these substances are an eco-friendly, economical, renewable, and healthier option. They are vital for organic farming.

As the hazardous effects of chemical fertilisers are becoming prevalent, modern-day agricultural practises are changing. Thus, the use of Biofertilizers is increasing day by day because of their benefits.

Note: According to FCO (Fertiliser Control Order) 1985 our country recommended only five fertilisers: Rhizobium, Azotobacter, Azospirillum, phosphate-solubilizing bacteria (PSB), and arbuscular mycorrhiza (AM) for commercialization.