Bio-Fertilisers

Environmental contamination has become a major source of worry due to our modern lifestyles. Chemical fertilisers used in order to fulfil the ever-increasing demand for agricultural produce have contributed greatly to this pollution. Of course, we’ve now realised that excessive use of chemical fertilisers causes difficulties, and there’s a lot of push to move to organic farming – towards the use of bio-fertilisers. Organisms that increase the nutritional quality of soil are known as bio-fertilisers. Bacteria, fungus, and cyanobacteria are the most common sources of bio-fertilisers. Let us understand what bio-fertilisers are and what is the purpose behind using them with suitable examples.

What are bio-fertilisers?

Bio-fertilisers include microorganisms that are important for soil fertility and plant development. When they are applied to the soil,  seeds, or plant surfaces, they provide beneficial nutrients. A bio-fertiliser includes live microorganisms that colonise the rhizosphere or the inside of the plant and boost the development by managing the quantity or availability of primary nutrients to the plant host.

Natural processes such as nitrogen fixation, phosphorus solubilisation, and the production of growth-promoting compounds are used in bio-fertilisers to provide nutrients to plants. They help to restore the natural nutrient cycle of the soil as well as the growth of soil organic matter.

Types of bio-fertilisers

Bio-fertilisers are divided into three types: bacteria, fungi and cyanobacteria. 

Bacteria– Bio-fertilisers include bacteria that produce nitrogen-fixing nodules on the roots of legumes. The bacteria ‘Rhizobium’ forms the nodules by interacting with the roots of these plants. This beneficial relationship is referred to as a symbiotic relationship.

The nodules aid the conversion of atmospheric nitrogen to organic forms, which the plants may subsequently utilise as food. To maintain an appropriate quantity of nitrogen in the soil, adding Rhizobium cultures to fields has become a widespread practice.

Azospirillum and Azotobacter are two other bacteria that operate as bio-fertilisers. In the soil, these bacteria are free-living. Cotton, wheat, mustard, maise, and other crops are commonly used with Azotobacter.

Fungi– Symbiotic relationships exist between plants and fungi as well. Mycorrhizae is the name for these types of connections. In this connection, the fungus collects phosphorus from the soil and gives it to the plant. Other beneficial qualities of plants that thrive with these relationships include drought tolerance and salinity tolerance. Other functions are:

• Resistance to diseases that are transmitted through the roots
• Increase in plant growth and development as a whole

Cyanobacteria are blue-green bacteria that may be found in both water and land. They also aid in the fixation of nitrogen in the atmosphere. Oscillatoria, Nostoc, and Anabaena are among the examples. For rice fields, the symbiotic relationship between the water ferns Azolla and Anabaena is critical. Anabaena obtains carbon and nitrogen from the plant in return for fixed nitrogen in this relationship. This improves the fertility of rice fields by adding organic matter to the soil.

Benefits of bio-fertilisers

Living microorganisms of bacterial, fungal, and algal origin are used as bio-fertilisers. They have different modes of action and can be used alone or in combination.

• In legume crop soil and root nodules, bio-fertilisers fix atmospheric nitrogen, making it available to the plant.
• They convert insoluble phosphates, including tricalcium, iron, and aluminium phosphates, to soluble forms.
• The soil strata are scavenged for phosphorus.
• Hormones and antimetabolites are generated, promoting root growth.

• They break down organic materials and aid in soil mineralisation.
• Bio-fertilisers, when applied to seed or soil, boost the availability of nutrients and increase yield by 10 to 25% without harming the soil or the environment.

Constraints of bio-fertilisers

Due to several challenges, bio-fertilisers are not widely used. The constraints are:

• Inadequate popularity due to their inability to respond in a timely and spectacular manner, as chemical fertilisers
• Lack of understanding regarding their use and advantages
• Insufficient promotion, extension, and publicity
• Farmers in remote locations do not have access to high-quality products in a timely manner

Measures to take while using bio-fertilisers

Precautions that need to be taken while using bio-fertilisers are mentioned below:

• Bio-fertiliser packets should be stored away from direct sunshine and heat in a cool, dry location.
• The right bio-fertiliser combinations must be employed.
• Rhizobium is crop-specific. Hence, it should only be used for that crop.
• Bio-fertilisers should not be used with other chemicals.
• When purchasing, make sure that each packet has important information such as the product’s name, the crop for which it is meant, the manufacturer’s name and address, the date of manufacturing, the date of expiration, the batch number, and the directions for usage.
• To achieve the optimum results, both nitrogenous and phosphatic fertilisers should be employed.
• Bio-fertilisers should be used in conjunction with chemical fertilisers and organic manures. Bio-fertilisers are not a substitute for fertilisers, but they can help plants meet their nutritional needs.

Conclusion

Bio-fertilisers provide nutrients by fixing atmospheric nitrogen, solubilising phosphorus, and stimulating plant growth through the creation of growth-promoting chemicals, all of which are natural processes. They can be classified in a variety of ways depending on their nature and purpose. Farmers can buy and utilise a variety of bio-fertilisers widely available in the market. These not only aid in the replenishment of soil nutrients but also assist in reducing reliance on artificial fertilisers. This aids in the preservation of the soil’s mineral content and greatly lowers pollution. When employing bio-fertilisers, several measures must be followed.