Why are biofertilizers used?

In recent years, a microbial green revolution is underway. Biofertilizers have their own advantages over chemical fertilizers and are economically and environmentally friendly as well. With the increasing demand in agriculture, it has become important for scientists and society to increase the productivity of the sector by using various fertilizers, insecticides and pesticides. However, with the tremendous use of these products, the soil has been badly affected because of the depletion of the essential minerals of the soil. Therefore, to overcome this problem, it has become important to use a different remedy for the production of various biofertilizers. They have the best economic value.

The following basic reasons to explore biofertilizers are outlined:

• The demand is much higher than the availability. It is estimated that by 2020, to achieve the targeted production of 321 million tonnes of food grain, the requirement of nutrients will be 28.8 million tonnes, while their availability will be only 21.6 million tonnes, leaving a deficit of about 7.2 million tonnes.
• Depleting feedstock/fossil fuels (energy crisis) and increasing cost of fertilizers. This is becoming unaffordable by small and marginal farmers.
• Depleting soil fertility due to widening the gap between nutrient uptake and supplies.
• Growing concerns about environmental hazards.
• Increasing threat to sustainable agriculture. Besides the above facts, the long-term use of biofertilizers is economical, eco-friendly, more efficient, productive and accessible to marginal and small farmers over chemical fertilizers.
• Bio-fertilizers, also known as microbial inoculants, have great potential as a supplementary, renewable and environmentally friendly source of plant nutrients and are an important component of Integrated Plant Nutrient System (IPNS).

How do biofertilizers work?

1. Biofertilizers fix atmospheric nitrogen in the soil and root nodules of legume crops and make them available to the plants.
2. They solubilize the insoluble forms of phosphate, such as tricalcium, iron and aluminum phosphates, into available forms.
3. They scavenge phosphates from soil layers.
4. They produce hormones and anti‐metabolites which promote root growth.
5. They decompose organic matter and help in the mineralization of soil.
6. When applied to the soils or seeds, these biofertilizers increase the availability of nutrients and improve the yield by 10% to 20% without adversely affecting the soil and the environment.

Biofertilizers are ready-to-use live formulates of such beneficial microorganisms, which upon application to seeds, roots or soil, mobilize the availability of nutrients by their biological activity in particular, and help build up the microflora and, in turn, the soil health in general, which consequently benefits crops. Biofertilizers are designed to improve the soil fertility in N and P. They provide growth promoting substances.

What are the benefits of using biofertilizers?

1. Increasing harvest yields
2. An average increase in crop yields by 20 to 37 percent.
3. Algae-based fertilizers give improved yields in rice at rates ranging between 10 and 45 %.
4. Improving soil structure
5. The use of microbial biofertilizers improves the soil structure by influencing the aggregation of the soil particles
6. Better water relation

   Arbuscular mycorrhizal colonization induces drought tolerance in plants by:

   • Improving leaf water and turgor potential,
   • Maintaining stomatal functioning and transpiration,
   • Increasing root length and development.
7. Lowering production costs
8. Made from easily obtained organic materials such as rice husks, soil, bamboo and vegetables etc.
9. Reduce the input expenses by replacing the cost of chemical fertilizers.
10. Providing protection against drought and some soil-borne diseases
    • Aquatic cyanobacteria provide natural growth hormones, proteins, vitamins and minerals to the soil.
    • Azotobacter infuse the soil with antibiotic pesticide and inhibit the spread of soil-borne pathogens like Pythium and Phytophthora.
11. Suppressing the incidence of insect pests and plant diseases

    Biofertilizers strengthen the soil profile, leave water sources untainted and improve plant growth without detrimental side effects.

What are the advantages and disadvantages?

We can list the basic advantages of using biofertilizers:

• They help to achieve high yields of crops by enriching the soil with nutrients and useful microorganisms necessary for plant growth.
• They replace the chemical fertilizers, as the latter are not beneficial for plants. Chemical fertilizers decrease the plant growth and pollute the environment by releasing harmful chemicals.
• Plant growth can be increased because biofertilizers contain natural components which do not harm the plants but do the opposite.
• They are eco-friendly due to the fact that they protect the environment against pollutants.
• If the soil is free of chemicals, it will retain its fertility, which will be beneficial for the plants as well as the environment, because the plants will be protected against diseases and the environment will be free of pollutants.
• Biofertilizers destroy those harmful components from the soil which cause diseases in plants. By using biofertilizers, plants can also be protected against drought and other restrictive conditions.
• Biofertilizers are cost effective. They are not costly and even low-income farmers can make use of them.

As disadvantages, using biofertilizers:

• Gives much lower nutrient density – it requires large amounts to get enough for most crops;
• Requires a different type of machinery to apply from that used for chemical fertilizers;
• Sometimes is hard to locate in certain areas; odour; difficult to store;
• Specific to the plants;
• Requires skills in production and application.
• There is inadequate awareness about the use and benefits of biofertilizers.