By Vaidehi Desai, PhD January 21, 2020
Our nation is an agricultural country. We have a very fast growing population. Therefore farmers are forced to use chemical fertilizers so as to produce crops in a very short time.
The food which comes from the farm, today its not 100% safe for consumption as our farmers are using lots of chemical fertilizers. Today we all are aware of the adverse effects of chemical fertilizers on our body and also environment.
Chemical fertilizers when applied on the farms, do not get completely used by the plants so the remaining gets washed up and mixes with the ground water, making it highly polluted and unfit for drinking. Chemical fertilizers when mixes with the agricultural soil, starts killing the healthy microbes present naturally in the soil thus reducing the natural fertility of the soil.
Researchers today have come up with a concept called as Biofertilizers.
A biofertilizer is a substance which contains living microorganisms which when applied to the plant surfaces or seeds, soil, colonize the rhizosphere or the interior of the plant and promotes the growth by making the primary nutrients available to the plants in a natural way.
Scope of biofertilizer in India
Due to the rising cost of chemically fixed nitrogen fertilizers used and the massive inputs for manufacturing it, have made the urgency to find other option for the same.
We have many helpful microorganisms which are already present in most of the agricultural soil, which help in supplying the nutrients in the natural way. We just need to understand the role of them specifically and just increase their inoculation (population). These microbes also help in reducing the harmful pathogens present in the agricultural soil which in turn reduces the plant diseases resulting in the less need of harmful pesticides and also make available the nutrients in simple form so that plants can easily absorb them from the soil for their healthy growth.
Types of Biofertilizers
They belong to the group of bacteria and is an example of symbiotic nitrogen fixation. Here the bacteria infect the legume root forming the root nodules within which they reduce the molecular nitrogen to ammonia which is later on utilized by the plants to produce vitamins, proteins along with other nitrogen containing compounds.
This symbiosis is within the root nodules. It has been estimated from the observation that 40-350 kg N/ha/year if fixed by different legume crops by these microbial activities of the Rhizobium.
It is a free living nitrogen fixing aerobic bacterium. It is used as a Biofertilizer for all non-leguminous plants eg., rice, cotton, vegetables, etc.
Azotobacter cells are not found on the rhizosplane but are found abundant in the rhizosphere region. The amount of organic matter in the soil decides the proportion of Azotobacter as it needs lots of organic matter to survive in the soil.
It also belongs to the family of bacteria and fixes considerable quantity of nitrogen in the range of 20-40kg N/ha in the rhizosphere in non-leguminous plants such as millets, oil seeds, cotton, cereals, etc.
They are also known as blue-green algae, they fix nitrogen by trapping sun’s energy which is captured during photosynthesis to fix nitrogen from the air and turn into an easy form which plants can absorb.
It is a free floating water fern which fixes atmospheric nitrogen in association with nitrogen fixing blue green alga Anabaenaazollae. Azolla is used as a biofertilizer for the production of rice.
Phosphate Solubilizing Bacteria(PSB)
They are group of beneficial microorganisms which are capable of solubilizing inorganic phosphorus from insoluble compounds. P-solubilization ability of rhizosphere microorganisms is considered to be one of the important traits associated with plant nutrition of phosphate.
Plant Growth Promoting Rhizobacteria (PGPR)
This group of bacteria colonize the roots or rhizosphere soil and are beneficial to crops and so are referred to as plant growth promoting rhizobacteria.