Bio-Fertilizers: A Brief Introduction

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“Biologically active products or microbial inoculants of bacteria algae and fungi are known as bio fertilizers”. These organisms can be used either separately or in combination which may help biological nitrogen fixation for the benefit of plants. By Nadia Hassan.

Emergence of bio fertilizers as agro-inputs:
The concept of microbial inoculation which started with legume Rhizobium inoculant has now been diversified to bacteria, fungi and actinomycetes.
During last fifteen years India has witnessed a rapid growth in commercialization of various biofertilizers.

Types of bio-fertilizers:
Bio-fertlilizers include the following
• Symbiotic nitrogen fixing Rhizobium spp
• Asymbiotic free nitrogen fixers such as Azobacter and Azospirillium
• Algae bio-fertilizers (Blue green algae in association with Azolla)
• Phosphate solubilizing bacteria
• Mycorrhizae
• Organic fertilizers

Bio fertilizers lead to increased fertility of the crop fertility. Three main classes of bio-fertilizers are:-
• Nitrogen bio-fertilizers
• Phosphate bio-fertilizers
• Organic matter decomposers

1) Bio-fertilizers micro-organism:
Rhizobium inoculants are commercially available bio-fertilizer USA Rhizobial inoculants market constitutes 4% world market.

2) Azospirillum:
It is used to increase N-fertility. It increases crop productivity in rice, oilseed and millet etc.

3) Phosphate solubiling micro-organism:
Polymyxa, Bacillus megatherium, Pseudomonas solubilize 30-35 kg P2O2/ha.

4) Blue green algae:
Used in flooded rice but are yet to be commercialized.

Methods of application:-
1) Seed treatment:
In this seeds are inoculated with the bio-fertilizers before sowing. It is recommended for the cereals, oil seeds and pulses.

2) Set treatment:
For the set of sugarcane, cut pieces of potatoes and base of banana suckers

3) Seedling treatment:
For the crops like paddy, tobacco, tomato, chilly, onion the seedings are inoculated with bio fertilizers.

4) Soil treatment:
This method varies from crop to crop depending upon its duration.

Advantages of bio-fertilizers:-
• Low cost inputs
• Leads to soil enrichment
• Compatible with long term sustainability
• Eco-friendly and poses no danger to the environment

Disadvantages:-
• Do not produces quick response
• Nutrients provided are not enough

Causes of disadvantages:
• Poor inoculation quality
• Lack of awareness among the farmers
• Non-availability of inoculants in easy reach of farmers
• Wide variations in response due to variability in agroclimate situation, soil reaction.