Biofertilizers: A Sustainable Way for Future Farming
With growing concerns over depleting natural resources, deteriorating soil health and rising costs of farming, it has become imperative to adopt more sustainable agricultural practices. One such promising approach is the use of biofertilizers in farming. Biofertilizers are microbial inoculants that help fix atmospheric nitrogen or solubilise soil phosphorus, making it available for plant uptake. Their use is gaining importance due to their numerous benefits.
What are Biofertilizers?
Biofertilizers refer to formulations containing live or latent cells of efficient strains of microorganisms that help in crop growth when applied to seed, plant surfaces or soil. The two main types of biofertilizers are nitrogen biofertilizers and phosphorus biofertilizers.
Nitrogen biofertilizers include Rhizobium, Azotobacter, Azospirillum etc. Rhizobium is used for legumes as it can fix atmospheric nitrogen in root nodules. This provides nitrogen for the plants and also improves the nitrogen status of the soil. Azotobacter and Azospirillum are free-living nitrogen fixers that live in the soil and help non-leguminous crops through nitrogen fixation.
Phosphate solubilizing biofertilizers contain microorganisms like Pseudomonas striata and Bacillus megaterium that solubilize insoluble soil phosphates. By solubilizing phosphates through the release of organic acids, these microbes make phosphorus available for plant uptake from soil.
Benefits of Using Biofertilizers
Environment Friendly
Biofertilizers are eco-friendly and help reduce the pollution load on soil and water bodies caused by chemical fertilizers. They do not have any harmful residues and reduces the requirement of chemical fertilizers.
Increase Crop Yield
Several field studies have demonstrated that biofertilizers like Rhizobium, Phosphate Solubilizing Bacteria (PSB) and Azotobacter significantly increase the yield of various crops. For example, Rhizobium increases legume yields by 15-30%.
Improve Soil Health
Regular use of biofertilizers increases the organic content and beneficial microorganisms in the soil. They improve soil structure and water holding capacity. This leads to overall improvement in long term soil fertility and productivity.
Reduce Production Costs
Biofertilizers provide partial or full substitution of chemical nitrogen and phosphorus nutrients. This reduces the fertilizer costs and increases the net returns for farmers.
Types of Biofertilizers Available
Rhizobium Biofertilizers
Rhizobium is the most common and important biofertilizer used for leguminous crops like pulses, soybean, etc. Some popular Rhizobium biofertilizer formulations and their crop specificity are:
- Rhizobium leguminosarum - For peas, chickpeas, lentils
- Rhizobium sp. - For groundnut
- Rhizobium phaseoli - For beans
- Rhizobium melilotii - For alfalfa
Azotobacter Biofertilizers
Azotobacter is a free-living nitrogen fixing bacteria. Some commercial products containing Azotobacter are:
- Azotobacter chroococcum - Used for wheat and sugarcane
- Azotobacter vinelandii - Used for rice and vegetables
Phosphate Solubilizing Microorganisms
- Pseudomonas striata - Used for various field crops
- Bacillus megatherium - Used for wheat and vegetables crops
- Bacillus polymyxa
Azospirillum Biofertilizers
Azospirillum contains nitrogen fixing anaerobic bacteria that helps cereals and grasses. Some popular formulations are:
- Azospirillum brasilense - Used for wheat and maize
- Azospirillum lipoferum - Used for rice
Application Method and Doses
The method of application of biofertilizers depends on the type of crop and microorganism used. Some common methods are:
Seed Treatment
It involves treating seeds with Biofertilizers powder or slurry before sowing. e.g. Rhizobium for pulses - 25-50g per kg of seeds.
Soil Treatment
Biofertilizer cultures are mixed in the soil before sowing. e.g. Azotobacter - 5kg per acre.
Foliar Spray
Spraying biofertilizer suspensions on leaves, e.g. Azospirillum - 2.5kg per acre, 2-3 times.
Rates also vary with the type of soil and crop. It is advisable to follow the manufacturers instructions or consult local agricultural experts.
Challenges and Future Prospects
While tremendous promise is shown by biofertilizers, their widespread adoption faces certain challenges:
- Issues with mass production and storage of microorganisms
- Quality control and standards are still evolving
- Lack of awareness among farmers
- Perceived slowgreening effect compared to chemicals
- Sensitivity to environment conditions during application
However, the future looks promising as research is ongoing to develop more efficient strains, better formulations and application methods. With policies supporting organic farming, the use of biofertilizers is sure to grow significantly. When integrated with other organic inputs and good management practices, biofertilizers can play a major role in sustainable agriculture over long term.
With depleting resources and growing need to reduce environmental pollution, the time is ripe for farmers and policymakers to give a serious thought to biofertilizers. Though initially costs may be higher than chemicals, biofertilizers offer multiple advantages which justify their use from an overall sustainability perspective. With more efficient varieties in the pipeline and increasing support measures, use of biofertilizers holds great potential for viable and resilient farming systems of the future.
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