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Biofertilizers: An Environment-Friendly Way to Enhance Soil Fertility
With growing concerns over chemical fertilizer usage and its impact on the environment and human health, biofertilizers are emerging as a sustainable alternative for nourishing the soil. Biofertilizers refer to natural products containing living microorganisms that help crop plants absorb nutrients from the soil. When applied correctly, they can significantly improve soil health and fertility.
What are biofertilizers?
biofertilizers are preparations containing living microorganisms that help in increasing the nutrient supply to plants or make the nutrients available in soil. They include bacteria, fungi and cyanobacteria that colonize the rhizosphere or the interior of the plant and promote the availability of nutrients by their biological activity. Some common types are:
- Nitrogen-fixing biofertilizers: These contain bacteria like Rhizobium, Azotobacter, Azospirillum, etc. that fix atmospheric nitrogen and convert it into plant usable form through biological nitrogen fixation. Legume crops like peas, beans utilize such bacteria to meet their nitrogen needs.
- Phosphate-solubilizing biofertilizers: They include bacteria like Pseudomonas and Bacillus that solubilize phosphorus locked in soil and make it available for plant uptake through the release of organic acids.
- Potash-mobilizing biofertilizers: Specific fungi like arbuscular mycorrhizal fungi form a mutualistic association with plant roots and help in absorption of potassium from soil.
- Others: Cyanobacteria, green algae and yeast are also used as biofertilizers for their plant growth promoting substances and nutrient supplementation abilities.
Benefits of biofertilizers
Following are some of the major advantages of using biofertilizers over chemical fertilizers:
Environment-friendly: Biofertilizers are eco-friendly and do not pollute the soil or water resources. They promote the overall soil fertility in a sustainable manner.
Reduce chemical fertilizer use: They aid in nutrient recycling and supplements the fertilizer need of crops, thereby reducing the chemical fertilizer load on farmlands.
Improve soil health: Regular application enhances the organic content and microbial activity in soil. This leads to improved soil structure aggregation.
Nutrient efficiency: When applied along with reduced chemical doses, the yields are maintained while saving on input costs due to better absorption of applied nutrients.
Disease suppression: Certain biofertilizers like Trichoderma also act as biocontrol agents, suppressing soil-borne pathogens and overall improving plant health.
Compatibility issues: They do not face leaching or volatilization losses like chemical fertilizers and are compatible with integrated nutrient management approaches.
Utilization of biofertilizers
For a biofertilizer to be effective, it is important that the carrier material, method and time of application is suitable for the specific microorganism. Some common techniques include:
- Seed treatment: Wet seeds are rolled/mixed with powder formulation before sowing to inoculate seedlings.
- Seed coating: Liquid formulation is applied on seeds that then carries the microbes to the growing roots.
- Soil application: Powder or liquid formulation is broadcast and mixed during final field preparations before sowing.
- Composting: Effective microbes are added during composting of organic matter to enrich the finished compost.
- Vermicomposting: Some phosphate solubilizers are given as feed to earthworms which then excrete microbe-rich vermicompost.
Research and development initiatives
Significant research worldwide is focusing on exploring new potentially useful microorganisms, developing efficient carrier materials and formulations and standardizing production technologies. Some examples are:
- Isolation of native rhizobia for specific pulses and oilseeds adapted to local agro-climatic conditions.
- Mass production technologies using low-cost substrates like sugarcane bagasse, rice straw etc.
- Development of bio capsule and bio granule formulations for ease of handling, storage and application.
- Genetic improvement of selected strains through mutation and recombinant DNA techniques.
- Commercial production and marketing by private companies and some state governments.
Challenges in biofertilizer usage
Despite the numerous benefits, biofertilizers are yet to penetrate mainstream agriculture on a large scale due to certain bottlenecks:
- High mortality rates of microbes due to adverse field conditions of temperature, moisture, soil pH.
- Lack of standardization in quality control and low shelf life of most products.
- Unavailability and awareness among farmers, especially small and marginal.
- High initial production costs compared to synthetic fertilizers.
- Inadequate extension services for technical know-how of suitable handling and application.
- Inability to meet the heavy nutrient needs of intensive cropping systems on their own.
To address these challenges, focused efforts are required from all stakeholders including industry, government, research and farmers in popularizing the use of biofertilizers in a systematic manner along with integrated nutrient management approaches. With ongoing advancements, biofertilizers surely represent a promising option for eco-friendly soil health and agricultural sustainability.
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