What are biofertilisers ? Name the catagories of organisms used as biofertilisers with examples of
each. How do they function in organic farming?
Answers
Answer:
Organic farming is increasing the production of pollutant-free crops. It involves the use of biofertilizers and biopesticides which increases the nutrient quality of the crop and controls any kind of pest and pathogen.
Biofertilizers are microorganisms that add to the nutrient quality of the soil. Bacteria, fungi, and algae are some of the beneficial microorganisms that help in improving the fertility of the soil.
Biofertilizers are classified as:
Free-living nitrogen-fixing bacteria like Azotobacter, and Rhodospirillum.
Free-living nitrogen-fixing Cyanobacteria like Anabaena, and Nostoc.
Loose association of nitrogen-fixing bacteria like Azospirillum.
Symbiotic nitrogen-fixing bacteria like Rhizobium, and Frankia
Microbes As Biofertilizers
The following microorganisms are used as biofertilizers:
Rhizobium: They form root nodules in leguminous plants and fix the atmospheric nitrogen into an organic form. Rhizobium also has no negative effect on soil quality and improves the quality, nutrient content, and growth of the plant.
Azotobacter: These are free-living nitrogen fixers found in all types of upland crops. These not only fix nitrogen but also provide certain antibiotics and growth substances to the plant.
Azospirillum: Unlike Azotobacter, these can be used in wetland areas. They are found inside the roots of the plant (non-free-living) where they fix the atmospheric nitrogen.
Blue-green algae: These are free-living nitrogen-fixing Cyanobacteria that are present only in wet and marshy lands. However, they do not survive in acidic soil.
Mycorrhiza: It is a symbiotic association between the fungi and the roots of a plant. The mycorrhizal fungi play an important role in binding the soil together and improves the activity of the microbes. The fungi draw water and nutrients from the soil thereby increasing the plant productivity. It also helps the plant to survive under various environmental stresses.
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What are Biofertilisers?
A biofertilizer is a substance which contains living microorganisms which, when applied to the soil, helps in the growth of the plant by increasing the supply of primary nutrients to the host plant.
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Name the catagories of organisms as biofertilisers with examples of each . How do they function in organic farming?
1. Symbiotic.
Examples: Rhizobium, Frankia
Function: N2-fixing biofertilizers
2. Associate symbiotic
Examples: Azospirillum
Function: N2-fixing biofertilizers
3. Bacteria
Examples: Bacillus subtilis, Bacillus circulans, and Pseudomonas striata
Function: P-solublizing biofertilizers
4.Fungi
Examples: Aspergillus awamori
Function: P-solublizing biofertilizers
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