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BIOFERTILIZERS

BIOFERTILIZERS. NITROGEN-FIXERS. Addition of Nitrogen to the soil Chemical fertilizers Biological nitrogen fixation (BNF) Chemical fertilizers: Pollution & soil contamination So, Biofertilizers / “Microbial inoculants” 100% natural and organic .

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BIOFERTILIZERS

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  1. BIOFERTILIZERS NITROGEN-FIXERS

  2. Addition of Nitrogen to the soil • Chemical fertilizers • Biological nitrogen fixation (BNF) • Chemical fertilizers: Pollution & soil contamination • So, Biofertilizers / “Microbial inoculants” • 100% natural and organic

  3. A large population of a specific / group of beneficial microorganisms for enhancing the productivity of soil either • by fixing atmospheric nitrogen or by solubilising soil phosphorus or • by stimulating plant growth through synthesis of growth promoting substances. • Main sources: Bacteria, fungi & cyanobacteria (blue-green algae) • Symbiotic relationship with plants

  4. End product of the various phases of Biodigestion has humus in it.  • Pure Biofertilizer, and it can be • Used on soil as a high quality organic fertilizer • Used as a corrector of pH • Has a high nutrient concentration and can be used directly over soil before planting. • Diluted Biofertilizer.

  5. Soil microbes used in biofertilizers are: • Phosphate Solubilizing microbes, • Mycorrhizae, • Azospirillum, • Azotobacter, • Rhizobium, • Sesbania, • Blue Green Algae, and • Azolla.

  6. Phosphate-solubilizing Microbes: • Phosphorus, important nutrient for plants • Microbes that can solubilize the cheaper sources of P – as rock phosphate. • Bacteria – Pseudomonas striata & Bacillus megaterium • Fungi – Aspergillus & Penicillium

  7. By secretion of organic acids • Also, releases soluble Pi into soil through decomposition of phosphate-rich organic compounds. • Usually, microbes inoculated to coffee husk along with rock phosphate while preparing compost.

  8. Mycorrhizae • Refers to fungus associated with plant roots. • 2 types: • Ectotrophic and • Endotrophic

  9. Important for adequate uptake of immobile ions such as phosphate, zinc and micronutrients • Stimulates branching of the root • Increases the absorption surface of the root. • Tolerance to drought, high soil temperature, soil toxins, and extreme pH levels • Protection against root pathogens

  10. Azopirillum • Nitrogen-fixing bacteria that lives in a symbiotic relationship in the root cortex of several tropical crops • Stimulate plant growth through N2 fixation • Helps in production of growth substances like auxins, gibberellins and cytokinins. • 10-15% of the required N2 is met by Azospirillum biofertilizer.

  11. Azotobacter • Triple action • Free-living, N2-fixing bacteria • Produces several plant growth promoting substances. • Protects plants against pathogenic microbes either by discouraging their growth or by destroying them – BIOCONTROL.

  12. Rhizobia

  13. Gram negative, motile, non-sporulating rods. • Forms root nodules in leguminous plants (Fabaceae) & fix atmospheric N2 (diazotrophy) in a symbiotic association

  14. Legumes: Peas, beans, clover, and soy • Rhizobia enter a root hair and travel down a tube to a relatively anoxic centre of the root hair cell. • Here, proliferating plant cells form a nodule. • Bacteria differentiate into bacteroids • Fixes N2 from atmosphere into a plant usable form, ammonium (NH4+), utilising the enzyme nitrogenase • Plant supplies carbohydrates, proteins, sufficient O2, malate and succinate to bacteria

  15. Sesbania

  16. Sesbania • A genus from the family Fabaceae with some aquatic species • A green manure plant which forms both root and stem nodules in association with rhizobium and so, fixes more atmospheric N2 • Produce 10 times more nodules than other legumes • Have a very high capacity to fix atmospheric N2

  17. Grown & turned into the soil while still green to enrich soil N2 • Enriches concentration of Ca, P, S & micronutrients. • Notable species • Rattlebox (Sesbania drummondii), • Spiny Sesbania (Sesbania bispinosa), and • Sesbania grandiflora (an edible plant)

  18. Blue Green Algae • or Cyanobacteria • Can carry out both photosynthesis as well as N2 fixation • Algal flakes are grown & then broadcasted.

  19. Azolla

  20. Mosquito fern / Duckweed fern / Fairy moss / Water fern) • A genus of 7 species of aquatic ferns • A floating fern, harbouring a blue green algae in its leaf cavities. • Form a symbiotic relationship with the blue-green alga Anabaena azollae, that fixes atmospheric N2 • Can grow at great speed - doubling its biomass every 2-3 days • Then, harvested, dried and used as biofertilizer

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