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Presentation on theme: "BIOFERTILIZERS NITROGEN-FIXERS."— Presentation transcript:


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 Main sources: Bacteria, fungi & cyanobacteria (blue-green algae)
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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