2 Addition of Nitrogen to the soil Chemical fertilizersBiological nitrogen fixation (BNF)Chemical fertilizers: Pollution & soil contaminationSo, 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 eitherby fixing atmospheric nitrogen or by solubilising soil phosphorus orby 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 beUsed on soil as a high quality organic fertilizerUsed as a corrector of pHHas 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, andAzolla.
6 Phosphate-solubilizing Microbes: Phosphorus, important nutrient for plantsMicrobes that can solubilize the cheaper sources of P – as rock phosphate.Bacteria – Pseudomonas striata & Bacillus megateriumFungi – 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 andEndotrophic
9 Important for adequate uptake of immobile ions such as phosphate, zinc and micronutrients Stimulates branching of the rootIncreases the absorption surface of the root.Tolerance to drought, high soil temperature, soil toxins, and extreme pH levelsProtection against root pathogens
10 AzopirillumNitrogen-fixing bacteria that lives in a symbiotic relationship in the root cortex of several tropical cropsStimulate plant growth through N2 fixationHelps 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.
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 bacteroidsFixes N2 from atmosphere into a plant usable form, ammonium (NH4+), utilising the enzyme nitrogenasePlant supplies carbohydrates, proteins, sufficient O2, malate and succinate to bacteria
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 N2Produce 10 times more nodules than other legumesHave 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 speciesRattlebox (Sesbania drummondii),Spiny Sesbania (Sesbania bispinosa), andSesbania grandiflora (an edible plant)
18 Blue Green Algae or Cyanobacteria Can carry out both photosynthesis as well as N2 fixationAlgal flakes are grown & then broadcasted.
20 Mosquito fern / Duckweed fern / Fairy moss / Water fern) A genus of 7 species of aquatic fernsA 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 N2Can grow at great speed - doubling its biomass every 2-3 daysThen, harvested, dried and used as biofertilizer