Bio fertilizerBio fertilizers are not fertilizers. “Bio fertilizer” is a substance which contains livingmicroorganisms which, when applied to seed, plant surfaces, or soil, colonizes therhizosphere or the interior of the plant and promotes growth by increasing the supplyor availability of primary nutrients to the host plant.Why bio fertilizers?It’s a microbial green revolution. Bio fertilizers are having it sown advantages overchemical fertilizers and it is economically and environmental friendly too. With theincreasing demand in agriculture it has become important for us to increase theProductivity by using various fertilizers insecticides Pesticides .But with the tremendoususe of these products the soil has been affected badly because of the depletion in theessential minerals of the soil. So to overcome this problem it has become important forall of us to use a different remedy for the production of various bio fertilizers. They arethe best at economic value.
Types of bio fertilizers: Nitrogen bio fertilizers Compost bio fertilizers Phosphorous bio fertilizers Nitrogen fixing fertilizers:Symbiotic: Rhizobium It belongs to rhizobiaceae family, the rhizobium bacteria present in the nodulesof these crops are not always efficient. Therefore, the competitive, efficientbacteria are isolated, screened, selected and produced as carrier basedinoculantsMorphology:1) Unicellular, cell size less than 2µ wide. Short to medium rod, pleomorphic2) Motile with peritricus flagella3) Gram negative4) Accumulate poly β-hydroxyl butyrate granules.
Physiology:1) Nature : chemo heterotrophic, symbiotic with legume2) C source: supplied by legume through photosynthesis, mono &disaccharide.3) N source: fixed from atmosphere.4) Respiration: aerobic.5) Growth: fast ( rhizobium), slow (Brady rhizobium)6) Doubling time: fast grower- 2-4 hours slow grower 6-12 hours.7) Growth media : YEMARecommended for :Pulses: chickpea, pea, lentil, black gram, green gram, cowpea, pigeon pea.Oil seeds: soybean, groundnut.
Non symbiotic: Azospirillum, Azotobacter.AzotobacterIt belongs to azotobacteriaceae .It produces growth promoting substances whichimprove seed germination and growth of extended root system. It producespolysaccharides which improve soil aggregation. Azotobacter suppresses the growth ofsaprophytic and pathogenic micro-organism near the root system of crop plantsMorphology:1) Cell size: Large ovoid cells, size ranging from 2.0-7.0×1.0-2.5µ.2) Cell character: polymorphic3) Accumulate poly β-hydroxyl butyrate granules.4) Gram reaction: negative
Physiology:1) Nature: chemo heterotrophic, free living2) C source: a variety of carbon source ( mono, di and certain polysaccharide)organic acids.3) N sources: Nitrogen through fixation, amino acid, NH4, NO34) Respiration: aerobic5) Growth media: Ashby Jensen’s medium6) Doubling time: 3 hoursContribution :1) 20-40 mg BNF/g of C source in laboratory condition equivalent to 20-40 kg N/ha.2) Production of growth promoting substance like vitamins of B groups, indoleaceticacid and gibberellin acid.3) Biological control of plant disease by suppressing Aspergillus, Fusarium.Recommended for:Rice, wheat, millets, other cereals, cotton, vegetable, sunflower, mustard, flowers.Increase in yield: 20 to 30%
Azospirillium It belongs to family spirillaceae. The bacteria have been found to live within the root ofsorghum, bajra and rage plants. They are chemoheterotrophic and association in naturesecrete growth regulatory substanceThe use of azospirillium inoculants help in increasing yield of millets. It significantlyincrease the growth, chlorophyll content and mycorrhyzal infection in root. Increasedgrowth and nutrient uptake by barley plants were observed when seed were co-inoculatedwith A. baselines and Glomus vermiform.Morphology:1) Cell size: curved rod, 1mm in diameter, size and shape vary.2) Accumulate: poly β-hydroxyl butyric acid.3) Gram reaction: negative4) Development of white pellicles 2-4mm below the surface of NFB medium.
Physiology:1) Nature: chemoheterotrophic, associative.2) C source: organic acid, L-arabinose, D-gluconate, D-fructose, D-glucose, sucrose, pectin.3) N sources: nitrogen through fixation, amino acids, NH4, NO34) Respiration: aerobic, micro aerobic.5) Growth media: N free bromothymol blue (NBF)6) Doubling time: 1hr in ammonia containing medium, 5.5 to 7hr. on malatecontaining semi-solid mediumContribution:1) 20-40 mg N/g malate under laboratory condition equivalent to 20-40 kg N/ha.2) Results in increase mineral and water uptake, root development, vegetative growthand crop yield.Recommended for: Rice, millets maize, wheat, sorghum, sugarcane and co-inoculants forlegumes.Response: Average increase in yield 15-30%.
Phosphate solubilizing bio fertilizerPhosphorus is one of the most important plant nutrients and may be critical nutrient for theoptimum growth of plants. Most of our soils are in available forms of phosphorus requiredphosphate application.In the rhizosphere of crops will render insoluble soil phosphate available to plants due toproduction and secretion of organic acid by them. The use of this bio fertilizer will alsoincrease the availability of phosphate from rock phosphate applied directly even to neutralto alkaline soil or when used for preparation of phosphor-compost. Phosphate solubilizingmicro-organism include efficient strain of bacteria, fungi, yeast and actinomycetes in thatorderBacteria Morphology:1) Cell size: rod shape, 1.1 to 2.2µm in diameter.2) Gram reaction: for Bacillus positive and for Pseudomonas negative3) Transparent zones of clearing around microbial colonies indicate extent of Phosphatesolubilization.
Physiology 1) Nature: chemoheterotrophic. 2) C source: Glucose is the main C source but they can utilize other carbon sources. 3) Respiration: aerobic, micro aerobic. Growth media: Pikovskaya’s media Advantages of using bio fertilizers:1)They help to get high yield of crops by making the soil rich with nutrients and usefulmicroorganisms necessary for the growth of the plants.2) Bio fertilizers have replaced the chemical fertilizers as chemical fertilizers are notbeneficial for the plants. They decrease the growth of the plants and make theenvironment polluted by releasing harmful chemicals.3) Plant growth can be increased if bio fertilizers are used, because they contain naturalcomponents which do not harm the plants but do the vice versa.4) If the soil will be free of chemicals, it will retain its fertility which will be beneficial forthe plants as well as the environment, because plants will be protected from getting anydiseases and environment will be free of pollutants.
5) Bio fertilizers destroy those harmful components from the soil which cause diseases inthe plants. Plants can also be protected against drought and other strict conditions byusing bio fertilizers.6) Bio fertilizers are not costly and even poor farmers can make use of them.7) They are environment friendly and protect the environment against pollutants. Disadvantages Much lower nutrient density -- requires large amounts to get enough for most crops. Requires a different type of machine to apply than chemical fertilizers. Sometimes hard to locate in certain areas odor.
Why do we need bio fertilizers……????????????? An estimate shows 100million tons of fixed N2 is required for global food production. Chemical fertilizers is the most common practice to increase crop yeilds Besides the cost factor the use of chemical fertilizers is associated with environmental pollution.
Process of making bio fertilizer:• Bio fertilizers are usually prepared as carrier-based inoculants containing effective microorganism.• Incorporation of microorganisms in carrier material enables easy-handling, long-term storage and high effectiveness of bio fertilizers.• Among various types of bio fertilizers, bacterial inoculant is one major group which includes rhizobia, nitrogen-fixing rhizobacteria, plant growth promoting rhizobacteria, phosphate-solubilizing bacteria.• Basically, the carrier-based inoculant of these bacteria can be prepared by a common procedure.
The most common way of inoculation Seed inoculation The inoculant (bacteria-carrier mixture) is mixed with water to make slurry-form, and then mixed with seeds. In this case, the carrier must be a form offine powder. To achieve the tight coating of inoculant on seed surface, use ofadhesive, such as gum arabic,methylethylcellulose, sucrose solutions, andvegetable oils, is recommended. Seed inoculation may not always besuccessful, i.e. the inoculation resulted in low nodule occupancy of theinoculated rhizobial strain, or low establishment of the inoculatedrhizobacterial strain. This might be due to low population and/or low survivalof the inoculated bacterial strain on the seed surface and in the soil.“soil inoculation” will be adopted, whereby a large population of abacterial strain can be introduced into the soil. For soil inoculation in general, granularinoculant is placed into the furrow under or alongside the seed. This enhances thechance for the inoculated strain to be in contact with plant roots.
Carrier materialVarious types of material are used as carrier for seed or soil inoculation. Forpreparation of seed inoculant, the carrier material is milled to fine powder with particlesize of 10 -40 μm.The properties of a good carrier material for seed inoculation are:(1) Non-toxic to inoculant bacterial strain.(2) Good moisture absorption capacity.(3) Easy to process and free of lump-forming materials.(4) Easy to sterilize by autoclaving or gamma-irradiation.(5) Available in adequate amounts(6) Inexpensive.(7) Good adhesion to seeds, and(8) Good pH buffering capacity.(9) Need less non-toxic to plant, is another important property.
Essential criteria for carrier selection relating to survival of theinoculant bacteria should be considered :(1) Survival of the inoculant bacteria on seed. Seeds are not always sownimmediately after seed coating with the inoculant bacteria. The bacteria haveto survive on seed surface against drying condition until placed into soil. (2) Survival of the inoculant bacteria during the storage period. (3) Survival of the inoculant bacteria in soil.After being introduced into the soil, the inoculant bacteria have tocompete with native soil microorganisms for the nutrient and habitableniche, and have to survive against grazing protozoa. Such carrier materialsthat offer the available nutrient and/or habitable micro-pore to theinoculant bacteria will be desirable. In this sense, materials with micro-porousstructure, such as soil aggregate and charcoal, will be good carrier for soilinoculant.
Sterilization:Carrier sterilization is autoclaving. Carriermaterial is packed in partiallyopened, thin-walled polypropylene bagsand autoclaved for 60 min at 121 ºC. Itshould be noted that duringautoclaving, some materials changes theirproperties and produce toxic substance tosome bacterial strains.
Inoculant Parameters Sterile Non-sterilePopulation of beneficial High VariablebacteriaChoice of materials to be Many materials are not Almost unlimitedused as carriers easily sterilized or change their chemical and physical composition upon sterilizationLabor requirements Skilled & expensive Mostly unskilledSterile production space Large and costly Not neededMonitoring of contamination Essential for quality Essential for quality control of the control of the product productTotal cost of production High Much lower than sterile productionLongevity High Relatively lowSterilization equipment Huge autoclave machine Not neededrequired they are very costly
New Trends in Formulations Using Unconventional Synthetic Materials These polymers have demonstrated potential as bacterial carriers that offeredsubstantial advantages : These formulations encapsulate the living cells protect the microorganisms against many environmental stresses, and release them to the soil, gradually but in large quantities. when the polymers are degraded by soil microorganisms, usually at the time of seed germination and seedling emergence. They can be stored dried at ambient temperatures for prolonged periods, offer a consistent batch quality and a better defined environment for the bacteria, and can be manipulated easily according to the needs of specific bacteria. These inoculants can be amended with nutrients to improve the short-term survival of the bacteria upon inoculation
Encapsulated Formulations• The encapsulation of microorganisms into a polymer matrix is still experimental in the field o f bacterial-inoculation technology.• At present there is no commercial bacterial product using this technology.• The concept underlying immobilized microbial cells, is to entrap beneficial microorganisms into a matrix.• The formulation (bacteria-matrix) is then fermented in a bacterial growth medium.• These formulations can produce many useful compounds for industrial and environmental applications (such as organic acids, amino acids, enzymes) and biodegrade toxic materials (bio remedation) over extended periods of time.
The main goal of these industrial formulations is to maintain the cellsentrapped in an active form for as long as possible. Any premature release ofthe microorganisms from these encapsulated forms is undesirable.Encapsulated bacterial formulations in agriculture have at least two distinctly differentgoals from those of the fermentation industry:a) To temporarily protect the encapsulated microorganisms from the soil environmentand microbial competition, andb) To release them gradually for the colonization of plant roots.
AlginateAlginate is the material most commonly used for encapsulation ofmicroorganisms. The resulting inoculation are used for various purposes: The immobilization of cell organelles and enzymes, The application of biological control agents and mycoherbicides To increase the stability of recombinant plasmids in the host cells.
REGULATION AND CONTROL OF CONTAMINATION OF COMMERCIAL INOCULANTSNaturally, an inoculant should contain a level of bacteria sufficient to inoculate plantsand produce an economic gain. The required level of bacteria cannot be established asa general standard because it varies from one bacterial species to another. Onlyrhizobial inoculants have legally established standards.Quality control methods to determine the number of bacteriawithin the inoculant are not standardized either. To measure the bacterialnumber, commonly known methods in microbiology are used; the traditionalPlate Count methods, Most Probable Number.
Examples of New Commercial Microbial InoculantsCommercial microbial inoculants of other beneficial microorganisms havebegun to appear on the market on a small scale. These include "Azogreen",a French-approved Azospirillum inoculant.COST OF DEVELOPMENT AND MARKETINGThe cost of developing a new product by the agrochemical industry has beenestimated at over $80 million US and rising . The development of resistance topesticides may shorten the commercial life of these products and thus theirpotential return. The development of bacterial inoculants is claimed to becheaper than that of agrochemicals.
The following are some factors that reduce the costs of development ofbacterial inoculants which makes them attractive to the agrochemicalindustry:(i) Reduced registration costs compared to those ofchemical-product test programs t hat are well- established and costly.(ii) Reduced registration time decreases the time span from first screening tomarket, thus increasing revenues(iii) The possibility of developing bacterial products for small markets. Since thecost involved in bringing a new chemical to the marketplace is so large, theproduct must be targeted to a market large enough to have a good returnon investment. This limits the choice of crops to the major crops only.(iv) Although fermentation is costlier than chemical production, thefermentation plant is more versatile.
Other motivational steps for the agrochemical industry to developbacterial inoculants might be:• It is less likely that pathogens will develop resistance as fast as they do to chemical products.• Some bacterial inoculants, especially those that use an organism employing a single mechanism against the pathogen, can also develop resistance.• They are "environment friendly". The "natural“ tag of bacterial inoculants (especially those that are non engineered and indigenous) make them more acceptable in the public eye, and especially t o the "Green movement" pressure groups, than chemicals.
Market requirementFirst, all the considerations mentioned above (efficient strains, optimizedformulations, cost-effective production, and good and practical inoculationtechniques) are not sufficient to launch a new product on the market nor guaranteeits success. The following practical variables should be considered:(i) The product must be efficient and reliable in large-scale field trials and especiallyunder "real life" conditions.(iii) Obviously, patents on industrial processes and registration of biological productsmust be secured(iv) For every potential customer country, a market survey must be done whichexamines customer demand, market size, and expected selling price.
CONCLUSIONS AND FUTURE PROSPECTS The agrochemical industry is more sympathetic now to the concept of bacterial inoculants than it has been previously. There is a genuine interest in developing bacterial products that are reliable and that can act as complements to chemicals already on the market Greenhouse crops are also primary targets for commercial inoculants Pioneering transgenic plants are already in the field expressing insecticidal proteins of B. thuringiensis in cotton plants, making them resistant to various insect pests. A gradual and modest increase in the use of bacterial inoculants is to be expected. Agriculture in developed countries is definitely the major promoter of microbial inoculants that are "environmentally friendly“.
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