BIOFERTILIZERSPresented by,
M.Uma Maheshwari,
M.Phil Botany
ORGANIC FARMING Organic agriculture excludes the use of
synthetic compounds It mainly rely on usage of organic
substances Organic farming is thus considered as
the movement directed towards the philosophy of “Back to nature”
It emerged as a priority area for growing demand, long term sustainability and concerns on environmental pollution.
Bio fertilizers Bio fertilizers or microbial inoculants are
carrier based ready to use live bacterial or fungal formulations, which on application to plants, soil or composting pits, help in mobilization of various nutrients by their biological activity.
They are the best modern tool for agriculture.
Bio fertilizers contain living micro organisms which promote adequate supply of nutrients
Essential component of organic faming Preparation consists of efficient strains
of Nitrogen fixing, phosphate solubilizing or cellulolytic micro organisms used for application to seed, soil or composting areas
Play a significant role in improving soil fertility by fixing atmospheric nitrogen, with or without plant roots.
Solubilizes insoluble phosphates and promote plant growth.
Need for bio fertilizers Use of chemical fertilizers leads to the
pollution and contamination of soil Demand is much higher than the
availability Energy crisis and increasing cost of
fertilizers Bio fertilizers are economical, eco-
friendly, more efficient, productive and accessible to marginal and small farmers
Characteristic features of some bio fertilizers
Nitrogen fixers› Rhizobium› Azospirillum› Azotobacter› Blue Green Algae (BGA)
Phosphate solubilizers Phosphate absorbers Zinc solubilizers
Rhizobium Rhizobium belongs to the
family Rhizobiaceae Useful for pulse legumes Fix nitrogen 50-100
kg/ha in association with legumes only
Nodulation depends on availability of compatible strain for a particular legume.
Rhizobium Rhizobium has the ability to
fix nitrogen in symbiotic association with legumes and non-legume like Parasponia
It coloniizes the root and produces the nodules, which acts as a factories of ammonia production
Artificial seed inoculation is needed to restore the population of effective strains of Rhizobium near the rhizosphere to hasten N-fixation
Each legume requires a specific species of Rhizobium to form effective nodules
Azospirillum It belongs to Spirilinaceae,
heterophytic and associative in nature
Fix nitrogen about 20 – 40 kg/ha
Many species› A. amazonense› A. halopraeferens› A. brasilense
But A. lipoferum, A. brasilense are worldwide distribution
It has symbiotic association with plants having C4-dicarboxylic acid cycle
They grow and fix nitrogen on salts of organic acids
Mainly recommended for maize, sugarcane, pearl millet, Sorghum, etc.,
They colonize the roots not only on root surface but also penetrates into the root tissues
They do not produce any visible nodules
Azotobacter Belongs to the family
Azotobacetriaceae, aerobic, living and heterotrophic in nature
Many species A. vinelandii, A. baijerinckii, A. insignis and A. macrocytogenes.
A. chroococcum is the most commonly occurring spp.
The number of Azotobacter exceeds 105/g soil due to lack of organic matter and presence of antagonistic organisms
The bacterium produces anti-fungal antibiotics- inhibits pathogenic fungus
Preventing seedling mortality The population is very low in
rhizosphere and uncultivated lands Mainly reported in crop plants like rice,
maize, sugarcane, bajra, vegetables and plantation crops
Blue Green Algae Belongs to eight different families Phototrophic in nature and produces
auxin, gibberllic acid and Indole Acetic Acid
Fix 20-30 kg/ha nitrogen Abundant in paddy fields so called
‘paddy organisms’ Forms symbotic association with fungi,
liverworts, ferns and flowering plants
The most common association had been found between floating aquatic fern Azolla, Anabaena azollae (BGA).
Important character is that it decomposes quickly
The most common species found in India is Azolla pinnata
The fern forms a green mat with a branched stem, deeply bilobed leaves and roots
India has recently introduced some species of Azolla for their large biomass production› A. caroliniana› A. microphylla› A. filiculoides› A. mexicana
Phosphate solubilzers Several reports have reported
that bacterial spp. Can solubilize insoluble inorganic phosphates
Genera like Bacillus, Burkholderia, Achromobacter, Agrobacterium, Microccous, Aerobacter, Flavobacterium and Erwinia
Only considerable populations are seen on the rhizosphere
The soil bacteria belonging to Bacillus and Pseudomonas are common
Phosphate absorbers Mycorrhiza – fungus root Symbiotic association between
host plants and certain group of fungi
The fungal partner is benefited by obtaining carbon requirements
Host is benefited by getting nutrients
They are mainly associated with agricultural crops excepts members of Polygalaceae, Cyperaceae, Amaranthaceae, Caryophyllaceae, Chenopodiaceae, Juncaceae and Brassicaceae
Zinc solubilizers Nitrogen fixers like Rhizobium,
Azospirillum, Azotobacter, BGA and phosphate solubilizing bateria like Bacillus magaterium, Pseudomonas striata and phosphate mobilizing Mycorrhiza can only supply major nutrients to host plants.
Zinc can be solubilized by Bacillus subtilis, Thiobacillus thioxidans and Saccharomyces spp.
Bacillus subtilis can be used as a biofertilizer in soil where native zinc is in higher concentration
Uses of biofertilizers Renewable source of nutrients Sustain soil health Supplement chemical fertilizers. Replace 25-30% chemical fertilizers Increase the grain yields by 10-40%. Decompose plant residues, and stabilize C:N ratio of soil Improve texture, structure and water holding capacity of
soil No adverse effect on plant growth and soil fertility. Stimulates plant growth by secreting growth hormones. Secrete fungistatic and antibiotic like substances Solubilize and mobilize nutrients Eco-friendly, non-pollutants and cost effective method
Conclusion Biofertilizers are essential components
in maintaining long term fertility and sustainablity by fixing atmospheric nitrogen, mobilizing fixed macro and micro nutrients thereby increasing their efficiency and availability
Organic manures would be a viable option for farmers to increase productivity per unit area.
Therefore reducing pollution and increasing sustainability.
Thank you
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