 |
| Biofertilizers in agriculture |
In this article, we will discuss about the - Roles of Biofertilizers in agriculture, Types of Biofertilizers and their uses, and the applications of biofertilizers.
Biofertilizers are ready to use live formulates of some beneficial microorganisms which on application to seed, root or soil help build up the micro-flora and in turn the soil health in general ,mobilize the availability of nutrients by their biological activity in particular, and the importance of soil organic matter in relation to soil fertility is widely recognized.
In the formation of fertile soil, organic substances play a direct role, as they are the sources of plant nutrients, which are liberated in available form during mineralization.
Although, incorpoarion of crop reaidues, green manure, farmyard manure, are the common practices in the fertility programme in many farms, the supply of organic manures is limiting to make any important contribution to the soil organic matter.
° Rhizobium for legume crops.
° Azotobacter / Azospirillum for non legume crops.
°Acetobactor for sugarcane only.
°Blue-Green Algae (BGA) and Azolla for low land paddy.
°Phosphatika for all crops to be applied with Rhizobium, Azotobacter, Azospirillum and Acetobactor.
° Cellulolytic fungal culture
°Phosphotika and Azorobacter culture
1) Increase crop yields by 20-30%.
2) Replace chemical nitrogen and phosphorus by 25%.
3) Stimulate plant growth.
4) Activate the soil biologically.
5) Restore natural soil fertility.
6) Provide protection against drought and some soil borne disease.
7) Cost effective.
8) Suppliment to fertilizers.
9) Reduces the costs towards Frfertilizer use, especially regarding nitrogen and phosphorus.
10) Renewable source of nutrients.
11) Sustain soil health.
12) Supplement chemical fertilizers.
13) Replace 25-30% chemical fertilizers.
14) Increase the grain yields by
10- 40%.
15) Decomposes plant residues, and stabilize C:N ratio of soil.
16) Improve texture, structure and water holding capacity of soil.
17) No adverse effect on plant growth and soil fertility.
18) Stimulates plant growth by secreting growth hormones.
19) secrete fungistatic and antibiotic like substances.
20) Solubilize and mobilize nutrients.
21) Eco-friendly, non-pollutants and cost effective method.
Rhizobium, a root nodule bacterium, has the ability to fix atmospheric nitrogen in symbiotic association with host legumes. In general, they are Gram-negative, motile, non-sporulating rod shaped bacterium.
It was estimated that a total of 175 million metric tones of N is fixed per year globally through biological nitrogen fixation involving Legume Rhizobium symbiosis.
Brand Name:
1) Raza (peak Chemical Industrial Ltd. , west Bengal) .
Form: Liquid
2) Rhizobium (National fertilizers Ltd. Vijaipur, Madya pradesh)
Form: Soild formulate.
1) Rhizobia invade legume roots through root hairs.
2) Form effective pink coloured nodules in the roots.
3) Lives symbiotically inside the nodules and fix nitrogen.
4) Convert atmospheric nitrogen to plant accessible forms.
5) Most rhizobia ate host specific in nature.
Host plant Bacterial symbiont
Alfalfa Rhizobium meliloti
Clover Rhizobium trifolii
Soyabean Bradyrhizobium japonicum
Beans Rhizobium phaseoli
Pea Rhizobium leguminosarum
Srsbania Azorhizobium caulinodans
It is a genus usually notile, Gram-negative bacteria, oval or spherical bacteria that form thick-walled cysts and may produce large quantities of capsular slime.
They are aerobic, free-living soil microbes which play an important role in the nitrogen cycle in nature, binding atmosphere nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil.
Apart from being a model organism, it is used by humans for the production of Biofertilizers, food additives and some biopolymers.
Azotobacter are free-living nitrogen-fixing bacteria, they normally fix molecular nitrogen from the atmosphere without symbiotic relations with plants, although some Azotobacter species are associated with plants.
Nitrogen fixation is inhibited in the presence of available nitrogen sources, such as ammonium ions and nitrates.
Azotobacter have a full range of enzymes needed to perform the nitrogen fixation: ferredoxin, hydrogenase and an important enzymes nitrogenease. The process of nitrogen fixation requires an influx of energy in the form of adenosine triphosphate (ATP).
Nitrogen fixation is highly sensitive to the presence of oxygen, and therefore Azotobacter develops a special defensive mechanism against oxygen,namely a significant intensification of metabolism that reduces the concentration of oxygen in the cells. There is also a special Portein shethna, which protects nitrogenease and is involved in protecting the cells from oxygen.
Brand Name:
Azotobacter (National Fertilizers Ltd. Vijaipur, Madya pradesh) .
Form: solid formulate
BGA also known as Cyanobacteria, obtain their energy through photosynthesis. Blue-Green algae are considered as the simplest, living autotropic plants. They are microscopic and are widely distributed in the aquatic environment.
The ability of BGA to photosynthesize food and fix atmospheric nitrogen accounts for their symbiotic associations and also for their presence in paddy fields.
Blue-Green algae are of immense economic value as they add organic matter to the soil and increase soil fertility. Barren alkaline lands in India have been reclaimed and made productive by including the proper growth of certain blue-Green algae.
Application: 20-30 kg N/ha increases yield 10-15%.
Limitation: Effective only in submergene paddy fields and demands bright sunlight.
e. g. Nostoc, Anabaena, Aulosira, Tolypothrix, etc.
Brand Name:
Nature Bio Fertilizers, Bio Nutritional Fertilizers
(Ecological products Industries, New Delhi)
Form: Liquid
Azolla floats on the surface of water by means of numerous, small closely-overlapping scale-like leaves, with their roots hanging in the water. They form a symbiotic relationship with the blue-Green algae Anobaena azollae, which fixes atmospheric nitrogen, giving the plant access to the essential nutrient.
Application : 30-100kgN/ha increses yield by 20-25%.
Limitation: Survival is difficult at high temperatures, great demand for phosphorus.
Brand Name: Azollae (Biomate India Pvt Ltd. New Delhi).
Form: Liquid.
Many heterotropic bacteria and fungi efficiently solubilize insoluble phosphate in the soil as well as the inert phosphorus sources. These organisms secrete organic acids that solubilize insoluble phosphorus which becomes then available for plant absorption.
Many bacteria belonging to Bacillus, Pseudomonas, Flavobacterium, Micrococcus, Streptomyces and fungi belonging to Aspergillus, Penicillium and Trichoderma efficiently solubilize insoluble phosphate of rock phosphate groups.
Brand Name : P.S.B (National Fertilizers Ltd. Vijaipur, Madya Pradesh).
Form: Solid formulate.
Green manure is a type to f cover grown primarily to add nutrients and organic matter to the soil. They are grown for the purpose of plowing them, thus increasing fertility through the incorporation of nutrients and organic matter into the soil.
Crops that are normally planted as inter-or reply crops for the sake of accumulating nitrogen in the soil, producing residues and ground cover. Green manure cover crops are not primarily planted to generate additional incomes (seed or grains). They are used for-
1) To produce nitrogen (legumes)
2) To control weeds (replacing fallow periods).
3) To produce mulch during non-crop periods.
4) To cycle soil nutrients.
5) Other positive effects on succeeding crops.
6) If there is not enough water for a cash crop.
7) When there is a free period between crops and enough moisture available or at the end of the croping season.
8) When producing a cash crop is not profitable or too risky.
9) Green manures, in the case of legumes, fix nitrogen and contribute to farm nitrogen needs.
10) It protects and enhances the soul's biological activity by providing nutrition for the soil organism.
11) It aerates the soil, consequently improving the soil structure.
12) Green manure crops cover the soil in between successive grain crops, thus protecting the soil against wind and water erosion.
13) Green manure crops reduce soil compaction.
14) Green manure crops provide a habitat for pollinators and other beneficial insects.
e. g. Crotalaria, Medicago sativa, Gliricidia, etc.
Gliricidia, alley cropping to Gliricidia sepium can provide 100-300kg N/ha per year.
Gliricidia sepium is a fast growing , tropical, leguminous tree. It is used as a live fencing in many tropical and tropical and sub-tropical countries.
There are considered to be only four species of which G. Sepium is the only species of real agronomic potential. The tree is used for timber, firewood, hedges, medicinal purpose, charcoal, live fence, plantation shade ,poles, soil stabilization, and as green manure.
The toxic property of the seeds and bark has given rise to the generic epithet (gliricidia=mouse killer). Gliricidia sepium adapts very well in a wide range of soils ranging from eroded acidic (ph 4.5 - 6.2) soils, fertile sandy soils, heavy clay, calcareous limestone and alkaline solids. Gliricidia tolerates fire and the trees quickly re-sprout with the onset of rains.
In the formation of fertile soil, organic substances play a direct role, as they are the sources of plant nutrients, which are liberated in available form during mineralization.
Although, incorpoarion of crop reaidues, green manure, farmyard manure, are the common practices in the fertility programme in many farms, the supply of organic manures is limiting to make any important contribution to the soil organic matter.
Types of Biofertilizers:
There are many different types of Biofertilizers. So, let's take one by one in details-
1) For Nitrogen
° Rhizobium for legume crops.
° Azotobacter / Azospirillum for non legume crops.
°Acetobactor for sugarcane only.
°Blue-Green Algae (BGA) and Azolla for low land paddy.
2) For Phosphorus
°Phosphatika for all crops to be applied with Rhizobium, Azotobacter, Azospirillum and Acetobactor.
3) For enriched compost:
° Cellulolytic fungal culture
°Phosphotika and Azorobacter culture
Advantages of Biofertilizers:
1) Increase crop yields by 20-30%.
2) Replace chemical nitrogen and phosphorus by 25%.
3) Stimulate plant growth.
4) Activate the soil biologically.
5) Restore natural soil fertility.
6) Provide protection against drought and some soil borne disease.
7) Cost effective.
8) Suppliment to fertilizers.
9) Reduces the costs towards Frfertilizer use, especially regarding nitrogen and phosphorus.
10) Renewable source of nutrients.
11) Sustain soil health.
12) Supplement chemical fertilizers.
13) Replace 25-30% chemical fertilizers.
14) Increase the grain yields by
10- 40%.
15) Decomposes plant residues, and stabilize C:N ratio of soil.
16) Improve texture, structure and water holding capacity of soil.
17) No adverse effect on plant growth and soil fertility.
18) Stimulates plant growth by secreting growth hormones.
19) secrete fungistatic and antibiotic like substances.
20) Solubilize and mobilize nutrients.
21) Eco-friendly, non-pollutants and cost effective method.
A) Rhizobium:
 |
| Rhizobium |
Rhizobium, a root nodule bacterium, has the ability to fix atmospheric nitrogen in symbiotic association with host legumes. In general, they are Gram-negative, motile, non-sporulating rod shaped bacterium.
It was estimated that a total of 175 million metric tones of N is fixed per year globally through biological nitrogen fixation involving Legume Rhizobium symbiosis.
Brand Name:
1) Raza (peak Chemical Industrial Ltd. , west Bengal) .
Form: Liquid
2) Rhizobium (National fertilizers Ltd. Vijaipur, Madya pradesh)
Form: Soild formulate.
1) Rhizobia invade legume roots through root hairs.
2) Form effective pink coloured nodules in the roots.
3) Lives symbiotically inside the nodules and fix nitrogen.
4) Convert atmospheric nitrogen to plant accessible forms.
5) Most rhizobia ate host specific in nature.
Host plant Bacterial symbiont
Alfalfa Rhizobium meliloti
Clover Rhizobium trifolii
Soyabean Bradyrhizobium japonicum
Beans Rhizobium phaseoli
Pea Rhizobium leguminosarum
Srsbania Azorhizobium caulinodans
B) Azotobacter:
 |
| Azotobacter |
It is a genus usually notile, Gram-negative bacteria, oval or spherical bacteria that form thick-walled cysts and may produce large quantities of capsular slime.
They are aerobic, free-living soil microbes which play an important role in the nitrogen cycle in nature, binding atmosphere nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil.
Apart from being a model organism, it is used by humans for the production of Biofertilizers, food additives and some biopolymers.
Azotobacter are free-living nitrogen-fixing bacteria, they normally fix molecular nitrogen from the atmosphere without symbiotic relations with plants, although some Azotobacter species are associated with plants.
Nitrogen fixation is inhibited in the presence of available nitrogen sources, such as ammonium ions and nitrates.
Azotobacter have a full range of enzymes needed to perform the nitrogen fixation: ferredoxin, hydrogenase and an important enzymes nitrogenease. The process of nitrogen fixation requires an influx of energy in the form of adenosine triphosphate (ATP).
Nitrogen fixation is highly sensitive to the presence of oxygen, and therefore Azotobacter develops a special defensive mechanism against oxygen,namely a significant intensification of metabolism that reduces the concentration of oxygen in the cells. There is also a special Portein shethna, which protects nitrogenease and is involved in protecting the cells from oxygen.
Brand Name:
Azotobacter (National Fertilizers Ltd. Vijaipur, Madya pradesh) .
Form: solid formulate
C) Blue Green Algae (BGA) :
 |
| Blue green algae |
BGA also known as Cyanobacteria, obtain their energy through photosynthesis. Blue-Green algae are considered as the simplest, living autotropic plants. They are microscopic and are widely distributed in the aquatic environment.
The ability of BGA to photosynthesize food and fix atmospheric nitrogen accounts for their symbiotic associations and also for their presence in paddy fields.
Blue-Green algae are of immense economic value as they add organic matter to the soil and increase soil fertility. Barren alkaline lands in India have been reclaimed and made productive by including the proper growth of certain blue-Green algae.
Application: 20-30 kg N/ha increases yield 10-15%.
Limitation: Effective only in submergene paddy fields and demands bright sunlight.
e. g. Nostoc, Anabaena, Aulosira, Tolypothrix, etc.
Brand Name:
Nature Bio Fertilizers, Bio Nutritional Fertilizers
(Ecological products Industries, New Delhi)
Form: Liquid
 |
| Blue green algae |
D) Azolla:
(Mosquito fern, duckweed fern, fairy moss, water fern) is a Pteridophyte, genus of seven species of aquatic gerns, the only genus in the family Azollaceae. They are extremely reduced in form and specilized, looking nothing like conventional ferns but more resembling duckweed or some mosses.
 |
| Azolla |
Azolla floats on the surface of water by means of numerous, small closely-overlapping scale-like leaves, with their roots hanging in the water. They form a symbiotic relationship with the blue-Green algae Anobaena azollae, which fixes atmospheric nitrogen, giving the plant access to the essential nutrient.
 |
| Anobaena azollae |
Application : 30-100kgN/ha increses yield by 20-25%.
Limitation: Survival is difficult at high temperatures, great demand for phosphorus.
Brand Name: Azollae (Biomate India Pvt Ltd. New Delhi).
Form: Liquid.
E) Phosphate Solubilizing Bacteria:
Many heterotropic bacteria and fungi efficiently solubilize insoluble phosphate in the soil as well as the inert phosphorus sources. These organisms secrete organic acids that solubilize insoluble phosphorus which becomes then available for plant absorption.
Many bacteria belonging to Bacillus, Pseudomonas, Flavobacterium, Micrococcus, Streptomyces and fungi belonging to Aspergillus, Penicillium and Trichoderma efficiently solubilize insoluble phosphate of rock phosphate groups.
Brand Name : P.S.B (National Fertilizers Ltd. Vijaipur, Madya Pradesh).
Form: Solid formulate.
F) Green Manure:
Green manure is a type to f cover grown primarily to add nutrients and organic matter to the soil. They are grown for the purpose of plowing them, thus increasing fertility through the incorporation of nutrients and organic matter into the soil.
 |
| Green manure |
Crops that are normally planted as inter-or reply crops for the sake of accumulating nitrogen in the soil, producing residues and ground cover. Green manure cover crops are not primarily planted to generate additional incomes (seed or grains). They are used for-
1) To produce nitrogen (legumes)
2) To control weeds (replacing fallow periods).
3) To produce mulch during non-crop periods.
4) To cycle soil nutrients.
5) Other positive effects on succeeding crops.
6) If there is not enough water for a cash crop.
7) When there is a free period between crops and enough moisture available or at the end of the croping season.
8) When producing a cash crop is not profitable or too risky.
9) Green manures, in the case of legumes, fix nitrogen and contribute to farm nitrogen needs.
10) It protects and enhances the soul's biological activity by providing nutrition for the soil organism.
11) It aerates the soil, consequently improving the soil structure.
12) Green manure crops cover the soil in between successive grain crops, thus protecting the soil against wind and water erosion.
13) Green manure crops reduce soil compaction.
14) Green manure crops provide a habitat for pollinators and other beneficial insects.
e. g. Crotalaria, Medicago sativa, Gliricidia, etc.
Gliricidia, alley cropping to Gliricidia sepium can provide 100-300kg N/ha per year.
Gliricidia sepium is a fast growing , tropical, leguminous tree. It is used as a live fencing in many tropical and tropical and sub-tropical countries.
 |
| Gliricidia |
There are considered to be only four species of which G. Sepium is the only species of real agronomic potential. The tree is used for timber, firewood, hedges, medicinal purpose, charcoal, live fence, plantation shade ,poles, soil stabilization, and as green manure.
The toxic property of the seeds and bark has given rise to the generic epithet (gliricidia=mouse killer). Gliricidia sepium adapts very well in a wide range of soils ranging from eroded acidic (ph 4.5 - 6.2) soils, fertile sandy soils, heavy clay, calcareous limestone and alkaline solids. Gliricidia tolerates fire and the trees quickly re-sprout with the onset of rains.
