INTRODUCTION-
Biofertilizer can be defined as biological products containing living microorganisms that, when applied to seed, plant surfaces, or soil, promote growth by several mechanisms such as increasing the supply of nutrients, increasing root biomass or root area and increasing nutrient uptake capacity of the plant
1. The Biofertilizer Manual
This biofertilizer manual is the product of the Biofertilizer Project in FNCA (Forum of Nuclear
Cooperation in Asia). Eight countries, China, Indonesia, Japan, Korea, Malaysia, Philippines, Thailand, and VietNam participate in this project. The Editor-in-Chief is Dr. Pham Van Toan, the Project Leader of VietNam. The activities of this project are introduced in FNCA homepage (http://www.fnca.jp/english/index.html) in English.
This project is aimed at improving and disseminating biofertilizer technology to increase the yields
of grain legumes and other crops which are important food and animal feed sources in Asia, and to enhance environmental friendly sustainable farming practices by reducing excessive amount of chemical fertilizer application.
The project formulation meeting was held in Bangkok, Thailand in August, 2001. In this meeting,
members agreed that this project deals with biofertilizers involving microorganisms which promote nutrient acquisition of the plants, such as N2 fixation by rhizobia or free living bacteria, arbuscular mycorrhizal fungi and phosphorous solubilizing bacteria which improve phosphorous nutrition, and other microorganisms that help nutrient uptake. These biofertilizers can be expected to reduce the use of chemical fertilizers.
Sometimes the term biofertilizer is used for various types of materials such as composts, agro-waste, and some liquid cultures of unidentified miscellaneous microbes. However, we do not include them in this project, because the evaluation of effectiveness of such products and their quality control is quite difficult as compared with biofertilizers from identified microbes under controlled conditions.
We agree the definition of biofertilizer proposed by Prof. Dr. Zulkifli Hj. Shamsuddin, University
Putra Malaysia, in Inaugural Lecture of 17th June 2005. “Biofertilizer is a substance which contains living microorganisms which, when applied to seed, plant surfaces, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant(Vessey, 2003) (Vessey, J.K. 2003. Plant growth promoting rhizobacteria as biofertilizers. Plant Soil 255,571-586). This definition separates biofertilizer from organic fertilizer.
The latter contains organic compounds which directly, or by their decay, increase soil fertility. Likewise the term biofertilizer should not be used interchangeably with the terms, green manure, manure, intercrop, or organic-supplemented chemical fertilizer. Not all plant growth promoting rhizobacteria (PGPR) can be considered biofertilizers. Bacteria that promote plant growth by control of deleterious organisms are biopesticides, but not biofertilizers. Similarly bacteria can enhance plant growth by producing phytohormones and are regarded as bioenhancers, not biofertilizer. Interestingly, some PGPR can promote growth by acting as both biofertilizer and biopesticide or bioenhancer.”
The production and use of biofertilizer is proposed, to improve yield of crops by using root nodule
bacteria (rhizobia), mycorrhizal fungi, and other microorganisms that are able to increase availability of plant nutrients from the soils. For this purpose, the most effective microorganisms for each specific crop will be identified, for example, by measuring N2 fixation activity by using nitrogen-15 isotope as tracer and using other methods too. Ionizing radiation is used to sterilize the carriers of the rhizobia and other biofertilizer.
microorganisms.
These microorganisms are selected by pot and field experiments, cultured and packed with carrier
materials, and provided commercially for the agricultural crops and reclamation of forest and devastated lands. Quality control is extremely important, especially for the population of infected effective microbes and other contaminants, which may often give adverse effects. The carrier sterilization by ionizing radiation is one of the best ways to keep biofertilizers in storage for a long period.
The working plan for the project was formulated as the following: Selection of effective
microorganisms (2002), Improvement of inoculant (2003), Improvement of soil microbial activities (2004), Field trials (2005), Economic analysis including assessment of impact on cost savings (2006).
This biofertilizer manual is written by project members and other experts to share information and
experiences of biofertilizer use in Asian countries, their effectiveness, efficient production processes, storage and application on different crops. The field demonstration was proposed in the 2002 Workshop. Each country carried out the field experiments using various biofertilizers. Some examples of field experiments are shown in this manual.
This manual has the following chapters:
1) Introduction
2) General methods to evaluate microbial activity
3) Carriers for biofertilizers
4) Inoculant for biofertilizers including rhizobia, non-symbiotic nitrogen fixers, mycorrhiza, phosphorous solubilizers
5) Quality control of biofertilizers, from advanced
basic information to practical methods in each participating country.
We try to write as easy as possible for scientists and technicians involved in biofertilizers in Asia.
However, we admit that this manual may be quite difficult for farmers. It is our hope that scientists and
technicians will translate some part of this manual into the respective mother language in some brochures or pamphlets for farmers. Each chapter was written by expert of this field. Please feel free to contact FNCA for eqquries for manual.
Biofertilizer
After the introduction of chemical fertilizer in the last century ,farmers were happy of getting increased yield in agriculture in the beginning .but slowly chemical fertilizers started displaying their ill-effects such as leaching out. and polluting water basins, destroying micro-organisms and friendly insects, making the crop more susceptible to the attack of diseases , reducing the soil fertility and thus causing irreparable damage to the overall system.
A number of intellectuals through out the world started working on the alternatives and found that biofertilizers can help in increasing the yield without causing the damage associated with chemical fertilizers.
Types of Biofertilizers
Following are the important types of biofertilizers:
Symbiotic Nitrogen-Fixing Bacteria
Rhizobium is one of the vital symbiotic nitrogen-fixing bacteria. Here bacteria seek shelter and obtain food from plants. In return, they help by providing fixed nitrogen to the plants.
Loose Association of Nitrogen-Fixing Bacteria
Azospirillum is a nitrogen-fixing bacteria that live around the roots of higher plants but do not develop an intimate relationship with plants. It is often termed as rhizosphere association as this bacteria collect plant exudate and the same is used as a food by them. This process is termed as associative mutualism.
Symbiotic Nitrogen-Fixing Cyanobacteria
Blue-Green algae or Cyanobacteria from the symbiotic association with several plants. Liverworts, cycad roots, fern, and lichens are some of the Nitrogen-fixing cyanobacteria. Anabaena is found at the leaf cavities of the fern. It is responsible for nitrogen fixation. The fern plants decay and release the same for utilization of the rice plants. Azolla pinnate is a fern that resides in rice fields but they do not regulate the growth of the plant.
Free-Living Nitrogen-Fixing Bacteria
They are free-living soil bacteria which perform nitrogen fixation. They are saprotrophic anaerobes such as Clostridium beijerinckii, Azotobacter, etc.
Among all the types of biofertilizers, Rhizobium and Azospirillum are most widely used.
Components of Biofertilizers
The components of biofertilizers include:
Bio Compost
It is one of the eco-friendly product composed of waste material released from sugar industries which are decomposed. It is magnified with human-friendly bacteria, fungi, and various plants.
Tricho-Card
It is an eco-friendly and nonpathogenic product used in a variety of crops as well as in horticultural and ornamental plants, such as paddy apple, sugar cane, brinjal, corn, cotton, vegetables, citrus, etc. It acts as a productive destroyer and antagonistic hyper parasitic against eggs of several bores, shoot, fruit, leaves, flower eaters and other pathogens in the field.
Azotobacter
It protects the roots from pathogens present in the soil and plays a crucial role in fixing the atmospheric nitrogen. Nitrogen is a very important nutrient for the plant and about 78% of the total atmosphere comprises of nitrogen.
Phosphorus
Phosphorus is one of the essential nutrients for plants growth and development. Phosphate solubilizing microorganisms, hydrolyze insoluble phosphorus compounds to the soluble form for uptake by plants. Many fungi and bacteria are used for the purpose such as Penicillium, Aspergillus, Bacillus, Pseudomonas, etc.
Vermicompost
It is an Eco-friendly organic fertilizer comprises of vitamins, hormones, organic carbon, sulfur, antibiotics that help to increase the quantity and quality of yield. Vermicompost is one of the quick fixes to improve the fertility of the soil.
Also refer: Vermicomposting
Applications of Biofertilizers
Following are the important applications of biofertilizers:
Seedling root dip
This method is applicable to rice crops. The seedlings are planted in the bed of water for 8-10 hours.
Seed Treatment
The seeds are dipped in the mixture of nitrogen and phosphorus fertilizers. These seeds are then dried and sown as soon as possible.
Soil Treatment
The biofertilizers along with the compost fertilizers are mixed and kept for one night. This mixture is then spread on the soil where the seeds have to be sown.
Discover more about what is biofertilizer, types of biofertilizers and applications of biofertilizers, only at BYJU’S Biology
Frequently Asked Questions on Biofertilizers
What do you understand by biofertilizers?
Biofertilizers are substances that contain microorganisms, which when added to the soil increases the crop yield and promotes plant growth.
What are the advantages of biofertilizers over chemical fertilizers?
- Biofertilizers are cost-effective.
- They reduce the risk of plant diseases.
- The health of the people consuming the vegetables grown by the addition of chemical fertilizers is more at risk.
- Biofertilizers do not cause any type of pollution.
What is the need of using biofertilizers?
Biofertilizers are required to restore the fertility of the soil. Prolonged use of chemical fertilizers degrades the soil and affects the crop yield. Biofertilizers, on the other hand, enhance the water holding capacity of the soil and add essential nutrients such as nitrogen, vitamins and proteins to the soil. They are the natural form of fertilizers and hence, widely used in agriculture.
Name a few microorganisms used as biofertilizers.
Microorganism used as biofertilizers are:
- Rhizobium
- Azotobacter
- Azospirilium
How do biofertilizers promote plant growth?
Biofertilizers utilise certain microorganisms. These microorganisms trap atmospheric nitrogen and convert it into nitrates and nitrites and make it available to the plants. They also convert insoluble phosphates into the forms required by the plants.
What are the main sources of biofertilizers?
The main sources of biofertilizers include bacteria, cyanobacteria and fungi.
Name an important nitrogen-fixing bacteria.
Rhizobium is an important nitrogen-fixing bacteria. Rhizobium lives in symbiotic association with the leguminous plants, specifically in their root nodules. It traps the atmospheric nitrogen and converts it into usable forms that enhance the growth of the plant.
Biofertilizer contains living microorganisms which, when applied to soil, colonizes the rhizosphere or the interior of the plant and promotes growth by increasing the availability of primary nutrients to the host plant.  |
| Classification of Biofertilizers (Cover) |
Types of Biofertilizers
The various types of biofertilizers which help the plant to grow at different levels of its growth are:
1. Nitrogen Fixing Biofertilizers
2. Phosphate Biofertilizers
a. Phosphorous Solubilizing Biofertilizers
b. Phosphorus Mobilizing Biofertilizers
3. Biofertilizers for Micro-nutrients
4. Plant Growth Promoting Rhizobacteria
5. Compost
1) Nitrogen Fixing Biofertilizers
i. Increase soil nitrogen level ii. Fixes the atmospheric nitrogen in the soil and make it available to the plants
Examples: Azotobacter, Nostoc, Rhizobium, Azospirillum
a) Azobacter
i. Free living N-fixing bacterium
ii. Non-leguminous plants
b) Cyanobacteria
i. Nostoc/Blue green algae
ii. Free-living as well as symbiotic
iii. Fix atmospheric nitrogen to soil
c) Rhizobium
i. Symbiotic N-fixing bacterium
ii. Leguminous plants
d) Azospirillum
i. Associative symbiotic N-fixing bacteriumii. Graminaceous plants
2) Phosphate Biofertilizers
a. Phosphorous Solubilizing Biofertilizersb. Phosphorus Mobilizing Biofertilizers
a) Phosphorus Solubilizing Biofertilizers
i. Solubilize the insoluble phosphate from organic and inorganic phosphate sources
ii. Releases insoluble phosphorus in soil and fix in clay minerals
iii. Secrete organic acids and lower the pH to dissolve bound phosphates in soil
Examples: Species of Bacillus, Pseudomonas, Penicillium, Aspergillus
b) Phosphorus Mobilising Biofertilizers
Transfer phosphorus from the soil to the root cortex
Examples: Arbuscular Mycorrhiza (AM fungi)
i.Fungus penetrates the cortical cells of the roots
ii. Increase surface area of roots
iii.Displace of absorption equilibrium of phosphate ions which increases the transfer of P ions
iv. Stimulate metabolic processes
v. Arbuscles absorb these nutrients into the root system
3) Biofertilizers for Micro-nutrients
i. Bacterial species are Silicate and Zinc solubilizers
ii. Degrade silicates and aluminium silicates in soil
iii. Help in silicate weathering
Example: Bacillus sp.
4) Plant Growth Promoting Rhizobacteria (PGPRs)
i. Act as both Biofertilizer and Biopesticides
ii. Promote growth by:
a) Improved Nutrient Availability (Biofertilizers)
b) Suppression of Plant Disease (Bioprotectants)
c) Phytohormones Production (Biostimulants)
 |
| Roles of PGPR |
Examples: Pseudomonas sp., Bacillus sp.
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| PGPR Action |
5) Compost Biofertilizers
i. Utilize animal dung to enrich soil with microorganisms
ii. Eco-friendly organic fertilizer
iii. Consists of nitrogen, phosphate solubilizing bacteria and various decomposing fungi
iv. Microorganisms breaks down organic matter (dead plants, farm yard waste, cattle waste etc.)
Examples: Cellulolytic fungi, Azotobacter
 |
| Compost Biofertilizers [Uses (Left) and mode of action(Right)] |
6) Liquid Biofertilizers
i. Liquid biofertilizers are suspensions having agriculturally useful microorganisms, which fix atmospheric nitrogen and solubilize insoluble phosphates and make it available for the plant
ii. Reduces the use of chemical fertilizer by 15-40%
iii. Long shelf life
iv. More temperature tolerant and contamination free
v. Easy to produce and apply
vi. Help to produce organic crops so as to compete in the global market
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