Biofertilizer is a substance which contains living microorganism 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. Biofertilizers are not fertilizers. Fertilizers directly increase soil fertility by adding nutrients. Biofertilizers add nutrients through the natural processes of fixing atmospheric nitrogen, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth promoting substances. They can be grouped in different ways based on their nature and function.
• Nintrogen fixing biofertilizers
Free-living Azotobacter
Symbiotic Rhizobium
Associative Symbiotic
Azospirillum
• Phosprous solubilizing biofertilizers
Bacteria Fungi
• Phosprous mobilizing biofertilizers
Arbuscular mycorrhizea
Ecto mycorrhizea
Orchid mycorrhizea
• Biofertilizers for micro nutrients
Silicate and Zinc solubilizers
• Plant growth promoting rhizobacteria
Pseudomonas
Advantages of biofertilizers:
These are cost effective relative to chemical fertilizers. These are environment friendly notonly prevent damaging the natural resource but help to clean the nature from precipitated chemical fertilizers and thus can provide better nourishment to plants.
Methods of application:
• Seed treatment:
One packet of the inoculant is mixed with 200 ml of water to make slurry. The seeds required for an acre are mixed in the slurry so as to have a uniform coating of the inoculant over the seeds and then shade dried for 30 minutes. The shade dried seeds should be sown within 24 hours. One packet of the inoculant (200 g) is sufficient to treat 10 kg of seed.
• Seedling root dip:
This method is used for transplanted crops. Two packets of the inoculant are mixed in 40 liters of water. The root portion of the seedlings required for an acre is dipped in the mixture for 5 to 10 minutes and then transplanted.
• Main field application:
Four packets of the inoculant are mixed with 20 kg of dried and powdered farmyard manure and then broadcasted in one acre of main field just before transplanting.
Present and future prospects for emerging biofertilizers:
One of the challenges of globalization and green revolution is not only to increase the yield but also to improve the nutritional quality of product so that it matches global standards. The world is undergoing a shift from inorganic conventional farming towards organic ecofriendly farming methods. This not only requires the isolation of bio inoculants with high potential for use as biofertilizers but also several other factors right from proper application procedures to correct marketing practices also being economically cheaper.
Future strategies:
Biofertilizers have been in use since 1960,s but still biological based product consumption has not picked up to expected levels. The major cause being its slow action and too low acceptance by farmers.
The writer is associated with the Department of Agronomy, University of Agriculture, Faisalabad, Pakistan. He can be reached at <Shakoor2914@gmail.com>
By Abdul Shakoor, Dr. Farrukh Saleem and Dr. Ashfaq Wahid