Various biofertilizers used in Indian agriculture and their application methodology.

Various biofertilizers used in Indian agriculture are:

• Nitrogen fixing biofertilizers: Rhizobium, Azospirillium and Azotobacter 
• Phosphorous solubilizing biofertilizers: Bacillus, Pseudomonas and Aspergillus 
• Phosphate mobilizing biofertilizers: Mycorrhiza 
• Plant growth promoting biofertilizers: Pseudomonas sp.

Rhizobium: Rhizobium has ability to fix nitrogen in association with leguminous plants. Rhizobium inoculation ensures adequate N supply for legumes (cowpea, green gram, blackgram, pea, chickpea, groundnut, soybean, berseem, subabul) in place of N fertilizer and observed that Rhizobium can fix 50-300 kg N/ha.

Azotobacter: Azotobacter free-living bacteria that fix atmospheric nitrogen in cereal crops and do not need a specific host plant. Azotobacter helps in saving 10 to 20 kg N/ha and it produces growth promoting substances (vitamins of B groups, indole acetic acid and gibberellic acid) which improve seed germination and growth of extended root system. It is recommended for Rice, wheat, millets, other cereals, cotton, vegetable, sunflower, mustard, flowers, etc.

Azospirillium: The bacteria have been found to live within the root of sorghum, pearl millet and rage plants. They fix atmospheric nitrogen at the rate of 15-30 kg N/ha and secrete growth regulatory substances. It is recommended for paddy, maize, wheat, sorghum, sugarcane, etc.

Phosphate Solubilizing Microorganisms: Phosphorus is one of the most important essential plant nutrients. Large amounts of phosphorus are fixed in the soil. The solubilization effect of phospho-bacteria is generally due to the production of organic acids that lower the soil pH and bring about the dissolution of bound forms of phosphate which increase the availability of phosphate in soil. Phosphate solubilizing micro-organism includes efficient strain of bacteria, fungi, yeast and actinomycetes. It is recommended for all the crops.

Vesicular Arbuscular Mycorrhiza (VAM): VAM symbiosis refers to a mutualistic, symbiotic relationship formed between fungi and living roots of higher plants. The plant roots transmit substances to the fungi, and the fungi aid in transmitting nutrients and water to the plant roots. Further, VAM fungi solubilise inorganic forms of nutrients through release of low molecular weight organic acids.

Plant Growth Promoting Rhizobacteria (PGPR): Plant growth-promoting rhizobacteria (PGPR) are a group of free-living bacteria that colonize the rhizosphere and benefit the root growth. Bacteria of diverse genera were identified as PGPR of which Bacillus and Pseudomonas sp. are dominant.

Application Methodologies of Biofertilizers:

Application method for seed, soil & planting materials Procedure Seed treatment with biofertilizers: Seed inoculation of cereals, oilseeds and pulses with culture one packet (200 g) is sufficient to treat 10-12 kg seed. Use of the respective inoculum properly and instant sowing of the inoculated seeds with minimal waiting period between treatment and sowing are necessary for greater effectiveness. The recommended rates/dosage is to be mixed with sufficient quantity of sticking agent/water to form slurry. Seeds are treated with the slurry of the culture in a manner that all the seeds are coated with culture slurry properly.

The seeds are then shade dried and sown with minimal waiting period.

• Prepare culture suspension by mixing one packet biofertilizer in about 400 ml water in 1:2 ratio 
• Spread culture suspension on the heap of the seeds and mix by hand so coating is uniformly applied to the seeds. 
• Spread the seeds under shade for some time for drying and then sow.

Seedling treatment: Sufficient quantity of water and organic fertilizer or field soil to form slurry and the seedling roots are immersed in this slurry for about 30 minutes before planting so that the roots are well drenched with the slurry.

Sugarcane sett treatment: Biofertilizers is mixed with sufficient quantity of water and organic fertilizer and sugarcane sets are soaked in the mix of biofertilizers + water + organic fertilizer for about an hour and planted in the fields.

Soil application: This method varies crop to crop depending on its duration. Generally, for a short duration (less than 6 months), 10-15 packets (each of 200 g) are mixed with 40- 60 kg of well decomposed cattle manure or with 40-60 kg soil for one acre land. Mixture of bio-fertilizer and cattle manure sprinkled with water is then broadcasted into soil at time of sowing. For long duration crop 20-30 packets of bio-fertilizer (each containing 200 g) are mixed with 80- 120 kg manure/acre.