Bio fertilizers : Use and importance

Nitin Kumar Pandey
Contd from previous issue
It saves nitrogenous fertilizers by 10 to 20 per cent. Apart from its ability to produce antifungal antibiotics and fungistatic compounds against pathogens like fusarium, Alternaria and Trichoderma. Vegetable crops in general respond better to azotobacter inoculation than other crops.
Azolla- It is a small aquatic fern with a branched stem and bi-lobed leaves having association with Anabaena that fixes atmospheric nitrogen. When it dies and decays in the soil, nitrogen becomes available to the plant. It contains 45 per cent nitrogen, 2.6 per cent phosphorus and 0.9 percent potash and fixes about 30-40 kg nitrogen per hectare. It survives well in temperature range of 20 to 300C and suitable with 5.5 to 7.5 pH of soil. Azolla can double its body weight in 3.5 days. Azollapinnata is the common species.
Azospirillum- azolla are a group of bacteria found in association with the root system of many vegetable crop plants. It is a type of symbiosis where the bacterial cells are found colonizing the root cortical cell or the intercellular space in the cortex. These bacteria grow better under reduced oxygen levels. It increases the yield mainly due to release of growth promoting substances and protection from disease than from the contribution of nitrogen fixation. Fix nitrogen from 10-40 kg per hectare. Azospirillum inoculation helps the plants in better vegetative growth and also save nitrogenous fertilizer up to 25-30 percent. Its effect is well pronounced in summer under irrigated conditions, where the optimum temperature of 32-350C is available for good growth. It is mainly used for oil seeds.
Mycorrhizal Fungi- It is the most common fungal association among angiosperms. It is prepared by fungifunji belonging to the genera, Gigaspora, Glomus etc. The VAM (Vesicular Arbuscular Mycorrhiza) fungi makes more nutrients available to the plants. It is also helpful in the biological control of root pathogens. Mycorrhiza increases capacity of the root absorbing surface and reaches outside the root depletion zones. It directly translocates nutrients like zinc, phosphorus, copper, potassium Aluminium, Magnesium from the soil to the root.
Phosphate Solubilizing Microorganisms (PSM)- PSM are one of the most important elements required for plant growth and yield. Pseudomonas, Bacillus produce organic acid and enzymes like acid phosphatases and phytases to solubilize insoluble inorganic phosphate compounds such as di-calcium phosphate, tri-calcium phosphate hydroxyapatite and rock phosphate. Many species of penicillium are capable of production of organic acids like fumaric, gluconic, citric, oxalic acids which may dissolve insoluble phosphate of the soil.
Application method of Biofertilizer
Biofertilizer is used in three ways for example,
1. Soil Application- It is very useful for control to soil prove pathogens. 500 ml phosphorus soluble mycorrhiza is sufficient for one hectare. 1200-1300 kg FYM mix with 500 ml PSM and have to keep under tree shade for 12 hrs and spraying water to maintain moisture. Then use the mixture as soil application after last ploughing. They are very effective bio fertilizers for plant growth.
2. Root Treatment- It is required for transplanting crops for example paddy and vegetable nursery. PSM/Azospirillum is used for treatment of vegetable and paddy crops. The required quantity of PSM or azospirillum mixed with 10-15 litres of water in a cane and roots of seedlings has to be dipped for a minimum half hour before transplanting. It is effective and economic for farmers.
3. Seed Treatment- It is a very important method used for healthy seedling and crops. The seed treatment is benefitted and effective for farmers. Seed treatment with azotobacter, Azospirillum, Rhizobium along with PSM can be done. The seed treatment can be done with any of two or moe bacteria. There is no side and antagonistic effect.

For further details contact: - Public Relations & Media Management Cell, CAU, Imphal. Email: prmmcell@gmail.com