It is the biological active compounds which help in biological nitrogen fixation for the benefit of the plants. Use of bio-fertilizers is essential in organic farming.
Commonly used bio-fertilizers are
- Rhizobium: By adding this, it gives rise to better root and stem nodulation and helps in nitrogen fixation mainly in pulses, legume green manures and oil seeds crops. It is applied during seed treatment.
- Azotobacter: It is suitable for applying in vegetables, orchards, tapiocas and plantation crops. In upland conditions, it fixes about 6-7kg/acre nitrogen and reduces the need of nitrogen fertilizer upto 10-20%. It is applied during seed treatment or seedling dip or through direct soil application.
- Azospirillum: Suitable for use in upland and wetland conditions. In ideal conditions, it fixes about 8-10kg/acre nitrogen and reduces the need of nitrogen fertilizer upto 25%. It helps in the formation of better roots.
- Azolla: Suitable for wetland rice cultivation. It fixes about 10-12kg/acre nitrogen.
- Blue green algae (BGA): Suitable for wetland rice cultivation. It fixes about 10-12kg/acre nitrogen. It is suitable for using in acidic soils having pH below than 6.0.
- Vesicular/ Arbuscular mycorrhiza (VAM/ AMF): Suitable for upland crops. It induces the better resistance again soil borne plant pathogens. It is applied through soil application.
Method of application
- Seed treatment: For the treatment of 5-10kg seeds, it requires 500gm of culture. Firstly moisten the seeds. Then take plastic tray or basin, add 500gm of culture and moistened seeds. Mix them well and then it is shade dried for 30 minutes. After drying, immediately sowing is done.
- Seedling root dip: The method is used at the time of transplanting. Firstly slurry is prepared by mixing 500gm culture in 50ml water. In slurry, roots are dipped for 15-20 minutes before transplanting.
- Soil application: Culture is mixed in FYM or compost in the ratio of 1:25 and then it is directly applied in the soil.
Factors
- Appropriate amount of organic manure is used along with bio-fertilizer application. It is important for good survival, growth and activity of introduced culture.
- Liming is necessary if soil has pH below than 6.0. In moderately acidic soil, application of lime is done @100kg/acre with bio-fertilizer treatment.
- In summers irrigation is necessary after bio-fertilizer application.
- Bio-fertilizers must be used as prescribed by the Bureau of Indian Standards.
- Bio-fertilizer must be used before the expiry date.
- For growth enhancement, top dressing with superphosphate @10kg/acre is done after inoculation of BGA.
