Organic Farming is a method of cultivation done in line with nature. For a cultivation which facilitates Biodiversity a cost effective method is to involve Bio-agents. Bio-agents include Biofertilizers, Bio-Pesticides and Bio-Control Agents. This piece deals with Biofertilizers – its types, uses and advantages. These are low cost inputs which helps farmers at both ends. In expenditure end, it is very cheap so affordable even to poor farmers at income end, the produces excels in quality compared to the chemically produces ones. Hence farmers gets premium price. As a bonus to the ecosystem and environment, the microbial load is increased, the farmers’ friends (insects like spider, earthworm and many beneficial insects) and their food web are protected.
For increased yield the farmer should main the fertility of the soil. Only when the soil is fertile, the crop can absorb the nutrients from soil. Nutrient transfer from source to sink decides the quality and quantity of the produce. Biofertilizers are eco-friendly means of supplying nutrients to the soil. Biofertilizers are ready to use live formulates of such beneficial microorganisms which on application to seed, root or soil mobilize the availability of nutrients by their biological activity in particular, and help build up the micro-flora and in turn the soil health in general.
With intensive agriculture farmers have dumped a lot of chemicals in the name of fertilizers which are actually salts which have drastically reduced the microbial load of the soil. Also fertilizers being a derivative of fossil fuels, make us more dependent on sources out of farm. Biofertilizers are a good alternative to the chemical fertilizers. Use of biofertilizers in crop cultivation helps in safeguarding the soil health and also the quality of crop products. It increases the crop yield by 20-30% as it stimulates plant growth.
For increasing the Nitrogen content, Rhizobium is used for legume crops like black gram, green gram, red gram, chick pea and so on. Azotobacter and Azospirillum are used for non-legume crops and Acetobacter for Sugarcane only. Blue-Green Algae (BGA) and Azolla are suitable for low land paddy only. There are biofertilizers to solubilize Phosphorus, Potash and Zinc.
To use biofertilizers, the farmer has to mix it with either farmyard manure or vermicompost and broadcast in field. Biofertilizers are inoculums which feed on the decomposed farm residues. On their decomposition it provides nutrition or it converts from one form to another (its excreta or exudes) which make the soil fertile by enriching with the needed nutrients. The texture of the soil is altered from hard to fragile which facilitates root penetration and facilitates the root system to perform better.
With the soaring price if chemical fertilizers, the farmers can use biofertilizers as an alternative and can keep agriculture going in a profitable way both economically and eco-friendly.
Azospirillum is a nitrogen fixing biofertilizer. Nitrogen is a major nutrient for all plants. Azospirillum lipofereum is a very useful soil and root bacterium. It is an associative symbiotic nitrogen fixing bacteria. It is found in the soil around plant roots and root surface. It also produces growth-promoting substances like indole acetic acid (iaa), gibberellins, pantothenic acid, thiamine and niacin and it promotes root proliferation and it improve the plant growth yield. It increases the rootlet density and root branching resulting in the increased uptake of mineral and water. Azospirillum is recommended for rice millets, maize, wheat sorghum etc. and it fixes 20-40 kg N/hectare.
The aerobic bacteria, Azotobacter chroococcum is known to fix considerable quantity of nitrogen in the range of 20-40 kg of nitrogen / ha in the rhizosphere in non-leguminous crops. The lack of organic matter in the soil is a limited factor in the proliferation of Azotobacter in the soil. The bacterium induces hormones that help plants in better germination, early emergence and better root development.
Azolla is a water fern. It fixes atmospheric nitrogen into the soil with the help of blue green algae by symbiosis process. Its application improves soil health and soil fertility. Azolla suppresses weed growth, reduces loss of applied chemical Nitrogen fertilizer. Azolla biofertilizer technology is simple, economic and ecofriendly. In rice field Azolla grown once before or after planting can produce upto 25 tons of fresh biomass and contribute upto 50 kg N/ha. Azolla grown once during the cropping season can easily supply 20-40 kg N/ha. Azolla can be used as a feed for poultry, duckery, fish and cattle. It is suitable for flooded condition which fixes upto 40-80 kg N/hectare. When applied in desired quantity. Around 10 q of Azolla is required for a hectare of land.
BGA is an algae, fixes 20-30 kg N/hectare. Its application to rice increases yield by 15-20%.
Rhizobium is a nitrogen fixing biofertilizer. Rhizobium sp. is the symbiotic nitrogen fixer which assimilates atmospheric nitrogen and fixes in the root nodule, formed in the roots of leguminous plants. These bacteria infect the roots of leguminous plants, leading to the formation of “lumps” or “nodules” where the nitrogen fixation takes place. The bacterium also produces enzymes (nitrogenase) that supply a constant source of reduced nitrogen to the host plant. Rhyzobium is suitable for Ground nut, Black gram, Green gram, Red gram, Cow pea, Bengal gram, Mustard, Soy bean, French bean, Cluster bean, Lab-lab, Sesbania sp, Leguminous trees etc.
- Rhizobium + Phosphobacteria at 200 gm each per 10 kg of seed as seed treatment are recommended for pulses such as pigeonpea, green gram, black gram, cowpea etc, groundnut and soybean.
- Azotobacter + Phosphobacteria at 200 gm each per 10 kg of seed as seed treatment are useful for wheat, sorghum, maize, cotton, mustard etc.
- For transplanted rice, the recommendation is to dip the roots of seedlings for 8 to 10 hours in a solution of Azospirillum + Phosphobacteria at 5 kg each per ha.
- Rhizobium is used for pulse legume. It fixes 50-100 kg N/hectare with legumes. For different pulse crops specific rhizobium cultures are required.
Seed treatment: 200 g of nitrogenous biofertilizer and 200 g of Phosphobacteria are suspended in 300-400 ml of water and mixed thoroughly. Ten kg seeds are treated with this paste and dried in shade. The treated seeds have to be sown as soon as possible.
Seedling root dip: For rice crop, a bed is made in the field and filled with water. Recommended biofertilizers are mixed in this water and the roots of seedlings are dipped for 8-10 hrs.
Soil treatment: 4 kg each of the recommended biofertilizers are mixed in 200 kg of compost and kept overnight. This mixture is incorporated in the soil at the time of sowing or planting.
Phosphorous plays the key role in the integrated nutrient management to plants next to nitrogen. It is the key factor for the crop productivity. It is one of the major essential macronutrients for plants and is applied to soil in the form of phosphate fertilizers. However, a large portion of soluble inorganic phosphate which is applied to the soil as chemical fertilizer is immobilized rapidly and becomes unavailable to plants.
Phosphobacteria solubilizes the available source of phosphate in the soil and made readily available to the plant and improves soil properties in turn sustains soil fertility as it aids utilization of Potash and other nutrients. It stimulates the growth of the plant. Hence it results in plumpness and succulence of fruits and grains with increased protein percentage. An increase in yield from 10% to 20% is documented. Such produces fetches good price.
Phosphorus is a major nutrient for plants inducing vigorous growth and also contributing to their disease resistance. Phosphorous helps in root formation and plant growth. The plants utilize only 10–15% of phosphate applied. The balance 85 – 90% remains in insoluble form in the soil. The bio promoter has highly efficient phosphate solubilizing bacteria (Bacillus megaterium) that grow and secrete organic acids, which dissolve this unavailable phosphate into soluble form and make it available to the plants. Thus, the residual phosphate fertilizers in the soil can be well utilized and external application can be optimized. It facilitates root formation and plant growth, improves soil quality with subsequent uses.
Potash Mobilizer is a beneficial bacterium capable of mobilizing Potassium available in soil into the root zone of plants. It works well in all types of soil. Use of such bacteria in powder form can increase the availability of more potash in usable form to the plants. When applied to soil, potash mobilizing bacterium multiplies, and helps to mobilize potassium fixed in soil. This mobilized potassium is easily available to the plants and reduces Potassium application. The mobilizing power is so high that it can save upto 50-60% of the chemical potassium fertilizer. Potash mobilized is immediately available to the plants. It stimulates flowering and fruiting. It improves soil properties and sustains soil fertility. It encourages plumpness and succulence of fruits and grains and increases brix level. Increases the yield from 10% - 20% and it improves the quality of produce and thus fetches good price.
Zinc Mobilizer is a bio-fertilizer made of pure cultures of naturally occurring soil-borne zinc solubilizing bacterium. Zinc solubilizing bacterium multiplies, secrete organic acids and helps to solubilize insoluble and chelated zinc fixed in the soil. This mobilized zinc is easily available to the plants.