Bio-Agents for Organic Farming
K. Amina Bibi
(second in a series of articles)
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 Bio-fertilizers, Bio-Pesticides and Bio-Control Agents. This piece
deals with Bio-fertilizers – its types, uses and advantages. These are low cost inputs which helps farmers. It is so affordable even to poor farmers and the produce excels in quality compared to the chemically produced ones. Hence farmers get 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, farmers should maintain 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. Bio-fertilizers
are eco-friendly means of supplying nutrients to the soil. Bio-fertilizers are ready to use live formulates of such beneficial microorganisms which, on application to seed, root or soil mobilize the available nutrients by their biological activity. They
also help build up the micro-flora and in turn the soil healthy.
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. Bio fertilizers 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 bio-fertilizers to solubilize Phosphorus, Potash and Zinc.
To use bio-fertilizers, the farmer has to mix it with either farmyard manure or vermicompost and broadcast in field. Bio-fertilizers are inoculums which feed on the decomposed farm residues. On decomposition they provide nutrition or they convert from
one form to another excreta or exudes) which make the soil fertile by enriching it 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 of chemical fertilizers, the farmers can use bio-fertilizers as an alternative and can keep agriculture going in a profitable way both economically and eco-friendly.
Dragon fly which eats many harmful insects' eggs, and their larvae
These are the photos of Organic Field and a photo of Dragon fly which eats many harmful insects' eggs, and their larvae, a photo of wolf-spider which eats many pests of paddy field.
Azospirillum is a nitrogen fixing bio-fertilizer. 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 limiting 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 bio fertilizer 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
BGA is an algae, fixes 20-30 kg N/hectare. Its application to rice increases yield by 15-20%.
Rhizobium is a nitrogen fixing bio-fertilizer. 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.
wolf-spider which eats many pests of paddy field.
Seed treatment: 200 g of nitrogenous bio-fertilizer 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 bio-fertilizers are mixed in this water and the roots of seedlings are dipped for 8-10 hrs.
Soil treatment: 4 kg each of the recommended bio-fertilizers 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 macro-nutrients 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 fetch good prices.
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.
(K. Amina Bibi is a Post Graduate in Agriculture with specialization in Plant Breeding and Genetics. She is currently working as Agriculture Officer in Karaikal, Department of Agriculture, Government of Puducherry)