-By Amanda Shylla, Phd
Bio-fertilizers are an integral part of the organic farming for the plants to obtain nutrients, same way as in conventional agriculture where chemical fertilizers are used for plant nutrition. Due to heavy usage of chemical fertilizers and harmful pesticides on the crops, sustainability of the agriculture systems collapsed, cost of cultivation soared at a high rate, income of farmers stagnated and food security and safety became a daunting challenge. Indiscriminate and imbalanced use of chemical fertilizers, especially urea, along with chemical pesticides and unavailability of organic manures has led to considerable reduction in soil health. Therefore, organic farming is a potential alternative solution to feed the world population.
Organic farming is not an alien to the North Eastern region. The small and marginal farmers of Meghalaya have been practicing organic farming in the form of traditional farming and Jhum cultivation since time immemorial. By doing so they used organic fertilizers like compost (which are food for the microorganisms) to replenish the soil, this method is time consuming and slow. In this modern world with more demand of organic product and more mouth to feed, there is a need to use agriculturally important microbial inoculants that will enrich the soil in a short period of time and increase the overall productivity in a sustainable and eco-friendlier way.
Bio-fertilizers contain carrier based (liquid or solid) agriculturally important microorganisms. The farmers in our State due to lack awareness and the shortcomings of solid bio-fertilizers are skeptical in adopting the use of agriculturally important microorganisms. To overcome this problem scientist has developed liquid carrier bio-fertilizers which is more effective than the solid carrier. Liquid Bio-fertilizers are a special liquid formulation containing not only the agriculturally important microorganisms and their nutrients, but also special cell protectants or substances that encourage the formation of resting spores or cysts for longer shelf life and tolerance to adverse conditions.
Role of Liquid Bio-fertilizers in various crops:
§ Enhances soil health and fertility
§ Increase crop yield.
§ Shorten the time of replenishing the soil in Jhum cultivation, hence net cultivated land can be increased.
§ Reduce the need for chemical N, P, K fertilizers.
§ Returns are economically viable
§ Besides the major nutrients, additional advantages like secretion of plant growth hormones and made available the important micronutrient like Zn, Mn, Cu, Fe, Co.
§ Diseases and pest occurrence reduced due to the antagonistic properties of the biofertilizers.
§ Advantages of Liquid Bio-fertilizers over conventional carrier-based Bio-fertilizers:
§ Longer shelf life 12-24 months.
§ No contamination.
§ No loss of properties due to storage up to 45oC.
§ No effect of high temperature.
§ Greater potentials to fight with native populations.
§ The high population can be maintained more than 109 cells/ml up to 12-24 months.
§ Better survival on seeds and soil.
§ Easy to be used by the farmer.
§ Dosage is 10 times less than carrier powder based bio-fertilizers.
Types of Liquid Bio-fertilizers available in the market:
A. Nitrogen fixers:
1) Rhizobial bio-fertilizers:
· Rhizobial bio-fertilizers contain Rhizobium spp. which are bacteria that occur in free living state in the soil but can fix atmospheric nitrogen only in an obligate symbiotic (strict) association with leguminous plants forming nodules in roots.
· They are crop specific inoculant i.e.; specific species infect specific leguminous crop. Example Rhizobium leguminoserum for pea, lentil; Rhizobium lupini for chickpea, Bradyrhizobium japonicum for soybean, therefore, application of specific Rhizobia is most important.
· Rhizobium culture has been routinely recommended as an input in pulse cultivation.
· In India about 30 million hectares of land is under pulses cultivation fix nitrogen 50-500 kg/ ha with legumes only.
· Its application has enhanced the crop yield to an extent of 18-20%.
· Azotobacter bio-fertilizers:
· Azotobacter spp. are aerobic, free living, and heterotrophic nitrogen fixing bacteria.
· They do not produce any visible nodules or out growth on root tissue.
· They secrete plant growth promoting substances like IAA, GA for the benefit of the plant growth.
· It is recommended for cereals crops, vegetable crops, fruit crops, ornamental plants, plantation, and commercial crops.
· It can fix N up to 25 kg/ha under optimum conditions and increase yield up to 50%.
· A. chroococcum is the most commonly occurring species in arable soils. A. vinelandii, A. beijerinckii, A. insignis and A. macrocytogenes are other reported species. Azotobacter indicum is suitable in acidic soils which can be apply in the north eastern region.
· They improve seed germination and plant growth by producing B-vitamins, NAA, GA and other chemicals (plant hormones) that are inhibitory to certain root pathogens.
· Azospirillum biofertilizers:
· Azospirillum spp. are nitrogen fixer soil bacteria, heterotrophic and associative in nature.
· They form close association with the roots of the plants but however they do not produce any visible nodules.
· They can be used in all cereals, grasses, millets, vegetables and ornamental plants.
· In addition to their nitrogen fixing ability of about 20‐40 kg/ha, they also produce growth regulating substances.
· A.lipoferum and A.brasilense has been found out to be more acid tolerant species and best suited in the North-Eastern region.
2) Phosphate Solubilizing Bacteria (PSB) biofertilizers:
· Most of the Indian soils are low to medium in P status due to soil fixation and hence become unavailable for the absorption by the plants.
· PSB play a major role in the solubilization and uptake of the fixed phosphate through various mechanisms.
· PSB also produce plant growth hormones (IAA, GA etc.) and help in plant growth and development.
· PSB belong mostly to the genera of Pseudomonas and Bacillus.
· Soluble phosphate is taken up easily by plants resulting in 10-20% increase in the yield of almost all the crops.
· This can be used for all monocots and dicots.
3) Potassium Mobilizing Bacteria (KMB) bio-fertilizers:
· Bacteria such as Frateuria aurantia and Bacillus sp are capable of mobilizing potassium in the soil into a usable form to the plants known as K solubilizing bacteria,
· KMB play a predominant role in potassium nutrient uptake.
· It enhances early root development and hence adds up to the soil health.
· By applying K mobilizers, 15-25% yield can be enhanced. It can reduce the potash application by 50-60%.
· This can be used in all types of crops.
· 4) Micronutrients bio-fertilizers:
· Microorganism that can transform micronutrients are there in soil that can be used as bio-fertilizers to supply micronutrients like zinc, iron, copper etc.,
· Zinc being of utmost importance is found in the earth’s crust to the tune of 0.008 per cent but more than 50 per cent of Indian soils exhibit deficiency of zinc with content mostly below the critical level of 1.5 ppm of available zinc.
· Zinc can be solubilized by microorganism’s viz., Bacillus subtilis, Thiobacillus thioxidans and Saccharomyces sp.
· These microorganisms can be used as Bio-fertilizers for solubilisation of fixed micronutrients like zinc and iron which are very important for plants especially for rice cultivation.
Fig. 2: Effect of the Bio-fertilizers on the growth of Coriandrum sativum
T1: Control, T2: Azotobacter, T3: PSB, T4: KMB
· It is a liquid bio-fertilizer containing a combination of the compatible microorganisms of nitrogen fixer, phosphate solubilizing bacterium and potash solubilizing bacterium.
· This bio-fertilizers have become very popular with the farmers especially the tea growers in Assam and other Northeastern region.
It can be used in all crops.
Methods of Liquid Bio-fertilizers Application:
S1. Seed treatment: Dilute 100ml (one small cup) of the liquid bio-fertilizers in one litre of water and mix thoroughly with the seed. Ensure that all the seeds are uniform and well coated, shade dry and sow immediately. For better result make jaggery (3rd grade) solution for uniform coating of the bio-fertilizers.
2. Root dipping: This method is commonly followed in paddy and vegetable crops. Dilute 100ml of the liquid bio-fertilizers in one litre of water, dip the roots for half an hour and transplant immediately.
3. Soil treatment: Mix 500 ml of the bio-fertilizers with 50Kg FYM/vermicompost/compost/ soil. Leave as such overnight and maintain 50% moisture. The mixture can be broadcast in one-acre area.
**The liquid bio-fertilizers can also be mass multiplied by adding 1 litre of the bio-fertilizers with 10 kg jaggery in 100 Lt of water in plastic drum.
(The Writer of this article can be contacted at the email id firstname.lastname@example.org)
(The Writer of this article can be contacted at the email id email@example.com)