Biofertilizers - An answer to hard soil and declining productivity of crop

Biofertilizers are natural and organic fertilizers that help to keep the soil enriched with all the nutrients and contain those tiny living microorganisms that are required for benefiting the plants. It is used in organic farming, sustainable agriculture, green farming, and non-pollution farming. It is one of the important components of integrated nutrient management, as it is cost-effective and a renewable source of supplement for plant nutrients compared to chemical fertilizers, for sustainable agriculture.

Biofertilizers consist of living microorganisms which when added to the soil, colonizes the rhizosphere or the interior of the plants and promote the growth of the host plant by increasing the availability of primary nutrients. They encourage plants to absorb essential nutrients on their own, in greater quantities even if they are naturally present in the soil but on occasions cannot be assimilated directly by the plants due to their insoluble form. Conventional chemical fertilizers, however, supply the soil with chemical elements which, despite functioning as a fertilizer, can end up contaminating aquifers if they are not managed in the right dose and at the right moment.

Drawbacks of chemical fertilizers :

Modern agriculture involves the excessive use of pesticides and chemical fertilizers with the essence of increasing the overall food production of the world. Thus, these behave as fast food for plants, causing them to grow very rapidly and efficiently. They can even cause several types of health hazards.

  • Our dependence on chemical fertilizers and pesticides has encouraged the production of life-threatening chemicals, which are not only hazardous for human consumption but are also the cause of disturbing the ecological balance.

  • The price of fertilizers is becoming very high. Apart from the high cost, inorganic fertilizers when applied incorrectly, excessively, or inadequately have negative effects.

  • Excessive application of fertilizers leads to salt burn and in most cases can cause the death of young plants.

  • Because they are non-biodegradable, long-term use of inorganic fertilizers results in the accumulation of harmful substances and acidification of the soil thereby decreasing the fertility of the soil.

Biofertilizer acts as an excellent alternative to chemical fertilizers and can provide nutrients to plants through the action of fixing nitrogen, solubilizing phosphorus, and triggering growth through the synthesis of growth promoters.

Types of biofertilizers :

The various types of biofertilizers that aid in the development of plants at different growth levels are:

Nitrogen-fixing biofertilizers :

(Azotobacter, Nostoc, Rhizobium, Azospirillum, etc.)

  • Increase soil nitrogen level

  • Fixes the atmospheric nitrogen in the soil and makes it available to the plants.

Phosphate biofertilizers :

(Species of Bacillus, Pseudomonas, Penicillium, Aspergillus)

  • Phosphorus solubilizing biofertilizers solubilize the insoluble phosphate from organic and inorganic phosphate sources.

  • Release insoluble phosphorus in soil and fix it in clay minerals.

  • Secrete organic acids and lowers the pH to dissolve bound phosphates in soil.

Phosphorus mobilizing biofertilizers :

(Arbuscular Mycorrhiza , AM fungi)

  • The fungus first penetrates into the cortical cells present in the roots of plants.

  • The surface area of roots increases.

  • Stimulate metabolic processes as Arbuscles absorb these nutrients into the root system.

Potassium solubilizing biofertilizers :

(Bacillus Spp. and Aspergillus niger)

  • Potassium in the soil occurs mostly as silicate minerals that are inaccessible to plants.

  • These minerals are made available only when they are slowly weathered or solubilized.

  • Potassium solubilizing microorganisms solubilize silicates by producing organic acids which cause the decomposition of silicates and helps in the removal of metal ions thereby making them available to plants.

  • Potassium solubilizing biofertilizers are considered broad-spectrum bio-fertilizers.

Potassium mobilizing biofertilizers :

(Potassium mobilizing bio-fertilizer is Bacillus Spp.)

  • They work by mobilizing the inaccessible forms of potassium (silicates) in the soil.

  • Some phosphate solubilizing bio-fertilizers such as Bacillus spp. and Aspergillus spp. have been found to mobilize potassium and also solubilize phosphorus.

Sulfur oxidizing biofertilizers :

  • An example of a sulfur-oxidizing microorganism is Thiobacillus spp.

  • These work by oxidizing sulfur to sulfates which are usable by plants.

Compost :

  • Utilizes animal dung to enrich the soil with microorganisms.

  • Eco-friendly organic fertilizer consists of nitrogen, phosphate solubilizing bacteria, and various other decomposing fungi.

  • Microorganisms break down organic matter (dead plants, farmyard waste, cattle waste).

Manure :

  • Manure is a solid organic matter that is basically derived from the waste of animals.

  • It is used to improve the soil quality and increase the yield of healthy crops.

  • Mainly a natural form of fertilizer and hence is cost-effective.

  • The livestock manure is rich in phosphorus, nitrogen and potassium.

  • Manure is highly rich in organic matter with hummus so it helps to improve the fertility of the soil.

  • It is both valuable and a renewable resource.

Liquid biofertilizers :

  • Liquid biofertilizers are suspensions having useful microorganisms for agriculture.

  • It fixes atmospheric nitrogen and solubilizes insoluble phosphates to make them available for the plants.

  • It reduces the use of chemical fertilizers by 15-40%, has a long shelf life plus easy to produce and apply.

  • Also, it helps to produce and manage organic crops, basically to compete in the global market.

Benefits of biofertilizers :
  • Biofertilizers are environmentally friendly and hence do not cause pollution like inorganic fertilizers.

  • Biofertilizers can help us solve the problem of feeding a demanding and increasing population, at a time when agriculture is facing major environmental problems.

  • The issue of excessive application does not arise in the use of biofertilizers and special skills are not required for its application.

  • Biofertilizers have long-lasting effects due to their slow nutrient release.

  • Biofertilizers have been found to control plant diseases such as Pythium root rot, Rhizoctonia root rot, chill wilt, and parasitic nematode infection.

  • Biofertilizers act as a soil conditioner by adding organic matter to the soil that helps the soil particles to bind together preventing soil eructing, desertification, and soil erosion while increasing the water retention capacity of the soil.

  • It enriches the soil with beneficial microorganisms while boosting the already existing ones.

  • Biofertilizers also contain a wide range of nutrients that are often absent in inorganic fertilizers.

  • Biofertilizers can be produced from cheap waste materials that are usually abundant and the production cost is comparatively lower than that of inorganic fertilizers which require high energy.


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