Bio Fertilizers and Sustainable Agriculture

 

Biofertilizers:

Biofertilizers are the microbial inoculants which can be usually defined as a preparation containing live or inactive cells of efficient strains of nitrogen-fixing, phosphate solubilizing, and cellulytic microorganisms, etc. In contrast to chemical fertilizers, biofertilizers are viable microorganisms that are not the source of nutrients but work mutualistically with plants in accessing the nutrient availability in the rhizospheric region.  The plant gets the required nutrients to grow whereas the microorganism gets shelter and food from the plant. Several microorganisms are commonly used as biofertilizers including nitrogen-fixing soil bacteria (Azotobacter, Rhizobium), nitrogen-fixing cyanobacteria(Anabaena) and phosphate solubilizing bacteria(Pseudomonas sp.). Similarly, phytohormone (auxin)-producing bacteria and cellulotic microorganisms are also used as biofertilizer formulation. These microbial formulations are used to enhance the certain microbial process to increase the availability of nutrients in a form which can be assimilated by plant. Biofertilizers are low-cost, renewable sources of plant nutrients. These are the strains of beneficial soil microorganisms which are cultured and packed in a suitable carrier in the laboratory. A carrier is a material, such as peat, ignite powder, vermiculite clay, talc, rice-bran, seed, charcoal, soil, rock phosphate pellet, paddy straw compost, wheat bran, or a mixture of such materials, etc. which provides better shelf life to biofertilizer formulation.

 

Recently, biofertilizers are gaining momentum due to the vast advantages such as maintenance of soil health and reduction of environmental pollution by using of the chemicals in agriculture Increased crop yield largely depends on the type of fertilizers used to increase essential nutrients for plant growth and development. For optimal plant growth, it requires nutrients in sufficient and balanced quantities but from the soil, only a small portion of nutrients are released every year through biological or chemical processes. Therefore, the aim of fertilizers use is to supplement the nutrients that already exist in the soil. Besides nutrient supplementation, biofertilizers have various other benefits for example control soil-borne diseases, improve soil health, soil properties, and result in higher yield rates.

Biofertilizer bacteria promoting plant growth activity:

Biofertilizers are artificially maintained cultures of the soil microorganism that can be used as microbial or soil inoculants to improve fertility and productivity of plant and soil. In another words, biofertilizer or microbial fertilizer is a substance composed of living microorganisms and mixture of biodegradable substances applied to seed, plant surfaces, or soil, which colonizes the interior part of the plant, via various means such as rhizosphere, intercellular spaces, and enhance the growth and yields by increasing the availability of primary nutrients to the host plant. It is also considered as key factors to develop an integrated nutrient management system with very low environmental impact The commercial history of biofertilizer start with the introduction of “Nitragin” by Nobbe and Hiltner, laboratory culture of Rhizobia in 1895, followed by the discovery of Azotobacter and then blue-green algae beneficial plant–microbiome interactions represent a promising sustainable solution to improve agricultural production instead of chemical fertilizers. Biopesticides and biofertilizers are a part of natural-based products being widely used to enrich the quality of the soil and as a biocontrol agent. A currently different group of microorganisms have been identified, which belongs to bacteria, fungi, and protozoan kingdoms, these colonize the rhizosphere or the internal plant tissues and used as biofertilizers for the enhanced agriculture production.

 

Following is a general picture of how nitrogen passes through several phases to be accumulated as part of the plant body.