Biofertilizers make nutrients that are naturally abundant in the soil or atmosphere usable for plants. They are effective and inexpensive inputs, free from the environmentally adverse implications that chemicals carry. Biofertilizers offer a new technology to agriculture, holding a promise to balance many of the shortcomings of the conventional chemical based technology.
Biofertilizers, more commonly known as microbial inoculants, are select cultures of soil organisms that can improve soil fertility and crop productivity. The commercial history of biofertilizers began with the launch of 'Nitragin', a laboratory culture of Rhizobia in 1895. The discovery of Azotobacter followed, then the blue green algae and a host of other micro-organisms. Azospirillum and Vesicular-Arbuscular Mycorrhizae (VAM) are fairly recent discoveries.
Rhyzobium (RHZ): These inoculants are known for their ability to fix atmospheric nitrogen in symbiotic association with plants forming nodules in roots.
Azotobacter (AZT): This has been found beneficial to a wide array of crops covering cereals, millets, vegetables, cotton and sugarcane. It is a free living and non-symbiotic nitrogen fixing organism that also produces substances good for the growth of plants, and antibodies that suppress many root pathogens.
Azospirillum (AZS): ): This is also a nitrogen-fixing micro organism beneficial for non-leguminous plants. Like AZT, the benefits transcend nitrogen enrichment through production of growth promoting substances.
Blue Green Algae (BGA) and Azolla: BGA are photosynthetic nitrogen fixers. They too add growth promoting substances, including vitamin B12, to improve the soil's aeration, and water holding capacity, as well as add to the bio mass when decomposed after a life cycle. There is a symbiotic relationship with BGA that helps crops through dual cropping or green manuring of soil.
Phosphate Solubilizing (PSB)/Mobilizing Biofertilizer: Phosphorus, both native in the soil and applied by inorganic fertilizers, becomes mostly unavailable to crops because of low levels of mobility and solubility, and its tendency to become fixed in the soil. PSB provides life forms that help to improve the phosphate uptake of plants.
Biofertilizers have various benefits. Besides accessing nutrients, for current intake as well as residual, different biofertilizers also provide growth-promoting factors to plants, and some have been successfully facilitating composting and effective recycling of solid wastes. By controlling soil borne diseases and improving the soil health, these organisms help utilize chemical fertilizers which results in higher yield rates.
Biofertilizers, particularly Rhizobium, can be a bridge between removals and additions to soil nutrients.
Biofertilizers have important environmental and long-term implications by negating the adverse effects of chemicals. The gains from increased use of this technology can spill over to other farms and sectors with less water pollution than chemical fertilizers and organic manures. Unlike chemical fertilizers, biofertilizers impact the soil and plant health methodically and constantly while building synergetic relationships between the soil, nutrients and the plants.
Biofertilizers are supplements or complements to chemical fertilizers. However, in reality they are two alternative means of accessing plant nutrients. The pricing of chemical fertilizers can be very cost prohibitive, due to the inability of the plant to utilize the nutrients in their chemical form. The price of biofertilizers is offset by improving the bioavailability of both the organic and chemical fertilizers by breaking down the nutrients into usable forms. The result being less fertilizer and better yield.
The conventional farming practices of today often borrow production from future generations by continuing to impoverish soils and destroying ecological balances. While all this may be an extreme view, the need to undo the ecological problems of the past, and introduce more sustainable patterns in the future cannot be over emphasized. Mother nature was, after all, not only the designer of the systems but the supplier of the cures.