Organica Bio fertilizers – Microbes Designing Soil Fertility
India has been an agricultural nation since time immemorial. Agriculture is the part and parcel of this nation’s rich cultural heritage. As of 2011, India had a large and diverse agricultural sector, accounting, on average, for about 16% of GDP and 10% of export earnings.
Therefore all the measures to improve the agricultural yield are of utmost importance for the overall development of its economy. Many practices and technologies have been employed to improve the yield of agricultural produce. Some common measures involve use of fertilizers, pesticides, hybrid seeds and many synthetic nutrients. The major concern in agriculture is variability of changing weather patterns, steadily declining soil fertility. The addition of various fertilizers and nutrients has not helped to increase the quality of soil. The use of biofertilisers in conjunction with traditional fertigation, would greatly enhance the utility of these nutrients being added to the soil.
Biofertilizers are microbes which have evolved their enzymatic machinery to sequester fixed nutrients from soil and assist in their assimilation into plants. They have a localized effect and since most of these organisms are symbiotic in nature they help in overall development of plants. The application of biofertilizers in soil help in improving the organic and macro nutrient content in it. Some biofertilizers also produce phyto-hormones which accelerate the growth of roots and shoots. The Biofertilizers group contains a wide variety of organisms but for suitability of application they are categorized as Phosphate solubilizing bacteria (PSB), Potash mobilizing bacteria (KMB), Nitrogen fixing bacteria (NFB), Zinc mobilizing bacteria (ZMB), Siderophore producers and many more.
Phosphate is one of the most important macronutrient for the overall development of plants. Although soil may contain the nutrient in ample quantity, its often fixed in form of insoluble salts of Calcium like rock phosphates which make it unavailable for assimilation by plants. Phosphate solubilizing bacteria belonging to the the genus of Pantoea spp., Bacillus spp., Klebsiella spp. and others are capable of producing large quantities of organic acids and enzymes which solubilize these insoluble salts of phosphorous and make it available to plants for absorption.
Potash again is a similar macronutrient which is of great significance for the growth of some high value crops like Grapes and Banana. As in the case of phosphates, potash too is fixed in soils in the form of potassium aluminium silicate. As the fixed form of potash is insoluble and chemically inert it is therefore necessary to mobilize it using the enzyme machinery of Potash mobilizers like Klebsiella spp., and Bacillus spp. Since these bacteria colonize the root rhizosphere they provide a quick access of solubilized nutrient to the roots.
Nitrogen fixing bacteria are the micro-organisms which play a pivotal role in nitrogen cycle and fixing of atmospheric nitrogen into soil. Bacterial species of Azotobacter spp., Azospirillum spp. and Rhizobium spp. are the major families of bacteria belonging to this group. These microbes also form nodules in plant roots and form a symbiotic system which promote plant growth by assimilating nitrogen in the rhizosphere.
Many other biofertilizers have been to known to possess additional plant growth promoting activities like auxin production, abscisic acid production, siderophore production and anti-bacterial activity. Thus biofertilizers act as a soil conditioning experts, who can mould soil fertility. As they are part of natural soil micro flora, their use wont disturb the ecological niche associated to their application. Thus it can be said that biofertilizers may lead our agricultural sector to the path of highly productive farming.