Biofertilizers PDF

Biofertilizers Skill Enhancement Course (SEC) as per NEP-2020 F.Y.B.Sc - Botany SYLLABUS AS PER NEP-2020 MODULE 1 - INTRODUCTION  WHAT ARE BIOFERTILIZERS? “Biofertilizers are substances that contain microorganisms, which when added to the soil increase its fertility and p...

Biofertilizers Skill Enhancement Course (SEC) as per NEP-2020 F.Y.B.Sc - Botany SYLLABUS AS PER NEP-2020 MODULE 1 - INTRODUCTION  WHAT ARE BIOFERTILIZERS? “Biofertilizers are substances that contain microorganisms, which when added to the soil increase its fertility and promotes plant growth.”  Introduction Chemical fertilizers are being used in increasing amounts in order to increase output in high yielding varieties of crop plants. However, chemical fertilizers cause pollution of water bodies as well as ground water, besides getting stored in crop plants. Therefore, environmen­talists are pressing for switch over to organic farming. Organic farming is the raising of unpolluted crops through the use of manures, bifertilizers and biopesticides that provide optimum nutrients to crop plants, keeping pests and pathogens under control.  Bio-fertilizers are micro-organisms which bring about nutrient enrichment of soil by enhancing the availability of nutrients to crops. The micro-organisms which act as bio-fertilizers are bacteria, cyanobacteria (blue green algae) and mycorrhizal fungi. Bacteria and cynobacteria have the property of nitrogen fixation while mycorrhizal fungi preferentially withdraw minerals from organic matter for the plant with which they are associated.  Nitrogen fixation is the process of conversion of molecular or dinitrogen into nitrogen compounds. Insoluble forms of soil phosphorus are converted into soluble forms by certain micro-organisms. This makes the phosphorus available to the plants. Phosphate is also solubilised by some bacteria and by some fungi that form association with plant roots.  History of Biofertilizers Although the beneficial effects of legumes in improving soil fertility was known since ancient times. But the field of the Biological Nitrogen Fixation opened with following discoveries : 1) Boussingault and Hellreigel (1886) – shown biological nitrogen fixation in legume crops. Nobbe and Hiltner (1895) – Produced for the first time a labortary culture of Rhizobia under the name “Nitragin”. Later vigorous research for other ‘N’ fixing microorganisms began and found that therewere other non-symbiotic bacteria such as Azotobacter which could fix atmospheric nitrogen. Then it was discovered that Blue Green Algae also fixed atmospheric nitrogen. After that in 1970 new group of bacteria Azospirillum was identified. Vesicular Arbuscular Mycorrhizae (VAM) are the latest introduction in the list of biofertilizers which mobilize phosphorus. N. V. Joshi (1920) – first study on legume Rhizobium Symbiosis. M. R. Madhok (1934) – documented production of Rhizobium Inoculant, In 1956, first commercial production of biofertilizer came into Indian markets. Sen and Pal (1957) – Study on solubilization of phosphorus by microorganisms. In 1964, Spurt in demand of Biofertilizer for Soyabean crops in Madhya Pradesh. V. Ishwaran (1970) – Shown use of charcoal, lignite and farm yard manure as alternative carrier to peat soil. In 1977, Use of ISI mark for Rhizobium Production. In 1983, Ministry of Agriculture, Government of India setting up of National Project on Development and Use of Biofertilizers. In 1990, At IARI, New Delhi setting up of National Facility for Collection of Rhizobium germplasm by Division of Microbiology, Department of Biotechnology. In 1986, At IARI, New Delhi setting up of National Facility for Blue Green Algae by Department of Biotechnology.  Types of Biofertilizers 1) Nitrogen fixing Biofertilizers The nitrogen-fixing biofertilizers contain microorganisms such as Rhizobium, Actinobacteria, Azotobacter, and Azospirillum. They help in transforming nitrogen into organic compounds. Biological nitrogen fixation is one way of converting elemental nitrogen into a usable form for the plants. It is the reduction of nitrogen (N2) to ammonia (NH3). Thus, increasing awareness of water pollution and nitrate emissions is driving the need for alternative sustainable sources such as nitrogen-fixing biofertilizers. 2) Phosphate solubilizers - microorganisms that are capable of solubilizing inorganic phosphorus from insoluble compounds. P-solubilization ability of rhizosphere microorganisms is considered to be one of the most important traits associated with plant phosphate nutrition. Ex. Pseudomonas striata , Aspergillus awamari 3) Sulphur oxidizers - These biofertilizers act by oxidizing sulfur to sulfates, which can be trapped by plants; the best example of sulfur-oxidizing microorganisms is Thiobacillus spp. 4) Organic matter decomposers - When plant residues are returned to the soil, various organic compounds undergo decomposition. Soil organisms, including micro-organisms, use soil organic matter as food. As they break down the organic matter, any excess nutrients (N, P and S) are released into the soil in forms that plants can use. This release process is called mineralization. The waste products produced by micro-organisms are also soil organic matter. Ex. Cellulomonas folia , Aspergillus niger 5) Potash solublizers - of the K is unavailable for plant uptake. Application of chemical fertilizers has a considerably negative impact on environmental sustainability. It is known that potassium solubilizing bacteria (KSB) can solubilize K-bearing minerals and convert the insoluble K to soluble forms of K available to plant uptake. Many bacteria such as Acidothiobacillus ferrooxidans, Paenibacillus spp., Bacillus mucilaginosus, B. edaphicus, and B. circulans have capacity to solubilize K minerals (e.g., biotite, feldspar, illite, muscovite, orthoclase, and mica). 6) Silicate solublizers - Silicate solubilizing bacteria not only increase the availability of silicates, P and K in the soil, but also provide a biological control system to the plants against pathogenic fungi. These bacteria release Si in soil which acts as a physical barrier to pathogens. Ex. Si SOLB strain of Bacillus sp.  Importance of biofertilizers in agriculture and farming Biofertilizers helps in the establishments and growth of crop plants and trees. They enhance biomass production and yield by 10 to 20 %. They are useful in sustainable agriculture. They are inputs containing microorganisms which are capable of mobilizing nutritive element from non-available to available form through biological process. They are less expensive, eco-friendly and sustainable. Biofertilizers on application remain in soil, multiply and keep benefitting to the growing crops. They do not get depleted as in case of chemical fertilizers and therefore if the optimum soil conditions prevails, population of added microbes build up continuously and no need of frequent application of biofertilizers.