Biofertilizer

Biofertilizers are the substance that contains microbes, which helps in promoting the growth of plants, trees by increasing the supply of essential nutrients to the plants. It comprises living organisms which include mycorrhizal fungi, blue-green algae, and bacteria. Mycorrhizal fungi preferentially withdraw minerals from organic matter for the plant whereas cyanobacteria are characterized by the property of nitrogen fixation. Nitrogen fixation is defined as a process of converting the di-nitrogen molecules into nitrogen compounds. For instance, some bacteria convert insoluble forms of soil phosphorus into soluble forms. As a result, phosphorus will be available for plants. Types of Biofertilizers: Following are the important types of biofertilizers: Symbiotic Nitrogen Fixing Bacteria Rhizobium is one of the vital symbiotic nitrogen-fixing bacteria. Here bacteria seek shelter and obtain food from plants. In return, they help by providing fixed nitrogen to the plants. Loose Association of Nitrogen-Fixing Bacteria Azospirillum is a nitrogen-fixing bacteria that live around the roots of higher plants but do not develop an intimate relationship with plants. It is often termed as rhizosphere association as this bacteria collect plant exudate and the same is used as a food by them. This process is termed as associative mutualism. Symbiotic Nitrogen-Fixing Cyanobacteria Blue-Green algae or Cyanobacteria from the symbiotic association with several plants. Liverworts, cycad roots, fern, and lichens are some of the Nitrogen-fixing cyanobacteria. Anabaena is found at the leaf cavities of the fern. It is responsible for nitrogen fixation. The fern plants decay and release the same for utilization of the rice plants. Azolla pinnate is a fern that resides in rice plants but they do not regulate the growth of the plant. Free-Living Nitrogen-Fixing Bacteria They are free-living soil bacteria which perform nitrogen fixation. They are saprotrophic anaerobes such as Clostridium, Beijerinckii, Azotobacter, and Bacillus polymyxin. Among all the types of biofertilizers, Rhizobium and Azospirillum are most widely used.