What is Biofertilizer?
Biofertilizers are the substance that contains microbes, which helps in promoting the growth of plants and 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 fields 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, etc.
Among all the types of biofertilizers, Rhizobium and Azospirillum are most widely used.
Importance of Biofertilizers
Biofertilizers are important for the following reasons:
- Biofertilizers improve soil texture and yield of plants.
- They do not allow pathogens to flourish.
- They are eco-friendly and cost-effective.
- Biofertilizers protect the environment from pollutants since they are natural fertilizers.
- They destroy many harmful substances present in the soil that can cause plant diseases.
- Biofertilizers are proved to be effective even under semi-arid conditions.
What are the advantages of biofertilizers over chemical fertilizers?
- Biofertilizers are cost-effective.
- They reduce the risk of plant diseases.
- The health of the people consuming the vegetables grown by the addition of chemical fertilizers is more at risk.
- Biofertilizers do not cause any type of pollution.
What is the need of using biofertilizers?
Biofertilizers are required to restore the fertility of the soil. Prolonged use of chemical fertilizers degrades the soil and affects the crop yield. Biofertilizers, on the other hand, enhance the water holding capacity of the soil and add essential nutrients such as nitrogen, vitamins and proteins to the soil. They are the natural form of fertilizers and hence, widely used in agriculture.