Rhizobium and blue-green algae are both fascinating contributors to soil fertility. Rhizobium is a type of bacteria that forms a symbiotic relationship with leguminous plants, such as peas, beans, and clover. These bacteria live in specialized structures called nodules on the plant's roots. In exchange for carbohydrates provided by the plant, Rhizobium fixes atmospheric nitrogen into a form that the plants can use as a nutrient, thus increasing soil fertility. Blue-green algae, also known as cyanobacteria, are photosynthetic microorganisms that can occur in various ecosystems, including rice fields. They play a crucial role in enhancing soil fertility as well. By performing photosynthesis, they convert sunlight and carbon dioxide into organic matter, thereby enriching the soil with nutrients. Additionally, some species of blue-green algae can fix atmospheric nitrogen, just like Rhizobium, providing a readily available nitrogen source for rice plants. In rice cultivation, a common blue-green algae used to boost soil fertility is called Anabaena azollae. This species forms a symbiotic relationship with a fern called Azolla, which grows on the surface of rice paddies. Azolla provides a habitat for Anabaena azollae, and in return, the algae fixes atmospheric nitrogen, providing a natural source of nitrogen for the rice plants.

Dr Asanka Aberathna thank you for your contribution to the discussion

i agree with Rana Hamza Shakil that some bacteria like rhizobium and blue green algae are able to fix nitrogen gas from the atmosphere to enrich the soil with nitrogen compounds and increase its fertility. The nitrogen-fixing bacteria and blue green algae are called biological nitrogen fixers. Rhizobia are found in the soil and after infection, produce nodules in the legume where they fix nitrogen gas (N2) from the atmosphere turning it into a more readily useful form of nitrogen. From here, the nitrogen is exported from the nodules and used for growth in the legume. Blue green algae fix the atmospheric nitrogen which increase the amount of nitrogen in soil hence fertility and bacteria digest the waste material which act as manure. Blue green algae fix nitrogen directly from air to enhance soil fertility. BGA fix atmospheric nitrogen and supply it to plants thereby having the capacity to reduce the consumption of urea. Cyanobacteria which is also called blue green algae is a perfect example of a bio-fertilizer. They work as both nitrogen fixing bacteria and photosynthetic bacteria. Carbon and nitrogen sources are essential for the soil because they help to enhance the soil productivity. They transform nitrogen from the atmosphere into nitrites or nitrates. They are known as microorganisms that fix nitrogen. Cyanobacteria were the earliest organisms to infiltrate terrestrial environments and are common members of biocrust communities. Rhizobium is a bacterium that lives in a symbiotic relationship between root nodules of leguminous plants. They fix the atmospheric nitrogen and convert it into soluble nitrates, nitrites and ammonium compounds. Nitrogen fixation helps in increasing soil productivity and soil fertility. Cyanobacteria are one of the major components of the nitrogen fixing biomass in paddy fields. The agricultural importance of cyanobacteria in rice cultivation is directly related with their ability to fix nitrogen and other positive effects for plants and soil. Blue green algae (cyanobacteria) play an important role in maintenance and build-up of soil fertility, consequently increasing rice growth and yield as a natural biofertilizer. They are photosynthetic nitrogen fixers and are free living. Increase in water-holding capacity through their jelly structure

Both Rhizobium and blue green algae are nitrogen fixers which take nitrogen from the environment and convert it into ammonia which get fixed in the form of amino acids. in this way, they enhance the fertility of the soil. BGA also form symbiotic association with Azolla a fern which add biomass and combined nitrogen to the rice fields.

Dr D V Pathak thank you for your contribution to the discussion

Here are some of the ways in which Rhizobium and blue-green algae increase soil fertility: Fixing nitrogen: Both Rhizobium and blue-green algae can fix nitrogen from the atmosphere. This is an important process because it adds nitrogen to the soil, which is a nutrient that is essential for plant growth. Rhizobium is a bacterium found in soil that helps in fixing nitrogen in leguminous plants. It attaches to the roots of the leguminous plant and produces nodules. These nodules fix atmospheric nitrogen and convert it into ammonia that can be used by the plant for its growth and development. Rhizobia are found in the soil and after infection, produce nodules in the legume where they fix nitrogen gas (N2) from the atmosphere turning it into a more readily useful form of nitrogen. From here, the nitrogen is exported from the nodules and used for growth in the legume. The organisms like blue-green algae and bacteria are extensively used to fix nitrogen in the soil for agriculture. This will improve the fertility of the soil. Bacteria help fix the atmospheric nitrogen with the help of nitrogenase enzyme and increase the nitrogen content in the soil. It is referred to as Nitrogen-fixing Bacteria. As, Nostoc, Anabaena, Azotobacter, etc. Cyanobacteria which is also called blue green algae is a perfect example of a bio-fertilizer. They work as both nitrogen fixing bacteria and photosynthetic bacteria. Carbon and nitrogen sources are essential for the soil because they help to enhance the soil productivity. Bacteria help in fixing atmospheric nitrogen and increase the nitrogen available for the plants. Bacteria decompose the decaying matter and increase the nutrient content. They also help in improving the texture and quality of the soil. Blue green Algae fix nitrogen directly from atmosphere, and increase the fertility of soil. Free-living nitrogen fixing blue green algae (Cyanobacteria): Anabeaena, Nostoc, Cylindrospermum, Trichodesmium, and Aulosira are the most common blue green algae that help in nitrogen fixation. Some of the blue-green algae used in rice fields to increase fertility include: Anabaena azollae: This alga is a symbiotic partner of the water fern Azolla. Together, they form a floating mat that can cover large areas of water. Blue green algae play an important role in maintenance and build-up of soil fertility, consequently increasing rice growth and yield as a natural biofertilizer. They are photosynthetic nitrogen fixers and are free living. Increase in water-holding capacity through their jelly structure. Azolla pinnata is especially grown in wet soil in rice fields during rice cultivation to generate a good amount of nitrogen rich fertilizer. The association of Azolla pinnata along with the blue green algae called Anabaena provides great importance to agriculture.