Nitrogen is provided to plants by microorganisms according to two mechanisms: symbiotic and non-symbiotic. Symbiotic Nitrogen Fixation is a cooperative relationship between microorganisms (rhizobia) and plants where the organism enters the root of the plant and forms a contract in which nitrogen is fixed and converted into a form that it benefits from. Plant, rhizobia (Rhizobia) is a group of root bacteria that live in the soil near the roots of plants, and form symbiotic relationships with these roots. Rhizobia are distinguished by their ability to convert atmospheric nitrogen into nitrogenous compounds that can be used by plants, and this is done in leguminous plants where nitrogen is fixed. To ammonia (NH3) and provide it to the plant, as the genera Rhizobium, Bradyrhizobium, Sinorhizobium, & Mesorhizobium carry out this process.

Dr Mohammad Ebrahim Al-Salloum thank you for your contribution to discussion

Bacteria increase soil fertility through nutrient recycling such as carbon, nitrogen, sulphur and phosphorus. Bacteria also help in the decomposition of dead organic matter and then give out simple compounds in the soil, which can be used up by plants. They increase soil fertility by incorporating air, minerals and nitrogenous compounds. They contribute in increasing plant growth by providing essential elements, minerals that plants cannot utilize by their Owen. Microorganisms decompose organic matter to simpler form that can be easily uptake by plants. 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. Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen e.g., Anabaena, Nostoc, Oscillatoria, etc. In paddy fields, cyanobacteria serve as an important biofertiliser. Soil microorganisms are responsible for most of the nutrient release from organic matter. When microorganisms decompose organic matter, they use the carbon and nutrients in the organic matter for their own growth. They release excess nutrients into the soil where they can be taken up by plants. Microorganisms regulate soil properties and fertility through different pathways: (1) microbes can activate soil nutrients and promote their availability; (2) nitrogen-fixing bacteria improve soil fertility by transforming the nitrogen elements; (3) the extracellular secretions of microbes can enhance the stability of soil productivity. It is calculated that one gram of healthy soil can contain up to 1 Billion microorganisms and several meters of fungal hyphae. This is particularly important as soil microbes are fundamental to not only soil fertility but also, they are key providers of all types of environmental services. Microorganisms increase the source of nitrogen in the soil, or they can supply it directly to the plant, as they have the ability to take and set nitrogen from the atmosphere. Thanks to microorganisms, there is an increase in the bioavailability of phosphorus in the soil. The rhizosphere serves as the microbial seed bank where microorganisms transform organic and inorganic substances in the rhizosphere into accessible plant nutrients as plants harbor diverse microorganisms such as fungi, bacteria, nematodes, viruses, and protists among others. Plant sugars from the roots feed the soil microbes; the bacteria and other organisms living in the rhizosphere make nutrients available to the plants and provide a protective layer against pests and diseases.

There are 3 systems of microorganisms affecting the availability of nutrients like N,P,Some of them fix N,other solublies P and other releases. Maintaining nutrients in available forms,increase the fertility of soil

Dr E. A. M. Awad thank you for your contribution to discussion

Microorganisms play a crucial role in nutrient cycling in soil. The composition and activity of microbiota impact the soil quality status, health, and nutrient enrichment. Microbes are essential for nutrient mobility and absorption. Through their varied functions, they stimulate plant growth and reduce diseases. These microbes may reside in rhizosphere and promote plant growth. Soil microorganism also contributes to a wide range of application in sustainability of all ecosystems. These microbes regulate nutrient cycling, regulation of dynamic of soil organic matter, and enhance efficiency of nutrient acquisition. Soil microorganisms are responsible for most of the nutrient release from organic matter. When microorganisms decompose organic matter, they use the carbon and nutrients in the organic matter for their own growth. They release excess nutrients into the soil where they can be taken up by plants. Beneficial soil microbes perform fundamental functions such as nutrient cycling, breaking down crop residues, and stimulating plant growth. While the role of microbes to maintain soil health and contribute to crop performance is clear, the soil biological component is extremely difficult to observe and manage. Living organisms are very important for improving soil fertility because when a living organism dies the organic matter of its body gets decomposed by the decomposers hence it provides humus to the soil. Humus is the organic matter present in the soil which in the course of time gets converted into humus. Microbes can make nutrients and minerals in the soil available to plants, produce hormones that spur growth, stimulate the plant immune system and trigger or dampen stress responses. In general a more diverse soil microbiome results in fewer plant diseases and higher yield. Organisms like bacteria, algae, earthworms etc, when added to the soil, helps in increasing the fertility of the soil. Rhizobium is an example of a symbiotic bacterium that attaches to the roots of leguminous plants and it increases soil fertility by converting atmospheric nitrogen into organic compounds. But based on the increased activities done by the bacteria in the soil for the absorption of nutrients by the plants we consider bacteria as the most important organism for soil fertility. Soil fertility can be further improved by incorporating cover crops that add organic matter to the soil, which leads to improved soil structure and promotes a healthy, fertile soil; by using green manure or growing legumes to fix nitrogen from the air through the process of biological nitrogen fixation. Bacteria increase soil fertility through nutrient recycling such as carbon, nitrogen, sulphur and phosphorus. Bacteria also help in the decomposition of dead organic matter and then give out simple compounds in the soil, which can be used up by plants.

Various microorganisms will solubilize mineral nutrients found in soils to make those nutrients like Phosphorus and Potassium available for absorption into the plant root system.

Dr David Feider thank you for your contribution to discussion

Some of bacteria fix atmospheric nitrogen by some legumes and others dissolve unavailable phosphorus and that improve the fertility of soils

Dr E.A.M. Awad thank you for your contribution to the discussion