Nitrogen fixation Objective To learn the process and importance of nitrogen fixation in plants Nitrogen is the most important component in living organisms in the form of DNA, RNA and proteins. Our atmosphere consists of about 78% nitrogen, although atmosphere nitrogen is not in a form that is usable for most living beings. They are able to use it when it takes the form of compounds. Atmospheric nitrogen can be converted into nitrogen compounds during a process known as nitrogen fixation. Nitrogen from the atmosphere precipitates and is deposited into the soil and water. Once in the soil, the nitrogen will combine with hydrogen to form ammonium ions through the aid of micro-organisms. This process of converting the atmospheric nitrogen into nitrogen compounds by micro-organisms is known as nitrogen fixation. One of the best known examples of nitrogen fixation is the association between leguminous plants and bacteria of the genus rhizopium. Leguminous plants, such as beans, have these bacteria within the nodules of their roots. The bacteria first enter an epidermal cell of the root causing the root to develop an infection thread. The bacteria will then move through the infection thread until it reaches a cell deep within the cortex. The cortex cells will divide quickly forming a nodule. The rhizopia will also multiply rapidly within the nodule. The bacteria now refer to as bacteriaoids. We'll pick in the conversion of nitrogen to ammonia. Once atmospheric air reaches the root nodule, oxygen will combine with the leg hemoglobin. Leg hemoglobin combines with oxygen thereby promoting nitrogenase activity. The nitrogen molecules, with the help of nitrogenase, will combine with hydrogen molecules to first form ammonia and then an ammonium ion. Nitrogen ions will be utilized by the plant as long as it lives. After plants die, the nitrogen will still remain in the soil where it will enrich it. Summary Nitrogen accounts for about 78% of the atmosphere. In nature, atmospheric nitrogen is converted to nitrogen compounds. With the aid of certain bacteria in a process known as nitrogen fixation, rhizobium bacteria fix nitrogen in leguminous plants.