The Nitrogen Cycle
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The Nitrogen Cycle
The Nitrogen cycle is the exchange of nitrogen gas in the earths atmosphere and living organisms. Nitrogen is a necessity to all living organisms in their production of proteins, DNA, and RNA in their cells . However, only a few organisms can use this gas directly, due to the fact that it may limit the growth of plants. Nitrogen takes up about 78% of the earths atmosphere. The nitrogen cycle has three main chemical transformations, including nitrogen fixation, nitrification, and denitrification .
The first main transformation of nitrogen gas is nitrogen fixation. Nitrogen Fixation is the process in which pure nitrogen is converted to various, usable nitrogen compounds. Three processes are responsible for most of the nitrogen fixation in the atmosphere , Atmospheric Fixation, Biological Fixation and Industrial Fixation. Lightning is responsible for atmospheric fixation. In atmospheric fixation, the energy of lightning breaks down the molecules of nitrogen, enabling nitrogens atoms to combine with oxygen, creating nitrogen oxides. Rain dissolves the nitrogen oxides, turning them into nitrates, which is carried to the earth. The second form of nitrogen fixation is Industrial fixation, which is a process that converts nitrogen to ammonia (NH3). Ammonia can be used directly as a fertilizer, but most of it is further processed to urea and ammonium nitrate (NH4NO3) . The usable nitrogen will take 2 forms: nitrate and ammonium. Plants then take up nitrate and ammonium, get lost in the subsoil or atmosphere, or are changed in the soil. The last form of nitrogen fixation is Biological Fixation. In biological fixation, some bacteria in Legumes, a special group of plants, are able to convert nitrogen into usable nitrogen compounds for plants. In biological fixation, Aminization takes place. Aminization is when microbes break down protein in plants and animal waste