What process primarily supports the nitrogen cycle in the environment?

Nitrogen fixation is crucial to the nitrogen cycle because it is the process by which atmospheric nitrogen (N2) is converted into a form that is usable by living organisms, specifically ammonia (NH3). Certain bacteria, including those found in the root nodules of leguminous plants, and free-living bacteria in the soil carry out nitrogen fixation. This process transforms inert atmospheric nitrogen into a biologically available form, allowing plants to take up nitrogen and utilize it for growth and development.

Once nitrogen is fixed, it can be used by plants to synthesize proteins and nucleic acids, which are essential for all forms of life. As plants are consumed by herbivores and subsequently by carnivores, the fixed nitrogen moves through the food web. When organisms die or excrete waste, nitrogen is returned to the soil through decomposition, where it can again be converted back into forms usable by plants, completing the nitrogen cycle.

While processes like evapotranspiration, phosphorylation, and decomposition play important roles in ecological cycles, they do not primarily support the nitrogen cycle itself. Evapotranspiration relates to water cycling, phosphorylation is connected to energy transfer and metabolic processes, and decomposition is important for nutrient cycling but does not initiate the nitrogen cycle. Thus,