The Marine Nitrogen Cycle

Nitrogen fixation is an integral component of the global nitrogen cycle, providing the link between the largest reservoir of nitrogen on earth, gaseous N2, and the pool of biochemically fixed nitrogen. The first suggestions that nitrogen could be biologically “fixed” occurred in the early 1800s with the realization that some types of leguminous plants thrive in nitrogen-poor soils. Researchers later identified the rhizobial symbionts that are responsible for this activity.