Nitrogen fixation

Nitrogen fixation converts atmospheric nitrogen gas into reactive compounds, chiefly ammonia, that organisms can use to build proteins and nucleic acids.

Nitrogenase: An enzyme complex that reduces atmospheric nitrogen to ammonia under oxygen-sensitive conditions. It catalyzes biological fixation and must be protected from oxygen.
Biological nitrogen fixation: The enzymatic conversion of atmospheric nitrogen into ammonia by certain microorganisms. It is the biological route that supplies fixed nitrogen to ecosystems.
Legume: A plant in the family Fabaceae, many members of which form nitrogen-fixing symbioses. Legumes host root-nodule bacteria and can enrich nitrogen in farming systems.
Eutrophication: The enrichment of water with nutrients that can drive excessive algal growth and oxygen depletion. Fixed nitrogen from fertilizers and runoff can contribute to nutrient enrichment.
Biological nitrification inhibition: The suppression of soil nitrification by compounds released from plants or microbes. Slowing nitrogen transformations may retain fixed nitrogen in forms crops can use.
Haber–Bosch process: An industrial process that synthesizes ammonia from nitrogen and hydrogen at high temperature and pressure. It fixes nitrogen chemically rather than through nitrogenase.
Nitrogen-fixing bacteria: Bacteria that convert atmospheric nitrogen into ammonia using nitrogenase. These microbes perform much of the natural fixation described here.
Crop rotation: The practice of growing different crops in sequence on the same land. Rotating legumes with other crops can improve soil nitrogen availability.
Nitrous oxide: A greenhouse gas produced by natural and human-driven nitrogen transformations. Reactive nitrogen added through fixation can later be converted into this potent gas.
Nitrogen-use efficiency: The fraction of supplied nitrogen that a crop absorbs and converts into harvestable product. Better efficiency can reduce losses from both biological and industrial nitrogen inputs.

Linked from 68 pages