nitrogen fixation
noun [ U ] chemistry specialized uk/ˈnaɪ.trə.dʒən fɪkˌseɪ.ʃən/ us/ˈnaɪ.trə.dʒən fɪkˌseɪ.ʃən/
固氮
the process by which nitrogen from the atmosphere is changed either naturally or in industry into compounds that are used in several processes