Nitrogen Fixation

Importance of Nitrogen Fixation

After photosynthesis, nitrogen (N2) fixation is the second most important biological process on earth. Estimates vary, but a common figure is of 175 million metric tons (MT) of N2 fixed per annum, accounting for 65% of the N used in agriculture. Biological nitrogen fixation studies have traditionally emphasized legumes and other symbiotic associations (see next section), but increasingly are also considering associative systems such as found in sugar cane and other endophytes,  N2 fixation in  tidal mudflats and cyanobacterial blooms, and even free-living N2-fixing organisms in soil.