Conditions for N2 fixation : There are following conditions necessary for N2 fixation :
(1) A strong reducing agent like NADPH : It supplies hydrogen to N2.
(2) ATP as source of energy : It provides energy. For fixation of NH3 molecules, 8 ATP molecules are needed.
(3) The enzyme system : Nitrogenase is necessary for N2 fixation.
(4) Compound for trapping ammonia : Ammonia is very toxic and needs to be trapped in the form of amino acids.
(5) Leghaemoglobin : It is O2 scavenger and maintains anaerobic environment otherwise in the presence of O2 the enzyme nitrogenase is toxicated.