Natural Nitrogen Fixation : (a) Atmospheric N2 combines with 02 under the effect of lightning and thunder in the clouds to form nitric oxide (NO).
(b) Nitric oxide is then oxidised with oxygen to form nitrogen peroxide (N02).
^ electric discharge _
N2 + 02 Thunder > 2NO (Nitric oxide)
2NO + 02 Oxidation > 2N02 (Nitrogen peroxide)
(c) During rains, nitrogen peroxide combines with water to form nitrous acid and nitric acid which come to ground with rain. Acid react with alkaline radical to form water soluble nitrates (N03“) and nitrites (N02~).
2NOz + H20 -x HN02 + HN03
HN03 + Ca or K salt —> Ca or K nitrates