Amount of nitrogen fixed by nitrogen fixing organism per year is about

A. 375 million tonnes

B. 275 million tonnes

C. 175 million tonnes

D. 75 million tonnes

Answer: Option C

Solution(By Examveda Team)

Amount of nitrogen fixed by nitrogen fixing organisms per year is about 175 million tonnes.
Biological fixation of the atmospheric nitrogen can be estimated at 175 million metric tons per year or about 70% of all nitrogen fixed on the Earth per year, the remaining is by some micro-organisms, autotrophs or heterotrophs 'free' fixers.