Question

Which two distinct microbial processes are responsible for the release of fixed nitrogen as dinitrogen gas (N₂) to the atmosphere?

(a) Aerobic nitrate oxidation and nitrite reduction

(b) Decomposition of organic nitrogen and conversion of dinitrogen to ammonium compounds

(c) Enteric fermentation in cattle and nitrogen fixation by Rhizobium in root nodules of legumes

(d) Anaerobic ammonium oxidation and denitrification

Answer 1

Ans : (d) Anaerobic ammonium oxidation and denitrification 

Explanation:

Denitrification is a chemical process in which nitrates in the soil are reduced to molecular nitrogen (N.) which is released into the atmosphere. It is done by denitrifying bacteria like Pseudomonas denitrificans. Anaerobic oxidation of ammonium (NH4) also releases nitrogen in the atmosphere.