- A Nitrification
- B Ammonification
- C Nitrogen fixation
- D Denitrification
Correct answer: D. Denitrification
Explanation: Denitrification is the conversion of nitrates (NO3-) to molecular nitrogen (N2) by denitrifying bacteria (Pseudomonas, Thiobacillus). It occurs in waterlogged anaerobic soil and removes nitrogen from the soil.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.