Question

Given below are two statements
Statement I: Application of nitrogenous fertilizer leads to \( N_2O \) emission from the soil
Statement II: Nitrous oxide is present in larger quantities compared to methane in the atmosphere, and therefore possesses a higher potent danger
In light of the above statements, choose the correct answer from the options given below

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

While \( CO_2 \) is the most abundant GHG, \( N_2O \) is the most potent agriculturally emitted gas. Nitrous oxide also contributes to ozone layer depletion.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Agriculture is a significant contributor to greenhouse gas (GHG) emissions.
The nitrogen cycle in soil involves microbial processes that can release nitrogen-containing gases into the atmosphere.

Step 2: Detailed Explanation:
Statement I is true. When nitrogenous fertilizers (like urea or ammonium nitrate) are applied to the soil, they undergo nitrification and denitrification.
Nitrification is the aerobic oxidation of ammonium to nitrate, while denitrification is the anaerobic reduction of nitrate to dinitrogen gas (\( N_2 \)).
During both these processes, nitrous oxide (\( N_2O \)) is produced as an intermediate or byproduct and escapes into the atmosphere.
Statement II is false regarding the relative quantities.
In the Earth's atmosphere, methane (\( CH_4 \)) is present in much larger concentrations (approximately 1.9 ppm) compared to nitrous oxide (approximately 0.33 ppm).
However, \( N_2O \) is indeed more dangerous on a per-molecule basis; its Global Warming Potential (GWP) is about 265-298 times that of \( CO_2 \), whereas methane's GWP is about 25-28 times that of \( CO_2 \).
The error in Statement II lies in the claim that \( N_2O \) is present in "larger quantities" than methane.

Step 3: Final Answer:
Statement I is a correct environmental fact. Statement II is incorrect because methane is more abundant in the atmosphere than nitrous oxide.