Which gas is emitted from the soil due to rice cultivation?

Correct option is C

The correct answer is (C) CH₄

Explanation:
• Methane ($CH_4$) is a potent greenhouse gas emitted primarily from flooded rice paddies. Rice is typically grown in submerged (puddled) conditions, which creates an anaerobic (oxygen-free) environment in the soil.
• Under these conditions, specialized microorganisms called methanogens decompose organic matter and produce methane as a byproduct.
• The methane is then released into the atmosphere through the rice plants (via specialized tissues called aerenchyma) or as bubbles from the soil.
• Rice cultivation is estimated to contribute significantly to global agricultural methane emissions.

Information Booster:
• Methane has a global warming potential (GWP) roughly 25-28 times higher than $CO_2$ over a 100-year period.
• Techniques like Alternate Wetting and Drying (AWD) and System of Rice Intensification (SRI) can significantly reduce methane emissions by introducing oxygen into the soil periodically.
• Nitrous Oxide ($N_2O$) is another greenhouse gas often emitted from rice fields due to fertilizer use.

Additional Knowledge:
• N₂ (Option A): This is harmless nitrogen gas; while it is released through denitrification, it is not a greenhouse gas concern like methane.
• C₂H₂ (Option B): Acetylene; used in laboratories to block the last step of denitrification, but not a significant natural emission from rice fields.
• SO₂ (Option D): Sulfur dioxide; usually associated with industrial pollution and volcanic activity, not agriculture.