Among the following crops, which one is the most important anthropogenic source of both methane and nitrous oxide?
Answer & explanation
Answer: (b) Rice
Paddy is grown in standing water, and bacteria decomposing organic matter in that oxygen-free soil release methane; the heavy nitrogen fertiliser used on rice, poorly taken up by the plant, adds nitrous oxide. No other field crop contributes so much of both gases.
- ✓ (b) Flooded paddy fields are one of the largest human-made sources of methane (about a tenth of global methane emissions), and fertiliser applied to rice releases nitrous oxide as well.
- ✗ (d) Wheat is grown on drained, aerated soil, so it produces little methane; its fertiliser gives some nitrous oxide but not both gases on rice's scale.
- ✗ (c) Sugarcane is a heavy user of water and fertiliser, but it is not grown under continuous flooding, so it is not a major methane source.
Remember · Flooded rice = anaerobic soil = methane; nitrogen fertiliser = nitrous oxide. Alternate wetting and drying, SRI and direct-seeded rice cut paddy methane.
Sources
- World Bank blog: Greening the rice we eat ↗ “significant greenhouse gas (GHG) emissions—methane, nitrous oxide (N 2 O) and carbon dioxide (CO 2 ) are byproducts of rice farming and the rice value chain. Rice is responsible for 10% of global methane emissions”
- PIB: Measures to Reduce Methane Emissions (Ministry of Environment, Forest and Climate Change, 24 July 2023) ↗ “As per India’s third Biennial Update Report, India’s methane emissions in 2016 (excluding LULUCF) were 409 million tone CO 2 e of which, 73.96% was from Agriculture sector”
Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·