WBCS Preliminary Examination 2023 — General Studies · Question 50 of 200

Answer: (D) Paddy fields

Flooded paddy fields have waterlogged, oxygen-free soil in which methanogenic bacteria decompose organic matter and release methane ($CH_4$), also known as marsh gas. Flower gardens, orchards and tea gardens stand on well-drained soils and emit very little. India's other large methane sources are enteric fermentation in ruminant livestock (the biggest single source), landfills, coal mines and biomass burning. Methane is the main constituent of natural gas, CNG and biogas, and has about 28 times the warming effect of $CO_2$ over 100 years. Emissions from rice can be cut by alternate wetting and drying, direct seeding and the System of Rice Intensification.