UPSC Prelims 2022 Q22: System of Rice Intensification — Explained
"System of Rice Intensification" of cultivation, in which alternate wetting and drying of rice fields is practised, results in:
1. Reduced seed requirement
2. Reduced methane production
3. Reduced electricity consumption
Select the correct answer using the code given below:
- 1 and 2 only
- 2 and 3 only
- 1 and 3 only
- 1, 2 and 3
Answer: (d) 1, 2 and 3
Statement-wise explanation
- 1: correct — SRI transplants one very young seedling (about 8–12 days old) per hill, in a square grid about 25 cm × 25 cm apart. Conventional transplanting puts clumps of 3–5 older seedlings in each hill. So a much smaller nursery is needed. Sources put the seed saving at 80–90% compared with conventional transplanting.
- 2: correct — In a continuously flooded paddy, the soil has no oxygen. Methane-producing microbes (methanogens) break down organic matter there and release methane. Alternate wetting and drying lets air back into the soil between irrigations, and that suppresses methanogenesis. FAO material citing IFPRI (2009) puts the methane cut from intermittent irrigation at about 40%.
- 3: correct — With alternate wetting and drying, fields are re-irrigated only after the water drops below the soil surface (about 15 cm under 'safe AWD'). That means fewer irrigation events and 15–35% less water (FAO). Much of India's paddy is irrigated by electric groundwater pumps, so fewer pumping hours mean less electricity. FAO notes that AWD lowers pumping costs and fuel use in pump-irrigated systems.
How to eliminate
Statements 1 and 2 follow from basic knowledge. SRI's best-known feature is planting single young seedlings, so it needs less seed. Methane from paddies comes from waterlogged soil without oxygen, so drying the field must cut it. Only two options contain both 1 and 2: '1 and 2 only' and '1, 2 and 3'. The question therefore comes down to statement 3. Here, reason through the steps: less water applied means fewer hours of pumping groundwater, and in India those pumps mostly run on electricity, so electricity use falls. The statement makes no absolute claim like 'eliminates'; it only says 'reduced', which is easy to defend. The fact to remember: AWD saves irrigation water and therefore pumping energy.
Know more
System of Rice Intensification (SRI) is a set of crop-management practices, not a new seed variety. It was developed in Madagascar by the French Jesuit priest Henri de Laulanié. Its basic idea is that rice is not an aquatic plant: it needs moist soil, not standing water.
Core practices compared
| Practice | Conventional transplanted rice | SRI |
|---|---|---|
| Seedling age | 21–30 days | 8–12 days |
| Seedlings per hill | 3–5 (clumps) | 1 |
| Spacing | Close, irregular | Wide square grid (~25 × 25 cm) |
| Water | Continuous flooding (5–10 cm) | Alternate wetting and drying, soil kept moist |
| Weeding | Manual or herbicide | Mechanical weeder, which also aerates soil |
| Nutrients | Mostly chemical | Organic matter encouraged |
Why AWD cuts methane. Under flooding, the soil runs out of oxygen. Methanogenic archaea decompose organic matter and release methane (CH₄), a greenhouse gas far stronger than CO₂ over a 20-year horizon. Drying the field lets oxygen in, which halts this process.
The trade-off. Alternating wet and dry conditions can increase nitrous oxide (N₂O) emissions, because nitrogen fertiliser is nitrified and denitrified in the cycling soil. FAO material notes that part of the methane benefit can be offset this way. The net climate gain depends on how water and fertiliser are managed.
Related practices. Direct Seeded Rice (DSR) skips the nursery, puddling and transplanting, which saves water and labour and also lowers methane. In India, climate-resilient rice practices are promoted under the National Mission for Sustainable Agriculture (NMSA) and through ICAR's NICRA project.
India's stance. India did not join the Global Methane Pledge (COP26, 2021). It calls paddy and livestock methane 'survival emissions' linked to food security.
In the news
At COP26 (November 2021), the Global Methane Pledge was launched, and India declined to sign it. India cited paddy cultivation and livestock as survival emissions. That put rice-paddy methane, and practices like SRI and AWD that cut it, in the news before the 2022 Prelims.
NCERT Concepts to Revise
- System of Rice Intensification: The question is about SRI's practices: seedling age, spacing and water management decide each statement.
- Direct seeded rice: Direct seeded rice is the other water- and methane-saving method that UPSC often contrasts with SRI.
- Methane: Statement 2 depends on how methane forms in waterlogged, oxygen-free paddy soil.
- National Mission for Sustainable Agriculture: NMSA is the national mission under which India promotes climate-resilient rice practices like SRI.