Stubble Burning and Delhi Pollution: What the Evidence Means

Stubble burning means burning crop residue left in a field after harvest. Paddy-residue fires in northwestern India can contribute to Delhi’s autumn pollution when winds and atmospheric conditions transport smoke towards the city. Their contribution changes from day to day.

Why residue management is difficult

Farmers need to prepare for the next crop while managing residue, machinery availability, labour and cost. The harvest-to-sowing window varies with crop, variety, weather and local practice. It is misleading to assume every farmer has exactly 15 days or that one policy made burning inevitable.

Residue does not always have to be removed to bare soil. Appropriate machinery can support sowing while managing residue in the field. ICAR’s October 2025 field demonstration included residue-management equipment and direct-sowing approaches such as the Happy Seeder.

What the alternatives address

Options include managing residue in the field, collecting it for other uses and using decomposition approaches where suitable. Each needs workable timing, equipment and logistics; there is no single method that fits every farm.

ICAR describes Pusa Decomposer as a microbial consortium used to support residue decomposition. Its presence is not proof that any field can be ready by a universal deadline. Local agronomic guidance and conditions matter.

How smoke reaches Delhi

The relevant questions are where fires occur, how much is emitted, the wind path and how pollution mixes in the atmosphere. A fire detected far away does not automatically contribute the same amount at a Delhi monitoring station as a closer or more intense fire.

Wintertime restricted mixing can compound an episode, alongside local emissions and other transported pollution. Read Delhi temperature inversions for the dispersion mechanism.

Fire counts are not a source percentage

Satellite fire detections, estimated burned area, emissions and modelled contribution to ambient PM2.5 are different quantities. Cloud, overpass timing, fire duration and detection methods can affect what is observed. A percentage decline in detected fires cannot simply be called the same percentage decline in Delhi’s PM2.5.

If a report gives a crop-burning contribution, retain its date, area, model and averaging period. One peak day’s share cannot establish an annual average. Equally, an annual average can conceal an important short episode. See how Delhi source studies are interpreted.

What this means at home

Follow local pollution advisories during smoke episodes without assuming that the calendar alone predicts the air. Check indoor PM2.5, filtration and ventilation, and reduce avoidable indoor smoke sources. Outdoor pollution also has sources beyond crop residue, so household measurements remain useful outside the burning season.

Read reducing PM2.5 at home. For aqi0, the technical note describes the installation and maintenance conditions behind its performance commitment.

FAQ

Are farmers the main cause of Delhi’s air pollution?

For about 30 autumn days, they are a major contributor. For the other 335 days, they contribute essentially nothing. Annual average contribution is 4–8%.

Why don’t they just use the Pusa decomposer?

It takes 20–25 days. The window between paddy harvest and wheat sowing is 15 days. Until that mismatch is fixed, the decomposer cannot replace burning at scale.

Has stubble burning increased or decreased?

Decreased overall — from ~80,000 fires in 2016 to ~30,000–40,000 in recent years. Per-fire emissions have intensified as remaining fires concentrate in fewer days.

Would banning combine harvesters help?

Manual harvesting leaves shorter stubble but is economically infeasible at current labour rates. Some experiments combine machine harvest with mechanical removal of standing stubble for fodder.

If I leave Delhi in October–November, will I be safe?

You will avoid the worst days. You will not avoid the other ten months of unhealthy air.