Stubble burning

Also called: Crop residue burning, Parali · Topic: Geographical Issues: Pollution, Urban Waste, Slums and Land Degradation · NCERT: Beyond NCERT

Meaning

Stubble burning (also called crop residue burning, or parali burning) means farmers set fire to the paddy stalks left in their fields after harvest. They do it to clear the land quickly for sowing wheat. It happens mainly in Punjab, Haryana and western Uttar Pradesh in October–November.

It matters because the smoke is a seasonal source of PM2.5, CO and black carbon. North-westerly winds carry this smoke down the Indo-Gangetic plain into Delhi. There it adds to the winter smog.

Explanation

Why farmers burn the stubble (cause)

• Stubble means the short stalks of the paddy plant left standing in the field after harvest.
• Machines leave tall stubble.
• Combine harvesters (machines that cut and thresh the crop in one go) cut high on the plant.

• So tall stalks are left standing in the field.

• A groundwater law pushed the harvest later.

• The Punjab Preservation of Subsoil Water Act, 2009 delays paddy transplanting to save groundwater.

• Late transplanting means a late harvest.

• The gap before the next crop is short.

• Farmers have only 2–3 weeks before they must sow wheat, the rabi (winter) crop.

• Burning is the fastest and cheapest way to clear the field.

• Paddy itself is the root crop choice.

• MSP (minimum support price) support keeps paddy attractive in north-west India.
• This means a very large area is under paddy, so a lot of straw is left every year.

How the smoke reaches Delhi (process → result)

• Step 1: Fires release pollution. Burning biomass gives off PM2.5 (fine particles that go deep into the lungs and blood), CO (carbon monoxide, a poison gas from incomplete burning) and black carbon (soot).
• Step 2: Wind carries it. North-westerly winds blow from Punjab and Haryana down the Indo-Gangetic plain towards Delhi.
• Step 3: Winter weather traps it.
• Temperature inversion means a layer of cold air sits near the ground under a layer of warmer air. The warm layer works like a lid, so the smoke cannot rise.
• Mixing height (the height up to which air near the ground mixes freely) falls to a few hundred metres in winter. So the smoke is packed into a small volume of air.

• Calm winds do not blow the smoke away.

• Step 4: Geography holds it in place.

• Delhi is in a land-locked plain, so no sea breeze cleans the air.

• The Himalaya to the north acts like a wall. Polluted air collects over the plain like water in a bowl.

• Result: the smoke mixes with local pollution, festival firecracker smoke (Diwali) and fog. Thick smog then covers Delhi-NCR from November to January.

Remedies (types of residue management)

Type	What it means	Methods
In-situ	Straw is handled inside the field	Happy Seeder (sows wheat straight through the stubble), Super Straw Management System (Super SMS) fitted on combines, rotavators, mulchers
Biological	Straw is rotted into manure	PUSA decomposer spray from IARI
Ex-situ	Straw is taken out and used elsewhere	Fuel in thermal power plants (co-firing with pellets), biomass plants, bio-CNG, packaging
Long-term	Grow less paddy	Crop diversification to maize, pulses and cotton

• Machine support: by October 2023, subsidised crop residue machines had reached Punjab (1,17,672), Haryana (80,071) and UP-NCR (7,986) [4].
• Monitoring: IARI (Indian Agricultural Research Institute, New Delhi) counts farm fires every day from satellite images, using a standard protocol.

Recent trend (official satellite counts)

• 2024: Punjab had 9,655 fire incidents and Haryana 1,118 [3].
• 2025: Punjab had 5,114 incidents. That is 53% lower than 2024 and 93% lower than 2021 [2].
• 2025: Haryana's count was 53% lower than 2024 and 91% lower than 2021 [2].

Where it occurs

• Punjab: the main source region. It had the most fire incidents in both 2024 and 2025 [3][2].
• Haryana: the second major source. Its count fell 91% between 2021 and 2025 [2].
• Western Uttar Pradesh: another paddy–wheat belt where stubble is burnt. UP-NCR received 7,986 residue machines by October 2023 [4].
• Delhi-NCR: the main area that receives the smoke. North-westerly winds bring it down the Indo-Gangetic plain.
• Indo-Gangetic plain: the wider region that carries and traps the smoke, between the Himalaya to the north and the land-locked plains.
• Who acts on it: the Commission for Air Quality Management in NCR and Adjoining Areas (CAQM) was set up by an Act of Parliament in 2021 [1]. It coordinates action on stubble burning in Punjab, Haryana, Rajasthan and UP [2].

Don't confuse with

• In-situ vs ex-situ management: In-situ means the straw stays in the field (Happy Seeder, Super SMS, mulchers). Ex-situ means the straw is taken out and used elsewhere (pellets in power plants, bio-CNG, packaging).
• Jhum (shifting cultivation) burning: Jhum burns forest or bush in the hills of north-east India to clear new land for farming. Stubble burning burns crop leftovers on permanent fields that are farmed every year.
• Delhi's winter smog: Delhi's smog has many causes: vehicles, dust, industry, firecrackers, plus inversion and calm winds. Stubble smoke is only one seasonal input to it. It is not the only cause.
• Classical (sulphurous) smog: Classical smog comes from coal smoke (SO₂ + soot) mixed with fog. Stubble burning mainly adds PM2.5, CO and black carbon, not SO₂.

Prelims Hooks

• Stubble smoke reaches Delhi on north-westerly winds from Punjab–Haryana, along the Indo-Gangetic plain.
• Happy Seeder and Super SMS are in-situ methods. Straw pellets co-fired in thermal power plants are an ex-situ method.
• The PUSA decomposer is a bio-decomposer spray developed by IARI. IARI also counts farm fires daily from satellite images.
• The Punjab Preservation of Subsoil Water Act, 2009 delayed paddy transplanting. This shortened the gap before wheat sowing to 2–3 weeks.
• 2025: Punjab had 5,114 farm fires, which is 93% lower than 2021. Haryana's count was 91% lower than 2021 [2].
• CAQM was created by an Act of Parliament in 2021 [1]. It covers Punjab, Haryana, Rajasthan and UP for stubble burning [2].

Mains Points

• Stubble burning is a farm-policy problem, not just a pollution problem (GS-III).
• MSP-driven paddy, the 2009 groundwater law and combine harvesters together leave farmers with tall stubble and only 2–3 weeks to clear it.

• So fines alone cannot work. Farmers need cheap and quick options instead.

• Machines and straw markets have cut fires sharply, but lasting change needs crop diversification.

• Subsidised machines [4] and ex-situ uses helped cut fires by about 90% between 2021 and 2025 [2].

• Moving north-west India away from paddy to maize, pulses and cotton would also save groundwater.

• Delhi's air needs action across the whole airshed, not just inside the city (GS-I/III).

• Winter inversion, low mixing height, calm winds and the Himalayan barrier trap smoke that comes from other states.
• Coordination across states through CAQM [1] is therefore needed, along with city-level programmes such as NCAP.

Related concepts

• Air pollution
• Smog
• Acid rain
• Delhi winter smog

Read more

• Air pollution: sources, smog, acid rain and Delhi's winter crisis