Winter crop stubble burning in North India: A matter beyond the fields

India is headed into winter in a few weeks, which is why it’s timely to recall that stubble burning accounts for 30-35% of Delhi-NCR’s air pollution during October and November. This is corroborated by data from both the Central Pollution Control Board (CPCB) and the Indian Council of Agricultural Research (ICAR). The practice has led to a persistent air quality issue that is driven by the burning of crop residue at this time, mostly in the neighbouring states of Punjab and Haryana.
The practice leads to the release of substantial amounts of particulate matter (PM2.5 and PM10) every year, which are carried into the NCR by prevailing seasonal winds. In quantifiable terms, the already poor air quality of a megacity like Delhi sees PM2.5 concentrations spiking to over 400 µg/m³ – far exceeding the annual safe limit of 5 µg/m³ set by the World Health Organization (WHO). The annual average for the city tends to be around 100 µg/m³, so the spike due to stubble burning is particularly dangerous as the PM2.5 particles can be inhaled into the bloodstream much quicker than PM10.
The clear relationship between the fire incidents and Delhi’s air quality index (AQI) levels is stark: on days without the fires, Delhi’s AQI averages 175 (classified as “Moderate”). However, when the fire counts rise beyond climatological averages, the average AQI shoots past 337, entering the “Very Poor” category.
The onset of winter brings lower temperatures, calm winds and temperature inversions, which leads to a blanket of cold air sitting close to the ground. The problem is that it traps pollutants close to the surface (such as dust and aerosols), preventing their dispersion and the result is Delhi’s infamous winter smog. The situation is exacerbated by the fact that the city acts as a bowl that sits at the centre of the Indo-Gangetic Plain (IGP) and accumulates pollutants from the surrounding regions.
While it may be tempting to simply blame farmers, the issue of stubble burning arose because, in 2009, Punjab and Haryana passed the Punjab Preservation of Subsoil Water Act and Haryana Preservation of Subsoil Water Act (respectively) to preserve groundwater. The reasoning was that preventing the transplanting of paddy before the onset of monsoon season would lower the need for groundwater-based irrigation, so the sowing of paddy crops was delayed from May to the middle of June. Consequently, paddy is now harvested in late October and early November, which leaves the farmers with a tight window of merely 10-15 days to prepare their fields to sow wheat. This leaves them with little choice but to burn the crop residue, as removing it by hand would take a long time.
What complicates the matter further is that these states were not historically places to cultivate paddy and wheat. High-yield varieties of crops were introduced here in the 1960s and 70s to help India’s objective of food security. However, the scale of the cultivation necessitated a switch to mechanised farming and the use of combine harvesters. While the machines are incredibly efficient, they also leave behind much greater volumes of stubble as they only target the upper part of the crop.
Additionally, the stubble from the high-yield paddy varieties is high in silica content and is not suitable as feedstock for the farm animals. Again, this is a deviation from the past where the higher percentage of the crop residue extracted was easily fed to the livestock – an elegant demonstration of circular operations.
The authorities have taken certain measures, such as encouraging farmers to diversify into less water-intensive and stubble-generating crops, such as pulses, millet and maize, and the use of subsidised machines. For instance, the Happy Seeder (to sow seeds and manage the crop residue in a single pass) and the Rotavator (to prepare the soil using mechanised blades) were introduced under the 2018 scheme for “Promotion of Agricultural Mechanization for In-Situ Management of Crop Residue”. These measures have been supplemented with fines for starting the fires in some cases and awareness generation campaigns.
However, the shift to the other crops has been slow due to the revenue potential of paddy and wheat.
Meanwhile, a 2022 survey of 810 farmers in Punjab showed that only 2% owned a happy seeder, while a mere 5.5% were using it for rent. The most popular machine was found to be the Super Seeder (combines tilling the soil, planting and covering the seed beds in one go), with 12% ownership and 34.5% of the respondents renting them.
Even so, the survey and on-ground reports indicate that the mechanised approach to stubble management is expensive and thus out of reach of most farmers, and the imposition of the fines has either been patchy or added to the farmers’ financial burdens instead.
On a positive note, the districts of Gurdaspur and Muktsar in Punjab and Karnal in Haryana have lowered their fire incidents, which shows that change is possible. What’s needed is for the reductions to be scaled up across the northern region through seamless inter-state coordination, and a much stronger emphasis on making the stubble-management machines affordable.
Also, over the longer term, a shift away from the rice-wheat monoculture will be essential since this would entail the added benefit of using less water. Better forecasting models that simultaneously monitor other pollutant sources and issue timely emergency alerts to the neighbouring states would be a useful tool as well. The most important facet, however, is that the authorities across Punjab, Haryana, Delhi and even Uttar Pradesh must treat this manic drop in air quality as a shared problem. Only then can the solutions transcend state boundaries, because until then, winters in Delhi-NCR will be, quite literally, dark and smoky.
Aarti Khosla, founder and director, Climate Trends. The views expressed are personal