As Delhi fears another blanket of polluted air in November, a look at the reasons and solutions for stubble burning, one of the most pressing issues that haunt the national capital region during the winter and beyond
Going by the annual pattern of atmospheric pollution in Delhi over the past decade, India’s capital city is set to fight yet another perilous slump in its air quality this November as well. For starters, the autumn month typically creates a thick smog, giving residents lung damage and related health hazards to both children and adults.
While pollution is a feature of most cities in the country, November works particularly bad for Delhi due to a unique reason: stubble burning. That is, setting fire to the residual straw in the fields after the harvest of foodgrains.
The rural practice is age-old, but its effect on the country’s capital is new. Delhi’s adjacent regions continue with agriculture as a major economic activity. Ahead of the winter (Rabi) crop of wheat, Uttar Pradesh and Haryana, with which the city shares its border, besides the northern state of Punjab has farmers typically burning the bottom half of their rice plants after (Kharif) harvest. It happens during November when Delhi’s temperature ranges between 14 and 29 degrees Celsius.
What are the triggers?
- First, mechanisation.
The operation with the sickle used to leave very less stubble vis-à-vis that with the machine running on the fields. Into the 21st century, increased labour cost is prompting more farmers/growers to replace manual harvesting with machines. The use of ‘combine harvesters’ (which reap, thresh and winnow the crop) has brought down farming expenses in Western UP, Haryana and Punjab. But the flip side is much higher volumes of post-harvest straw.
- Delayed harvest
Equally, the monsoon-time paddy crop preparations start much later of late compared to the classical calendar. Farmers delay transplantation; experts claim this is owing to two reasons. One, to tune into the prescription of Monsanto (a US biotechnology foundation, acquired by German pharma MNC Bayer AG in 2018) and, two, bound to obey laws for groundwater preservation (in Punjab).
From 2009, Punjab enacted a law that ensured a delayed start to the rice crop. This was to ensure that seasonal rains replenished the groundwater. That made the harvest late, too. A mere fortnight’s time was left between the rice and wheat seasons. It left farmers with no option but to burn the stubble if the fields were to ready for the winter crop.
- Temperature drop
In October, when temperatures begin to drop, pollutants closer to the ground remain trapped owing to a reduction in the height of the mixing layer (the layer adjacent to the ground over which an emitted particle rests). So, pollution levels rise even if emissions remain the same.
Delhi’s history of air pollution in November, the month of Diwali when crackers are burst and the allied fireworks are on the rise with a burgeoning population (more so the middle class), has been particularly alarming in the past decade.
Authorities declared a public health emergency in November 2019 after certain parts of the city had AQI (air quality index) exceeding 800, which is more than three times the “hazardous” level.
On November 6, 2018, Delhi recorded its worst air quality of the season, as pollution levels inched towards ‘severe plus emergency’.
In November 2017, airborne pollutants surged to levels beyond what instruments could measure, as AQI read the maximum of 999, prompting Chief Minister Arvind Kejriwal to term the Delhi a ‘gas chamber’.
Delhi in November 2016 suffered perilous air pollution that a study said might have temporarily triggered a spike in the rate of death in the city.
In 2015, WHO found Delhi having an average of 153 micrograms of the smallest particles when the international ‘safe’ level is 6 micrograms per cubic metre.
Typically, Delhi is choked by vehicle exhaust (responsible for pollution up to 30%), biomass burning (including seasonal open fires, cooking, and heating – 20%), industries gases (20%), soil and road dust (15%) and diesel generators (15%), open waste burning besides power plants. Stagnant air (no wind), less investment on pollution-reducing infrastructure and large-scale construction of buildings are other causes.
As many as 21 of the world’s 30 top air-polluted cities are in India, with places such as Gurugram, Ghaziabad, Faridabad and around the country’s capital featuring in the first six. Delhi stands first in the list of the planet’s national capital cities with the worst air quality.
If you want to know more about Delhi’s pollution, here’s an interesting video.
What needs to be done?
Several experts, belonging to the public and private sectors, have offered suggestions on tackling the burning issue. Recently the Supreme Court appointed former Judge Madan Lokur to monitor and lead ground-level efforts to stop stubble burning in the three states.
When stubble burning comes to the fundamental cause of air pollution, here are a few tips:
Develop combine harvesters (such as ‘happy seeders’) that leave less stubble behind, tweaking their design
Incentivise farmers who don’t burn stubble, provide the crop residue economic value by converting them into cattle feed or fuel
Subsidise industries that make good use of agri waste
Encourage farmers to go for early paddy crop
Educate growers on alternate fruit and vegetable crops that consume less water and give better economic returns
Use a tractor-mounted machine that sows wheat seeds simultaneously while cutting
Devise a system where the stubble, too, is procured along with the paddy crop
Use paddy straw chopper-cum-spreader that chops the stalk into pieces and spreads them around the field in a single operation, making wheat-sowing easy
Employ the Pusa solution that can decompose crop residue into manure by accelerating decomposition
Convert stubble into biochar by burning it in a kiln to be used as a manure
Replace long-duration paddy varieties with shorter-span ones like Pusa Basmati-1509 and PR-126
Popularise use of paddy straw as fodder as part of feed-mixture preparations.
Farmers, experts and residents of Delhi feel finding a suitable and immediate solution for stubble burning is important especially today when the country is fighting a pandemic and its impacts and Delhi is struggling to offer its citizens a healthy atmosphere to live.
Here’s a short documentary on stubble burning that you may find useful