What is stubble burning? How much does it contribute to Delhi’s air woes?

Delhi residents woke up to ‘very poor air’ quality after Diwali with AQI hitting 326 on Tuesday morning. Air quality was also ‘very poor’ in Narela, Delhi University, Anand Vihar, India Gate and Dwarka with Ghaziabad, Noida, Greater Noida, Gurugram and Faridabad also suffering. An AQI between 0-50 is considered good, 51-100 satisfactory, 101-200 moderate, 201-300 poor, 301-400 very poor and 401-500 severe. But why is this happening? And does it have anything to do with stubble-burning? Let’s take a closer look: What is stubble burning? As per Business Standard, stubble burning is a way of clearing fields of paddy crop residue in order to sow wheat. It is achieved by setting afire the straw stubble left after the harvest. It is usually required in areas that use the combined harvesting method which leaves crop residue behind. Punjab, Haryana, and Uttar Pradesh follow this practice from the last week of September to November to clear the fields for rabi crop, as per India Today. The paddy crop is harvested between the first and last weeks of October in Punjab and Haryana, as per Business Today. Farmers then sow the wheat crop from the first week of November until the middle of December. How much does it contribute to Delhi’s air woes? It is a factor, along with vehicular emissions, in contributing to the air crisis facing the National Capital and NCR. [caption id=“attachment_10907681” align=“alignnone” width=“640”] Representational image. ANI[/caption] First, it is important to note that a prolonged spell of rain in the first half of October delayed paddy harvesting and consequently stubble burning this year. On Monday evening alone, the Indian Agricultural Research Institute reported 1,019 farm fires in Punjab, 250 in Haryana and 215 in Uttar Pradesh.

According to the System of Air Quality and Weather Forecasting and Research (SAFAR), stubble burning’s contribution to Delhi’s pollution on Diwali was around 10 per cent.

However, the good news is that this figure is far lower than in previous years – 25 percent on Diwali in 2021; 32 per cent in 2020 and 19 per cent in 2019, as per  SAFAR, the forecasting agency under the Union Ministry of Earth Sciences. “The share of PM2.5 in Delhi’s air has increased which is indicative of contribution from firecrackers and stubble burning,” said Gufran Beig, chair professor, National Institute of Advanced Studies, Indian Institute of Science. “Though the active fire counts have doubled, the wind direction is north westerly and the wind speed is moderate (not very favourable for the transport of stubble smoke). Hence, the contribution of stubble burning is not significant,” he said. Till Sunday, the share of stubble burning in Delhi’s PM2.5 pollution remained low (up to five per cent) as transport-level winds were not strong enough to carry smoke from farm fires to the National Capital Region. This year, some Punjab farmers, defying the stubble-burning ban, have vowed to continue the practice until they are ‘suitably compensated’, as per India Today. As per News18, the Centre in 2021 identified “major hotspots of paddy residue burning" in Punjab’s Amritsar, Tarn Taran, Patiala and Ludhiana districts and Haryana’s Karnal, Kaithal and Kurukshetra.

These areas respectively accounted for 72 per cent and 80 per cent of all stubble burning incidents in the aforementioned states.

While farmers burn crop residue in the summer months also, it is in winter that low temperatures and low wind speeds combine to worsen air quality. ‘Does not play major factor’ The Centre last year told the Supreme Court it does not play a ‘major factor’ in poor air quality in Delhi, as per Hindustan Times. [caption id=“attachment_10962071” align=“alignnone” width=“640”] Supreme Court of India. ANI[/caption] In an affidavit filed in the apex court, the Union ministry of environment, forest and climate change said, “As per a scientific study carried out and to get indicative figures to show average sectoral contributions in PM 2.5 and PM 10 concentrations in Delhi” the respective contribution of agricultural burning to PM 2.5 and PM10 was just four per cent and seven per cent each in winter and summer”. But according to the Hindustan Times, Delhi’s AQI was in the ‘severe category’ between 20 October and 14 November last year with the contribution of farm fires to Delhi’s PM 2.5 contribution between 26 per cent and 48 per cent. The newspaper quoted a 2018 article entitled Objective evaluation of stubble emission of North India and quantifying its impact on air quality of Delhi, published in the international journal Science of the Total Environment as saying, “Although the stubble burning was a regular process during the said period (October 10-December 10, 2018), with varied fire count, the impact of biomass burning on Delhi’s PM 2.5 is found to vary on day -to day basis with percentage contribution of stubble burning ranging from 1% to 58% as it is highly dependent on transportation pathway of air mass, controlled by source to target region meteorological parameters led by wind direction and wind speed.” “The impact of stubble burning on Delhi’s air quality depends not only on amount of biomass burned in Punjab and Haryana but a combined effect of high wind speed at intrusion height, wind direction and air residence time in the Delhi airshed,” the paper further stated. This year, some Punjab farmers, defying the stubble-burning ban, have vowed to continue the practice until they are ‘suitably compensated’, as per India Today. The Punjab government had made a U-turn after saying it would offer Rs 2,500 per acre to paddy growers – the Centre was to provide Rs 1,500 per acre while the Punjab and Delhi governments were to provide Rs 1,000 per acre. With inputs from agencies Read all the  Latest News ,  Trending News ,  Cricket News ,  Bollywood News , India News  and  Entertainment News  here. Follow us on  Facebook,  Twitter and  Instagram.