• The Punjab Government’s policy of delaying sowing of paddy has resulted in deteriorating air quality, a study carried out by researchers of Harvard University, US, has found.
• The study titled “Detection of delay in post-monsoon agricultural burning across Punjab, India: potential drivers and consequences for air quality” carried out by Tianjia Liu of the Department of Earth and Planetary Sciences and Loretta J Mickley of the School of Engineering and Applied Sciences of Harvard University has found that a shortened harvest-to-sowing period of paddy may further encourage farmers to burn crop residue in order to sow winter wheat on time.
• The study based on daily satellite remote sensing data expressed concern over the increase in aerosol loading associated with an increasing trend in post-monsoon burnt area and shift toward a later peak in post-monsoon fires in northwestern India.
• However, the burning of post-monsoon paddy residue can severely degrade air quality downwind of agricultural fires over the Indo-Gangetic Plains.
• “A temporal shift in fire activity to later in the year could exacerbate air quality degradation since late autumn-to-winter meteorology in the IGP favours smog formation due to weak winds, frequent temperature inversion and a shallow boundary layer,” the study observes.“Such a shift would have implications for air quality, since peak burning is more likely to coincide with meteorological conditions that are favourable in amplifying persistent haze.”
• It estimates that on an average, the timing of peak post-monsoon fire intensity has shifted later in Punjab by 1.16 days per year in the past one-and-a-half decade. It indicates that the burning of rice residue has shifted later by over two weeks from 2003-2016.
• The study finds that the peak fire intensity of the post-monsoon burning season in Punjab has shifted by more than two weeks from 2003 to 2016, with a 40 per cent increase in overall fire intensity. This delay is gradual, likely influenced by steady increase in crop production and mechanisation, which yield higher amount of excess crop residue.
• Besides, the timing of peak crop residue burning may increasingly coincide with winter meteorology that favours severe smog events downwind across the Indo-Gangetic Plains, where the study diagnoses a 50 per cent increase in aerosol optical depth (a measure of the extinction of the solar beam by dust and haze) exceedances between 2003 and 2016.

The solution

The study has observed that the solution lies in alternative technology that combines co-benefits of incorporating wheat seeds with rice residue and eliminating the need to burn residue, as well as switching to less water-intensive and stubble-producing crops, may alleviate the double bind of having to conserve groundwater while reducing public health exposure to smoke from post-monsoon fires.