Scientists rubbish study saying air pollution can reduce wheat yield by 50%

  • Chetan Chauhan, Hindustan Times, New Delhi
  • Updated: Nov 05, 2014 20:55 IST

Agriculture scientists have questioned the credibility of a new study stating that India’s wheat production in India has fallen by 50% since 2010 because of rise in air pollution.

“I don’t think that (50%) reduction in wheat production was possible,” said H S Gupta director of the public sector Indian Agriculture Research Institute (IARI). “Smog has its impact on wheat production but not of the scale the study estimates”.

Contrary to the claim in the study of the dip in production, the World Bank data shows that per hectare wheat yield in India has increased from 2,581 kg in 2009 to 2,975 in 2012. Soon after Independence when the air was relatively clean, per hectare yield was just 633 kg hinting that the link between air pollution related smog and production was not as big as being claimed in the study.

Jennifer Burney of University of California at San Diego in the United States and V Ramanathan of Scripps Institution of Oceanography in the study said that their statistical model suggested that averaged over India, yields in 2010 were up to 36% lower for wheat than they otherwise would have been, absent climate and pollution emission trends.

Rubbishing the claim, an agriculture ministry official termed it as “pure western media sensationalism” aimed at creating panic. He added that the Indian Council for Agriculture Research (ICAR) studies showed that smog had an impact on wheat production but not of the extent being claimed.

“Even in PUSA, our agriculture laboratory in Central Delhi, such impacts are not visible,” the official not willing to be quoted as he was not authorised to speak to media said. Gupta added that high smog can reduce sunlight in crop areas slowing down photosynthesis but it cannot reduce production by 50%.

The ICAR had estimated that India’s wheat production can go down by 30% by 2050 because of climate change and rise in pollutants if no corrective steps are taken. The ICAR estimate has been widely accepted across the world.

Studies in India and across the world have also shown that high carbon and methane --- two global warming causing gases --- content in air can increase agriculture production as it enhances photosynthesis. Plants and trees do carbon sequestration and as the environment ministry estimates that 10% of carbon emissions from India are absorbed by the country’s forests.

India climate and agriculture scientists, however, agree with the study that reduction in air pollution and climate change causing gases can improve yields but added that impact on production is because of multiple factors such as degrading soil quality, water crises and high chemical use in the sector.

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