Coal power is costing India up to 10% of its rice and wheat crops Premium

New research from Stanford University reveals coal power plants in India are harming crop yields, impacting agriculture significantly.

According to new research led by researchers at Stanford University in the US, coal-fired power plants are quietly depleting India’s rice and wheat output, destroying up to 10% of the yield in several states.

The emissions from coal power plants include carbon dioxide, nitrogen oxides, sulphur oxides, fly ash, soot, suspended particulate matter, and other trace gases. These pollutants have been linked to smog, acid rain, eutrophication and various other environmental burdens.

In the new study, PhD student Kirat Singh and his colleagues turned the spotlight on the less explored consequences of nitrogen dioxide (NO2) on crop productivity.

The nitrogen oxides in general are an established side effect of India’s coal dependence. They are phytotoxic, meaning they stress plants, and have been known to hinder cellular function and interfere with crucial enzymatic activities. The oxides also contribute to the formation of ozone, which in turn exacerbates crop damage and produces particulate matter that limits the amount of sunlight available for photosynthesis.

“We know that coal-fired power plants contribute significantly to air pollution,” Singh said. “And we also know from past studies that various pollutants, including NO2, can negatively impact crop growth. But there hadn’t been a study linking the two in a systematic way at the power-plant level, particularly in India.”

To compensate for the lack of ground monitoring stations in agricultural areas, the researchers used data from satellite images to glean high-resolution insights into NO2 concentration across India. Since multiple power plants contribute to NO2 pollution across different distances, the researchers summed up all coal-attributable NO2 emissions reaching each location instead of isolating individual sources. This approach gave them a comprehensive picture of the amount of pollution to which agricultural regions were exposed.

Then, to estimate how NO2 from coal-fired power plants affected crop yield, the researchers turned to a satellite-derived vegetation index. They used a physical signal called near-infrared reflectance of vegetation (NIRv) as a proxy for plant health. NIRv measures greenness. Healthy crops are richer in chlorophyll, which can’t be detected by visible light but is sensitive to near-infrared light. So a higher percentage of near-infrared light is reflected by leaves in healthy plants.