Why India Needs to Count Nitrogen Emissions Alongside Carbon

In his book, ‘The Nitrogen Bomb’, Jacob Koshy examines the overlooked link between nitrogen fertilisers, agricultural practices and the PM2.5 pollution choking India’s cities. In an exclusive interview to DC, he discusses the scientific gaps and political choices India must confront to balance food security with cleaner air and more sustainable farming.

Excerpts:

Nitrogen fertiliser is essential to India’s food security, yet its use contributes to the pollution choking our cities. Have we built a food system whose success is quietly undermining the health of the people it feeds?

Yes, and that's the argument I try to present in the book. Without chemical, nitrogenous fertiliser humanity cannot exist because modern food systems are premised on high-yielding crops. Chemical fertilizers really took off in much of the developing world, India included, by the mid 60s and early 70s with Green Revolutions. But there’s so much of it today and humanity forgot that nothing in nature comes for free. Unchecked ammonia use (the main nitrogenous fertiliser) volatilises into the air and forms a primary layer that combines with fossil fuel emissions (vehicles, coal plants) to form particulate matter that, when inhaled,is harmful to our health.

Air pollution is usually discussed as an urban problem, while fertiliser use is treated as an agricultural necessity. What does connecting these two reveal about the blind spots in India’s environmental policy?

The blind spot is in the paucity of scientific investigation, on the degree to which particulate pollution (PM2.5) is attributable to fertiliser emissions. As my book points out, there are only a handful of Indian scientists trying very hard to quantify the problem. Just as we have inventories of carbon, it is high time we have similar accounting of the emissions from reactive nitrogen. Addressing this is critical to other remedial action.

India’s fertiliser subsidies are deeply tied to farm economics and political realities. Is the country’s nitrogen problem ultimately a scientific challenge, or does solving it require confronting a political system built around cheap fertiliser?

A bit of both but overwhelmingly, confronting a political system. There are technologies, as the book points out, to reduce and decelerate the leakage of nitrogenous ammonia from the soil or tap into alternate sources for nitrogenous fertiliser. But they have limited effectiveness. To make an appreciable dent, would require intelligent and conscious control. For years, advisories from the government have gone out to farmers asking them to use fertiliser judiciously but that is usually because of the heavy subsidies the government must bear to keep them cheap. It’s time to confront this and to frame the argument as one of environmental pollution. This is akin to the sensitising farmers about how stubble burning contributes to massive spikes in winter pollution in north India.

Nitrogen has helped humanity produce food on an unprecedented scale, but its environmental costs are becoming harder to ignore. At what point does a technological breakthrough become an ecological liability, and who should be held accountable?

Nearly everything is a liability when in excess. In my book, I give the example of oxygen. We imagine pure oxygen as indisputably ‘good.’ However the body’s cells can absorb oxygen only at a given rate. Paul Bert showed that oxygen at high pressure sent birds and mammals into convulsions and death, even with plenty to breathe, establishing that the same molecule sustaining life could also extinguish it. James Lorrain Smith then showed that milder excess, sustained over time, destroys lung tissue. The history of technology is rife with such examples.

If the ammonia from farms can combine with urban emissions to create dangerous PM2.5, does this mean that some of our most consequential air pollution interventions are targeting the wrong sources, or at least an incomplete picture of them?

An incomplete picture. For my book, I’ve interviewed scientists who say that so far it is unclear if reducing ammonia alone, or ammonia in combination with other sources of fossil pollution, can lead to measurable reduction in particular matter. But this ties into our overall paucity of scientific investigation into the links between chemical entities and health.

If India must feed a growing population while reducing pollution and greenhouse gas emissions, what would a genuinely different nitrogen economy look like, and what uncomfortable trade-offs would the country have to accept to build it?

It’s known for long that Indian agriculture expends too much fertiliser for a certain degree of yield. There are steps that can be taken to cut this wastage and in theory should not lead to higher prices. One of the doable approaches, as some scientists say, is to increase pulse production as well as boost its nitrogen use efficiency. This means moving away from the current regime that inordinately favours the rice-wheat system. However tinkering with agricultural systems can have political ramifications that may incentivise governments to avoid action. A different nitrogen economy can mean harnessing nitrogen from sewage or improving the nitrogen use efficiency of compost.