Agricultural soil emissions impact population health and climate

Agricultural soil pollution comes from the prairie, but its economic impact on humans is a problem for cities.

Agricultural soil emissions impact population health and climate

A study led by environmental scientists at Rice University’s George R. Brown School of Engineering puts numbers to the toll of reactive nitrogen species produced in America’s croplands. The study led by Daniel Cohan, an associate professor of civil and environmental engineering, and graduate student Lina Luo quantifies emissions of nitrogen oxides, ammonia and nitrous oxide from fertilized soils over three years (2011, 2012 and 2017) and compares their impacts by region on air quality, health and climate.

While seasonal and regional impacts differ across types of emission, the study found total annual damages from ammonia were much larger overall — at $72 billion — than those from nitrogen oxides ($12 billion) and nitrous oxide ($13 billion).Air pollution damages are measured by increased mortality and morbidity and the value of statistical life, while monetized damages from climate change include the threats to crops, property, ecosystem services and human health. On that basis, the researchers found the health impact of air pollution from ammonia and nitrogen oxides, which react to form particulate matter and ozone, substantially outweighed climate impact from nitrous oxide in all regions and years.

The highest social costs arose from agriculture-heavy regions of California, Florida and the Midwest, where ammonia and nitrogen oxides form air pollution upwind of population centers. For both pollutants, emissions peak in the spring after fertilizers are applied. The study in the American Chemical Society journal Environmental Science & Technology concludes air pollution, health and climate should all be considered in future assessments of how farming practices affect reactive nitrogen emissions.She noted farming strategies that reduce greenhouse gases can increase air pollutants and vice versa. “We need to see if they can reduce all three nitrogen species — or make some tradeoffs and still not decrease crop yield,”

Nitrogen is essential for crop growth, Cohan added, but the study shows the importance of controlling Agricultural soil emissions has been largely neglected by air quality management and climate policy, even as the Environmental Protection Agency considers tightening air quality standards and the Biden administration seeks to slash greenhouse gas emissions.He said federal agencies have focused on controlling transportation and industrial emissions, leaving agriculture as the largest source of damaging nitrogen pollutants in the United States, a problem exacerbated by climate change and increased crop production. “Our group had been studying nitrogen oxide emissions for a number of years and began to realize that we can’t just focus on that,” Cohan said. “We needed to consider the range of emissions that come from soils, and we became curious about the relative impacts of different air pollutants and greenhouse gases the emanate from agricultural soils.

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