Crop yields improve with reduced air pollution levels

Nitrogen oxides are actively making agricultural production less efficient, according to a new study.

One of the most common types of air pollutant, mainly produced through industrial and vehicle emissions, is having a detrimental impact on the yield of crops.

Scientists at Stanford University led a study looking at whether nitrogen oxides (NOx) change the productivity of farmland, and found the gases cause cell damage in crops and indirectly affect growth due to their role as precursors to the formation of ozone, a dangerous airborne toxin which is widely understood to reduce agricultural yields. 

‘Nitrogen oxides are invisible to humans, but new satellites have been able to map them with incredibly high precision. Since we can also measure crop production from space, this opened up the chance to rapidly improve our knowledge of how these gases affect agriculture in different regions,’ said study lead author David Lobell, the Gloria and Richard Kushel Director of Stanford’s Center on Food Security and the Environment.

It has long been known that nitrogen dioxides have the potential to cause harm to crops, but due to the disconnect between air monitoring stations and agricultural areas, and the confounding effects of different pollutants, research has previously been severely limited. To work around these problems, the team married satellite data on crop greenness with nitrogen dioxide levels between 2018 and 2020 – the primary nitrogen oxide which provides a good measure of overall levels and, due to its distinct interaction with ultraviolet light, can be measured at much higher spatial and temporal resolutions than other air pollutants. 

‘In addition to being more easily measured than other pollutants, nitrogen dioxide has the nice feature of being a primary pollutant, meaning it is directly emitted rather than formed in the atmosphere,’ said study co-author Jennifer Burney, an associate professor of environmental science at the University of California, San Diego. ‘That means relating emissions to impacts is much more straightforward than for other pollutants.’

According to the results, a 50% reduction in nitrogen oxides would improve yields by 25% for winter and 15% for summer crops in China, 10% for each in Western Europe, and 6% for winter and 8% for summer crops in India. Research also shows levels of the gases were lowest in North and South America.

The latest print issue of Air Quality News marks the magazine’s tenth birthday, and includes a feature looking at progress made in the fight against air pollution over the last decade – you can read the article online here. 

Image credit: Evi Radauscher