Study on fertilizer and smog is alarmist

Cameron Mauritson walks among his 350 acres of vines near Healdsburg last October.
Cameron Mauritson walks among his 350 acres of vines near Healdsburg last October. The New York Times

The Sacramento Bee published an article based on a study just published in Science Advances (“Fertilizer on farms a key source of smog, study says,” Page 1A, Feb. 1).

So readers can have a clearer view of work that has already been done on this issue, some additional information is in order. The contribution of nitrogen oxide from agricultural lands related to fertilizers has been studied for more than a decade in California by multiple regulatory agencies, including the state Air Resources Board, Department of Food and Agriculture, and state Energy Commission. The studies were conducted by academic institutions including UC Berkeley, Fresno State and UC Davis.


All of these multiyear studies have demonstrated that fertilizers on agricultural lands are minor contributors to nitrogen oxide. These studies have been reviewed by other scientists, agencies and agricultural groups.

The researchers behind the new study allege that prior studies are not correct because they did not evaluate emissions in agricultural areas. That is incorrect. Fresno State is located in the heart of California agriculture.

Unlike this study, the prior studies are based on actual on-site monitoring, not computer modeling, and use real application rates, not the highly exaggerated rates in this study. Previous research also looked at specific crops to evaluate if they pose higher risks.

What has been documented is that growers who apply fertilizers are minor contributors to nitrogen oxide. Even so, growers continue to be proactive so that as much as agronomically possible, all fertilizers reach their intended crops.

We hope that the researchers involved in this study take the time and effort to present their findings to agricultural groups and their scientists, and not just present findings via press releases or journals.

Kayla Gangl is director of communication and public outreach for the Western Plant Health Association, which represents fertilizer and crop protection manufacturers in California, Arizona and Hawaii. She can be contacted at