Ag Today February 12, 2018

Ag leader critical, air officials cautious, about UC study on valley air pollution

BY STEVEN MAYER Feb 7, 2018 –

Roger Isom was not in a mood to be polite.

When the president and CEO of the Fresno-based Western Agricultural Processors Association read about a UC Davis study published last week that attributed a huge chunk of the air pollution in the San Joaquin Valley to emissions from fertilized farm fields, Isom was, at best, perplexed, and at worst, fighting mad.

And now he’s pushing back.

The study, published Jan. 31 in the research journal Science Advances, says unused fertilizer in agricultural soils contributes as much as 41 percent of nitrogen oxide, or NOx, the key air pollutant in the valley.

“There’s been plenty of previous research done that puts it not at 40 percent, but at 4 percent,” Isom said.

Indeed, Bart Croes, chief of research at the California Air Resources Board, or CARB, said a 2013 study — also connected to UC Davis — estimated 3.8 percent of the valley’s NOx is emitted by cropland. In fact, the new report recognizes that CARB officially uses the 3.8 percent estimate, but disagrees.

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