Inconsistencies undermine the conclusion that agriculture is a dominant source of NO x in California.

Almaraz et al. reported that agricultural soils are a dominant source of NO x pollution in California (20 to 32% of total statewide NO x emissions). However, this conclusion may be undermined by the lack of agreement between their modeled estimates and previously reported empirical measurements, the extrapolation of NO x fluxes during hot moments to derive annual estimates, and the overestimation of nitrogen fertilizer consumption in California.