Iron: The Forgotten Driver of Nitrous Oxide Production in Agricultural Soil

In response to rising interest over the years, many experiments and several models have been devised to understand emission of nitrous oxide (N(2)O) from agricultural soils. Notably absent from almost all of this discussion is iron, even though its role in both chemical and biochemical reactions that generate N(2)O was recognized well before research on N(2)O emission began to accelerate. We revisited iron by exploring its importance alongside other soil properties commonly believed to control N(2)O production in agricultural systems. A set of soils from California's main agricultural regions was used to observe N(2)O emission under conditions representative of typical field scenarios. Results of multivariate analysis showed that in five of the twelve different conditions studied, iron ranked higher than any other intrinsic soil property in explaining observed emissions across soils. Upcoming studies stand to gain valuable information by considering iron among the drivers of N(2)O emission, expanding the current framework to include coupling between biotic and abiotic reactions.