Data from: Nitrification is a minor source of nitrous oxide (N2O) in an agricultural landscape and declines with increasing management intensity

The long-term contribution of nitrification to nitrous oxide (N2O)
emissions from terrestrial ecosystems is poorly known and thus poorly
constrained in biogeochemical models. Here, using Bayesian inference to
couple 25 years of in situ N2O flux measurements with site-specific
Michaelis-Menten kinetics of nitrification-derived N2O, we test the
relative importance of nitrification-derived N2O across six cropped and
unmanaged ecosystems along a management intensity gradient in the U.S.
Midwest. We found that the maximum potential contribution from
nitrification to in situ N2O fluxes was 13-17% in a conventionally
fertilized annual cropping system, 27-42% in a low-input cover-cropped
annual cropping system, and 52-63% in perennial systems including a late
successional deciduous forest. Actual values are likely to be less than
10% of these values because of low N2O yields in cultured nitrifiers
(typically 0.04 to 8% of NH3 oxidized) and competing sinks for available
NH4+ in situ. Most nitrification-derived N2O was produced by ammonia
oxidizing bacteria (AOB) rather than archaea (AOA), who appeared
responsible for no more than 30% of nitrification-derived N2O production
in all but one ecosystem. Although the proportion of nitrification-derived
N2O production was lowest in annual cropping systems, these ecosystems
nevertheless produced more nitrification-derived N2O (higher Vmax) than
perennial and successional ecosystems. We conclude that nitrification is
minor relative to other sources of N2O in all ecosystems examined.