Particulate organic matter predicts spatial variation in denitrification potential at the field scale
Emily R. Stuchiner,
Wyatt A. Jernigan,
Ziliang Zhang,
William C. Eddy,
Evan H. DeLucia,
Wendy H. Yang
Affiliations
Emily R. Stuchiner
Institute for Sustainability, Energy, and Environment, University of Illinois, Urbana-Champaign, IL, USA; Agroecosystem Sustainability Center, University of Illinois, Urbana-Champaign, IL, USA; Currently at Renewable and Sustainable Energy Institute, University of Colorado Boulder, CO, USA; Corresponding author.
Wyatt A. Jernigan
Institute for Sustainability, Energy, and Environment, University of Illinois, Urbana-Champaign, IL, USA; Agroecosystem Sustainability Center, University of Illinois, Urbana-Champaign, IL, USA
Ziliang Zhang
Institute for Sustainability, Energy, and Environment, University of Illinois, Urbana-Champaign, IL, USA; Agroecosystem Sustainability Center, University of Illinois, Urbana-Champaign, IL, USA; Currently at School of Ecology and Environment, Northwestern Polytechnical University, China
William C. Eddy
Institute for Sustainability, Energy, and Environment, University of Illinois, Urbana-Champaign, IL, USA; Agroecosystem Sustainability Center, University of Illinois, Urbana-Champaign, IL, USA; Department of Plant Biology, University of Illinois, Urbana-Champaign, IL, USA
Evan H. DeLucia
Institute for Sustainability, Energy, and Environment, University of Illinois, Urbana-Champaign, IL, USA; Agroecosystem Sustainability Center, University of Illinois, Urbana-Champaign, IL, USA; Department of Plant Biology, University of Illinois, Urbana-Champaign, IL, USA
Wendy H. Yang
Institute for Sustainability, Energy, and Environment, University of Illinois, Urbana-Champaign, IL, USA; Agroecosystem Sustainability Center, University of Illinois, Urbana-Champaign, IL, USA; Department of Plant Biology, University of Illinois, Urbana-Champaign, IL, USA
High spatiotemporal variability in soil nitrous oxide (N2O) fluxes challenges quantification and prediction of emissions to evaluate the climate change mitigation outcomes of sustainable agricultural practices. Triggers for large, short-lived N2O emission pulses, such as rainfall and fertilization, alter soil oxygen (O2) and nitrate (NO3–) availability to favor N2O production via denitrification. However, the organic C (OC) needed to fuel denitrification may exhibit subfield variation that constrains the potential for high denitrification rates to occur, leading to spatial variation in N2O hot moments. We tested the hypothesis that the particulate organic matter (POM) fraction of soil organic matter (SOM) controls subfield variation in denitrification potential by regulating availability of dissolved organic C (DOC), the form of OC used by denitrifiers. Among 38 soil samples collected across a maize field in central Illinois, USA, we found that potential denitrification rate was best predicted by POM C concentration (R2 = 0.35). Using multiple linear regression analysis that included other soil properties as explanatory variables, we found that POM C fraction of bulk soil (mg POM C/g SOC) was the most important predictor based on regression coefficient size (P < 0.01). Our results, which provide support for our hypothesis, suggest that consideration of the link between C and N cycling may be a key to predicting spatiotemporal variation in soil N2O emissions when denitrification is the dominant N2O source process.
