A test of a field-based 15N-nitrous oxide pool dilution technique to measure gross N 2O production in soil

Wendy H. Yang, Yit Arn Teh, Whendee L. Silver

Research output: Contribution to journalArticlepeer-review

Abstract

Soils are both a major source and sink of nitrous oxide (N 2O), but the proportion of soil N 2O production released to the atmosphere (termed the N 2O yield) is poorly constrained due to the difficulty in measuring gross N 2O production. The quantification of gross N 2O fluxes would greatly improve our ability to predict N 2O dynamics across the soil-atmosphere interface. We report a new approach, the 15N 2O pool dilution technique, to measure rates of gross N 2O production and consumption under laboratory and field conditions. In the laboratory, gross N 2O production and consumption compared well between the 15N 2O pool dilution and acetylene inhibition methods whereas the 15NO 3 - tracer method measured significantly higher rates. In the field, N 2O emissions were not significantly affected by increasing chamber headspace concentrations up to 100 ppb 15N 2O. The pool dilution model estimates of 14N 2O and 15N 2O concentrations as well as net N 2O fluxes fit observed data very well, suggesting that the technique yielded robust estimates of gross N 2O production. Estimated gross N 2O consumption rates were underestimated relative to rates calculated as the difference between gross and net N 2O production rates, possibly due to heterogeneous and/or inadequate tracer diffusion to deeper layers in the soil profile. Gross N 2O production rates were high, averaging 8.4 ± 3.2 mg N m -2 day -1, and were most strongly correlated to mineral nitrogen concentrations and denitrifying enzyme activity (R 2 = 0.73). Gross N 2O production rates varied spatially, with the highest rates in soils with the best drainage and the highest mineral N availability. Estimated and calculated N 2O consumption rates constrained the average N 2O yield from 0.70 to 0.84. Our results demonstrate that the 15N 2O pool dilution technique can provide well-constrained estimates of N 2O yields and field rates of gross N 2O production correlated to soil characteristics, improving our understanding of terrestrial N 2O dynamics.

Original languageEnglish (US)
Pages (from-to)3577-3588
Number of pages12
JournalGlobal change biology
Volume17
Issue number12
DOIs
StatePublished - Dec 2011
Externally publishedYes

Keywords

  • Denitrification
  • N O yield
  • Nitrous oxide
  • Pool dilution
  • Sacramento-San Joaquin Delta

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • General Environmental Science

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