Open AccessNitrous oxide fluxes over establishing biofuel crops: Characterization of temporal variability using the cross‐wavelet analysis
Author(s) -
Zeri Marcelo,
Yang Wendy H.,
CunhaZeri Gisleine,
Gibson Christy D.,
Bernacchi Carl J.
Publication year - 2020
Publication title -
gcb bioenergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.378
H-Index - 63
eISSN - 1757-1707
pISSN - 1757-1693
DOI - 10.1111/gcbb.12728
Subject(s) - miscanthus , environmental science , panicum virgatum , eddy covariance , water content , nitrous oxide , biofuel , atmospheric sciences , agronomy , greenhouse gas , spatial variability , soil water , moisture , soil science , bioenergy , chemistry , ecosystem , ecology , mathematics , statistics , geotechnical engineering , organic chemistry , engineering , biology , geology
Emissions of nitrous oxide (N 2 O) over croplands are a major source of greenhouse gases to the atmosphere. The precise accounting of sources of N 2 O is essential to national and global budgets, as well as the understanding of the spatial and temporal relationships with environmental variables such as rainfall, air and soil temperature, and soil moisture. The objective of this work was to investigate the temporal correlations of N 2 O fluxes with soil and air temperatures, as well as soil moisture. N 2 O fluxes were measured over four biofuel crops in Central Illinois during their establishment phase. Measurements were carried out from 2009 to 2011 using a trace gas analyzer (TGA) with tunable laser technology. Measurements of concentrations of N 2 O and CO 2 were taken at the center of four plots of maize/soybean rotation, miscanthus ( Miscanthus × giganteus ), switchgrass ( Panicum virgatum ) and a mixture of native prairie plants. Cumulative fluxes indicate an average emission of nitrogen via N 2 O fluxes on the order of 1.5 kg N ha −1 year −1 , in agreement with chamber measurements previously reported for the site. N 2 O fluxes were associated with peaks in soil and air temperature, and soil moisture, particularly during spring and winter thaws. Cross‐wavelet analysis was used to investigate the correlation between N 2 O fluxes and those variables. Results indicate that N 2 O fluxes and meteorological variables have significant covariance in time scales ranging from 4 to 32 days. In addition, temporal delays of 1–8 days were found in those relationships. Cross‐wavelet patterns were similar when relating N 2 O fluxes with soil temperature, air temperature and soil moisture. The temporal patterns of fluxes and environmental variables reported here support the modeling of emissions and highlight the importance of considering the timing of fluxes in relation to trends in meteorological variables.