Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Discussion papers
https://doi.org/10.5194/bg-2019-396
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-396
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 05 Nov 2019

Submitted as: research article | 05 Nov 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Measuring frequently during peak soil N2O emissions is more important than choosing the time of day to sample

Jordi T. Francis Clar and Robert P. Anex Jordi T. Francis Clar and Robert P. Anex
  • Department of Biological Systems Engineering, University of Wisconsin, Madison, 53706, USA

Abstract. Manual gas sampling from static soil chambers is commonly used to measure the flux of nitrous oxide (N2O) from soil. Because manual sampling is labour intensive, sampling frequencies are often insufficient to fully capture daily variability of N2O soil flux, which compromises the accuracy of estimates of daily and cumulative emissions. Knowledge of the diurnal fluctuation of N2O flux has been used to choose a flux sampling time that maximizes the accuracy of N2O flux estimates and thereby reduces the required frequency of flux measurements, but results of previous studies have been inconsistent. We analysed N2O soils emissions measured quasi-continuously over three years from a highly fertilized (> 200 kg N ha−1) maize system grown in southern Wisconsin, USA. This is the first study of N2O flux temporal variability that includes multiple difficult-to-measure peak emission events (hot moments) and estimates the relative contribution of hot moments to cumulative emissions. Analysis of diurnal fluctuation in N2O flux was performed using all measured data (≈ 22 000 fluxes) as well as using subsets of the data grouped by flux magnitude. The relationship between the observed hourly average flux and the mean daily flux was assessed using linear regression. Results show that diurnal variation in N2O soil flux was closely associated with normalized flux size. During low emission periods, N2O soil fluxes exhibited a diurnal pattern such that N2O flux measured at particular times of day, Preferred Measuring Times (PMTs), were not significantly different from the mean daily flux. During high emissions periods N2O flux did not exhibit a diurnal pattern and there was no PMT. High emissions periods included difficult-to-measure hot moments that did not exhibit a PMT and contributed up to 50 % of the cumulative emissions. We conclude that in order to accurately measure soil N2O flux in this type of system, it is necessary to sample frequently, particularly during peak flux events, and that constraining sampling to particular times of day provides little benefit.

Jordi T. Francis Clar and Robert P. Anex
Interactive discussion
Status: open (until 17 Dec 2019)
Status: open (until 17 Dec 2019)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Jordi T. Francis Clar and Robert P. Anex
Data sets

N2O Flux data J. Francis Clar and R. P. Anex https://doi.org/10.21231/6a7b-xy41

Model code and software

R Code, statistical analysis J. Francis Clar and R. P. Anex https://doi.org/10.21231/6a7b-xy41

Jordi T. Francis Clar and Robert P. Anex
Viewed  
Total article views: 166 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
126 39 1 166 2 2
  • HTML: 126
  • PDF: 39
  • XML: 1
  • Total: 166
  • BibTeX: 2
  • EndNote: 2
Views and downloads (calculated since 05 Nov 2019)
Cumulative views and downloads (calculated since 05 Nov 2019)
Viewed (geographical distribution)  
Total article views: 147 (including HTML, PDF, and XML) Thereof 147 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 16 Nov 2019
Publications Copernicus
Download
Short summary
The daily pattern of soil nitrous oxide (N2O) emissions has guided the choice of a sampling time meant to maximize the accuracy of N2O flux estimates. We analyzed several years of soil N2O emissions from a highly fertilized system including several difficult-to-measure peak emissions events. In this system, accurate estimation of N2O fluxes requires continuous and frequent sampling, especially during peak events; scheduled sampling based on the daily pattern of emissions provides little benefit.
The daily pattern of soil nitrous oxide (N2O) emissions has guided the choice of a sampling time...
Citation