Comparison of Simultaneous Soil Profile N₂ O Concentration and Surface N₂ O Flux Measurements Overwinter and at Spring Thaw in an Agricultural Soil

Abstract

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Non‐Legume Cover Crops Can Increase Non‐Growing Season Nitrous Oxide Emissions

“…This provides evidence that the N 2 O flux was limited by NO 3 and that denitrification in the surface soil was an important source of over-winter N 2 O production (Tenuta and Sparling, 2011). This is consistent with other studies that have indicated de novo N 2 O production was a large N 2 O source over the non-growing season in temperate regions (Wagner-Riddle et al, 2008;Németh et al, 2014;Risk et al, 2014;Congreves et al, 2016). In Winter 2013-2014, there was no apparent correlation between pre-winter NO 3 levels and the mean winter N 2 O fluxes (Fig.…”

“…It appeared over-winter soil conditions favored the use of NO 3 by facultative anaerobes as a terminal electron acceptor. However, we cannot dismiss the physical release of N 2 O from the soil solution and soil layers beneath the thawed surface layer during the over-winter period, which represented 22% of spring thaw N 2 O emission in a temperate climate (Risk et al, 2014). Nevertheless, the major source of N 2 O production during these freeze-thaw transitions appears to be of biotic origin Wagner-Riddle et al, 2008;Risk et al, 2014;Wertz et al, 2016).…”

“…In the non-growing season, thaw events are associated with the greatest N 2 O fluxes and denitrification is considered the dominant N 2 O production pathway (WagnerRiddle et al, 2008;Risk et al, 2014). Denitrification occurs when O 2 availability is low, which is most affected by increasing soil water content (Linn and Doran, 1984;Wallenstein et al, 2006;Kool et al, 2011), and to a lesser extent when labile C stimulates heterotrophic microbial activity, creating O 2 depleted microsites (Parkin, 1987;Butterbach-Bahl et al, 2013).…”

Molecular techniques and stable isotope ratios at natural abundance give complementary inferences about N2O production pathways in an agricultural soil following a rainfall event

“…However in a different study, Heil et al (2014) To interpret subsurface N 2 O concentrations, we modelled the production, transport and storage of N 2 O in the subsurface on the three sampling dates. The soil was divided into three equally-sized layers from 0 to 45 cm and the total molar N 2 O content (gaseous and aqueous) in each 15 cm layer was determined (Risk et al, 2014). The total porosity (4; m 3 m À3 ) of each layer was determined according to:…”

“…The flux of N 2 O between layers was determined using a onedimensional gas diffusion model based on Fick's Law (Pumpanen et al, 2003;Pihlatie et al, 2007;Goldberg et al, 2008),…”