Measuring denitrification and the N2O:(N2O + N2) emission ratio from terrestrial soils

Friedl, Johannes; Cardenas, L. M.; Clough, Timothy J.; Dannenmann, Michael; Hu, Chunsheng; Scheer, Clemens

doi:10.1016/j.cosust.2020.08.006

Cited by 40 publications

(17 citation statements)

References 56 publications

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“…The total 15 N recovery determined in this study has some uncertainties. Gaseous N losses from soil included N 2 , NO x , and N 2 O, of which N 2 was the main product of denitrification (Friedl et al., 2020; Wang et al., 2020), accounting for an important ratio, even in acid soil (Qu et al., 2014). Thus, as this study only considered N 2 O emissions, the gaseous N losses might be greatly underestimated.…”

Section: Discussionmentioning

confidence: 99%

Long‐Term ¹⁵N Balance After Single‐Dose Input of ¹⁵N‐Labeled NH₄⁺ and NO₃⁻ in a Subtropical Forest Under Reducing N Deposition

Xie

Duan

et al. 2021

Global Biogeochemical Cycles

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Section: Discussionmentioning

confidence: 99%

Long‐Term ¹⁵N Balance After Single‐Dose Input of ¹⁵N‐Labeled NH₄⁺ and NO₃⁻ in a Subtropical Forest Under Reducing N Deposition

Xie

Duan

et al. 2021

Global Biogeochemical Cycles

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“…Data on denitrification rates reported in the literature is typically derived from laboratory incubation experiments, using inhibitors, 15 N tracers, or controlled systems with an N2 free atmosphere (Friedl et al, 2020). Disturbance associated with these experimental setups may enhance denitrification, thereby inflating estimates on terrestrial ecosystem N2 loss.…”

Section: Gross N2o Production Consumption and N2o:(n2o+n2) Ratiosmentioning

confidence: 99%

“…Over the past decades, various appraoches have been used to estimate total denitrification rates. These include, but are not limited to, acetylene-based inhibition methods, 15 N tracers, direct N2 quantification, N2:Ar ratio quantification, mass balance approaches, methods based on natural abundance stable isotopes of nitrous oxide (N2O), and molecular approaches (Groffman et al, 2006;Friedl et al, 2020). To date, none of these methods have adequately quantified total denitrification (gross N2O consumption) under field conditions over extended periods of time.…”

Section: Introductionmentioning

confidence: 99%

“…To date, none of these methods have adequately quantified total denitrification (gross N2O consumption) under field conditions over extended periods of time. Acetylene inhibition, N2:Ar ratio quantification and molecular approaches merely provide insights into potential denitrification and are not effective at quantifying absolute denitrification rates (Friedl et al, 2020;Gallarotti et al, 2021). 15 N tracers have been applied under field conditions, but were shown to underestimate total denitrification due to difficulties of homogenous mixing of tracers with substrate pools for denitrification in soil microsites (Wen et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Process Rate Estimator: A novel model to predict total denitrification using natural abundance stable isotopes of N₂O

Decock

Lee

Barthel

et al. 2022

Preprint

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Abstract. Total denitrification, the natural process capable of removing reactive N from ecosystems through conversion to N2, is one of the most poorly constrained processes in terrestrial N cycling. In situ quantification of total denitrification could help identify mitigation options for N pollution. This study provides proof-of-concept for a novel natural abundance isotope based model for depth differentiated in situ quantification of total denitrification; it does so by examining the use-case of the impact of wheat (Triticum aestivum) varieties with different root biomass on total denitrification. We set up a mesocosm experiment in 1.5 m tall lysimeters with four wheat varieties, each replicated three times. Temporal data for soil moisture, nitrous oxide (N2O) concentrations in the soil pore space, site preference (SP) and δ18O values of soil pore space N2O were collected at soil depths of 7.5, 30, 60, 90 and 120 cm over a five month growing period and used as input variables in the new model. Here, we define total denitrification as gross N2O consumption, with N2O produced either through nitrification or denitrification. The model, further referred to as ‘Process Rate Estimator’ or PRE, constrains temporally explicit gross N2O production and consumption rates at each depth increment based on a combination of diffusion and isotope mixing and fractionation models. Estimated production and consumption of N2O, integrated over the five month experiment, ranged from 3.9 to 170.3 kg N ha-1, with a trend for greater N2O production from denitrification compared to nitrification. N2O concentrations where greatest at 60 and 90 cm depth, while N2O production and consumption peaked at 7.5 and 30 cm depth, illustrating the important role of N2O dynamics along the soil profile in understanding ecosystem N budgets. Both N2O production and consumption were greater in varieties that had previously been characterized to have greater root biomass. We demonstrate that PRE is able to constrain nitrification and denitrification leading to gross daily N2O production, and gross reduction to N2 across the depth profile, based on the temporal change in concentrations, δ18O and SP of N2O. We conclude that our results support the potential of PRE to estimate total denitrification in situ, which could form the basis for developing promising strategies to reduce N pollution.

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“…was used to calculate 60% of all N 2 uxes. The headspace concentrations of N 2 O and N 2 were multiplied by the respective f p values giving N 2 and N 2 O produced via denitri cation (referred to as N 2 and N 2 O d ), with their respective uxes expressed in g N 2 or N 2 O d -N emitted g −1 soil day −1 .The between batch precision of the IRMS for N 2 based on the standard deviation of atmospheric air samples (n=36) at 95% con dence interval(Friedl et al 2020a) was 4.4 × 10 −7 and 6.61 × 10 −7 for 29 R and 30 R, respectively. The corresponding method detection limit ranged from 34 g N 2 -N ha −1 day −1 with a p assumed at 60 atom % to 303 g N 2 -N ha −1 day −1 with a p assumed at 20 atom %.Soil gas diffusivity D P /D O was calculated for 0 -10 cm soil depth using the structure dependent, water induced linear reduction model of Moldrup et al (2013) with the media complexity factor of 2.1 for intact soil.…”

mentioning

confidence: 99%

Amplitude and Frequency of Wetting and Drying Cycles Drive N2 and N2O Emissions From a Subtropical Pasture

Friedl

Deltedesco

Keiblinger

et al. 2022

Preprint

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Changes in amplitude and frequency of wetting and drying cycles in pasture systems due to climatic variation and irrigation management are likely to affect magnitude and partitioning of N2 and N2O emissions. This study investigated the effects of irrigation frequency on N2 and N2O emissions from an intensively managed pasture in the subtropics. Irrigation volumes were estimated to replace evapotranspiration and were applied either once (Low-Frequency) or split into four applications (High-Frequency). To test for legacy effects, a large rainfall event was simulated at the end of the experiment. Over 15 days, 7.9 ± 2.7 kg N2+N2O-N ha−1 was emitted on average regardless of irrigation frequency, with N2O accounting for 25% of overall N2+N2O. Repeated, small amounts of irrigation produced an equal amount of N2+N2O losses as a single, large irrigation event. The increase of N2O emissions after the large rainfall event was smaller in the High-Frequency treatment, shifting the N2O/(N2O+N2) ratio towards N2. Our findings suggest that reduced soil-gas diffusivity predominantly drives N2O and N2 emissions following large wetting events, while microbial O2 consumption largely drives N2O and N2 emissions after small, repeated wetting events in high N turnover pasture soils. The abundance of marker genes for N cycling did not differ between treatments, indicating that N and C availability, not gene abundance determined magnitude and N2O:N2 partitioning after rainfall. The observed legacy effect suggests that increased irrigation frequency can reduce the environmental impact (N2O), but not overall magnitude of N2O and N2 emissions from intensively managed pastures.

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Measuring denitrification and the N2O:(N2O + N2) emission ratio from terrestrial soils

Cited by 40 publications

References 56 publications

Long‐Term ¹⁵N Balance After Single‐Dose Input of ¹⁵N‐Labeled NH₄⁺ and NO₃⁻ in a Subtropical Forest Under Reducing N Deposition

Long‐Term ¹⁵N Balance After Single‐Dose Input of ¹⁵N‐Labeled NH₄⁺ and NO₃⁻ in a Subtropical Forest Under Reducing N Deposition

Process Rate Estimator: A novel model to predict total denitrification using natural abundance stable isotopes of N₂O

Amplitude and Frequency of Wetting and Drying Cycles Drive N2 and N2O Emissions From a Subtropical Pasture

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Measuring denitrification and the N2O:(N2O + N2) emission ratio from terrestrial soils

Cited by 40 publications

References 56 publications

Long‐Term 15N Balance After Single‐Dose Input of 15N‐Labeled NH4+ and NO3− in a Subtropical Forest Under Reducing N Deposition

Long‐Term 15N Balance After Single‐Dose Input of 15N‐Labeled NH4+ and NO3− in a Subtropical Forest Under Reducing N Deposition

Process Rate Estimator: A novel model to predict total denitrification using natural abundance stable isotopes of N2O

Amplitude and Frequency of Wetting and Drying Cycles Drive N2 and N2O Emissions From a Subtropical Pasture

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Product

Resources

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Long‐Term ¹⁵N Balance After Single‐Dose Input of ¹⁵N‐Labeled NH₄⁺ and NO₃⁻ in a Subtropical Forest Under Reducing N Deposition

Long‐Term ¹⁵N Balance After Single‐Dose Input of ¹⁵N‐Labeled NH₄⁺ and NO₃⁻ in a Subtropical Forest Under Reducing N Deposition

Process Rate Estimator: A novel model to predict total denitrification using natural abundance stable isotopes of N₂O