Improved isotopic model based on 15N tracing and Rayleightype isotope fractionation for simulating differential sources of N2O emissions in a clay grassland soil
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Castellano Hinojosa, Antonio; Loick, Nadine; Dixon, Elisabeth; Matthews, G. Peter; Lewicka Szczebak, Dominika; Well, Reinhard; Bol, Roland; Charteris, Alice; Cardenas, LauraEditorial
Wiley
Date
2019Referencia bibliográfica
Castellano‐Hinojosa, A., Loick, N., Dixon, E., Matthews, G. P., Lewicka‐Szczebak, D., Well, R., ... & Cardenas, L. (2019). Improved isotopic model based on 15N tracing and Rayleigh‐type isotope fractionation for simulating differential sources of N2O emissions in a clay grassland soil. Rapid communications in mass spectrometry, 33(5), 449-460.
Sponsorship
This study was funded by BBSRC project BB/K001051/1. D.Abstract
Isotopic signatures of N2O can help distinguish between two sources
(fertiliser N or endogenous soil N) of N2O emissions. The contribution of each
source to N2O emissions after N‐application is difficult to determine. Here,
isotopologue signatures of emitted N2O are used in an improved isotopic model
based on Rayleigh‐type equations. The spatial dispersal of N and C significantly affected the quantity, but not
the timing, of gas fluxes. Cumulative emissions are larger for treatment 3c than
treatment 1c. The 15N‐enrichment analysis shows that initially ~70% of the emitted
N2O derived from the applied amendment followed by a constant decrease. The
decrease in contribution of the fertiliser N‐pool after an initial increase is sooner
and larger for treatment 1c. The Rayleigh‐type model applied to N2O isotopocules
data (δ15Nbulk‐N2O values) shows poor agreement with the measurements for the
original one‐pool model for treatment 1c; the two‐pool models gives better results
when using a third‐order polynomial equation. In contrast, in treatment 3c little
difference is observed between the two modelling approaches. The importance of N2O emissions from different N‐pools in soil for the
interpretation of N2O isotopocules data was demonstrated using a Rayleigh‐type
model. Earlier statements concerning exponential increase in native soil nitrate pool
activity highlighted in previous studies should be replaced with a polynomial increase
with dependency on both N‐pool sizes.