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Evaluation of denitrification and decomposition from three biogeochemical models using laboratory measurements of N-2, N2O and CO2

Grosz, Balazs and Well, Reinhard and Dechow, Rene and Koester, Jan Reent and Khalil, Mohammad Ibrahim and Merl, Simone and Rode, Andreas and Ziehmer, Bianca and Matson, Amanda and Hongxing, He (2021). Evaluation of denitrification and decomposition from three biogeochemical models using laboratory measurements of N-2, N2O and CO2. Biogeosciences. 18 , 5681-5697
[Research article]

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Abstract

Biogeochemical models are essential for the prediction and management of nitrogen (N) cycling in agroecosystems, but the accuracy of the denitrification and decomposition sub-modules is critical. Current models were developed before suitable soil N-2 flux data were available, which may have led to inaccuracies in how denitrification was described. New measurement techniques, using gas chromatography and isotope-ratio mass spectrometry (IRMS), have enabled the collection of more robust N-2, N2O and CO2 data. We incubated two arable soils - a silt-loam and a sand soil - for 34 and 58 d, respectively, with small field-relevant changes made to control factors during this period. For the silt-loam soil, seven treatments varying in moisture, bulk density and NO3- contents were included, with temperature changing during the incubation. The sandy soil was incubated with and without incorporation of litter (ryegrass), with temperature, water content and NO3- content changing during the incubation. The denitrification and decomposition sub-modules of DeNi, Coup and DNDC were tested using the data. No systematic calibration of the model parameters was conducted since our intention was to evaluate the general model structure or "default" model runs. Measured fluxes generally responded as expected to control factors. We assessed the direction of modeled responses to control factors using three categories: no response, a response in the same direction as measurements or a response in the opposite direction to measurements. DNDC responses were 14 %, 52% and 34 %, respectively. Coup responses were 47 %, 19% and 34 %, respectively. DeNi responses were 0 %, 67% and 33 %, respectively. The magnitudes of the modeled fluxes were underestimated by Coup and DNDC and overestimated by DeNi for the sandy soil, while there was no general trend for the silt-loam soil. None of the models was able to determine litter-induced decomposition correctly. To conclude, the currently used sub-modules are not able to consistently simulate the denitrification and decomposition processes. For better model evaluation and development, we need to design better experiments, take more frequent measurements, use new or updated measurement techniques, address model complexity, add missing processes to the models, calibrate denitrifier microbial dynamics, and evaluate the anaerobic soil volume concept.

Authors/Creators:Grosz, Balazs and Well, Reinhard and Dechow, Rene and Koester, Jan Reent and Khalil, Mohammad Ibrahim and Merl, Simone and Rode, Andreas and Ziehmer, Bianca and Matson, Amanda and Hongxing, He
Title:Evaluation of denitrification and decomposition from three biogeochemical models using laboratory measurements of N-2, N2O and CO2
Series Name/Journal:Biogeosciences
Year of publishing :2021
Volume:18
Page range:5681-5697
Number of Pages:17
Publisher:COPERNICUS GESELLSCHAFT MBH
ISSN:1726-4170
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
URN:NBN:urn:nbn:se:slu:epsilon-p-114256
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-114256
Additional ID:
Type of IDID
DOI10.5194/bg-18-5681-2021
Web of Science (WoS)000710803600001
ID Code:26022
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:04 Nov 2021 15:25
Metadata Last Modified:04 Nov 2021 15:31

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