Modeling denitrification: Can we report what we don’t know?

Authors: GROSZ, BALÁZS - Thunen Institute Of Climate-Smart Agriculture; MATSON, AMANDA - Wageningen University And Research Center; WEIL, REINHARD - Thunen Institute Of Climate-Smart Agriculture; DECHOW, RENE - Thunen Institute Of Climate-Smart Agriculture; Del Grosso, Stephen - Steve; VOGELER, IRIS - Aarhus University; KUHNERT, MATTHIAS - University Of Aberdeen; HAAS, EDWIN - Karlsruhe Institute Of Technology; PETERSON, SØREN - Aarhus University; DIAMANTOPOULOS, EFSTATHIOS - University Of Bayreuth; KRAUS, DAVID - Karlsruhe Institute Of Technology; SIHI, DEBJANI - Emory University; HE, HONGXING - McGill University - Canada; DÖRSCH, PETER - Norwegian University Of Life Sciences; ZHANG, JIE - Aarhus University; LÉONARD, JOËL - Inrae; BUTTERBACH-BAH, KLAUS - Karlsruhe Institute Of Technology; CLOUGH, TIM - Lincoln University Of Missouri; HUI, DAFENG - Tennessee State University; YELURIPATI, JAGADEESH - University Of Aberdeen; KLEINEIDAM, KRISTINA - Justus-Liebig University; MÜLLER, CHRISTOPH - Justus-Liebig University; HENRI, CHRISTOPHER - Geological Survey Of Denmark And Greenland (GEUS); DAVIDSON, ERIC - University Of Maryland; SCHEER, CLEMENS - Karlsruhe Institute Of Technology

Submitted to: AGU Advances
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2023
Publication Date: 10/29/2023
Citation: Grosz, B., Matson, A., Weil, R., Dechow, R., Del Grosso, S.J., Vogeler, I., Kuhnert, M., Haas, E., Peterson, S., Diamantopoulos, E., Kraus, D., Sihi, D., He, H., Dörsch, P., Zhang, J., Léonard, J., Butterbach-Bah, K., Clough, T., Hui, D., Yeluripati, J., Kleineidam, K., Müller, C., Henri, C., Davidson, E., Scheer, C. 2023. Modeling denitrification: Can we report what we don’t know? AGU Advances. 4(6). Article e2023AV000990. https://doi.org/10.1029/2023AV000990.
DOI: https://doi.org/10.1029/2023AV000990

Interpretive Summary: Most ecosystem models calculate the entire nitrogen (N) balance to describe soil N turnover, but published results are generally limited to environmentally harmful N losses like nitrous oxide emissions and nitrate leaching. Scientists from USDA-ARS and colleagues argue that the publication and presentation of the full N cycle calculated by models is crucial for model development, quality control and model intercomparison. Although it would mean publishing some results that are not yet validated by measured data, we ask the ecosystem N modeling community to support and encourage the presentation of all relevant N model results. We focus mainly on denitrification and specifically the publishing of modeled molecular nitrogen (N2) emissions because this gas makes an important contribution to N budgets but is rarely measured under field conditions. This opinion paper will spur further model development and identify data gaps that should be prioritized in future observational studies.

Technical Abstract: Biogeochemical models are useful tools to simulate soil nitrogen (N) turnover and are often used to assess environmental N losses associated with the microbial processes of nitrification and denitrification. However, while the models themselves simulate complete ecosystem N cycling, only the results of specific N pools/processes of interest are usually published (often harmful N compounds like N2O, NO3-, NH3 or NOx). Presenting a full N balance would allow for more comprehensive model assessment, specifically with regard to needed developments, quality control and interoperability. Full N balances are likely not reported because they have not been validated with measured data. Field studies rarely include full N balances, especially if that requires measurements of N2 fluxes, which are very difficult. Limiting the publication of modeling results based on available field data is a missed opportunity to share knowledge and improve our understanding of modeled processes. In future denitrification studies, we ask the modeler community to support the publication of all simulated N pools and processes to whichever extent possible.