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N2O hotspots modeling - gaining an understanding of the physical and microbial processes associated with soil N cycling

During her PhD studies, Jie Zhang researched modeling methods to estimate the emissions of nitrous oxide (N2O), also known as the dominant ozone-depleting substance and a powerful greenhouse gas, from agricultural soils.

Photo: Jie Zhang

The expanding agricultural sector has been recognized as the largest contributor to the increasing N2O emissions, largely through emissions from agricultural soils after fertilization. Therefore, a greater understanding of the complexity of N2O production and emission in agricultural soils and quantification of N2O emissions are therefore urgently needed. Jie Zhang studied how to conduct and improve the approach of soil N2O hotspot modeling. While the existing process-based modelling showed to be a strong tool for understanding the natural interactions between microbes and soil environments, there are limitations that hinder hotspot modeling as revealed in her studies. Jie Zhang developed a novel model to simulate nitrogen (N) cycles and microbial dynamics in soil based on a laboratory incubation experiment. The new approach aims to provide a high-resolution prediction of N cycling in hotspot-associated soils. The research findings and strategies contribute to the development of scientific mechanistic understanding of the complex interplay between physical and microbial processes associated with soil N2O emissions.

The PhD study was completed at the Department of Agroecology, Faculty of Technical Sciences, Aarhus University.

This summary was prepared by the PhD student.

Time: Monday, 12 February 2024 at 13:00
Place: Auditorium Foulum, Aarhus University, Blichers Allé 20, 8830 Tjele
Title of PhD thesis: Modelling N2O emissions from soil: Explicit representation of organic hotspots (Position 1) (MNesEr)
Contact information: Jie Zhang, email: jiezh@agro.au.dk

Members of the assessment committee:
Professor Eric A. Davidson, Center for Environmental Science, University of Maryland

External researcher Merete Styczen, Section for Environmental Science, University of Copenhagen

Senior Researcher Anne Grete Kongsted, Department of Agroecology, Aarhus University (Chair)

Main supervisor:
Professor Søren O. Petersen, Department of Agroecology, Aarhus University

Professor Per-Erik Jansson, Department of Land and Water Resources Engineering (LWR), KTH Royal Institute of Technology

Researcher Wenxin Zhang, Department of Physical Geography and Ecosystem Science, Lund University

Language: The PhD dissertation will be defended in English