SPATIALLY DIFFERENTIATED SCENARIOS TO REDUCE AGRICULTURAL NITROGEN EMISSIONS

PhD defence, Thursday 17 May 2018, Fatemeh Hashemi.

2018.05.17 | Trine Berndt Turtiainen Scheelke

Fatemeh Hashemi

A review of 130 published articles was carried out with scenario-based modelling of methods for reducing the nutrient load to the aquatic environment. Based on this overview, new methods developed for scenario analysis in two Danish catchments (Norsminde and Odense) based on spatially differentiated aspects of nitrogen emissions (N) to the aquatic environment. Furthermore, the potential for actions in agriculture and in the landscape for reducing nitrate load was investigated in the Odense catchment. The methods were based on retention (reduction) of nitrate in groundwater, but since the mapping of this retention is subject to great uncertainty, new methods were developed to investigate the importance of the uncertainty for the effect of targeting actions (especially fallowing) relative to retention and N load. It was found that spatially differentiated strategies for N reduction can significantly reduce the N load with low impact on agricultural production, and this potential gain varies considerably between catchments, depending on spatial variation in groundwater N reduction and land use. However, it will be difficult to exploit the full potential in practice due to the current agricultural structure and the uncertainty associated with higher resolution of groundwater N-reduction maps. The results of the research contribute to a better understanding of how spatial variation in groundwater N reduction can be utilized to limit the nitrogen emissions from agriculture to the aquatic environment. From a methodological point of view, it provides a basis for realistic assessments of the possibilities for spatial targeting of N mitigation measures based on natural N reduction in Denmark.

The PhD degree was completed at the department of Agroecology, Science and Technology, Aarhus University.

This résumé was prepared by the PhD student.

Time:
Thursday 17 May 2018 at 10:00
Place:  Lecture Theatre, Aarhus University Foulum, Blichers Allé 20, 8830 Tjele
Title of PhD thesis: Methods for Assessing Spatially Differentiated Nitrogen Mitigation in Agriculture
Contact information:  Fatemeh Hashemi, e-mail: Fatemeh.hashemi@agro.au.dk, tel.: +45 26333547
Members of the assessment committee:
Professor Patrick Durand,  INRA UMR Sol Agro et hydrosystème Spatialisation, Agrohydrology-Team, France
Research Officer Karl Richards, Teagasc Crops Environmentla and Land Use Programme, Ireland
Senior Scientist Chris Kjeldsen  (chair), Department of Agroecology, Aarhus University
Main supervisor:
Professor Jørgen E. Olesen, Department of Agroecology, Aarhus University
Co-supervisor:
Senior scientist Christen D. Børgesen, Department of Agroecology, Aarhus University
Professor Tommy Dalgaard, Department of Agroecology, Aarhus University
Language: The PhD dissertation will be defended in English

The defence is public.
The PhD thesis is available for reading at the Graduate School of Science and Technology/GSST,
Ny Munkegade 120, building 1520, rooms 128-134, 8000 Aarhus C.

PhD defence
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Revised 17.05.2018