Aarhus University Seal / Aarhus Universitets segl

Nitrogen fertilization of grass-clover – importance of N2-fixation and botanical composition

PhD defence, Tuesday 5 April 2022, Rebekka Kjeldgaard Kristensen

Portrait of Rebekka Kjeldgaard Kristensen
Photo: Rebekka Kjeldgaard Kristensen

During her studies Rebekka studied the fertilizer nitrogen dynamics in grass-clover, a common agricultural crop used for cattle feed all over the world. Grass-clover is very beneficial in terms of nitrogen acquisition since clover, opposite grass, fix N2 from the atmosphere. Rebekka studied how different types and rates of nitrogen fertilizers (i.e. cattle slurry and mineral nitrogen fertilizers) affected N2-fixation activity and clover proportion of the sward.

The new research findings contributes in understanding the importance of knowing the actual N2-fixation activity and clover proportion when optimizing nitrogen use efficiency in temporary and permanent grasslands.

The PhD degree was completed at Institute of Agroecology, Faculty of Technical Sciences, Aarhus University.

This summary was prepared by the PhD student.

Time: Tuesday 5 April 2022 at 10.00
Place: Building 8814, room 3075, Auditorium (250 Videolink), Institute of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele
Title of dissertation: The dynamics of nitrogen fixation and grass/clover proportions in grass-clover swards influenced by the type and amount of nitrogen fertilizer applied 
Contact information: Rebekka Kjeldgaard Kristensen, e-mail:rekk@au.dk , tel.: +45 60920454
Members of the assessment committee:
Senior scientist Ralf Loges, Institute of Crop Science and Plant Breeding, Christian-Albrechts-University, Germany

Associate professor Sigrun Dahlin, Department of Soil and Environment, Swedish University of Agricultural Sciences, Sweden
Senior researcher Per L. Gregersen (chair), Department of Agroecology, Aarhus University, Denmark
Main supervisor:
Professor Jørgen Eriksen, Agroecology, Aarhus University
Co-supervisor:
Senior researcher Jim Rasmussen, 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 Technical Sciences/GSTS, Katrinebjergvej 89F, building 5132, 8200 Aarhus N.