Nitrogen dynamics in multi-species grasslands

PhD defence, Wednesday 28 june 2017, Nawa Raj Dhamala

2017.06.28 | Helle Karvonen

Nawa Raj Dhamala

During his studies, Nawa Raj Dhamala investigated how inclusion of non-leguminous dicot forage herbs (forbs) chicory, ribwort plantain and caraway in the perennial ryegrass-red clover mixture, and species mixture containing only forage legumes red clover, white clover and lucerne influence plant production and Nitrogen (N) dynamics in temporary grasslands. He demonstrated addition of forbs to perennial ryegrass-red clover mixtures increases plant-diversity without affecting total biomass production, percentage of red clover N2 fixation, red clover N transfer to the companion non-legumes and short-term residual soil N fertility to the subsequent cereal crop in the rotation. Similarly, mixtures of only forage legumes increases plant-diversity with no negative effect on biomass production and percentage of N2 fixation.

The results from his study showed implications to design and implement multi-species temporary grasslands including forbs in the grass-clover mixture or only forage legumes combining the valuable inputs of N from legumes N2 fixation and efficient use of legume fixed N for plant production in low-input grassland agricultural systems.

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

This résumé was prepared by the PhD student.

Time: Wednesday 28 June 2017 at 10:00
Place: Auditorium, AU Foulum, Blichers Alle 20, 8830 Tjele
Title of dissertation: Nitrogen dynamics in temporary multi-species grasslands
Contact information: Nawa Raj Dhamala, e-mail:,, tel.: +45 91430207
Members of the assessment committee:
Head of Research Group, Jöelle Fustec, ESA, Ecole Supérieure d'Agriculture d'Angers, University of Angers, France
Senior Research Scientist,  Sissel Hansen, NORSØK, Norwegian Centre for Organic Agriculture, Norway
Senior Researcher, Chris Kjeldsen (chair), Department of Agroecology, Aarhus University
Main supervisor: Professor Jørgen Eriksen, Department of Agroecology, Aarhus University
Researcher, Jim Rasmussen, Department of Agroecology, Aarhus University
Senior Scientist, Karen Søegaard, Department of Agroecology, Aarhus University
Researcher, Georg Carlsson, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Sweden
Language: The PhD dissertation will be defended in English

The defence is public.
The dissertation 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 23.02.2018