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Cover crops, soil structure and soil microbes – research for better modelling of N leaching in agriculture

PhD defense, Monday August 22nd 2022. Jorge Federico Miranda-Vélez

Jorge Federico Miranda Velez
This image shows an orthogonal projection of a soil µCT scan (grayscale), overlaid with a 3D image of the soil macropores, color-coded after local diameter. Large soil pores (macropores) are very important for the hydrology of soils, as water nutrients and pollutants can move very fast through them. Macropores are also thought to be hotspots for microbial activity and the mineralization of organic molecules containing N. As part of their PhD, Jorge Federico Miranda Vélez investigated how reduced tillage affects N leaching through macropores, as well as how macropores respond to freezing and thawing, a common disturbance in temperate climates.

During their PhD studies, Jorge Federico Miranda Vélez investigated different soil processes and properties that take part in the phenomenon of nitrogen (N) leaching in agriculture. N leaching depletes the soil from this essential plant nutrient and can lead to serious nutrient pollution in groundwater, rivers, lakes and oceans. Computer models of cropping systems (crop models) help scientists and advisors watch out for risks and research new strategies for sustainably reducing N leaching in agriculture. Jorge Federico Miranda Vélez investigated how N contained in cover crop residues is mineralized again by soil microbes, how tillage affects the way macropore water flow carries NO3- through the soil, and how the physical disturbance from freezing and thawing interacts with soil structure.

This research contributes to the continuing effort to achieve greater spatial, temporal and functional accuracy in crop models.

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

This summary was prepared by the PhD student.

Time: Monday, 22 August 2022 at 13:00
Place: 8814 -3075, Auditorium, Aarhus University, Blichers Allé 20, 8830 Tjele
Title of PhD thesis: Modelling nitrogen leaching in agriculture – Exploring interdependencies between cover crops, soil structure and organic matter turnover

Contact information: Jorge Federico Miranda Vélez, e-mail: jorge_mv@agro.au.dk, tel.: +45 30747037

Members of the assessment committee:

Professor Dr. Kurt-Christian Kersebaum, Ecosystem Modelling Group, Leibniz Centre for Agricultural Landscape Research (ZALF), Germany

Professor Dr. David Parsons, Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences (SLU), Sweden

Senior Researcher Dr. Jim Rasmussen (chair), Department of Agroecology, Aarhus University, Denmark

Main supervisor:
Senior Researcher Dr. Iris Vogeler, Department of Agroecology, Aarhus University, Denmark

Language: The PhD dissertation will be defended in English

The defense is public.
The PhD thesis is available for reading at the Graduate School of Technical Sciences/GSTS, Jens Baggesens Vej 53, building 5221, second floor, 8200 Aarhus N.

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