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The project holds its annual meeting with all partners at AU Campus on the 5^th February 2025.

Shristi Khanal has joined orgANIC as a PhD at the Dept. of Agroecology – Climate and Water at Aarhus University. Shristi is a graduate in Soil Science and Global Changes (IMSOGLO) from Ghent University and has a keen interest in soil biogeochemical cycling, nitrogen use efficiency and effective research-extension approaches.

Her PhD will be focused on DON leaching with the following project description:

DON leaching study- Project orgANiC

The release of different forms of Nitrogen into the environment is closely associated with agricultural practices and fossil fuel combustion, which are fundamentally linked to food production and energy conversion. Nitrogen in soil undergoes various transformation processes, some of which result in its loss from soil–plant systems, contributing to environmental pollution in water bodies and the atmosphere. This study delves into one of the key nitrogen loss pathways, specifically focusing on DON (Dissolved Organic Nitrogen) leaching with following objectives.

1. Quantification of OM and ON leaching in soil water from different combinations of climate, soil types and cropping systems
2. Quantification of occurrence and losses of DON to deeper soil layers
3. Utilization of nano-LC-FT-ICR-MS method to directly analyze DOM and its molecular composition

Several existing and ongoing long-term experiments of Aarhus University at three locations in Denmark (Askov, Foulum and Flakkebjerg) will be utilized to test effects of different factors on DON leaching:

• tillage intensity,
• cover crop,
• grassland termination,
• crop type,
• fertilizer type and levels,
• crop rotation history and type

Likewise, measurements of molecular composition of DOM and DON at different depths utilizing the long-term experiments, PLAP and LOOP fields will be done to study transformation processes occurring in the upper 1 m and up to 5 m depth in soil. Furthermore, the conventional subtraction method to calculate DON concentration will be compared to the direct measurement of DON using the Size Exclusion Chromatography.

• The project held its kickoff meeting with all partners at AU Campus on the 2^nd February 2024.
• The project held its 2^nd all partner meeting at AU Campus on the 28^th May 2024.
• The project held its 3^nd all partner meeting at Agroecology, AU in Foulum on Monday 16^th September 2024.