Agroecosystem tower for measuring greenhouse gas, water and energy fluxes

• Subject Area: Agriculture, Forestry and Veterinary Medicine
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 574305313

Agroecosystems play a significantly role in the global climate system through their soil organic carbon storage potential and their emission and consumption of GHGs, such as carbon dioxide (CO2) and nitrous oxide (N2O). Nitrous oxide is a potent GHG with a global warming potential 273 times than that of CO2. Agricultural soils are the largest anthropogenic N2O source, mostly due to the application of nitrogen (N) fertilizers. Thus, accurately quantifying N2O fluxes and understanding the mechanisms behind them is essential for the sustainable N management in agroecosystems. Agricultural management also influences energy partitioning into evapotranspiration (latent heat flux, LE) and sensible heat flux (H). Eddy covariance (EC) measurements enable continuous monitoring of gas and energy exchanges between ecosystems and the atmosphere and has long been used for measuring CO2 and energy fluxes (i.e. LE and H). However, EC measurements of N2O fluxes are limited due to recent availability of instru-ments capable of high-frequency N2O measurements that are suitable for long-term field deployment, and the sporadic and often minimal nature of the fluxes. Consequently, only a few flux towers worldwide measure N2O with EC. The proposed instrument is an EC flux tower designed to continuously measure at 30-minute resolution H, LE, net ecosystem exchange of CO2 (NEE) and N2O fluxes from a cropland. It will also include measurements of solar-induced-chlorophyll fluorescence (SIF), which can be used as a proxy for estimating photosynthesis and enables the partitioning of NEE into gross primary productivity (GPP) and ecosystem respiration (ER). In addition, continuous soil respiration measurements will be performed using automated chambers. The instrument will provide comprehensive measurements of meteorological and soil variables, as well as nitrate (NO3-) leaching, enabling robust assessments of CO2 and N2O fluxes, their drivers and the mechanisms responsible for the fluxes. This instrument will utilize state-of-the-art technologies, will run continuously, and is intended for long-term use. It has been designed to meet the highest technical requirements of the Ecosystem Stations (Class 1) within the Integrated Carbon Observation System (ICOS), the European network providing long-term and standardized observations of carbon cycling and GHG gases. The instrument will be installed at the Campus Klein-Altendorf (CKA) of the University of Bonn and is intended to be-come an ICOS Class 1 ecosystem station. Additionally, it will become part of international flux networks (Fluxnet) and will serve as a platform for collaborative research on ecosystem fluxes (e.g. within multidisciplinary projects such as PhenoRob2 and DETECT). This instrument will provide unique, high-quality data of global relevance on the capacity of cropping systems to mitigate and adapt to climate change.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Agrarökosystemturm zur Messung von Treibhausgas-, Wasser- und Energieflüssen
• Instrumentation Group: 0590 Sonstige meteorologische Geräte und Einrichtungen
• Applicant Institution: Rheinische Friedrich-Wilhelms-Universität Bonn
• Leader: Professorin Ana Meijide, Ph.D.