BVOCs vary widely among different crops, an aspect that has been largely neglected in emission inventories. In particular, bioenergy-related species can emit mixtures of highly reactive compounds that have received little attention so far. For such species, long-term field observations of BVOC exchange from relevant crops covering different phenological phases are scarcely available. Therefore, we measured and modelled the emission of three prominent European bioenergy crops (maize, ryegrass, and oil-seed rape) for full rotations in north-eastern Germany. Using a proton transfer reaction–mass spectrometer combined with automatically-moving large canopy chambers, we were able to quantify the characteristic seasonal BVOC flux dynamics of each crop species. The measured BVOC fluxes were used to parameterize and evaluate the BVOC emission module (JJv) of the physiology-oriented LandscapeDNDC model, which was enhanced to cover de novo emissions as well as those from plant storage pools. Parameters are defined for each compound individually. The model is used for simulating total compound-specific reactivity over several years and also to evaluate the importance of these emissions for air chemistry. We can demonstrate substantial differences between the investigated crops with oil-seed rape having 37-fold higher total annual emissions than maize. However, due to a higher chemical reactivity of the emitted blend in maize, potential impacts on atmospheric OH-chemistry are only 6-fold higher.

BVOCs: PTR-QMS 500 (Inonicon Analytik GmbH, Innsbruck, Austria)

CO2: LI-840 gas analyzer (LICOR Bioscience, Lincoln, Nebraska, USA)

Ambient Air

CO2: April 2015 to September 2017

BVOCs: 24. July 2015 to 16. September 2015; 09. April 2016 to 20.MAy 2016; 09. June 2017 to 29. June 2017

Field experiment

2015: Zea mays L.; 2016: Brassica napus L.; 2017: Lolium multiflorum L.