Calibration of soil erosion models for perma-nent bioenergy crops.

Agricultural management systems are in transition amongst others through the promotion of renewable energy by legislations such as the renewable energy law (EEG) in Germany or the EU Green Deal. Biomass production as renewable energy source has been increased continuously. So far, maize is mostly used as feedstock in e.g. biogas plants. However, the production of maize as an energy crop has led to criticism due to an increased risk of water erosion and associated water body eutrophication. This problem is further aggravated through the increase in precipitation extremes due to climate change. Alternative strategies for biogas crop production are strongly required with permanent crops being of particular interest. Well-calibrated models are essential to make proficient statements about the erosion reduction potential of alternative biogas crops on erosion prone sites in order to support planting and political decisions. To calibrate soil erosion models, it is necessary to parameterise the underlying model equations. Monitoring and quantifying water erosion of soil is labour and time consuming and therefore rarely conducted. A case study is presented that addresses the quantification of soil erosion under commercial conditions and thus gains experimental data to calibrate and validate soil erosion models for permanent bioenergy crops. The study starting in 2021 is conducted in the Elm low mountain region near Braunschweig and on the Pfullendorfer young moraine landscapes near Sigmaringen. It compares in a randomized block design with three replicates conventional maize cultivation, direct seeding management of maize, and the permanent plant Silphium perfoliatum L. Preliminary data obtained during the year of experimental establishment (2021) demonstrated that the experimental design of the runoff plots will allow the calibration of the physically based model Erosion 3D. First erosive natural rainfall events with EI30 intensities ranging from 8 N/h up to 73 N/h. Additionally, artificial precipitation extremes will be simulated if necessary in 2022 and 2023. It is expected that increasing positive effects of the permanent crop will be seen with each additional year. [ABSTRACT FROM AUTHOR]