Undersowing rare arable plants in cereals as a new instrument in weed management - restoration ecology meets weed science

Weed control is necessary in agriculture, but it is also known to be one of the main drivers of plant biodiversity loss in agricultural landscapes. Since biodiversity is essential for ecosystem service provision, new approaches in weed management are needed to simultaneously increase biodiversity and prevent yield losses due to weed competition. In this study, we investigated the establishment of undersowing cereals with rare arable plant (RAP) species, their weed suppression ability, and influence on spring barley yield. We collected data at the species level for RAP and weed coverage and their fluctuations during a three-year on-farm trial (Hirrlingen), supplemented by a second one-year on-farm trial (Bettenreute) to confirm the results, both located in Southwestern Germany. The experiments were set up as randomised complete block designs with four treatments consisting of a control (1), a topsoil translocation (4), and two treatments with seeded RAP species mixtures at two levels (low (2) vs. high (3) number of seeds). Main analyses were done using plant coverage data (assessed according to Braun-Blanquet and re-transformed according to van der Maarel (2007)), and yield data (spring barley; each location for one season) for both locations. Biomass was only analysed for Bettenreute.