Yield of lucerne-grass mixtures did not differ from lucerne pure stands in a multi-site field experiment

• Published in: European journal of agronomy 2023-10, Vol.150, p.126927, Article 126927
• Main Authors: Glowacki, Sebastian Christoph, Komainda, Martin, Leisen, Edmund, Isselstein, Johannes
• Format: Article
• Language: English
• Subjects: agronomy; Alfalfa; atmospheric precipitation; Botanical composition; Dactylis glomerata; Festuca; Festuca arundinacea; field experimentation; forage; Forage legumes; forage yield; grasses; grasslands; Ley grassland; Medicago sativa; nitrogen; Northern European region; Orchard grass; soil; species; water shortages
• ISSN: 1161-0301; 1873-7331
• DOI: 10.1016/j.eja.2023.126927

Changing climatic conditions in north-western Europe require adaptations in management of ley grassland, requiring new grass-legume mixture designs in response to increased variability in precipitation and warmer summers. Evaluation of lucerne (Medicago sativa L.)-grass swards with the grasses cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.), which are potentially more tolerant to summer water shortage, have yet to be evaluated under the agro-climatic conditions of north-western Europe. We tested these grasses in three-species swards and binary lucerne grass swards and compared them against pure stands and a standard lucerne-grass mixture. The study was conducted in eight environments resulting from the combination of four soil sites during the two full main production years 2020 and 2021 with an annual precipitation range of 416–839 mm. Swards were harvested three to five times annually and the accumulated herbage dry matter (DM) and nitrogen (N) yields, as well as species proportions were recorded. We found an average yield of 11.1 t DM ha-1 and no significant differences in herbage DM yields between lucerne pure stands and the different mixture swards. This pattern was stable irrespective of environmental conditions, but in general herbage yield and aboveground N yield were affected by precipitation amount. Swards with cocksfoot had a greater grass proportion than those with tall fescue. The N yield of lucerne-grass swards was lower and declined as the grass proportion increased, and reached on average 353 kg N ha-1. The maximum N yield of lucerne pure stands was 547 kg N ha-1. Species mixtures yielded higher than expected from the pure stands (net mixture effect, NE) pointing at overyielding. Consequently, synergistic interspecific interactions occurred but did not lead to transgressive overyielding. The results indicate that the inclusion of grass species with tolerance to water shortage into lucerne-based swards offers the potential to diversify grasslands without losses of agronomic potential, at least during the first two main production years. •Lucerne pure stands were tested against binary and three-species mixtures with tall fescue and cocksfoot.•Precipitation had a strong positive influence on the productivity of all mixed swards.•Positive interspecific interactions in lucerne-grass swards resulted in overyielding without transgressive overyielding.•Grass identity effects were of less importance for yield and cock