Influence of contrasting environments on forage quality of ryegrass and four legumes growing in binary swards

Forage legumes are valuable alternatives for mineral N fertilizers in grassland, due to their N fixing capacity and the assumed increase in forage quality of the sward. However, forage quality of binary swards may differ in response to site and legume species. The objective of the present study, carried out within the frame of the COST Action 852, was to identify the influence of legume species growing in contrasting environments on legume proportion, crude protein (CP) and metabolisable energy (ME) contents. At each of the five participating sites the experiment was carried out as a completely randomized block design with three replications. Four legume species were tested: white clover, red clover, alfalfa and birdsfoot trefoil. The first cut was performed in spring after first node detection in grass and repeated 30±3 days afterwards (5-cut system). Legume proportion varied largely from 5% to 79%, with birdsfoot trefoil showing the lowest legume proportion in the swards across sites. Alfalfa had the highest N contents at all sites. Results show that, especially in ME content, legumes are less responsive to variation due to contrasting environments than the companion grass.