Reed canarygrass binary mixtures with alfalfa and birdsfoot trefoil in comparison to monocultures.

Maintenance of both components in a grass-legume mixture is an important objective of temperate perennial grassland management, yet one species is often lost from the stand within a few growing seasons. Factors were studied that influence the persistence of reed canarygrass (Phalaris arundinacea L.) in binary mixture with alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.). 2 divergent cycle-2 specific leaf weight (SLW) populations of reed canarygrass were grown in binary alternate-row mixture under a 3-cut-per-year management with each of 4 legume cultivars: Olympic and Baker alfalfa and Norcen and Dawn birdsfoot trefoil. By the 8st harvest, alfalfa had competitively excluded reed canarygrass. Calculations of relative yield total indicated that competition between alfalfa and reed canarygrass was for de Wit's different space (the 2 species limited by different factors to at least some extent and therefore at least somewhat complementary in their exploitation of environmental resources) at early harvests. Birdsfoot trefoil mixtures reached equilibrium by the spring after establishment, with botanical composition thereafter varying from 67 to 81% legume. In contrast to alfalfa-reed canarygrass mixtures, competition between birdsfoot trefoil and reed canarygrass was for the same space at early harvests and for different space at late harvests. No yield differences between SLW populations were found in mixture, although high SLW yielded 19% more than low SLW in monoculture over eight harvests. Reed canarygrass had higher in vitro digestible dry matter concentration in mixture than in monoculture as long as reed canarygrass yields in mixture did not exceed yields in monoculture. Legumes were taller and more mature in mixture than in monoculture at early harvests. Increased height and advanced maturity may be mechanisms responsible for the legume's dominance. Performance of forage species for agronomic and quality traits in monoculture, however, did not predict their performance in mixture.