Grass Dominance and Mixture Yield and Quality in Perennial Grass-Alfalfa Mixtures

The suitability of new, low-alkaloid reed canarygrass (Phalaris arundinacea L.) cultivars for intensively managed mixtures with modern alfalfa (Medicago sativa L.) cultivars is unknown. Our primary objective was to determine the grass dominance and yield, as well as total forage yield and quality of binary seedings of reed canarygrass, smooth bromegrass (Bromus inermis Leyss) and orchardgrass (Dactylis glomerata L.) with alfalfa. Field experiments were conducted on a Tallula silt loam (coarse-silty, mixed, mesic Typic Hapludoll) and on a Waukegan silt loam (fine-silty over sandy or sandy-skeletal, mixed mesic Typic Hapludoll). A low-alkaloid reed canarygrass germplasm (MN-76) and a recently released low alkaloid variety (Venture) generally had yields similar to a standard high-alkaloid reed canarygrass cultivar (Rise) when grown in mixture with alfalfa and subjected to a diversity of cutting schedules. Venture had less stand persistence than Rise in mixtures with alfalfa but similar yields and persistence in monoculture. Total mixture yields and forage quality were not consistently affected by grass species or reed canarygrass cultivar. There was a consistent negative relationship, however, between the proportion of grass in the mixture and total forage intake potential (NDF concentration). There was no consistent difference in total yields of mixtures and those of alfalfa monocultures or N-fertilized grass monocultures. When subject to four annual cuttings, the ultimate proportion of grass in mixtures was lower (average of 23% across locations) and proportion of alfalfa was greater for reed canarygrass-alfalfa mixtures than for orchardgrass-alfalfa mixtures (average grass proportion of 52%). This trend also occurred for three annual cuttings; however, the proportions of reed canarygrass and orchard-grass were less (18 and 46%, respectively). If grass dominance and yield are desired, orchardgrass was the superior species for mixture with alfalfa; however, for producers who desire a consistently small amount of grass composition with alfalfa and high forage quality, reed canarygrass was superior to smooth bromegrass or orchardgrass.