Dry matter yields of cool-season grass monocultures and grass-alfalfa binary mixtures

Cultivars used in grass-alfalfa (Medicago sativa L.) mixtures for hay production in the semiarid Northern Great Plains have often lacked long-term productivity. This study was conducted to compare dry matter (DM) yields of grass monocultures and grass-alfalfa binary mixtures receiving annual applications of 0 and 50 kg N ha(-1) over a 5-yr period. 'Reliant' and 'Manska' intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. and Dewey],'Lincoln' smooth bromegrass (Bromus inermis Leyss.),'Nordan' crested wheatgrass [Agropyron desertorum (Fisch.) Schult.],'Lodorm' green needlegrass (Stipa viridula Trin.), and 'Dacotah' switchgrass (Panicum virgatum L.) were seeded in monoculture and in binary mixtures with 'Range-lander' alfalfa [Medicago sativa subsp. x varia (Martyn) Arcang.] on a Parshall fine sandy loam (coarse-loamy, mixed, superactive, frigid, Pachic Haplustolls) near Mandan, ND. Plant stands of green needlegrass and switchgrass were inadequate, and yields were not measured. Total seasonal DM yields from two cuttings averaged 8.74 and 2.71 Mg ha(-1), respectively, for grass-alfalfa mixtures and grass monocultures at 0 kg N ha(-1). At 50 kg N ha(-1) grass-alfalfa mixtures and grass monocultures averaged 8.72 and 5.04 Mg ha(-1) DM yield, respectively. Yields of the grass component of first cut grass-alfalfa mixtures averaged 35% of total yield for intermediate wheatgrass, 33% of total yield for smooth bromegrass, and 30% of total yield for crested wheatgrass in the fifth production year. Cultivars included in this study, except those of green needlegrass and switchgrass, would be suited for use in binary grass-alfalfa mixtures for dryland hay production in the Northern Great Plains.