Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 24, 2000
Publication Date: N/A
Interpretive Summary: Cultivars used in grass-alfalfa mixtures for hay production in the semiarid Northern Great Plains have often lacked long-term productivity. This study was conducted to compare dry-matter yields of four commonly used grass cultivars in pure stands and in simple two-species mixtures with Rangelander alfalfa over a 5-year period. Two recently released cultivars of intermediate wheatgrass, Reliant and Manska, were included, and two nitrogen fertility levels were established by applying either 0 or 45 lb nitrogen per acre annually. Grass-alfalfa mixtures with no nitrogen fertilizer had higher yields than pure stands of grass that were fertilized. Reliant and Manska intermediate wheatgrass averaged higher yields than smooth brome and crested wheatgrass at both fertility levels when grown in pure stands and in mixtures with alfalfa. These data will promote use of the two improved intermediate wheatgrass cultivars in grass- -alfalfa mixtures to produce hay for beef cattle enterprises in the region. Persistent grass-alfalfa mixtures have both economic and environmental benefits over use of grass in pure stands.
Technical Abstract: 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 yields of grass monocultures and grass-alfalfa binary mixtures receiving annual applications of 0 and 50 kg N/ha over a 5-yr period. 'Reliant' and 'Manska' intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & Dewey], 'Lincoln' smooth brome (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 'Rangelander' alfalfa [Medicago sativa subsp. x varia (Martyn) Arcang.] on a Parshall fine sandy loam (coarse-loamy, mixed Pachic Haploborolls) near Mandan, ND. Plant stands of green needlegrass and switchgrass were inadequate, and yields were not measured. Comparing dry-matter yields and persistence of grass monocultures over 5 yr, smooth brome averaged 66 and 64% of intermediate wheatgrass at 0 and 50 kg N/ha, respectively, and crested wheatgrass averaged 59 and 64%, respectively, of intermediate wheatgrass at the two N levels. Total seasonal dry-matter yields from two cuttings averaged 8.74 and 2.71 Mg/ha, respectively, for grass-alfalfa mixtures and grass monocultures at 0 kg N/ha. At 50 kg N/ha, grass-alfalfa mixtures and grass monocultures averaged 8.72 and 5.04 Mg/ha dry-matter yield, respectively. Cultivars included in this study except those of green needlegrass and switchgrass would be suited for binary grass-alfalfa mixtures for dryland hay production in the Northern Great Plains.