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Submitted to: Forage and Grazinglands
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/5/2012 Publication Date: 1/21/2013 Citation: Peel, M., Waldron, B.L., Jensen, K.B., Robins, J.G. 2013. Alfalfa and forage kochia improve nutritive value of semiarid rangelands. Forage and Grazinglands. doi:10.1094/FG-2013-121-01-RS. Interpretive Summary: Improving forage quality on semiarid grazing lands of the western United States is challenging. This study compared the late summer forage quality parameters crude protein (CP) and neutral detergent fiber (NDF) of 'Vavilov' Siberian wheatgrass, 'Mustang' Altai wildrye, two alfalfas and two forage kochias in monocultures and binary mixtures with each other at plant densities on 0.25, 0.5, 0.75, and 1.0 meter centers. Measurements were on individual components of species within mixtures. Overall CP of the alfalfas averaged 8.7%, and forage kochias averaged 9.6%. CP of the grasses was 4.3% and 7.9% for Vavilov and Mustang, respectively. The CP of individual species' components of the mixtures did not differ, or were plus or minus 1%, from their respective monoculture. Average NDF of forage kochia, alfalfa, and the grasses was 45, 50, and 63%, respectively. The NDF of individual species' components remained largely unchaged whether grown in a monoculture or mixture. The average CP of forage kochia in both mixtures and monocultures increased from 8.7 to 10.8% with increasing plant spacing. CP in the Mustang - S-Select forage kochia mixture decreased 3.4% from the 0.25 to 1.0 spacing; otherwise, CP did not change with plant spacing in the alfalfa and grass comparisons. NDF did not change with changing plant density. Under semiarid conditions, CP and NDF content of alfalfa, rangeland grasses and forage kochia are reflective of species' differences rather than neighboring plants or plant density. Technical Abstract: Improving forage quality on semiarid grazing lands of the western United States is challenging. This study compared the late summer forage quality parameters crude protein (CP) and neutral detergent fiber (NDF) of 'Vavilov' Siberian wheatgrass (Agropyron fragile). 'Mustang' Altai wildrye (Leymus angustus), two alfalfas (Medicago sativa) and two forage kochias (Kochia prostrata) in monocultures and binary mixtures with each other at plant densities on 0.25, 0.5, 0.75, and 1.0 m centers. Measurements were on individual components of species within mixtures. Overall CP of the alfalfas averaged 8.7%, and forage kochias averaged 9.6%. CP of the grasses was 4.3% and 7.9% for Vavilov and Mustang, respectively. The CP of individual species' components of the mixtures did not differ, or were plus or minus 1%, from their respective monoculture. Average NDF of forage kochia, alfalfa, and the grasses was 45, 50, and 63%, respectively. The NDF of individual species' components remained largely unchanged whether grown in a monoculture or mixture. The average CP of forage kochia in both mixtures and monocultures increased from 8.7 to 10.8% with increasing plant spacing. CP in the Mustang - S-Select forage kochia mixture decreased 3.4% from the 0.25 to 1.0 spacing; otherwise, CP did not change with plant spacing in the alfalfa and grass comparisons. NDF did not change with changing plant density. Under semiarid conditions, CP and NDF content of alfalfa, rangeland grasses and forage kochia are reflective of species' differences rather than neighboring plants or plant density. |
