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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #321114
Title: Forage production of grass-legume binary mixtures on Intermountain Western USA irrigated pastures

Author
item COX, STEVEN - Utah State University
item Peel, Michael
item CREECH, J - Utah State University
item Waldron, Blair
item EAN, JUNG-SU - Utah State University
item ZOBELL, DALE - Utah State University
item MILLER, RHONDA - Utah State University
item SNYDER, DON - Utah State University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2016
Publication Date: 3/9/2017
Citation: Cox, S., Peel, M., Creech, J.E., Waldron, B.L., Ean, J., Zobell, D.R., Miller, R.L., Snyder, D.L. 2017. Forage production of grass-legume binary mixtures on Intermountain Western USA irrigated pastures. Crop Science. 57:1742-1753.

Interpretive Summary: A well-managed irrigated pasture will have high forage production with the use of nitrogen fertilizer. The purpose of this study was to determine which grass-legume mixture and mixture planting ratio of the grasses tall fescue, meadow brome, orchardgrass, timothy, and perennial ryegrass when grown in a mixture with one of the legumes alfalfa, birdsfoot, or cicer milkvetch have high forage production and eliminate the need for nitrogen fertilizer. Mixtures were planted to obtain plant population ratios of 0:100 (legume monoculture), 25:75, 50:50, 75:25, and three 100:0 (grass monocultures), harvested four times seasonally in 2011-2013. The grass monocultures fertilized at 0.67 (low rate), or 134 (high rate) kg nitrogen ha-1. Seasonal forage production of the tall fescue-alfalfa mixture was 12.69 Mg ha-1, equal to tall fescue monoculture fertilized at a high rate. Alfalfa mixtures with meadow brome, orchardgrass, timothy and perennial ryegrass produced from 8 to 40% more forage than their respective grass monocultures fertilized at a high rate. Seasonal production of birdsfoot trefoil in mixtures with tall fescue, meadow brome, and orchardgrass were statistically equal to their respective grass monoculture fertilized at the high rate. Birdsfoot trefoil mixtures with timothy and perennial rye grass averaged 12% higher seasonal production than their respective grass monocultures fertilized at a high rate. Production of CMV-grass mixtures were similar to grass monocultures fertilized at the low rate. Seasonal distribution of forage production was more uniform in the alfalfa- and birdsfoot trefoil-grass mixtures than grass monocultures producing on average 30% more at the second and third harvests than the grass monocultures fertilized at a high rate. Forage production in the tall fescue- and meadow brome-legume mixtures was highest in the 50:50 planting ratios. The orchargrass- and timothy-legume mixtures the 50:50 and 25:75 ratios were similar to each other, with both producing more than the 75:25 ratio. In the perennial ryegrass-legume mixtures the 25:75 planting ratio were the most productive. Forage production of grass-legume mixtures can equal or exceed grass monocultures under high fertility and with more uniform distribution of forage over the growing season eliminating the need for nitrogen fertilizer.

Technical Abstract: A well-managed irrigated pasture is optimized for forage production with the use of N fertilizer which incurs extra expense. The objective was to determine which binary grass-legume mixture and mixture planting ratio of tall fescue (Festuca arundinacea Schreb.) (TF), meadow brome (Bromus biebersteinii Roem. & Schult.) (MB), orchardgrass (Dactylis glomerata L.) (OG), timothy (Phleum pratense L.) (TM), and perennial ryegrass (Lolium perenne L.) (PRG) when grown with alfalfa (Medicago sativa L.) (ALF), birdsfoot (Lotus corniculatus L.) (BFTF), or cicer milkvetch (Astragalus cicer L.) (CMV) maximize productivity without the use of N. Mixtures were planted to obtain plant population ratios of 0:100 (legume monoculture), 25:75, 50:50, 75:25, and three 100:0 (grass monocultures), harvested four times seasonally in 2011-2013. The grass monocultures fertilized at 0, 67,or 134 kg N ha-1. Seasonal forage production of the TF-ALF mixture was l2.69 Mg ha-1, equal to the TF monoculture fertilized at 134 kg N ha-1. ALF mixtures with MB, OG, TIM, and PRG yielded 12.57, 10.97, 11.77, and 10.74 Mg ha-1, respectively, 8 to 40% higher production than their respective grass monocultures fertilized at 134 kg N ha-1. Seasonal production of BFTF in mixtures with TF, MB, and OG were 11.69, 11.45, and 9.95 Mg Ha-1, respectively, and were no different than their respective grass monoculture fertilized at 134 kg N ha-1. BFTF mixtures with TIM and PRG averaged 12% higher seasonal production than their respective grass monocultures fertilized at 134 kg N ha-1. Production of CMV-grass mixtures were similar to grass monocultures fertilized at 67 kg N ha-1. Seasonal distribution of forage production was more uniform in the ALF- and BFTF-grass mixtures than grass-monocultures producing on average 30% more at the second and third harvests than the grass monocultures fertilized at 134 kg N ha-1. Forage production in the TF and MB legume mixtures averaged 7% higher in the 50:50 planting ratios than the 25:75 and 75:25, while in the OG and TIM-legume mixtures the 50:50 and 25:75 ratios were similar, producing on average 12% more than the 75:25 ratio. In the PRG-legume mixtures the 25:75 planting ratio averaged 9% more than the other two planting ratios. Forage production of grass-legume mixtures, particularly TF-ALF, TF-BFTF, and MB-ALF, can equal or exceed grass monocultures under high fertility and with more uniform distribution of forage over the growing season.