Performance of irrigated tall fescue-legume communities under two grazing frequencies in the southern Rocky Mountains, USA
2006
Lauriault, L.M. | Guldan, S.J. | Martin, C.A. | VanLeeuwen, D.M.
Irrigated pastures form a significant component of agriculture in the irrigated steppe of the southern Rocky Mountains, USA. Information is limited, however, describing performance of grazed binary perennial cool-season grass-legume mixtures in the region. Established monoculture tall fescue [Festuca arundinacea Schreb. = Lolium arundinaceum (Schreb.) S.J. Darbyshire] + 134 kg N ha(-1) (MONO) and tall fescue mixed with alfalfa (Medicago sativa L.) (ALF/TF), birdsfoot trefoil (Lotus corniculatus L.) (BFT/TF), cicer milkvetch (Astragalus cicer L.) (CM/TF), or kura clover (Trifolium ambiguum M.B.) (KC/TF) at New Mexico State University's Sustainable Agriculture Science Center at Alcalde were subjected to two grazing frequencies (grazed monthly or bimonthly mid-May to mid-September) from 1998 to 2000. Grass, legume, and combined dry matter (DM) yields were measured in May 1998 to 2001. A year x grazing frequency x pasture interaction for legume DM yield was moderated by a lack of effect in grass DM yield, leaving a year x pasture interaction for combined DM yield in which MONO, ALF/TF, and CM/TF increased linearly across years and cubic trends were exhibited by ALF/TF and KC/TF. Despite the cubic trend of KC/TF, it and BFT/TF had the most uniform yield distribution across years because of nonsignificant linear effects. Annual combined DM yield averaged 2.21, 3.90, 2.43, 1.93, and 3.03 Mg ha(-1) for MONO, ALF/TF, BFT/TF, CM/TF, and KC/TF, respectively, from 1998 to 2001 (5% LSD = 0.77). Kura clover-tall fescue offers an alternative to alfalfa-tall fescue for long-term pastures in the irrigated steppe of the southern Rocky Mountains.
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