Management Effects on Productivity of Alfagraze Alfalfa-Tall Fescue Mixtures

Abstract

Persistence and productivity of grazing-tolerant «Alfagraze» alfalfa (Medicago sativa L.) grown with endophyte-free tall fescue (Festuca arundinacea Schreb.) is not well known. Our primary objectives were to determine yield and persistence of the grass and legume in mixture and monoculture with and without N fertilizer at three Georgia locations over 3 yr. Small-plot field experiments with four replications harvested at 4-wk intervals were conducted at Blairsville in the mountains on a Clifton clay loam (clayey, mixed, mesic Typic Hapludults) and at Eatonton in the lower Piedmont on a Davidson loam (clayey, kaolinitic, thermic, Humic Paleudult). The five treatments were «AU Triumph» tall fescue with 0 N; tall fescue with 50 lb N/acre in September, February, and April; tall fescue and Alfagraze alfalfa with 0 N; tall fescue + alfalfa with 50 lb N/acre in February; and alfalfa alone, all harvested at 4-wk intervals. At Athens in the Piedmont on Cecil sandy clay loam (clayey, thermic, kaolinitic Typic Hapludult) the same treatments were harvested at 3-, 4-, and 6-wk intervals. Alfagraze alfalfa persisted well and was productive in mixture with AU Triumph tall fescue with 0 N, averaging about 8000 lb/acre dry forage at the three locations when cut at 4-wk intervals over 3 yr. During the third year, alfalfa constituted 50 % or more of the mixture by estimate at 4- and 6-wk cutting invervals and greater than 25 % at the 3-wk interval with no additional N fertilizer. Alfalfa monoculture and tall fescue-alfalfa mixtures without N fertilization had similar annual yields, which were superior to grass monoculture with 150 lb N/acre except at Athens where unfavorable soil conditions hindered alfalfa growth. Nitrogen fertilization (50 lb N/acre) of mixtures increased total yield but did not affect percentage alfalfa in the forage. Summer production of alfalfa was superior to tall fescue. Results suggest that Alfagraze alfalfa adequately fertilized with P and K can be successfully grown with endotype-free tall fescue when harvested at 3- to 4-wk intervals, suggesting good persistence under rotational stocking with livestock