LAUSR

Assigned to Associate Editor Joao Vendramini. Abstract In order to utilize alfalfa (Medicago sativa L.), alone or in mixtures with grasses, defoliation management practices must be evaluated to assess their performance. The objective was to determine the forage accumulation (FA) and nutritive value of alfalfa grown as a monoculture (ALF) and in mixtures with tall fescue [Lolium arundinaceum (Schreb.) Darbyish] (ATF) or bermudagrass [Cynodon dactylon (L.) Pers] (ABG) subjected to four harvest intervals (clipped every 21, 28, 35, and 42 d). The study was conducted in Crossville, TN, and Charleston, OH, during the 2016 and 2017 growing seasons, and in Salisbury, NC, during the 2017 and 2018 growing seasons. Harvest intervals of 35 d or greater showed optimal FA, with greatest productivity in spring. In summer, the plot productivity of ATF was not different from ABG. The ATF mixture was superior to ABG in FA for the entire season. Although tall fescue can be very competitive with alfalfa in mixtures, it results in greater FA while reducing weed competition. Botanical composition indicated greater weed infestation in ALF than in mixtures. Growing alfalfa–grass mixtures can increase sward crude protein compared with grass monocultures (average of 128 g kg for ATF and 161 g kg for ABG). We conclude that harvest intervals of 35 d or longer should be adopted to provide greater FA, and the ALF and ATF treatments resulted in superior FA compared with ABG in the southern United States.