Binary legume-grass mixtures improve forage yield, quality, and seasonal distribution

Yield and forage quality of kura clover (Trifolium ambiguum Bieb.) and intermediate wheatgrass [Thinopyrum intermedium (Host.) Barkw. & D.R. Dewey] mixtures compared with commonly grown forages such as alfalfa (Medicago sativa L.) and smooth bromegrass (Bromus inermis Leyss.) have not been fully explored. Our objective was to evaluate the effects of alfalfa, birdsfoot trefoil (Lotus corniculatus L.), and kura clover grown in binary mixtures with orchardgrass (Dactylis glomerata L.), smooth bromegrass, and intermediate wheatgrass on seasonal distribution of forage yield and quality. Plots of each species in monoculture and binary legume-grass mixtures were established in a randomized complete block design in 1994 near Boone, IA. Yield was measured monthly during the 1995 and 1996 seasons. In vitro dry matter digestibility (IVDMD), neutral-detergent fiber (NDF), and crude protein (CP) concentrations were determined for each monoculture or mixture. Total yield was highest for monoculture alfalfa, alfalfa-intermediate wheatgrass, and alfalfa-smooth bromegrass with 13 400, 12 700, and 12 600 kg ha(-1) respectively in 1995, and 7500, 6800, and 6700 kg ha(-1) respectively, in 1996. Kura clover had the lowest NDF (357 g kg(-1)) and highest IVDMD (740 g kg(-1)) concentrations compared with other forages. Yield, CP, and IVDMD concentrations of monoculture grasses were lower than those of the legume-grass mixtures or of the monoculture legumes. Legumes improved the seasonal distribution of yield and forage quality by beig more productive at later harvests. Yield of alfalfa-intermediate wheatgrass was equal to or better than other alfalfa-grass mixtures and could make a valuable legume-grass alternative.