Grass-Legume Mixtures for Improved Yield, Quality, Persistence, and Economic Return.

Yield reduction and legume disappearance are common in grass-legume stands. The objectives of this study were to identify the optimum seeding proportion of grass and legume in mixtures and compare forage yield, forage quality, stand persistence, and economic return. Field experiments were established at two locations (Lingle and Laramie, Wyoming) in 2011-2012 growing season in fall and spring. Meadow bromegrass, orchardgrass, and alfalfa were the test species. There were 16 treatment combinations including monoculture grass, monoculture legume, two grass mixtures, one grass and one legume mixtures, and two grasses and one legume mixtures. Monoculture grass and two grass mixtures received either no nitrogen (N) or N fertilizer (150 kg N ha^-1 as urea) whereas grass-legume mixtures received no N fertilizer. The experimental design was a RCBD with three replicates. The plots were harvested 3-4 times each year from 2011-2012 to 2013-2014 growing seasons. Forage yield, forage quality, and alfalfa biomass proportion were measured at each harvest. The highest total dry matter (DM) yield (32,796 kg DM ha^-1 for 4 years) and economic return ($ 898 ha^-1 yr^-1) was obtained from 50-50% mixture of meadow bromegrass and alfalfa from fall planting at Lingle, and from 50-50% mixture of orchardgrass and  alfalfa from spring planting at Lingle (16,426 kg DM ha^-1 for 3 years, economic return $476 ha^-1 yr^-1) and Laramie (17,015 kg DM ha^-1 for 3 years, economic return $ 555 ha^-1 yr^-1). In general, forage quality was higher in grass-legume mixtures than 150 kg N ha^-1 grass monoculture plots. The 50-50% mixture of meadow bromegrass and alfalfa had constant grass and alfalfa stand during study period. These results indicate that 50-50% would be ideal for grass and alfalfa in mixture for improved forage yield, quality, stand persistence and economic return.