Grass–Legume Proportions in Forage Seed Mixtures and Effects on Herbage Yield and Weed Abundance

Abstract

Formulating grass-legume mixtures requires knowledge of how the proportion of species in a seed mixture (i.e., species evenness) affects productivity and weed abundance. We hypothesized that mixtures with more equal proportions of species in the seed mixture (i.e., greater species evenness) would have greater productivity and fewer weeds than mixtures dominated by one or two species or monocultures. Two experiments with 15 mixtures and monocultures of orchardgrass (Dactylis glomerata L.), quackgrass (Elytrigia repens L.), alfalfa (Medicago sativa L.), and white clover (Trifolium repens L.) (Exp. 1) or 15 mixtures and monocultures of meadow fescue [Schedonorus pratensis (Huds.) P. Beauv.], reed canarygrass (Phalaris arundinacea L.), red clover (T. pratense L.), and kura clover (T. ambiguum L.) (Exp. 2) were sown in autumn 2008 at four locations in Pennsylvania and Wisconsin. In each experiment, there were four monocultures, four mixtures dominated by one species, six mixtures dominated by pairs of species, and one equal mixture. Mixtures and monocultures were harvested four to five times each year from 2009 to 2011. Mixtures often had more biomass than the average of legume or N-fertilized grass monocultures. Mixtures with more equal proportions of species in the seed mixture, however, did not have more biomass or fewer weeds than other mixtures. Rather, differences in yield were related to the dominant species in the mixture. Optimal legume percentages (30-40%) in the harvested biomass were achieved with a wide range of grass and legume seed proportions, which suggested that farmers have wide flexibility in formulating seed mixtures for pastures.

Grass and Legume Effects on Nutritive Value of Complex Forage Mixtures

“…Picasso et al (2008) . Similar results have been observed when the effects of species evenness on forage mass were tested; differences in mass were related to the dominant species in the mixture (Mulder et al, 2004;Sanderson et al, 2013). Botanical composition was used to calculate the additive effect of each species, or the expected change in nutritive value associated with a change in proportion of a species in the mixture from 0 to 100%.…”

“…In mixtures with one dominant species, forage NDF concentration was generally greatest in 2009 when orchardgrass constituted 70% of the sown mixture (Table 2). In mixtures with two dominant species, forage NDF concentration in 2009 was governed (increased by grasses; reduced by legumes) primarily by the species which contributed the greatest proportion of the mixture DM (Sanderson et al, 2013), due to greater initial seeding rate or superior growth in competition with other species. Few differences in NDF concentration existed among any of the mixtures in 2010.…”

Yield and energy balance of annual and perennial lignocellulosic crops for bio-refinery use: A 4-year field experiment in Belgium

“…Comparing the cropping systems at the low F level, the average annual DMY of the pasture mixture (18.2 t ha −1 y −1 ) was the second highest, after M. × giganteus (21.1 t ha −1 y −1 ). This stresses once more the positive effect of using mixtures of forage species with legumes on the energy efficiency by significantly reducing the need for fertilizer (Papadopoulos et al, 2012;Sanderson et al, 2013).…”

Floristic composition of vegetation in habitats suitable for Erigeron × huelsenii (Asteraceae)

“…In segetal habitats sampled for the study, in contrast, the process of secondary succession is hindered by the regular cutting of grass-legume crops for hay, thus there are no woody plant species. Nevertheless, many herbaceous plants can thrive in arable fi elds with grass-legume mixtures as weeds (Sanderson et al 2013), especially on poor sandy soils where the canopy of cultivated plants is usually not dense or there are gaps in the canopy. The results of principal component analysis (Fig.…”