Performance of Cool‐Season Perennial Grasses in Pure Stands and in Mixtures with Legumes1

Abstract

AbstractClarification of relationships among species in mixed stands is essential to enlightened management of forage mixtures. During 1976–1979, we evaluated several grass‐legume mixtures in a field study in eastern Kansas. Grasses were: commercial smooth brome, Bromus inermis Leyss.; ‘Regar’ Turkish brome, B. biebersteinii Roem. &Schult.; ‘Kentucky 31’ tall fescue, Festuca arundinacea Scbreb.; and ‘Ioreed’ reed canarygrass, Phalaris arundinacea L. Legumes were: ‘Kanza’ alfalfa, Medicago sativa L.; ‘Kenstar’ red clover, Trifolium pratense L.; ‘Dawn’ birdsfoot trefoil, Lotus corniculatus L.; and ‘Emerald’ crownvetch, Coronilla varia L. Each grass was grown in a two‐species mixture with each legume, and in a pure stand with 0 and 90 kg N ha‐1 as NH4NO3. Mixtures were obtained by alternating all‐grass and all‐legume drill rows. Legumes were grown in pure stands in an adjacent planting. Both plantings were on a Woodson silt loam of the fine, mixed, thermic family in the Abruptic Argiaquolls subgroup of the Mollisols. Dry matter (DM) yields were obtained from all plots. Proportion of grass in mixtures was determined from hand‐harvested samples. Dry matter yield of the grass component of each mixture was computed as the product of the DM yield of the whole stand and the proportion of grass in the mixture. Crude protein (CP) contents of whole stands and grass components of mixtures were computed as 6.25 times N. Although comparisons varied across years, mixtures averaged as much grass DM (3.21 Mg ha‐1) as unfertilized all‐grass stands (3.07 Mg ha‐1) during the 4‐year period. Crude‐protein contents of grass components of mixtures consistently ranked above those of unfertilized all‐grass stands; differences usually were significant (P < 0.05) but varied in magnitude with year and type of stand. Legumes differed significantly (P < 0.05) every year in DM yield and every year except 1979 in CP content. Over the 4‐year period, however, no legume was clearly superior in either variable.