Influence of Grass Species on Composition, Yield, and Quality of Birdsfoot Trefoil Mixtures1

Abstract

AbstractMixtures with noncompetitive perennial grasses have been recommended to reduce weed invasion which commonly occurs in pure stands of birdsfoot trefoil (Lotus corniculatus L.). Our objective was to determine the potential of competitive vs. noncompetitive grass species in mixtures with birdsfoot trefoil to prevent weed invasion while maintaining stands with maximum birdsfoot trefoil composition and forage quality. ‘Leo’ and ‘Viking’ birdsfoot trefoil were established in monoculture and in binary mixtures with nine grass species on a Waukegan silt loam (fine‐silty over sandy, mixed, mesic Typic Hapludolls) in southeastern Minnesota. The same treatments, except one, were also established on a Cowhorn sandy loam (coarseloamy, mixed nonacid sand, frigid Aeric Haploquepts) in northcentral Minnesota. Conventional (when Leo reached first flower) and stockpiled (when Leo reached full bloom) harvest managements were applied for 2 years. Mixtures with high yielding competitive grasses (Phalaris arundinacea L., Bromus inermis Leyss., or Dactylis glomerata L.) had the least weed infestation and greatest weed‐free forage yield, but had consistently lower forage quality than the birdsfoot trefoil monoculture or mixtures with noncompetitive grasses (Phleum pratense L., K2‐106; Lolium perenne L.; or Poa pratensis L.) at the southeastern location. Competitive grasses also maximized birdsfoot trefoil persistence in southeastern Minnesota, while noncompetitive grasses and the birdsfoot trefoil monoculture maximized birdsfoot trefoil persistence in northcentral Minnesota. Relative mixture differences in weed infestation, forage quality, and yield were generally not affected by harvest management (stockpiled vs conventional). Stockpiled forage had lower quality than did conventionally harvested forage at both locations, and greater yields at the southeastern location. Stockpiled mixtures containing Leo had a greater final birdsfoot trefoil composition than did mixtures containing Viking only at the southeastern location. Birdsfoot trefoil cultivar selection did not affect final composition when mixtures were conventionally managed at either location. Because competitive vs noncompetitive grasses led to differing birdsfoot trefoil persistence depending on location, noncompetitive companion grasses may maximize birdsfoot trefoil persistence in mixtures in some environments, whereas competitive grasses may ultimately maximize birdsfoot trefoil in others. If forage quality is the primary concern, noncompetitive grasses should be used; if total weed‐free forage yield is the primary concern, competitive grasses may be advisable.