Sod-Seeding Alfalfa into Cool-season Grasses and Grass-Alfalfa Mixtures Using Glyphosate or Paraquat

Abstract

Sod-seeding alfalfa into swards of smooth and meadow bromegrass, tall and intermediate wheatgrass, and orchardgrass and mixtures of these grasses with alfalfa using glyphosate or paraquat to suppress the existing vegetation was evaluated. Glyphosate (1.7 kg/ha) or paraquat (0.6 kg/ha) was applied 12 days prior to sod-seeding alfalfa (645 PLS/m2). Glyphosate completely suppressed or killed all the grasses and as a result, excellent stands of alfalfa were obtained producing 5.8 to 6.4 Mg/ha the establishment year at Mead, Neb., without irrigation. The grass-alfalfa mixtures were also converted into pure stands of alfalfa by using glyphosate. Glyphosate suppressed but did not kill the existing alfalfa. Sod-seeding in pure stands of grasses following paraquat application produced stands that were approximately 50% grass and 50% alfalfa. Paraquat had a limited suppressive effect on alfalfa and sod-seeded alfalfa did not become established in plots containing old alfalfa.