PRODUCTIVITY, AND COMPOSITION OF SMOOTH AND MEADOW BROMEGRASS MIXTURES WITH ALFALFA UNDER FREQUENT CUTTING MANAGEMENT

The value of smooth bromegrass (Bromus inermis Leyss.)-alfalfa (Medica go sativa L.) mixtures for pastures in central Alberta is limited by p oor seasonal distribution of yield and low alfalfa persistence. Regrow th of meadow bromegrass (Bromus riparius Rehm.) exceeds that of smooth bromegrass. The effect of these grasses on yield, seasonal distributi on and sward composition when grown in mixtures with alfalfa was evalu ated. The DM yield of binary mixtures of Carlton or Manchar smooth bro megrass, or Regar meadow bromegrass with Peace or Beaver alfalfa was e xamined under a four-cut system at three sites in central Alberta for 3 yr. Annual yield was similar at all sites. Alfalfa cultivar did not consistently affect yield, but annual yield of meadow bromegrass-mixtu res was 9 to 19% higher than mixture containing smooth bromegrass at L acombe. Summer and fall production of meadow bromegrass mixtures was 1 8 to 53% and 40 to 69% greater (P less than or equal to 0.0001) than s mooth bromegrass mixtures. Tiller weight of smooth bromegrass equalled or exceeded that of meadow bromegrass, so superior regrowth of meadow bromegrass mixtures was due to higher tiller density. Over 3 yr, annu al yield of the alfalfa component was similar in smooth bromegrass-and meadow bromegrass mixtures, but alfalfa yield decreased (P less than or equal to 0.0001) 43 to 70% due to dramatic declines in alfalfa stem density. Competition from the associated grass and frequent defoliati on reduced alfalfa longevity.