PRODUCTIVITY AND COMPOSITION OF BROMEGRASS ALFALFA MIXTURES FOR HAY IN THE ASPEN PARKLANDS OF WESTERN CANADA

Dry matter yield of smooth bromegrass (Bromus inermis Leyss.) - alfalf a (Medicago sativa L.) mixtures is restricted by short growing seasons and poor legume persistence in the Aspen Parklands of western Canada, Meadow bromegrass (Bromus riparius Rehm.) has recently gained accepta nce, but comparative information on smooth and meadow bromegrass in gr ass-alfalfa mixtures is unavailable. We examined DM yield of binary gr ass-legume mixtures containing either Carlton or Manchar smooth bromeg rass or Regar meadow bromegrass with Peace or Beaver alfalfa under a t wo-cut hay-management system at four sites in central Alberta for 3 yr . Annual DM yield was 40% greater (P less than or equal to 0.0001) at sites near Lacombe (7570 kg ha(-1)) than at Bluffton and Vegreville (5 420 kg ha(-1)). Dry matter yield of smooth bromegrass mixtures (8020 k g ha(-1)) was 20% higher (P less than or equal to 0.01) than that of m eadow bromegrass mixtures (6690 kg ha(-1)) near Lacombe. Alfalfa DM yi eld was 2.1 times higher at Bluffton and Vegreville (2770 kg ha(-1)) t han near Lacombe (1300 kg ha(-1)). Near Lacombe, alfalfa regrowth was suppressed (P less than or equal to 0.0001) by smooth bromegrass, whic h had 2.3 times larger (P less than or equal to 0.001) tillers than me adow bromegrass at first cut. At Bluffton and Vegreville, DM yield of meadow bromegrass mixtures equalled or exceeded (P less than or equal to 0.05) that of smooth bromegrass mixtures. Although first-cut tiller weight of smooth bromegrass was 73% more (P less than or equal to 0.0 001) than that of meadow bromegrass at Bluffton and Vegreville, tiller density of meadow bromegrass was 1.7 times greater (P less than or eq ual to 0.0001) than that of smooth bromegrass. Results indicate that s mooth bromegrass mixtures were superior to meadow bromegrass mixtures for hay production at moist fertile locations, despite reduced alfalfa persistence. At drier or less fertile sites, however, DM yield of mea dow bromegrass mixtures was higher than that of smooth bromegrass mixt ures when weather conditions for regrowth were favourable.