COMPARISON OF CONTINUOUSLY GRAZED BROMEGRASS–ALFALFA WITH ROTATIONALLY GRAZED CRESTED WHEATGRASS–ALFALFA, BROMEGRASS–ALFALFA, AND RUSSIAN WILD RYEGRASS

Abstract

A continuously grazed mixed sward of bromegrass (Bromus inermis Leyss.) and alfalfa (Medicago media Pers.) was compared with two pasture treatments in which separate paddocks of crested wheatgrass (Agropyron cistatum Gaertn.) and alfalfa, bromegrass and alfalfa, and Russian wild ryegrass (Elymus junceus Fish.) alone were grazed in rotation by yearling Hereford steers. In one of the rotationally grazed treatments, Russian wild ryegrass was harvested for seed prior to grazing whereas in the other it was utilized as pasture only. Seventy-five kg N/ha were applied annually (1960–66) to the Russian wild ryegrass. The same amount of N was applied to the bromegrass–alfalfa and crested wheatgrass–alfalfa for only the last 4 yr of the experiment (1963–66). The 7-yr average dry matter yields and steer gains (kg/ha) were 4,794 and 326 for the continuously grazed bromegrass–alfalfa; 3,949 and 343 for the treatment in which Russian wild ryegrass was used exclusively for pasture, and 3,325 and 277, respectively, for the treatment in which Russian wild ryegrass was used for seed and pasture. Harvesting seed from Russian wild ryegrass reduced the dry matter available for grazing from 3,603 to 2,183 kg/ha and liveweight gain from 295 to 168 kg/ha. Seed yield averaged 410 kg/ha.