Pasture residue amount and sowing method effects on establishment of overseeded cool-season grasses and on total annual production of herbage.

摘要

Warm-season pasture residue may create problems for no-till overseeding with cool-season grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above-surface residues of warm-season pasture averaging 1.62, 2.48 or 3.36 t DM ha-1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no-till drilling into dormant warm-season pasture. On average, no-till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool-season grass production was increased by 0.16 when no-till drilled, but combined yearly total herbage production of cool- and warm-season grasses was increased by 0.07 when cool-season grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of cool-season grass, but increased residue in autumn resulted in a 0.16 increase in total herbage production in the year following sowing. Residue amount did not affect over-winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm-season pasture residue in autumn.