Poster Number 358
Wednesday, 8 October 2008
George R. Brown Convention Center, Exhibit Hall E
Overseeding cool-season grasses into dormant or nearly dormant warm-season pasture can increase total year-round herbage production. Reduced input sowing methods and minimal ground preparation prior to overseeding are of interest for cost-reduction, but there is concern that any cost savings may be offset by reduced herbage yield due to poor establishment. Italian ryegrass (IRG) and tall fescue (TF) were broadcast or no-till drilled into warm-season grass that had been trimmed to a stubble height of 7cm, untrimmed to leave a 20cm stubble or thinned to leave 50% of a 20cm stubble, providing above-ground residue amounts at sowing of 2020, 3390 or 2600 kg ha-1, respectively. On average the established stand of cool-season grasses achieved with broadcast seeding was 70% of that produced with no-till drilling. Herbage yields of cool-season grass sown broadcast were 85% of those obtained with grass that was no-till drilled. However, broadcast seeding caused less damage to warm-season pasture than no-till drilling, so that reduction in cool-season yield was compensated by increased production from warm-season grass and there was no significant difference in year-round total herbage yield arising from method of sowing cool-season grasses. The amount of warm-season grass residue at sowing had no significant effect on establishment or herbage yield of cool-season grass. Cool-season herbage yield of IRG was greater than that obtained with TF, and total year-round grass yield was also greater when IRG rather than TF was oversown into warm-season grass stubble. Although broadcast seeding may be less effective than no-till drilling for establishing oversown cool-season grasses it can provide a similar total annual herbage yield. Broadcast seeding may therefore offer an alternative reduced-input method of sowing that is productive and more accessible to small and resource-limited farmers than no-till drilling, which requires specialist equipment.