Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/29/2010
Publication Date: 11/30/2010
Citation: Coblentz, W.K., Bertram, M.G., Martin, N.P. 2010. Planting Date Effects on Fall Forage Production of Oat Cultivars in Wisconsin. Agronomy Journal. 103:145-155. Interpretive Summary: From a forage-only perspective, an important criterion for evaluating cereal-grain forages is the optimization of fall-forage growth. This is important for beef producers because cereal-grain forages can provide a source of high-quality pasture for fall-weaned calves, or simply limit the need for supplemental hay during the winter. For other livestock producers, fall-forage growth from cereal grains may serve as a useful tool in meeting other management objectives, such as extending the grazing season, or providing emergency forage following summer drought. Our objectives for this project were to assess the effects of establishment date (15 July, 1 August, or 15 August) on the fall-forage growth of four oat cultivars that include both grain (Dane, Ogle, and Vista) and forage (ForagePlus) types, and that exhibit early- to late-maturation characteristics, respectively. Based on the results of this 3-yr trial, yields of fall forage are likely to be greatest by selecting a late-maturing forage-type cultivar (ForagePlus) for establishment during mid-to-late July. Depending on growing conditions, this yield advantage may persist with delayed establishment dates as late as the first week of August. Within these establishment guidelines, ForagePlus oat will remain structurally upright and physically suitable for a single harvest as silage throughout October. With July establishment dates, rapidly maturing grain-type cultivars are likely to exhibit physical deterioration after 1 October that would limit their suitablity as a silage crop after that date. Based on this work and previous research, grain-type cultivars will likely produce greater forage yields than forage-type cultivars by late-October if establishment is delayed beyond the first week of August. With mid-August establishment, forage-type cultivars will produce increased late-October growth relative to grain-type cultivars, and tillers will likely not develop beyond early stem elongation. This may delay winterkill and provide a more desirable forage base for late-fall grazing by livestock. This research is important because it provides more forage options for livestock producers that can easily be adapted to meet their specific production goals.
Technical Abstract: Previous research has shown that cereal-grains, such as oat (Avena sativa L.), that undergo stem elongation following late-summer establishment will likely exhibit a 2:1 forage DM yield advantage before winter compared to other cereals that remain vegetative until spring. Our objectives for this project were to assess the effects of establishment date on the fall-forage growth of 4 oat cultivars that include both grain (Dane, Ogle, and Vista) and forage types (ForagePlus). Over a 3-yr trial, oat cultivars were seeded on 3 target establishment dates (15 July, 1 August, and 15 August), and subsequently evaluated on 5 target harvest dates (15 September, 1 October, 15 October, 1 November, and 15 November). Within the initial analysis, yields of forage DM generally were affected strongly by year, as well as interactions of year with other treatment effects (P < 0.001). For the 15 July target establishment date, a late-maturing forage cultivar (ForagePlus) produced yields that ranged as high as 8100 kg/ha, and these responses were explained generally by linear (P < 0.001) and quadratic (P = 0.032) effects of time. Accumulation of DM was superior to grain-type cultivars because ForagePlus matured more slowly, and it was better able to respond to sometimes erratic late-summer precipitation. In addition, ForagePlus remained structurally upright and physically suitable for a single harvest as silage throughout October, while rapidly maturing grain-type cultivars exhibited physical deterioration after 1 October that would limit their suitablity as a silage crop. With a 1 August target establishment date, maximum forage yields generally were similar to those observed with mid-July establishment, but peak yield was often delayed by approximately 2 wk. For the 15 August target establishment date, maximum yields of forage DM were only 42.3, 79.9, and 20.5% of those observed following establishment on approximately 1 August of 2007, 2008, and 2009, respectively. Under these circumstances, the late-maturity characteristics of ForagePlus were less advantageous, resulting in poorer yields throughout early harvest dates compared to grain-type cultivars. Based on this work and previous research, forage-type cultivars, such as ForagePlus, will produce more forage DM with early (mid-July) establishment, but grain-type cultivars will likely produce the greatest forage yields by late-October if establishment is delayed beyond the first week of August.