Overseeding Eastern Gamagrass with Cool‐Season Annual Grasses or Grass–Legume Mixtures

Abstract

Eastern gamagrass [Tripsacum dactyloides (L.) L.] can serve as an alternative warm‐season perennial forage in the southeastern United States. A 2‐yr study was conducted to evaluate effects of (i) overseeding with cool‐season forages and (ii) N fertilization in the spring on herbage accumulation, nutritive value, and persistence of ‘Highlander’ eastern gamagrass. Overseeding treatments included: control (no overseeding), early‐maturing ‘Florida 401’ rye (Secale cereale L.), mid‐maturity ‘Wrens Abruzzi’ rye, and a mixture of ‘Wrens Abruzzi’ and ‘AU Red Ace’ red clover (Trifolium pratense L.). During late spring, eastern gamagrass was fertilized with either 67 or 135 kg N ha−1 to evaluate growth response following overseeding and differing N input levels. Herbage accumulation (kg dry matter [DM] ha−1) and nutritive value (in vitro dry DM digestibility and crude protein) were measured during the cool‐ and warm‐season production window. Forage canopy cover and botanical composition determinations measured persistence and compositional change during each growing season. Mob‐stocking was implemented every 28 d to simulate rotational grazing. There was no effect of overseeding with cool‐season annual grasses or grass–legume mixtures on seasonal eastern gamagrass herbage accumulation or persistence during the trial. Cool‐season forage herbage accumulation in this study was limited. Spring N fertilization stimulated a rapid growth response in eastern gamagrass, but N‐level effects dissipated as the season progressed. Results indicate that overseeding may be a viable option in eastern gamagrass swards, but given the low level of cool‐season forage production observed in this study, evaluation of additional cool‐season species/blends and economic viability of this system is needed.

Overseeding cool‐season annual grasses into dormant lowland switchgrass stands

“…Yields of CAGs exceeded those of Fribourg and Overton (1973), who reported 2.1, 4.0, and 4.1 Mg ha −1 for rye, ryegrass, and wheat, respectively, and Mason et al. (2019) (<1.1 Mg ha −1 ) but were similar to those reported by Beck et al. (2007) and Butler et al.…”

“…Overseeding all three CAG species into existing SG produced acceptable yields from the annuals and could improve overall production from a given land area while extending grazing seasons. Yields of CAGs exceeded those of Fribourg and Overton (1973), who reported 2.1, 4.0, and 4.1 Mg ha −1 for rye, ryegrass, and wheat, respectively, and Mason et al (2019) (<1.1 Mg ha −1 ) but were similar to those reported by Beck et al (2007) and Butler et al (2013) at their Oklahoma study site. Variability of CAG yields can be strongly affected by timing and amount of rainfall (McLaughlin et al, 2005;Mullenix & Rouquette, 2018), soil fertility (Butler et al, 2013), or density of the vegetation into which the annuals are being established (Fribourg & Overton, 1973;Mason et al, 2019;Mullenix & Rouquette, 2018).…”

“…Studies examining overseeding cool-season legumes into native warm-season grasses have reported reduced canopy cover (Keyser et al, 2016) and yield of SG (George, Blanchet, Gettle, Buxton, & Moore, 1995). On the other hand, Mason et al (2019) did not detect any reductions in eastern gamagrass (Tripsacum dactyloides L.) production as a result of overseeding CAGs. Butler et al (2013) reported reduced yields for Alamo SG overseeded with rye despite an early April harvest date.…”

“…(2013) at their Oklahoma study site. Variability of CAG yields can be strongly affected by timing and amount of rainfall (McLaughlin et al., 2005; Mullenix & Rouquette, 2018), soil fertility (Butler et al., 2013), or density of the vegetation into which the annuals are being established (Fribourg & Overton, 1973; Mason et al., 2019; Mullenix & Rouquette, 2018). In our case, establishment success was good in both years for all three CAGs.…”

“…On the other hand, Mason et al. (2019) did not detect any reductions in eastern gamagrass ( Tripsacum dactyloides L.) production as a result of overseeding CAGs. Butler et al.…”