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.