Wheat cover crop and seed treatment for improving native warm‐season grass establishment

Abstract

AbstractSwitchgrass (Panicum virgatum L.) and other perennial native warm‐season grasses (NWSG), such as big bluestem (BB) (Andropogon gerardii Vitman) and eastern gamagrass (EG)[Tripsacum dactyloides (L.) L.] are excellent biofeedstocks, forages, and dual‐purpose biomass–forage crop candidates. However, reliable establishment is a challenge. Therefore, we conducted an experiment at two locations in Tennessee, repeated over 2 yr (2012 and 2013) to evaluate establishment strategies for BB, EG, and switchgrass. Treatments included a wheat (Triticum aestivum L.) cover crop with and without inorganic nitrogen (60 and 0 lb acre–1) and an insecticide–fungicide seed treatment (Gaucho XT and an untreated control). Although establishment success varied by site and year, switchgrass generally produced stands with greater seedling densities than BB, with EG producing the weakest stands. The N treatment did not affect NWSG seedling density or yields in subsequent years at either location for either planting year. Seed treatment improved seedling density in 2013 at one location for switchgrass but not the other species (P = .029). At the second location, seed treatment improved seedling density (0.43 vs. 0.29 seedlings ft–2) across all species (P = .006), apparently driven by the response of BB (0.69 vs. 0.44 seedlings ft–2; P = .094). Neither treatment influenced yield, which increased (P < .001) each year (1.91, 2.69, and 3.60 ton acre–1) across all species. According to these results, dormant‐season NWSG planting in wheat appears to be equally successful regardless of N fertilization. Seed treatments offer some potential for improved establishment success.