Effect of Establishment Method and Harvest Intensity on Forage Yield and Subsequent Regrowth of Native Warm-Season Grasses.

To assess effects of planting method and harvest intensity on performance of newly established native warm-season forage grasses in southeastern USA, biomass yields and subsequent sward heights of transplanted and seeded stands were compared. High-tunnel raised 6-week old seedlings of Andropogon gerardii (big bluestem), Tripsacum dactyloides (eastern gamagrass), Sorghastrum nutans (indiangrass) and Panicum virgatum (switchgrass), were transplanted to clean seedbeds in June, spaced 30 x 45 cm (within and between rows). For each species similar 6 x 7 m plots were seed-drilled at ≤ 2 cm deep for comparison. Tall-growing broadleaf weeds were chopped down as needed. Plants were not fertilized but allowed uninterrupted growth in the first year and dead standing biomass mowed down early in the succeeding spring. During the second year of establishment, plots were subdivided into three harvest strips and assigned to one, two, or three cuts/year. Subsequent sward heights in the following year were recoded. Data were analyzed as a randomized complete block design for effects of planting method, number of harvests, and species on biomass yield and subsequent sward heights. Year total yields were consistently greater for transplanted than seeded plots and averaged 15,056, 12,360, 9,180, and 8,240 kg DM/ha for switchgrass, indiangrass, gamagrass, and big bluestem, respectively, with greater subsequent sward heights for one harvest > two > three. Data indicate that transplanting mostly results with better yielding stands and that intensive harvesting may compromise subsequent performance of newly established stands. More data is needed on combined effects of harvest intensity and fertilizer application on subsequent stand performance.