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Fall harvest management of eastern gamagrass in central Wisconsin

Coblentz, Wayne K, Bertram, Michael G., Hoffman, Patrick C., Esser, Nancy M., Cavadini, Jason S.
ARS USDA Submissions 2014
Tripsacum dactyloides, autumn, crop yield, frost, harvest date, heat sums, nutritive value, straw, Wisconsin
Recent research has suggested that eastern gamagrass (EGG) may be an effective alternative to chopped straw in the blended diets of dairy heifers and cows. Extension materials discussing appropriate fall management of EGG often recommend avoiding harvest within six weeks of first frost. However, previous research has shown that single-harvest yields of DM are not maximized by mid-August in central Wisconsin; most likely this occurs because of inadequate accumulation of growing degree days by that date. Our objectives were to evaluate yields of DM, plant persistence, and nutritive value for EGG harvested at 15-d intervals between 1 August and 1 November. Yields of DM (2010 through 2013) increased with linear (P = 0.001) and quadratic (P < 0.001) effects over harvest dates, peaking at > 7400 kg/ha on 15 September and 1 October. Overall DM yields varied with year, but were greatest (P ≤ 0.001) during the final year (2013) of the trial (7967 kg/ha). Percentage of continuous row coverage also was assessed, but was not affected by harvest date (P ≥ 0.218). In central Wisconsin, single-cut harvests of EGG timed as late as 1 October improved DM yields relative to August harvest dates without compromising plant persistence.