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Unique Dairy Applications of Eastern Gamagrass Forages in Central Wisconsin: I. Yield Potential
Author(s) -
Coblentz Wayne K.,
Jokela William E.,
Hoffman Patrick C.,
Bertram Michael G.
Publication year - 2010
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2010.0259
Subject(s) - dry matter , perennial plant , silage , human fertilization , agronomy , biology , yield (engineering) , forage , zoology , dairy cattle , materials science , metallurgy
Replacement dairy heifers ( Bos taurus ) offered diets comprised largely of corn ( Zea mays L.) silage or other high‐energy forages often become overconditioned, which may damage their future performance as lactating cows. Our objective was to assess the yield potential of a perennial C4 grass, eastern gamagrass [ Tripsacum dactyloides (L.) L.], for incorporation into fiber‐demanding, dairy‐heifer or dry‐cow diets. Replicated field plots of ‘Pete’ eastern gamagrass were evaluated within nine harvest systems and four N fertilization regimes. For single‐harvest systems, dry matter (DM) yields increased across harvest dates, reaching numerical maximums of 7192, 9764, and 7554 kg ha −1 by mid‐August of 2007, 2008, and 2009, respectively. During each year, there was a strong linear ( P < 0.001) effect of harvest date; however, higher‐ordered effects varied within year. Relatively large yield increases (≥1812 kg ha −1 ) between early and mid‐August during 2008 and 2009 suggest that better yields could be achieved by delaying single harvests of eastern gamagrass beyond mid‐August. Yields of DM from double‐harvest systems were not competitive with single‐harvest systems timed in mid‐August. Nitrogen fertilization increased ( P < 0.001) DM yields, exhibiting both linear ( P < 0.001) and quadratic ( P = 0.027) effects of application rate. However, efficiency of N usage was reduced as fertilization rates increased.