Grazing management and nitrogen fertilization effects on vaseygrass persistence in limpograss pastures
2005
Newman, Y.C. | Sollenberger, L.E.
Vaseygrass (Paspalum urvillei Steud.) is a weed in environments where limpograss [Hemarthria altissima (Poir.) Stapf & Hubb.] is a productive pasture grass. The objective of this study was to determine grazing management and N fertilization effects on persistence of vaseygrass in limpograss pastures on a Pomona sand (sandy, siliceous, hyperthermic Ultic Alaquod). Treatments were arranged in a split-plot experiment; combinations of grazing method (continuous vs. rotational) and stubble height (15 and 30 cm) were the main plots, and N fertilization (50 and 150 kg N ha(-1)) was assigned to subplots. Continuous stocking for two grazing seasons reduced vaseygrass cover by 15 percentage units (-3 units for rotational) and increased limpograss cover by 6 units (-8 units for rotational). A stubble height x N rate interaction occurred because at the shortest height and lowest N rate the decline in vaseygrass cover (15 units) and increase in limpograss cover (7 units) were most pronounced. After 2 yr of continuous stocking, vaseygrass stem-base mass was lower than for rotational stocking (12 vs. 23 g plant(-1)), and stem-base (0.40 vs. 0.78 g plant(-1)) and root (0.46 vs. 0.91 g plant(-1)) content of total nonstructural carbohydrate (TNC) were lower under continuous compared to rotational stocking, respectively. Grazing to a 15- vs. 30-cm stubble height resulted in lower vaseygrass stem-base mass (12 vs. 23 g plant(-1)) and TNC content (0.44 vs. 0.73 g plant(-1)). Continuous stocking reduced vaseygrass plant mass and density while limpograss cover increased, but careful management of stubble height is required to avoid subsequent invasion by other undesirable species.
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