Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 27, 2009
Publication Date: June 21, 2009
Citation: Brink, G.E., Casler, M.D. 2009. Nitrogen Fertilization of Orchardgrass, Tall Fescue, and Meadow Fescue - How Much is Enough? In: Proceedings of the American Forage and Grassland Council Conference. 2009 Annual Conference, June 21-23, 2009, Grand Rapids, Michigan. 2009 CDROM. Interpretive Summary: Nitrogen has greater influence on pasture growth than any other factor except temperature and precipitation. The rising cost of nitrogen fertilizer dictates that grazing-based producers apply this nutrient input prudently. Our objective was to compare the response of two typical cool-season grasses, orchardgrass and tall fescue, and one receiving renewed interest, meadow fescue, to five different nitrogen rates under a harvest regime similar to rotational grazing. Annual yield of all grasses increased as nitrogen rate increased, but the efficiency of nitrogen use (yield produced per unit of nitrogen applied) declined after the nitrogen rate exceeded 120 lb nitrogen/acre/year. Thus, less forage was produced with each added unit of nitrogen at higher application rates. We also found that, although meadow fescue usually produced less annual yield than orchardgrass or tall fescue, meadow fescue had greater nutritive value at each harvest. This information will help prevent grazing-based producers from applying excessive nitrogen to pastures, thus saving them money and also reducing the potential for nitrogen leaching to ground water.
Technical Abstract: Nitrogen has greater influence on temperate grass growth than any other factor except temperature and moisture. As N fertilizer costs increase, understanding grass response to N will help producers determine the most appropriate application rate. Five N rates (0, 60, 120, 180, 240 lb/acre) were applied to orchardgrass (Dactylis glomerata L.), soft-leaf tall fescue [Schedonorus phoenix (Scop.) Holub], and meadow fescue [Schedonorus pratensis (Huds.) P. Beauv.] in three equal applications at two Wisconsin locations in 2005 and 2006. Plots were harvested to a 4-in residual sward height (RSH) when sward height reached 10 to 12 in to represent a typical defoliation scheme for managed grazing. Annual yield and herbage protein concentration of all varieties increased linearly as N rate increased in all environments. However, N use efficiency (yield produced/unit N applied) increased from 15 to 20 lb DM/lb N as rate increased from 60 to 120 lb N/acre/year, but declined as N rate increased above 120 lb N/acre/year. Although meadow fescue yielded less than tall fescue and orchardgrass in the second year, meadow fescue varieties generally had greater cell wall digestibility at each harvest.