Submitted to: Forage and Grazinglands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 2008
Publication Date: January 30, 2009
Repository URL: http://www.plantmanagementnetwork.org/sub/fg/research/2009/rate/
Citation: Brink, G.E., Casler, M.D. 2009. Meadow Fescue, Tall Fescue, and Orchardgrass Response to Nitrogen Application Rate. Forage and Grazinglands. Available: http://www.plantmanagementnetwork.org/sub/fg/research/2009/rate/. Interpretive Summary: Nitrogen has a greater influence on pasture growth than any other factor except precipitation. The rising cost of nitrogen fertilizer dictates that grazing-based producers apply this nutrient input prudently. We conducted a study at two Wisconsin locations for two years to compare the response of three pasture grasses (meadow fescue, tall fescue, and orchardgrass) to nitrogen rate (0, 60, 120, 180, 240 lb/acre/year) under a harvest regime similar to grazing. Plots were harvested whenever grasses reached 10 to 12 inches, or about six times per year. 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 N/acre/year. Thus, at higher rates the ability of these grasses to convert nitrogen into forage declined, and more nitrogen was required to produce the same amount of forage. We also found that, although meadow fescue usually produced less annual yield than tall fescue and orchardgrass, meadow fescue had greater forage quality at each harvest.
Technical Abstract: Nitrogen has a greater effect on grass growth than any other input except moisture. As N costs continue to increase, understanding grass response to nitrogen will help producers determine the most appropriate application rate. Five N rates (0, 60, 120, 180, 240 lb/acre) were split-applied to meadow fescue, soft-leaf tall fescue, and orchardgrass in three equal applications at two Wisconsin locations in 2005 and 2006. Plots were harvested to a 4 inch stubble when sward height reached 10 to 12 inches to represent grazing management. Annual yield and herbage protein concentration of all varieties increased linearly as N application rate increased in all environments. In contrast, N use efficiency (yield produced per unit of N applied) increased from 15 lb DM/lb N 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 varieties produced less annual yield than tall fescue and orchardgrass by the second year, meadow fescue varieties generally had greater cell wall digestibility at each harvest.