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Title: TALL FESCUE RESPONSE TO NITROGEN AND HARVEST DATE FOR STOCKPILED GRAZING IN THE UPPER MIDWEST

Author
item Singer, Jeremy
item HINTZ, R - IA STATE UNIVERSITY
item MOORE, K - IA STATE UNIVERSITY
item WIEDENHOEFT, M - IA STATE UNIVERSITY
item BRUMMER, E - IA STATE UNIVERSITY

Submitted to: Crop Management at www.cropmanagement.org
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2003
Publication Date: 9/4/2003
Citation: SINGER, J.W., HINTZ, R.L., MOORE, K.J., WIEDENHOEFT, M.H., BRUMMER, E.C. TALL FESCUE RESPONSE TO NITROGEN AND HARVEST DATE FOR STOCKPILED GRAZING IN THE UPPER MIDWEST. CROP MANAGEMENT at www.cropmanagement.org. 2003. AVAILABLE FROM: www.plantmanagementnetwork.org/pub/cm/research/2003/fescue.

Interpretive Summary: Tall fescue is a cool-season grass with physiological and morphological traits suitable for stockpiled grazing. Stockpiling refers to the accumulation of forage during the fall that is available for grazing in late fall and winter. Forage producers and grazers need more information about how tall fescue responds to delayed fall harvest and nitrogen to help plan fall forage management systems. It was found that late summer nitrogen application on existing stands of tall fescue increased dry matter by 15 to 19 lb/acre for each lb of nitrogen up to 100 lb nitrogen per acre. Dry matter increases varied by harvest and nitrogen application rate because of above average rainfall in 1999 and below average rainfall in 2000. Forage crude protein and in vitro dry matter digestibility (IVDMD) increased as nitrogen rate increased, while neutral detergent fiber (NDF) decreased. Interactions between year and harvest date were observed for all quality measures. Interactions between year and nitrogen rate were observed for crude protein and NDF. Late summer nitrogen application increased dry matter yield and crude protein of the first cutting the following spring. Forage producers who apply late-season nitrogen can increase the quantity and quality of tall fescue forage available for fall grazing.

Technical Abstract: Tall fescue (Festuca arundinacea Schreb.) is a cool-season grass with physiological and morphological traits suitable for stockpiled grazing. The effect of late summer nitrogen (N) application on existing swards of tall fescue stockpiled for fall grazing was measured for yield and quality responses during 1999 and 2000 using three fall harvest dates and four N rates (0, 25, 50 and 100 lb/acre). Averaged across harvest date, linear increases of dry matter (DM) in response to N rate occurred in 1999 and 2000. In 1999, the equation was yield = 1747 + 15Nrate (R2 = 0.92, RMSE = 235) and in 2000, yield = 672 + 19Nrate (R2 = 0.96, RMSE = 202). Year by harvest date and year by N rate interactions were observed for yield because of above average rainfall in 1999 and below average rainfall in 2000. Yield losses for the third harvest in 2000 were high because of above average rainfall after frost. Forage rude protein (CP) and in vitro dry matter digestibility (IVDMD) increased as N rate increased, while neutral detergent fiber (NDF) decreased. Year by harvest date interactions were observed for CP, NDF and IVDMD and year by N rate interactions were observed for CP and NDF. Late summer N application increased DM yield and CP of the first cutting the following spring. Forage producers who apply late-season N can increase the quantity and quality of tall fescue forage available for fall grazing.