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Title: Forage yield, weed suppression and fertilizer nitrogen replacement value (FNRV) of alfalfa-tall fescue mixtures

Author
item TRACY, BEN - Virginia Polytechnic Institution & State University
item ALBRECHT, KEN - University Of Wisconsin
item FLORES, J - Virginia Polytechnic Institution & State University
item HALL, MARVIN - Pennsylvania State University
item ISLAM, ANWAR - University Of Wyoming
item JONES, G - Virginia Polytechnic Institution & State University
item LAMP, WILLIAM - University Of Maryland
item MACADAM, JENNIVER - Utah State University
item Skinner, Robert
item TEUTSCH, CHRIS - Virginia Polytechnic Institution & State University

Submitted to: Grasslands Federation European Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/12/2012
Publication Date: 6/23/2013
Citation: Tracy, B., Albrecht, K., Flores, J.P., Hall, M., Islam, A., Jones, G., Lamp, W., Macadam, J., Skinner, R.H., Teutsch, C. 2013. Forage yield, weed suppression and fertilizer nitrogen replacement value (FNRV) of alfalfa-tall fescue mixtures. Grasslands Federation European Proceedings. 18:192-194.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: Adding plant diversity to forage systems may help growers deal with increasing fertilizer costs and a more variable climate. Maintaining highly diverse forage mixtures in forage-livestock production is difficult and may warrant a closer reexamination of simpler grass-legume mixtures to achieve similar objectives. This study evaluated the performance of alfalfa (Medicago sativa L.) and tall fescue (Schedonorus phoenix (Scop.) Holub) mixtures against tall fescue monocultures fertilized with nitrogen across six different sites in the United States. Experimental treatments included three alfalfa-fescue mixtures, an alfalfa monoculture, and six tall fescue monocultures that received 0, 50, 100, 150, 200 and 300 kg N/ha, respectively. Total forage yield, grass N yield, weed biomass, within season yield stability and fertilizer nitrogen replacement values (FNRV) were measured during the 2011 growing season. Mixtures yielded an average of 6860 kg/ha, which was similar to fescue monocultures fertilized with 100 kg N/ha. Alfalfa dominated plots exhibited the highest seasonal yield stability and mixtures effectively suppressed weeds. Most FNRVs for alfalfa were lower than reported in other studies (mean 116 kg N/ha). Overall, good mixture yield mainly depended upon the alfalfa component as tall fescue growth did not benefit greatly from the association. Although replacing N fertilizer with alfalfa has environmental benefits, forage yield in mixture might be improved with cultivars that better complement each other when grown together.