ORIGINAL ARTICLE Productivity and botanical composition of orchardgrass– white clover swards in a cool-temperate hill land region of the eastern United States Dariusz P. Malinowski 1 , David P. Belesky 2 , Joyce M. Ruckle 2 and James M. Fedders 2 1 Texas AgriLife Research & Extension Center, Vernon, Texas, USA 2 United States Department of Agriculture – Agricultural Research Service, Appalachian Farming Systems Research Center, Beaver, West Virginia, USA Keywords Canopy height; herbage mass; regrowth interval; residue height; sward composition. Correspondence David Belesky, P.O. Box 824 Skelton, WV, 25919 USA. Email: dpb.vlb@gmail.com Received 16 February 2012; accepted 18 July 2012. doi: 10.1111/j.1744-697x.2012.00259.x Abstract Understanding the growth dynamics of grass–legume swards is critical as pasto- ral management practices are adapted to varying economic constraints and emerging environmental considerations. Efficient management must synchro- nize the use of accumulated herbage with the needs of grazing livestock. This must be accomplished against the dynamic background of within and among year weather patterns interacting with herbage growth and grazing animal behavior. In the Appalachian region of the eastern United States, pastures often are dominated by orchardgrass (Dactylis glomerata L.) and white clover (Trifo- lium repens L.). We determined botanical composition and herbage productiv- ity of orchardgrass and white clover swards during four consecutive years when managed as a function of canopy development and regrowth interval. Produc- tivity was influenced by defoliation practices when mixtures were managed according to canopy development. Productivity was greatest when swards were managed as hay or when clipped to a 5-cm residue each time mean canopy height reached 20 cm. White clover declined and orchardgrass increased in the sward irrespective of defoliation treatment. Botanical composition of mixtures with the erect growing orchardgrass tended to be more stable, whereas swards including the decumbent orchardgrass tended to be invaded by weeds. Some increase in productivity occurred during the first growing season when mix- tures were clipped at either 2- or 4-week intervals. Regardless of defoliation practice, white clover, and in some instances orchardgrass, presence declined during two consecutive growing seasons with various other volunteer grasses and forbs contributing to productivity. Productivity and persistence of sown sward components may be less dependent on management practices than on the expression of interactions responding to within and among year weather patterns. Introduction Grass–legume mixtures are the foundation of productive pastures in the Appalachian region of the eastern United States and similar humid temperate regions else- where. Pastures in the central Appalachian region typified by those growing in West Virginia often comprise a mix of native and naturalized grasses, legumes and forbs (Baker and Nestor 1979), often differing from what was sown. Orchardgrass (Dactylis glomerata L.) and Kentucky bluegrass (Poa pratensis L.), along with white clover (Trifolium repens L.), are widespread naturalized compo- nents of the pasture floristic community in the region. Pastoralists have a somewhat better understanding of bluegrass-white clover than orchardgrass-white clover pasture management in the region (Robinson and Spra- gue 1947; Blaser et al. 1969). Botanical shifts occur in response to among- and within-year variation in weather, management including fertilizer inputs, defoliation and grazing practices, and various abiotic and biotic stresses Published 2012. This article is a US Government work and is in the public domain in the USA., 58, 188–200 188 Japanese Society of Grassland Science ISSN1744-6961 Japanese Society of Grassland Science