Productivity, botanical composition, and nutritive value of swards including forage chicory

Pure stands of 'Grasslands Puna' chicory (Cichorium intybus L.) are productive and responsive to N fertilization in the eastern USA. We conducted a field experiment for 3 yr to investigate productivity and nutritive value of swards including chicory, orchardgrass (Dactylis glomerata L.), and birdsfoot trefoil (Lotus corniculatus L,) as a function of clipping frequency (3- and 6-wk intervals). Each treatment was replicated three times on an upland site of Dekalb series soil (loamy-skeletal, mixed, subactive, mesic Typic Dystrochrept). Modest rates of N, P, and K were applied annually. Herbage mass, botanical composition, in vitro organic matter disappearance (IVOMD), and crude protein (CP) were determined. Cumulative herbage yield was not influenced by initial sward composition with chicory, chicory-orchardgrass, and chicory-orchardgrass-trefoil averaging 6.8 Mg ha(-1) during a growing season. Clipping frequency influenced yield with canopies clipped at 6-wk intervals producing 26% more herbage than those clipped at 3-wk intervals. Growth rates of canopies clipped at 6-wk intervals averaged 51 kg ha(-1) d(-1) early in the growing season, suggesting that swards including chicory would be responsive to nutrient inputs and where rapid herbage regrowth and nutrient use by the growing crop are needed. Chicory declined in swards with time, regardless of initial sward composition or clipping frequency, Fluctuations in IVOMD and CP were related to changes in sward composition arising from the interaction of time and clipping frequency, Including orchardgrass and trefoil retarded invasion of less desirable species and so provided a means to control overall sward productivity and herbage composition.