|Muller, L - PENN STATE UNIV|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 7, 2005
Publication Date: September 19, 2005
Citation: Sanderson, M.A., Soder, K.J., Muller, L., Klement, K.D., Skinner, R.H., Goslee, S.C. 2005. Forage mixture productivity and botanical composition in pastures grazed by dairy cattle. Agronomy Journal. 97:1465-1471. Interpretive Summary: Producers in the Northeast often plant complex mixtures of grasses and legumes. Results from ecological studies linking plant species diversity to ecosystem functioning (e.g., plant production, resistance to weed invasion) suggest that managing complex mixtures of plants may be one ecological approach to increase productivity of pastures. In this grazing experiment, we tested the hypothesis that pastures planted to complex mixtures of forage species would yield more herbage and reduce weed invasion compared with a simple grass-legume mixture. Complex forage mixtures were more productive than a simple grass-legume mixture during drought and also had reduced weed pressure. The abundance of individual species, however, fluctuated widely in most mixtures. Legume and chicory proportions decreased greatly after two years and the pastures became dominated by orchardgrass. Our results point to short-term benefits of complex forage mixtures for pastures. Producers would have to reestablish the clovers and chicory relatively frequently to maintain these benefits.
Technical Abstract: Some producers believe that planting pastures to several forage species benefits sustainability. We conducted a grazing study to determine if forage species diversity in pastures affects herbage productivity and weed invasion. One-ha pastures were planted to mixtures of 2, 3, 6, or 9 species in August 2001 and then grazed with lactating dairy cattle during 2002 and 2003. The mixtures were: 1)orchardgrass (Dactylis glomerata L.), white clover (Trifolium repens L.); 2) orchardgrass, white clover, chicory (Cichorium intybus L.); 3) orchardgrass, tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), red clover (Trifolium pratense L.), birdsfoot trefoil (Lotus corniculatus L.), chicory; and 4) mixture 3 plus white clover, alfalfa (Medicago sativa L.), and bluegrass (Poa pratensis L.). The 2-species mixture produced less herbage than the other mixtures (4800 vs. 7600 kg dry matter ha-1) during 2002, a dry year. Mixtures did not differ in 2003 (avg herbage yield = 9800 kg ha-1) when rainfall was plentiful. The 6- and 9-species mixtures had fewer nonsown species in the sward than the 2-and 3-species mixtures indicating less weed invasion for these complex mixtures. The proportions of individual species were very unstable in most mixtures. Red clover and chicory proportions decreased by 80% after 2 yr. By May 2004, orchardgrass dominated in all pastures. We conclude that planting a mixture of grasses, legumes, and chicory will benefit herbage production during dry years and will reduce weed invasion for a few years after planting under management similar to ours. Producers would have to reestablish the chicory and legume components relatively frequently to maintain these benefits.