Forage Mixture Productivity and Botanical Composition in Pastures Grazed by Dairy Cattle

Abstract

Some producers believe that planting pastures to several forage species benefits sustainability of grazing systems. We conducted a grazing study to determine if forage species diversity in pastures affects herbage productivity and weed invasion. One‐hectare pastures were planted to four mixtures in August 2001 and then grazed with lactating dairy cattle during 2002 and 2003. The mixtures were two species [orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.)], three species [orchardgrass, white clover, and chicory (Cichorium intybus L.)], six species [orchardgrass, tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), red clover (Trifolium pratense L.), birdsfoot trefoil (Lotus corniculatus L.), and chicory], and nine species [the six‐species mixture plus white clover, alfalfa (Medicago sativa L.), and bluegrass (Poa pratensis L.)]. When rainfall was plentiful (2003), there were no differences in herbage yield among the mixtures; all averaged 9800 kg ha−1 dry matter. During 2002, which was dry, the two‐species mixture produced less herbage than the other mixtures (4800 vs. 7600 kg ha−1 dry matter). The proportion of nonsown species in the sward was lower for the six‐ and nine‐species mixtures than the two‐and three‐species mixtures, indicating less weed invasion for these complex mixtures. Red clover and chicory proportions decreased by 80% after 2 yr, and orchardgrass dominated in all pastures by May 2004. 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.