Higher yield and fewer weeds in grass/legume mixtures than in monocultures - 12 sites of COST Action 852

A common experiment was established in 39 sites in Europe, Australia and Canada within Working Group 2 of COST action 852 to 1) assess the benefits of grass / legume mixtures over monocultures, 2) test their stability and 3) evaluate the consistency of the observed patterns over broad environmental gradients. Results of the first harvest from 12 sites covering a North-South gradient from Iceland to Spain suggest that mixing grasses and legumes enhances productivity and increases the stability of the sward by reducing weed invasion. Mixing fast- and slow-growing grasses was found to provide yield benefits in a few sites, but mixing fast- and slow-growing legumes did not produce any effect. Effects of fast- and slow-growing species are expected to become more important over time, when succession of the species may increase the stability of the mixtures. The emerging patterns were quite consistent and, due to the large environmental gradient taken into account in this study, they are considered to be reliabl