Production fourragère de mélanges prairiaux et d’associations à diversité spécifique initiale variée

Forage production of pasture mixtures and of associations with various initial specific diversities

Several studies have shown that when the diversity of species increases in pasture swards, the forage production is larger and the weeds less abundant. This hypothesis was tested in a trial with 25 micro-plots comprising mixtures of grasses or grass-legume associations, where the initial diversity varied from 1 to 8 species. These micro-plots were subjected to 2 different cutting rates and to 2 different levels of nitrogen fertilisation. The results show that the number of species sown had no effect on the dry matter production nor on the distribution of this production within a year or among years; neither was there any effect on the weeds. On the other hand, the choice of species , especially in the case of tall fescue and cocksfoot, had an important effect on the dry matter production per hectare. The specific diversity of the associations decreased sharply with time, and after 5 years; the associations with the most complex initial diversities had only 2 or 3 species left.