Grassland improvement by overseeding

To assess the influence of the seeding method on the success of overseeding, we compared four kinds of seeders – seed broadcaster with roller, seed broadcaster with harrow, drill seeder and seeder with rotary band cultivator – and two seasons (mid-Mai and mid-August) in grasslands of different initial sward composition. At two locations we tested the application of glyphosate at low dosage to weaken the stoloniferous grass species. The proportions of sown grass species were improved at three of the seven locations, with only small differences between seeders. The seeder with rotary band cultivator gave slightly better results. At the other four sites, none of the seeder types tested was able to improve the botanical composition. Similar results were obtained with the overseedings of mid-August and those of mid-Mai. Low dosage herbicide treatment did not or only shortly improve the proportion of sown grass species. At two locations, unfavourable moisture conditions were responsible for the failure. On the other unsuccessful sites, the concurrence situation probably was particularly unfavourable for the seedlings. In one case, the rapid growth of stoloniferous grass species out-competed the seedlings. In the other case, fertilizer application close to overseeding triggered the growth of the established plants. We conclude that the seeding method has only a minor influence on the success of overseeding. To succeed in improving grasslands by overseeding, long-term planning and appropriate management adapted to the needs of the seedlings are crucial.