Summary:

The aim of the study was the estimation of six mixtures for renovation of pastures located on the soils of V and VI quality class under differentiated nitrogen fertilization. The experiment was carried out in the farm specializing in breeding Limousin beef cattle in the years 2008-2012. The most important factor verifying the suitability of mixtures has proved the botanical stability and the resistance to weed infestation of plant communities created by these mixtures. These features were guaranteed by the multispecies mixtures of cocksfoot, but turned out to be completely unreliable in case of mixture with dominance of tall fescue. Cocksfoot was the most dynamic species of the communities of pasture. This species was increasing its percentage in the subsequent years of utilization, effectively reducing their weed infestation. Valuable component of mixtures has also proved the perennial ryegrass which was persisting in significant quantities during the four years. Its significant share in mixtures without cocksfoot grass turned out to be far less competitive with respect to the developing dicotyledonous weed species. Also the amount of cocksfoot negatively affect the development of perennial ryegrass, especially at higher levels of nitrogen fertilization. The dose of 120 kg of nitrogen, used together with the phosphorus and potassium, significantly increased the yields plant communities and limited dicotyledonous weed infestation. Therefore this dose turned out to be fully justified economically on the light soils.