The Impact of Nitrogen Fertilisation on the Evolution of Floristic Composition in Mixtures of Festuca rubra L.

Festuca rubra L. is a good competitive species that makes up the floristic structure of temporary meadows and that are used for grazing or mixed use (haymaking field – grassland) together with Festuca pratensis L., Phleum pratense L., Poa pratense L., Trifolium repens L. and Lotus corniculatus L. The paper aims at pointing out the evolution of the floristic composition of the vegetal cover in different mixtures based on (creeping) red fescue (Festuca rubra L.), Dutch / white clover (Trifolium repens L.) and bird’s-foot trefoil (Lotus corniculatus L.). Analysis of mean results concerning the structure of the floristic composition of mixtures based on Festuca rubra L. (60%) shows that in all 9 types of mixtures there was balance between the degree of participation of (creeping) red fescue and the share of the other two legume species studied. In the control variants, in the two simple mixtures, the share of Dutch / white clover was 48% and that of bird’s-foot trefoil was 44%. These values decreased, on the average, with 10% when applying a rate of N50 and with 14% when applying a rate of N100. In the complex mixture, there was a mean value of the degree of participation of the two species of legumes of 46% (with a higher share of the bird’s-foot trefoil) in the control variant, of 34% in the variant treated with N50 and of 30% in the variant treated with N100