Biological fixation of the nitrogen (NFB) in the temporary grasslands with Festuca rubra L.

In the conditions from our country, even Festuca rubra is a well spread species in the permanent grasslands from mountains it was less studied in different structures of mixtures for the setting of the temporary grasslands. From this point of view the realised researches had as main purpose the estimation of the fixation capacity of the biological nitrogen (NFB) in the framework of the studied floristic structures. The experiment consisted of a bi-factorial experiment, with the following factor graduations: A- Mixture types: a1 = Festuca rubra L. (100%); a2 = Festuca rubra L. (60%) + Trifolium repens L. (40%); a3 = Festuca rubra L. (60%) + Lotus corniculatus L. (40%); a4 = Festuca rubra L. (60%) + Trifolium repens L. (20%) + Lotus corniculatus L. (20%) and B- Nitrogen rates: b1 = N0; b2 = N50; b3 = N100. The mixtures of Festuca rubra L. and of the legume species we studied produced between 14.03 and 52.25 kg of NFB per ha per year. With no nitrogen fertilisation, the amount of NFB ranged between 14.03 and 48.01 kg/ha/year. The largest amounts of NFB were produced by the complex mixture, where the share of legumes and of dry matter also was higher than in the other types of mixtures we analysed