Abstract. From 2002 to 2005, the behaviour of local population of birdsfoot trefoil in binary mixtures with meadow grass species was conducted in the experimental field of RIMSA–Troyan. The variants of the experiment include testing of birdsfoot trefoil–variety Turgovishte 1 (reference–St), cultivated its own and local population of birdsfoot trefoil in binary mixtures with tall fescue (Albena); perennial ryegrass (Pleven population); bromegrass (Nika); smooth–stalked meadow grass (Troyan population); orchard grass (Dabrava); red fescue (Troyan population); wheatgrass (Ruff). The height of plants shall be amended under the influence of weather conditions, the rate of growth and development of grasses interrelation and competitiveness of the components in grass composition indicative of received Variation coefficients.The production of birdsfoot trefoil and grass types varied with regard to treatments and years. The variation coefficients indicating yields stabilityshowed that it was best expressed in the mixture of birdsfoot trefoil and tall fescue (CV=45.42%) andorchagrdgrass(CV=48.65%).The values of crude protein in all variants were negative correlation coefficient. The correlationcoefficient of the compound with crude fiber content was very positive and strong correlations.
Key words: birdsfoot trefoil, mixtures, productivity, chemical composition, correlation analysis, height