Applying nitrogen fertilisers in legume species has been subjected to scientific research due to the efficacy of these fertilisers on yield (symbiotic atmospheric nitrogen fixation). In general, applying high rates of nitrogen fertilisers on legume species does not correlate directly with green matter production because these species take the necessary nitrogen from the atmosphere. This feature is specific also to bird’s-foot-trefoil, which fixes important amounts of atmospheric nitrogen during vegetation. This paper presents the impact of the interaction between organic and mineral fertilisers on bird’s-foot-trefoil within a bifactorial experiment. Differences in yield at both unilateral effect of the factors and at that of the interaction of the factors are statistically ensured. Keywords: common bird’s-foot-trefoil (Lotus corniculatus L.), organic and mineral fertilisers, dry matter