In all conventional agricultural systems based on the application of mineral or organic fertilisers, their impact is assessed depending on the final product (production of green matter or of seeds) and on its quality. At plant level, the impact of fertilisers differentiates depending on the structure and morphological features of the plants. This paper presents the differentiated impact of applying organic and mineral fertilisers on the growth and development of the root system and of the aerial vegetative system in bird’s-foot-trefoil. Keywords: common bird’s-foot-trefoil (Lotus corniculatus L.), organic and mineral fertilisers, root system, aerial vegetative system.