EN
The studies were carried out in years 1998-2000 at the Tomaszkowo Experimental Station belonging to the University of Warmia and Mazury in Olsztyn. The objective of the work was to determine usabilify of perennial ryegrass (Lolium perenne L.) cv. 'Anna' for 50% mixture with white clover (Trifolium repens L.) cv. 'Astra' under four levels of mineral fertilization. The studies aimed to determine yield and nutritional value of the mixture as well as the content of nutritional components in the soil after 3-year utilization. In the Olsztyn Lakeland the average yield of the ryegrass - clover mixture reached 10-13 t ha⁻¹ DM. A significant increase in the dry mass mixture yield under the influence of fertilization with nitrogen was observed. The chemical composition of the mixture met all the nutritional requirements of the fodder for ruminants. Chemical analyses of the soil indicated a higher organic matter content rendering 2.5-6.2 t ha⁻¹. The highest increase in the soil abundance was found on the plots fertilized with 60 kg ha⁻¹ N. The root mass depended, to the highest extent, on the papilionaceous plants content in the ground cover. Cultivation of the mixture differentiated the total content of nitrogen in the soil. The highest soil enrichment in nitrogen was obtained on the plots fertilized with 120 kg ha⁻¹ N and the lowest one - on the control fields.