The possibilities and ways of improving well-composed sown sward and natural sward were investigated during 2004–2005 at the Research Station of the Lithuanian University of Agriculture. The aim of the study was to determine the impact of monomial N, P and K fertilizers, their combinations and rates on improving the floristic composition of well-composed sown fodder sward
as well as on natural sward of a poor nutrient value not improved for more than 10 years.
Data on the floristic composition of sown and natural swards are presented. The share of legumes in sown swards decreased and the share of grasses increased in the 3rd year after sowing, irrespective of the fertilizing background. The increase of legumes in these swards was not determined by any treatment. The share of grasses increased from 4 to 14%. The share of legumes was by 4–12% higher on the P and K background versus other treatments in 2005. In the 3rd year after sowing, the percentage of legumes decreased sequentially with increasing N rates. The biggest share of legumes remained in treatments with P medium rates, while the K background supported legume persistence to a lesser extent. The impact of fertilizer background on floristic composition was similar both in natural swards and in sown ones.

Keywords: sown sward, floristic composition, natural sward, grasses, legumes, dry matter