Described studies were performed in a long-term irrigated meadow experiment at varied fertilisation. The aim of the study was to assess the effectiveness of meadow renovation in terms of yielding, botanical composition of meadow sward and its protein content in relation to diverse fertilisation. Seven variants were compared including five fertilised with mineral fertilisers at a rate of 60, 120, 180, 180bis and 240 kg of N·ha-1 and two fertilised with organic-mineral fertilisers applied as cattle liquid manure at a rate of 180 kg of N ha-1 (G1) and 240 kg of N ha-1 (G2) with missing amounts of phosphorus and potassium supplemented with mineral doses proportional to nitrogen fertilisation. Fertilisation with phosphorus was abandoned in variant N-180bis 15 years before renovation. Inappropriate composition of meadow sward characterised by the share of low grasses up to 60 %, a lack of legumes and the presence of stubborn weeds in amounts from 12 to 26.5% were the reasons for renovation. The renovation was performed in spring 2012 with the method of direct undersowing with a special harrowing and seeding machine. Decreased weeding to a level of 5% and remarkable increase in yields and total protein content evidenced the effectiveness of renovation. Increased yields were observed since 2013 i.e. one year after renovation. Increased share of grasses, particularly of the oat-grass (Arrhenatherum elatius (L.) P. Beauv. ex J. & C. Presl), after renovation resulted in decreasing content in total protein in subsequent years of the experiment. High protein content of the sward before renovation was an effect of a large percent of dandelion (Taraxacum officinale F.H. Wigg) and other dicotyledons, all rich in protein. However, total protein yield was higher in the years after renovation (2013 and 2014) compared to the year 2011.