Studies were carried out at the Experimental Farm in Falenty on the permanent productive meadow, situated on mineral soil (proper dry ground habitat) at the four consecutive years (2011-2014). The aim of the study was to assess the effect of undersowing permanent meadow with the red clover (Trifolium pratense L.) at various ways of fertilisation. Plots has been selected randomly and fertilised with mineral (phosphorus and potassium) or natural fertilisers (manure and liquid manure). In spring 2011, part of selected plots has been undersown with the tetraploid Bona variety of red clover, in the amount of 8 kg·ha–1. Botanical composition of the meadow sward, yields and protein content in the sward has been assessed in each of consecutive years. Nutritive components content in the sward have been determined in the years 2013-2014. Undersowing with red clover was the most effective on the manure fertilised plot and the least of all on the plot fertilised with the liquid manure, where the contribution of red clover was 2-fold lower, than in the other plots. Increased share of red clover in the meadow sward enabled obtaining by 20% higher dry matter yields and by 1000 kg·ha–1 greater protein yields on the manure fertilised plot. The presence of red clover improved the nutritive value of obtained green forage, through an increased protein content, but on the other hand its usefulness as a raw material for ensilage has been slightly decreased.