Effects of fertilisation on a mat-grass grassland

Mat-grass (Nardus stricta L.) produces poorly palatable forage. We assessed the effects of nine forms of fertilisation on yield and botanical composition of a mat-grass sward of the central Alps at 1950 m of altitude. Moderate fertilisation with stored solid manure, stored solid manure plus slurry, or mineral PK fertilizer combined with liming achieved a significant yield increase and agricultural improvement of the sward. The effects of slurry alone or mineral PK fertilizer without liming were much smaller. After 14 years, the mat-grass proportion was only 35 % in the plots fertilized with solid manure plus slurry, compared to 65 % in the unfertilised plots. Mat-grass swards can thus be agriculturally improved by applications of farm manure. The number of plant species was significantly decreased by the moderate fertilisation only in two treatments. Nevertheless, some species typical of nutrient poor sites and present in the unfertilized plots could not be found in the fertilized ones. It therefore seems best for summer farms with mat-grass grasslands, for both production and species conservation, to preferentially keep the produced manure for the area with the best production potential.