Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Zurich

Effects of nitrogen and potassium fertilization on a low input meadow

We assessed the evolution of the yield, the nutritive value of the herbage and the botanical composition of a low input permanent meadow that received different amounts of nitrogen (N) and potassium (K) fertilisers. The yield was reduced in similar proportion by the cessation of the N or the K fertilisation. A yield loss was observed when the K fertilisation replaced less than 40 % of the K withdrawn through the harvested herbage. The K availability in the soil significantly decreased in all the treatments during the experiment. The higher the K fertilisation, the higher the K and the lower the magnesium contents in the plant. At the end of the experiment, the yield proportion of the grasses, the legumes and the forbs were 65 %, 16 % and 19 % in the plots receiving no N-fertilisation and 73 %, 3 % and 24 % in the plots without K application. In spite of these differences, the same plant species and a similar proportion of plants typical of low input meadows were found in all the plots. On this site, a plant community of the Arrhenatherion-type could be maintained with different level of N and K in the fertilisation.

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