Auswirkungen langjähriger N-Düngung auf Standorteigenschaften, Erträge, Stoffgehalte und Vegetationszusammensetzung des Niedermoorgrünlandes

A grassland permanent experiment with graduated N-fertilization and constant PK-fertilization was carried out on a fen site over a period of 40 years. The present contribution serves the examination of long term effects taking into account sustainable land use. Graded N-fertilization of 0–480 kg N ha^–1 didn’t have any verified influence on single characteristic soil values. Indications on accelerated mineralization of peat due to increasing N-fertilization could not be found. During the experimentation period, yield and N-effects almost stayed the same inspite of year fluctuations in the trend. Long term N-fertilization during the examination period did not lead to a decline of yield of the fen site. Increasing N-applications caused an increase in the share of Elymus repens and at the same time a decrease in the share of herbs. Varying N-fertilization at constant basic fertilization led to varied PK-contents in the soil and in the plant. There are verified relations between potassium contents in the soil and in the plant. Concerning the yield however, none could be proved. In order to avoid an over and/or under supply of main nutrients, the PK-basic fertilization should be adjusted to the N-fertilization and the resulting withdrawal.