Bewirtschaftungsfreie Zeitfenster für den Naturschutz - Auswirkung auf die N2-Fixierleistung von Luzernebeständen

We studied the effect of a mulching regime optimised with respect to nature conserva-tion on yield and nitrogen fixation rate of Lucerne. The first harvest was two weeks earlier and the second harvest was two weeks later than usual. At the first harvest in 2004, the shoot yield from the nature conservation variant was significantly lower than the yield from the usual treatment. At the second harvest date in 2004, there where no differences. The total nitrogen fixation in 2004 did not differ between the treatments. In 2005, both shoot yield and total nitrogen fixation showed no differences between the two variants as well. From this study it can be concluded that a displacement of mulching dates of Lucerne in most cases will have no significant effect on the total nitrogen fixation and percentage of N derived from the air. A negative effect, like at the first harvest in 2004, is only to be expected if weather conditions are moist until the first harvest and extremely dry further on until the second harvest. The results were used in recommendations for the agricultural practice to diminish the mortality rate of wild game and were regarded in the agricultural legislation in Austria.