Die Bodenkultur - Journal for Land Management, Food and Environment
V. Zeller, E. Kandeler and V. Mair:
N dynamic in mountain grassland with different intensity of cultivation
The aim of this research was to investigate the N dynamics in mountain grassland with different intensity of cultivation. We compared three meadows (extensive, medium intensive and intensive) on Entic Hapludoll (American Soil System) and one medium intensive meadow on Dystrochrept. Microbial biomass, Nmin content and net nitrogen mineralization (NNM) were measured at a depth of 0-20 cm from April to September at 6-week intervals. The plots on Entic Hapludoll showed an increase of microbial biomass N, Nmin and Norg content from extensive to medium intensive cultivation. Compared with the medium intensive plot the intensive plot showed generally similar Nmin contents, but lower biomass N and Norg contents. The medium intensive plot on Entic Hapludoll differed from the Dystrochrept plot greatly in biomass N, Norg and Nmin contents. The ratio biomass N to total N (Nmik/Norg) was the lowest in the extensive plot. The NNM was greatest in the intensive plot. Due to high variability the differences were significant only for the medium intensive plot on Dystrochrept. The NNM (medium intensive on Dystrochrept, medium intensive and intensive on Entic Hapludoll 126, 153 and 251 kg N ha-1 24 weeks-1, respectively) showed, with exception of the extensive plot, good responses to the N output through cutting (medium intensive on Dystrochrept, medium intensive and intensive on Entic Hapludoll 139, 208 and 283 kg N ha-1, respectively). The N supply from NNM and the N output were not always synchronous over the season.
Key words: Intensity of cultivation, microbial biomass N, mountain grassland, N dynamic, net nitrogen mineralization.