Abstract
Meadows form an important part of the European landscape and play a crucial role in the maintenance of the native biodiversity. Additionally, in different European countries meadows provide through agronomical management a large part of the forage needed for animal husbandry. For a higher production of forage, these meadows have been often intensified in terms of mowing frequency and nutrient input through fertilisation. In general, across the entire range of fertilisation intensity, there is a clear trade-off between yield and plant diversity in managed meadows. When striving an increase of plant diversity, the transition of an intensive, species-poor to an extensive species-rich meadow can be a big challenge. The soil seed bank (SSB) in this context is one of the main addressed points in literature, but still to the best of our knowledge, there is no clear understanding how management, and especially the fertilisation, is affecting the SSB. Moreover, there is no study in literature which is simultaneously investigating the effect of different organic manures and of a nutrient input gradient on the SSB. The aim of our study was therefore to investigate the mid-term effects of different organic manure types (MT; farmyard manure, slurry, and farmyard manure combined with manure effluent) and different nutrient input (NI; 0, 0.65 and 1.3 livestock units (LU) ha-1) on the SSB of moderately species-rich and moderately species-poor meadows in South Tyrol (Italy). In a field experiment conducted from 2018 to 2024 arranged as a split plot design, we tested every pair of organic fertilizer and nutrient level with three replicates (n = 54) randomly distributed in two different meadow classes (MC; legacy effect of mowing frequency and vegetation type) in three different study areas (S). We sampled the SSB in spring 2018 and 2024. In our model the interaction S*MC was set as random term, while S, MC, MT, NI and their interactions were set as fixed terms. A significance level of p < 0.05 was considered. In total, we found 3943 seedlings of 80 species emerged in the SSB in both years. From the initial average of 10 species emerged in each tray (no differences between MC’s), we didn’t find any clear trend, whether positive nor negative, even if we found significant three-way interactions on the species number and density of extensive and intensive indicator species, suggesting limited effects of organic fertilisers on the SBB on mid-term.