Since alluvial meadows of river valleys of the Cnidion dubii are protected by the EU Habitats Directive, reconciling farmers’ demands for forage quality with the objective of maintaining them in good conservation status is an important issue in grassland research. In a long-term experiment from 2010 to 2018, we investigated the impact of fertilizing on forage quality and species assembly on a species-rich and twice-mown alluvial grassland in the Dessau Elbe floodplain (Germany). The experiment was composed of an unfertilized control, PK, N60, N60PK and N120PK applications. A significant improvement in forage quality was achieved by nitrogen fertilization only for crude protein, with higher feeding requirements for sheep met only in individual years. The legume cycle was inhibited by the application of nitrogen and high grass cover was maintained, but not increased, at the highest nitrogen application after an exceptional summer flood. The target forbs persisted in numbers over the study period in all treatments. For cover, the low-competitive target forbs responded neutrally to nitrogen fertilization, whereas detrimental effects were demonstrated for the competitive ones. Thus, we recommend not applying more than 60 kg year−1 of nitrogen and only in combination with phosphorus and potassium.

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Photovoltaics is one of the key technologies for reducing greenhouse gas emissions and achieving climate neutrality for Europe by 2050, which has led to the promotion of solar parks. These parks can span up to several hundred hectares, and grassland vegetation is usually created between and under the panels. Establishing species-rich grasslands using native seed mixtures can enhance a variety of ecosystem services, including pollination. We present an overall concept for designing native seed mixtures to promote pollinators, especially wild bees, in solar parks. It takes into account the specific site conditions, the small-scale modified conditions caused by the solar panels, and the requirement to avoid panel shading. We highlight the challenges and constraints resulting from the availability of species on the seed market. Furthermore, we provide an easy-to-use index for determining the value of native seed mixtures for wild bee enhancement and apply it as an example to several mixtures specifically designed for solar parks. The increased availability of regional seed would allow a more thorough consideration of pollinator-relevant traits when composing native seed mixtures, thereby enhancing ecosystem services associated with pollinators such as wild bees.