No abstract

This report provides answers to the research question posed by the Ministry of Agriculture of the Netherlands: Could Miscanthus, Silphium perfoliatum and fallow sown in with melliferous plants comply with the expectations of the EU greening policy to be added to the Dutch general list for ecological focus areas? In addition to that the Ministry wants to know if it will be wise to accept sunflowers in seed mixture of catch crops. Miscanthus should not be considered for the EFA list, whilst Silphium perfoliatum is a suitable permanent crop. A list of melliferous plants suitable for green fallow land practice is compiled based on pollen and nectar quality as well as the timing of flowering. Sunflowers bring an added value to catch crop seed mixtures.

No abstract

Nitrogen fertilisation is a common form of agricultural intensification, aimed at increasing biomass, which can affect plant species diversity and ecosystem functioning. Using a systematic review and meta-analysis of nitrogen fertilisation studies in European permanent grasslands, we asked: (i) what relationship form exists between nitrogen application rate and change in plant diversity, compared to zero fertilisation controls; and (ii) how grassland, management and study characteristics affect this relationship. Meta-analysis of 34 control-treatment effects from 14 studies conducted across nine European countries revealed a negative linear relationship between nitrogen fertilisation rate and change in plant species richness, equivalent to approximately 1.5 species/m2 lost for every 100 Kg ha−1 yr−1 of nitrogen added. Fertilisation induced reductions in plant species richness were greater when defoliation rates were lower. We found some evidence that grasslands with a higher baseline plant diversity lost more species when fertilised compared to more species poor grasslands, although uncertainty was high. Due to the diverse grassland types included in the analysis, the variability in fertilisation-driven changes in plant diversity was high. We identified several remaining limitations to our understanding, including uncertainty about non-linear effects, which could aid efforts to optimise the trade-off of plant diversity and increasing grassland yields.