This intervention involves adding yellow rattle Rhinanthus minor seed to grassland to help establish meadow plant communities. Yellow rattle is an annual wildflower native to the UK which parasitizes other wildflowers and grasses (Natural England 2009). By parasitizing other plants, particularly grasses, yellow rattle can reduce the dominant plant biomass in grasslands allowing other wildflower species to establish (Natural England 2009). See also ‘Restore species-rich, semi-natural grassland’ for studies that used yellow rattle in the restoration or creation of semi-natural grassland.
Natural England (2009) The use of yellow rattle to facilitate grassland diversification. Natural England Technical Information Note TIN060.
A randomized, replicated controlled trial in 1995-1997 in Oxfordshire, UK (Coulson et al. 2001) found that yellow rattle Rhinanthus minor could be effectively established on a pasture field by ‘slot seeding’. Different management treatments, cutting, grazing or both, did not affect survival or establishment. However yellow rattle seeds were spread a greater distance when hay was cut in July than without a hay cut. Seeds were sown in strips previously sprayed with herbicide by a tractor-mounted slot seeder, in October 1995. Four management treatments were replicated five times in 20 x 10 m plots. The treatments were cut once (July), cut twice (July and September), cut July and autumn grazed. Monitoring of plant dispersal was carried out using seed traps at the soil surface, from June to October 1997.
A 2005 review (Jefferson 2005) found three studies looking at the role of yellow rattle Rhinanthus minor as a tool when restoring upland hay meadow vegetation on semi-improved grassland. One study in North Yorkshire, UK (Smith et al. 2003) found that sowing key functional species (legumes and yellow rattle) helped other sown target meadow species to colonize. At the same site, Smith (2005) found that when more yellow rattle was present, herbaceous species increased at the expense of perennial rye grass Lolium perenne. The rate of nitrogen mineralization was also faster in the presence of yellow rattle. One study (Pywell 2004) found that when restoring species-rich grassland on a semi-improved grassland site, more plant species were found when yellow rattle was present.