Reseeding of a Long‐Term Permanent Grassland With a Multi‐Species Sward: 1. Biomass Yield Effects

ABSTRACT Grassland is a key resource for livestock production, but it also provides biodiversity within agricultural landscapes. Improved management practices are required to reconcile competing demands for different ecosystem services provided by grasslands. This study investigated the effects of applied nutrients and sward composition on herbage biomass dry‐matter (DM) yield in Northern Ireland. A long‐term grassland experiment established with eight nutrient treatments (unfertilised control, inorganic fertiliser [NPK], cow and pig slurry at three application rates each) and two sward types (multi‐species sward, MSS; permanent grassland, PG) was harvested as a silage‐cut system three times (spring, summer and autumn) over 3 years. The mean annual yield of the MSS (12,010 kg DM ha −1 year −1 ) was 24% higher than PG (9670 kg DM ha −1 year −1 ). Seasonal effects on DM yield were highly significant for both sward types, with the greatest production in spring followed by summer and the lowest yield in autumn. Sward type × nutrient treatment interactions significantly affected the DM yield with the greatest DM yield for the high slurry treatments, while the NPK fertiliser treatment was similar to the low cow slurry treatment. The MSS had a greater DM production over a wide range of nutrient input levels which suggests that MSS can be introduced to both intensive (high input) and extensive (low input) grassland systems. Future research is required to evaluate the long‐term performance of the MSS to provide greater DM production and the persistence of introduced species to improve sward biodiversity.