Red and white clover sustain high and stable yields in diversified perennial grasslands under low N input

Summary

Increasing species richness and functional diversity in managed grasslands can enhance ecosystem services, particularly when legumes are included. However, it remains unclear whether higher species richness consistently improves productivity and stability in intensively managed grasslands under low nitrogen (N) inputs, or if species identity plays a more dominant role. This study evaluated how legume identity, non-legume identity, and species richness influence dry matter (DM) yield, N yield, and biological N₂ fixation (BNF) in grass–legume–forb mixtures managed with low fertilizer inputs. In a 3-year field experiment, we tested (i) 2-species mixtures of white clover ( Trifolium repens , Tr) or red clover ( Trifolium pratense , Tp) with perennial ryegrass ( Lolium perenne , Lp), tall fescu