Utilising commercial farm grass growth data to evaluate long-term dry matter production of perennial ryegrass varieties

Abstract

Little data are currently available on either the dry matter (DM) production of perennial ryegrass (PRG) swards as they age beyond 5 yr (i.e. permanent pasture) or the performance of PRG varieties on commercial grassland farms. Previous work has generally assumed a connection between DM production and ground score (GS) and this link has been used as a proxy for variety persistence. The evolution of technology in the form of PastureBase Ireland has led to agronomic data of individual paddocks being made available for analysis over multiple years which has allowed the long-term assessment of varieties sown as monocultures on commercial farms. This technology allowed for the inclusion of eight PRG varieties sown in 649 paddocks across 101 farms in Ireland in the current analysis. The results show little association between GS and variety DM production as varieties age to 7 yr. Dry matter production of 1- to 4-yr-old swards appeared to provide a strong indication of variety DM production in years 5–7 post-sowing (r = 0.72, P < 0.05). The interaction of variety and sward age was not associated with DM production. Generally, varieties which produced the most DM in younger swards also produced the most DM in permanent pasture swards. Over longer-term periods these variety differences can manifest into large differences in DM produced and consumed on farm. The current analysis suggests that the long-term production benefits of utilising improved PRG varieties in pasture reseeding may be underestimated.