Incorporating Plantain Into a Perennial Ryegrass–White Clover Mixed Sward for an Environmentally Sustainable Dairy System: A Three‐Year Farm System Study

Over three production years (2021–2024), this study investigated the effects of incorporating plantain into a perennial ryegrass–white clover (RGWC) mixed sward on dairy farm productivity and environmental footprint. Seventy‐two Friesian × Jersey cows were allocated to six farmlets across two replicated herbage treatments (n = 3): RGWC with no plantain (PL0) or RGWC plus 3 kg/ha of plantain seed (PL3). Farmlet production data were used to estimate profitability using the FARMAX model and the environmental footprint using the OverseerEd model. Plantain content in PL3 averaged 23. 5% (±2. 31%; SD) in Year 1, 16. 8% (±2. 46%) in Year 2 and 12. 3% (±1. 12%) in Year 3. Annual herbage production was similar across treatments when estimated by FARMAX (15. 7 kg DM/ha) but showed a year × treatment interaction (p < 0. 001) when estimated by calibrated rising plate meter. Annual imported silage (1. 24 t DM/ha) and milksolids production (1458 kg/ha) were similar across treatments. Farm profitability did not differ between treatments (NZD 5800/ha), indicating no economic disadvantage from plantain inclusion. Modelled annual nitrogen leaching was 17. 5% lower in PL3 than PL0 (p = 0. 032), with no difference in methane emissions. These results suggest that incorporating plantain into RGWC‐based dairy systems can improve environmental sustainability without compromising milk production or profitability.