Economic performance of 3 farm systems differing in sward species diversity and nitrogen fertilization level across a range of future economic scenarios

The objective of this study was to compare the economic performances of 3 pasture-based systems: a perennial ryegrass (Lolium perenne L.; PRG) receiving 250 kg N/ha (PRG-250N); a PRG-white clover (Trifolium repens L.; WC) receiving 125 kg N/ha (PRGWC-125N); and a multispecies (MSS) sward composed of grasses, legumes, and herbs receiving 125 kg N/ha (MSS-125N). Sward and animal performances were measured over 3 years in a system-scale study involving 3 farmlets at Teagasc Moorepark, Ireland. Subsequently, based on the physical data collected, an economic performance of each sward system was evaluated using current output prices and input costs in the Moorepark Dairy Systems Model. The economic results show similar net farm profitability for both PRG-250N and PRGWC-125N. The PRGWC-125N system had lower costs linked to fertilizer; however, more grass silage was purchased due to reduced grass production. The MSS-125N system outperformed both PRG-250N and PRGWC-125N in net farm profitability (+€167/ha and +€148/ha, respectively) due to increased milk output coupled with reduced N fertilizer use. Sensitivity analyses indicated that MSS-125N was the most profitable system under varying milk and fertilizer prices. Given the variability of clover and herb establishment between paddocks for PRGWC-125N and MSS-125N, an increase in the reseeding frequency and oversowing frequency was simulated and resulted in reductions in farm profitability for both systems (€-14.25/ha per year and €-28.25/ha per year, respectively). This study underscores the potential of increasing sward species diversity using clovers and herbs to sustain economic performances of pasture-based systems while reducing fertilizer N reliance and enhancing animal performance. Further long-term research is required to investigate persistence and economic viability of both PRGWC and MSS under varying climatic and management conditions to validate the longer-term results of the first 3 years of the study.