The potential to reduce the risk of diffuse pollution from agriculture while improving economic performance at farm level

► Average over application of chemical fertilizers ranged from 22.8 to 32.8 kg N ha−1 and 2.9 to 3.51 kg P ha−1. ► Average excess of imported feedstuffs equated to 5.82-7.44 kg LU−1 of N and 0.92-1.17 kg LU−1 of P. ► Potential cost savings on chemical fertilisers across all systems on average ranged from €38.9 ha−1 to €48.5 ha−1. ► Potential cost reductions on imported feeds of €65-84 LU−1 were indicated for dairy farms versus efficient cohort benchmark farms. ► Farmers with a formal agricultural education had significantly higher level of efficiency.