Recent developments, such as the introduction of milk quota and concern about nitrogen (N) losses in dairy farms, have started a downward trend in N inputs. Consequently there is renewed interest in white clover in the Netherlands. From May 1990 to April 1993 two 60-cow dairy systems based on either grass-N swards or grass-clover swards were compared. Because of the expected yield difference of 15-20%, the grass-N and grass-clover farm had pasture areas of 34 and 41 ha, respectively. The grass-N and grass-clover swards were fertilised with 275 and 69 kg N/ha/year, respectively. The main objective was to compare both systems on their technical, environmental and financial performance. With similar amounts of concentrates, the annual milk production per cow was slightly higher in the grass-clover system, the difference occurring during the grazing season. Gross margin per cow was also higher in the grass-clover system, but the lower stocking rate gave a lower gross margin per ha. Nitrogen surplus and energy use were approximately 15% lower with grass-clover than with grass-N. The technical and environmental results demonstrate that white clover-based swards are a viable option for the future, but at present dairy farming is still very intensive and for most dairy farmers it is financially unattractive to switch from grass-N to grass-clover. Keywords: dairy system, energy use, gross margin, milk production, nitrogen balance, Trifolium repens
