Grass clover swards: key for Dutch dairy farms under legislative pressure?

Dutch dairy farms are facing further strengthening of legislation to minimize the environmental impact of production. One of these recent policy measures is the planned abolition of derogation. Derogation allowed dairy farmers to go beyond the 170 kg N ha-1 of animal manure under specific conditions. Establishing grass-clover swards might be a strategy towards more sustainable production and to deal with the uncertainty imposed by expected policy changes and other external factors such as feed and mineral fertilizer prices. The aim of this study was to quantify and evaluate the environmental and economic implications of implementing a perennial ryegrass-white clover or a perennial ryegrass-red+white clover sward on a representative dairy farm with sandy soils in the Netherlands in a post-derogation era. The changes in environmental impacts (e.g. nitrogen losses), economic performance (e.g. labour income) and farm configuration (e.g. diet composition) were assessed. We combined a whole-farm dairy model based on linear programming with a nutrient balance to quantify and evaluate the environmental and economic implications. Results show that the use of clover swards after derogation abolition could be an economically viable strategy and can result in a lower N surplus depending on the sward type.