Technical Abstract: The reliance of dairy farms on grassland is currently expanding, particularly in areas where confined operations have recently predominated. At the same time, some pasture based dairy systems, such as those found in New Zealand, are turning toward seasonal confinement of herds for production and even environmental benefit. In this chapter of the book “Grassland Productivity and Ecosystem Services” we examine the cycling and loss of phosphorus within different dairy farming systems. The merits of dairy systems in different settings are explored, and consideration is given to how losses of phosphorus within each system can be better managed to make most efficient use of this valuable fertilizer resource.