In dairy production systems, trade-offs occur can between fertilizer N applications and crop N use, feed N consumption and manure N excretion, and environmental impacts. This paper examines (i) how stocking rates affect N imports and management on dairy farms, N use efficiency, and N loss; (ii) how reductions in fertilizer N and feed N may affect crop and milk production, NUE, and N loss; and (iii) why trade-offs in N use outcomes should be considered when attempting to enhance overall NUE and reduce N loss.