Nitrogen (N) fertilizer is required by turfgrass in larger quantities than any other mineral nutrient because the plant demand for N is high and the supply of N from the natural environment is normally low. In instances where N is not applied according to the University of Kentucky recommendations, applied N can increase the risk of surface and ground water contamination. The objective of this document is to describe the function of N in turfgrass, explain how soil and tissue tests can be used to manage N applications, and to describe the various N fertilizer sources available for application to turfgrass.