When carrots (Daucus carota L.) are mechanically harvested, sufficient nitrogen (N) must be balanced between the roots and carrot tops; weak tops reduce yield. A 2-year study was conducted in Montcalm County, Michigan, where four replications of four N treatments (45, 90, 135, and 180 kg ha −1 ), were arranged in a randomized complete block design. Results showed the importance of determining pre-existing N sources, in as much as the deep taproot of carrot accessed unmeasured N in the subsoil and nitrate concentrations in irrigation water added N. The greatest yield occurred at 153-189 kg ha −1 available N while tops continued to take up N through 200-232 kg ha −1 . When the last N application was made less than 35 days before harvest, the rate of N uptake exceeded dry-matter accumulation rate.