Corn was grown in both continuous corn and corn/soybean cropping systems under irrigation in the Platte Valley of Nebraska. The objective of the study was to determine whether in-season N stress measured by using chlorophyll meters could be used to determine N fertilizer applications. Four corn hybrids differing in yield potential, maturity, and stay green characteristics were tested in both the monoculture and rotation systems in combination with five N fertilizer rates. In-season chlorophyll meter readings at various growth stages appeared to be indicative of various levels of N stress for the various preseason N fertilizer applications.