With the increase in corn yields over time, more Ontario producers are achieving yields which would not have been well represented in existing nitrogen yield response data. It is unknown how greater yield potential may impact yield response to nitrogen, and as a result the accuracy of current recommendations under these high yielding environments is unknown. In conjunction with calibrating nitrogen recommendations, development of tools which aid in tailoring side-dress nitrogen rates to deliver the maximum economical rates of nitrogen while accounting for changes in nitrogen supply have also been an ongoing effort. In Ontario, validation of these tools is limited, though some are advertised in the marketplace for this purpose. The objective of this research is to calibrate the nitrogen recommendations for corn in high yielding environments, and to evaluate the ability of existing nitrogen management tools such as the SPAD meter, Greenseeker and pre-sidedress soil nitrate tests for their ability to quantify nitrogen requirements at sidedress time.