A long-term experiment was established in 2013 at the Northern Research and Demonstration Farm to study the responses to nitrogen (N) and potassium (K) on continuous corn. Results of a previous long-term study with continuous corn conducted at this farm from 1963 through 2001with different N, phosphorus (P), and K fertilization rates showed a positive interaction between N and K, but not between N and P, or P and K. A deficiency of either N or K reduced the maximum yield level and also limited the yield response to increasing rates of the other nutrient. The study summarized in this report was established to further assess possible N by K interactions.