Results of a long-term study with continuous corn conducted at this farm from 1963 to 2001with several nitrogen (N), phosphorus (P), and potassium (K) fertilization rates showed a positive interaction between N and K, but not between N and P or between P and K. A deficiency of either N or K not only reduced the maximum corn grain yield level, but also limited the yield response to increasing rates of the other nutrient. A new study with continuous corn was established in 2013 and was evaluated until 2017 to further assess possible N by K interactions. A previous report summarized early years of this new study. These reports summarize data across the five years.