Farm Progress Reports




Southeast Research and Demonstration Farm




Many experiments have been conducted at this farm over the years to study the corn grain yield response to nitrogen (N) and potassium (K). Only one experiment included combinations of N and K rates, and the results showed a positive interaction between these two nutrients. A deficiency in one nutrient reduced the maximum yield level and limited the yield response to increasing rates of the other. Scarce research was conducted in this region of the state to study the corn response to sulfur (S) fertilization, and results showed small and inconsistent responses. A new long-term experiment was established in 2013 to study the continuous corn responses to several combinations of N, K, and S. No Iowa research has studied the possible interactions among these three nutrients. Results for the first three years summarized in a previous report confirmed the N by K interaction and showed no statistically significant corn yield increases from S application. This report summarizes data across five years, although one year was omitted due to low yields and extreme rainfall.





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