What corn yield increase can you expect from the next unit of applied N?

Given the tighter corn enterprise margin facing us in 2025, the question in the title is one to consider. There are uncertainties in nitrogen rate management. Weather is the primary variable that affects soil nitrogen cycling and corn yield. Yet one certainty is that there are diminishing returns to increasing rates with the next pound of N applied, increasing yield less than the previous pound.   

Table 1 summarizes corn yield increases from nitrogen trials at our Western Agricultural Research Station (WARS) in Clark County and Northwest Agricultural Research Station (NWARS) in Wood County. The annual trials have been conducted since 2006, and the data summary is for 2006 to 2024. The 18-year time frame captures year-to-year weather variation that impacts corn yield response to nitrogen.

The table shows the change in corn yield after adding 25 pounds of additional N to the total N rate. The 0 total N rate is when no nitrogen was added, and corn yields 123 bushels per acre at WARS and 81 bushels per acre at NWARS.… Continue reading