Sports teams designate their star performer as a “franchise player” and won’t consider trading him or her. If growing corn was a sport and inputs were your players, which one would you designate as the franchise player? Nitrogen fertilizer likely would be named most often. You may consider shaving rates or tweaking application methods, but you likely won’t remove nitrogen from your roster of inputs for 2025.

“Economics will be tougher in 2025, so it is important to keep learning and understanding about inputs,” says Dan Quinn, Purdue Extension corn specialist. Quinn helped monitor the Corn Commentary field in 2025.

“What worked and didn’t work within your own fields in 2024?” Quinn asks. “Think back over the season and learn from what you saw. What inputs provided a benefit? What inputs didn’t provide benefits? Maybe we can cut those out or reduce them.”

Evaluating nitrogen rate

The grower managing the Corn Commentary field won’t eliminate nitrogen. But he may take another look at nitrogen rates. Is he applying too much? Or, for 250 bushels per acre, is he applying too little?

Tools available for assessing the amount of nitrogen left after the season include a stalk nitrate test and a PSNT soil test. A&L Great Lakes Labs, Fort Wayne, Ind., offers both tests. Representatives for the lab note that one grower using these services wants some nitrogen left over, indicating the crop didn’t run short. Others prefer seeing very little nitrogen left, meaning they didn’t waste money on luxury input levels.

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Visual observations also can provide information about nitrogen programs. Neither a stalk nitrate test nor PSNT test was conducted in the Corn Commentary field. However, careful observations were made during the season by walking through different spots.

Observe, decide, tweak

Early-season scouting trips indicated that corn in the Corn Commentary field was dark green in color. Tissue samples were pulled, beginning at about V10. Nitrogen was sufficient early in the season. That was in line with the grower’s expectations. Over 200 pounds per acre of total nitrogen was applied on the field.

Later scouting trips, however — after pollination and silking — began to pick up symptoms of nitrogen deficiency, especially on older, lower leaves on some plants. Tissue analysis from leaves sampled at R1 indicated nitrogen levels were not as strong as earlier in the season.

Seeing some signs of nitrogen deficiency on lower leaves late doesn’t always mean applying more nitrogen would have been profitable, Quinn notes. He explains that weather patterns and environmental stresses can affect what you see in plants at that moment. Plus, a 250-plus-bushel corn crop puts heavy nitrogen demand on crops.

“Keep your observations in mind as you plan for next season,” Quinn says. “For example, in this case, seeing some signs of nitrogen deficiency might influence you not to increase rates for next year. But maybe you don’t want to drop them either.

“Plus, if you’re applying any N this fall, wait until soil temperatures are below 50 degrees F. You may also want to consider adding a nitrification inhibitor.” Fall nitrogen application is not recommended in the most southern parts of the Corn Belt, Quinn adds.