Are the yellowish spots in the lowest ground within the field worth worrying about when you farm 3,000 acres? With the way crop budgets are today, most people would still say yes. That's why many work with ag consultants to keep an eye on situations like that for them.
Whether the spot is an acre or two acres and whether it will recover or whether it could use additional N later remains to be seen. Right now the yellowish color indicates that plants there are suffering from nitrogen deficiency. It may only be 3% of the field, but it's 3% that could yield considerably less than the rest of the field if the situation doesn't correct itself, or if the farmer doesn't take corrective action.
Crop Watch 6/16: Once-Ponded Plants Still Alive One Week Later
The question now is whether the nitrogen applied has denitrified and is gone, which seems unlikely since it was applied fairly soon before planting, or whether with drying weather and sunshine the roots will find the nitrogen and green up again.
By the time that question can be answered, the corn may be too big to go in with a sidedress rig and add more nitrogen. However, a high-clearance rig can go in almost to or sometimes at tasseling. It's also likely the best choice since in this case it's only a small area of the field that appears to be involved. The rest of the field is dark green and growing. Obviously plants in most of the field have tapped into the nitrogen, and despite the wet weather, are growing rapidly.
Crop Watch 6/20: Corn in Crop Watch Field Brings Growing Point Above Ground
We'll keep an eye on these yellow spots in lower, wetter soils to see what happens as the season progresses. Expect quite a bit of it to depend upon whether rains drop off and drier weather sets in. If they still remain yellow after that, then it's possible enough N was lost that there simply isn't enough nitrogen for the plants to get.