Look at the picture. Now imagine you're riding in this combine cab. Look to your right. What you see out of the window in the next couple of passes yet to be run are gaping holes – maybe 50 feet long. Instead of corn there is nothing, just some grass which has already been killed by a fall freeze.
Poor weed control wasn't the problem here. Pete Illingworth, part of the Throckmorton Ag Center farm crew, says the rest of the field was clean. Corn in this area was drowned out by early season rains that caused ponding after planting. With corn plants wiped out, there was no competition to help shade out late-emerging grasses later in the season.
The Throckmorton Ag center is part of Purdue University's system of ag centers around Indiana. This one is located just north of Romney and is home to a wide variety of corn, soybean and vegetable types of research.
The problem with this field is that soils are naturally poorly drained, and also have depressional areas. The complicating factor is that it has already been drained with tile! Water can still accumulate in the low areas and doesn't get away fast enough to avoid wiping out crops in some years.
The other problem, Illingworth says, is that besides the bare spot, the stands are typically thinner than they should be leading into the wet areas and leaving them. This can reduce yield, even in areas that don't appear to be badly affected.
These differences will show up on yield maps. These maps can help document not only the areas of no yield, but the areas of reduced yield around the wet spots. If no tile was in the field, it might help make a case to justify installing tile.
With tile in the field, it might be cause to study if closer tile spacings are needed, or if some sort of surface drainage would help.