If soil type ever mattered, it mattered this year. Soils which allowed plants to run out of moisture first, and which left them to swelter on hot days typically produced little, if any corn. Within the same field other soil types may have raised 100 to 150 bushels per acre. It's one reason yield monitors jumped all over the board on the same pass through the field this fall on many farms in many fields.
Take a look at these soil pit profiles. These are holes dug four feet deep that reveal properties of the soil. These holes were used for various competitions this fall to teach soils evaluation to 4-H and FFA students.
In some counties if you know the soil type, you can guess the corn yield.
Some general rules apply. Dark gray or light gray colors tend to indicate drainage problems. In a normal year this may be ground that floods out if it's in a low position. This year it may be where the yield monitor recorded the highest yield. Brown colors typically indicate better drainage. However, if there is a limiting layer, such as till so dense roots can't penetrate, then the crop may have performed poorly.
Here's a look at key properties in certain soils that could have affected crops on these soils this year.
Less than perfect drainage
This soil is on a strong slope, and should be well drained, but it's not. The presence of gray mixed with the brown in the top 18 inches indicates somewhat poor drainage. However, the soil below is so dense that roots still may not have lasted very long before running out of water if this field was in corn. It was in wheat, so the wheat crop was able to mature before drought set in.
Down by the creek
Here's a dark gray, poorly drained flood plain. It's located near a natural drainage way. The dark gray color indicates drainage problems. Some of the better corn yields were in fields like these along creeks, as long as the soil was poorly or somewhat poorly drained. Flood plain soils can also be moderately well or even well drained.
Evaluate the soil
Judgers determine drainage and slope to know how to handle the soil best. They also need to know color and texture, and whether there is a limiting layer that could prevent root growth.
Notice the tile
Tile in the soil isn't always the sign of poor drainage, because tile lines may cross through better drained soils. In this case, however, the soil is poorly drained. Note the dark gray colors in the subsoil.
Check the landform
Notice the low spot where the pit is dug. This is called a depression, and soils there are usually poorly drained. These students found gray soils, indicating poor drainage. Corn would have likely performed well there this year.
Hard for roots
Note the layers and bright, brown clay-based soils in the middle of the rulers. This represents dense till and starts at about 15 inches. That means the plants would have had only 15 inches of topsoil to work with this year, and would have likely not fared well.
Fooler!
This pit shows light gray, poorly drained soils, which should have held moisture well. However, at about 30 inches it switches to dense till, which would be hard for roots to penetrate. It's probably also why the soil over the years has held water in the top couple of feet, causing poor drainage. Located in a depression, this unusual hole left no place for the water to go.