The soil health movement of today has forgotten two unsung heroes. It was Purdue University Extension soil scientist Gary Steinhardt and Ohio State University Extension ag engineer Randall Reeder, now retired, who began beating the drum about soil compaction in the early 1980s. This is when the results of a couple decades of abandoning rotations and working soils wet began to show up in soil compaction, which in turn showed up in tall corn, short corn, and even yellow corn, especially when it was dry.
Soils are still subject to compaction today if they are worked too wet and the weather doesn't cooperate. On the end rows in one high-yielding field in 2013, yield was off 40%. The primary reason was lack of grass control. The grass got an early start and was nearly as tall as the corn by late in the season. There was virtually no grass in the rest of the field off the end rows.
The farmer believes he can attribute it to spreading manure for years on the end rows, starting on the affected set of end rows with a full load of manure, sometimes when soils weren't always right.
He believes soil compaction and changes in the soil may have contributed to less than perfect weed control, which took its toll later in the season.
Soil compaction itself likely played a role by resulting in a smaller root mass where soils were compacted. When it turned dry late in the season, the end rows didn't have the roots to find the moisture and continue growing and finishing the crop as well as plants did in the rest of the field where soil compaction was not a problem.
The bottom line is that although it was a great corn year, there were still lessons to be learned. In isolated places, soil compaction still made an impact. In years which aren't as kind on rainfall and temperature, like 2012, the impact is magnified.