Because of the enormous benefits, over half the corn in Kentucky is already being no-tilled. And the figure is much higher on the state’s erodible land.

Since many fields have received little or no tillage for 10 to 20 years, this has led some growers to wonder if soil compaction increases over time on long-term no-till fields due to equipment traffic. As a result, some farmers are subsoiling every second year after soybean harvest with a no-till corn, wheat and soybean rotation.

No Compaction Problem?

Yet research at the University of Kentucky has shown soil compaction does not commonly occur with no-till. With increased soil organic matter at the surface with long-term no-till, this has greatly reduced the ability of the soil to be compacted by farm machinery.

Kentucky agronomist Lloyd Murdock says many producers who subsoil don’t take field measurements to determine if compaction exists. “This is unfortunate because our research has shown that subsoiling fields that are not compacted only increases the expense of crop production, but doesn’t improve grain yields,” he says.

As a result, Murdock and other researchers designed an experiment to test the impact of subsoiling on yields of long term, no-tilled fields. They studied three fields in Kentucky’s Caldwell County that had been no-tilled for 10 to 15 years with only an occasional light discing. A Paraplow unit which left most of the residue on the surface was used for subsoiling in the fall.

Except for one low area, Murdock says soil penetrometer readings…