December 13, 2006 | By: Laura Skillman

Crop fields across Kentucky bear the scars of a difficult harvest. Poor weather forced farmers to harvest their crops when fields were wet, leaving them rutted and in need of repair.

But the damage likely is more cosmetic than anything serious, said Lloyd Murdock, soils specialist with the University of Kentucky College of Agriculture. Farmers may fear they compacted the soil where the wheels of their equipment sank into the ground, but Murdock said it is not possible to compact waterlogged soils. If water and mud were squirting out from beneath the wheels, compaction may not be a problem.

“You can’t compact a bucket of water,” he said.

It is easy to determine if the soil is compacted, he noted. Simply take a long spike and push it into the soil when the soil is wet. If it goes into the ground easily, the soil is not compacted. If it is difficult to push through and suddenly breaks and moves easier, then compaction could be a problem.

“If you’ve got compaction then you’ve got to get below that compacted layer with a tool to take it out,” he said. “You really don’t have a choice. If you don’t have compaction and it’s just a rut from tires, and that happens a lot in these kinds of years, then all you need to do is smooth out those ruts.”

The challenge will be to find a time when the land will be dry enough to smooth it out and have it back in shape for the coming planting season.

“We’ve had these winters before and these deep ruts before and what I’ve found is that if you have compaction in the first 12 inches but it’s too wet to till that deeply, if you can till the first six inches, it does a lot to alleviate the compaction,” Murdock said. “You probably remove about 70 percent to 80 percent of the potential yield loss.”

Compacted soils limit water and nutrient movement to the plant as well as reduce root growth. As a result, yields are reduced. 

Compaction is something farmers are concerned about each year and some use deep tillage every few years. However, oftentimes the tillage is not necessary.

“It seems to me that a lot of times it’s based on emotion or what a person thinks rather than anything scientific,” he said. “The only way tillage pays is when it is actually doing something for us.”

To check soils for compaction in any given year, a penetrometer should be used. The device is pushed into the soil and measures the pounds of pressure it takes to push it into the ground. Before tillage will pay for itself, the field must have at least 30 percent of its measurements at 300 or more pounds per square inch.
“I can just about guarantee you will have compaction on the end rows and where you enter the field, but outside of those areas, it really depends on what you’ve done in the past,” Murdock said. “Using a penetrometer is the only way I know that a guy can make a decent decision.”


Lloyd Murdock, 270-365-7541, ext. 207