Wet harvest could cause soil compaction

By Katie Pratt
PRINCETON, Ky., (Nov. 25, 2009) – Wet weather in September and October caused many producers to harvest corn and soybeans in less-than-ideal conditions. With the majority of this year’s crop now harvested, producers should check their fields for signs of compaction, said Lloyd Murdock, a soil scientist with the University of Kentucky College of Agriculture.
Compaction occurs when soil is compressed into a smaller volume. Serious compaction can lead to nutrient deficiencies in those areas as well as yield losses in next year’s crop. “It is caused by large field equipment running over wet ground,” he said. “Since the equipments’ tires do not run over every section of the field, compaction occurs only in certain areas.”
Growers can use any type of rod to test for soil compaction. However, a penetrometer provides the most accurate results, and they are available at many county extension offices. To test for soil compaction, growers should puncture the ground with a rod in the wheel tracks. If a layer of the soil is difficult or impossible to penetrate, it is compacted. This also should be compared to penetrometer readings in the untracked soil.
To correct compaction, growers need to use a tool that goes below the compacted layer to break up the soil. If the compaction is not too deep in the soil, a chisel plow will probably do the job, but if it’s deeply compacted, growers may need a subsoiler to move the soil.
The key is waiting until the ground is dry enough to work the soil. If producers try to correct compaction while the soil is wet, it could cause additional compaction, Murdock said.
As producers check fields for compaction, they also may find large ruts caused by equipment tires on excessively wet ground. This may cause compaction concerns for some producers; however, often these types of ruts are not compacted because the soil was full of water when trafficked. If no compaction is found, producers just need to smooth out these ruts.