The fall grain harvest in Butler County has been unpredictable, at best, due to an unusually wet fall.

Many areas of the county were able to get corn, grain and soybeans harvested, but portions are still struggling to get harvest completed, or in some cases, even begin. Many producers may be feeling pressure to harvest due to desires to plant cover crops; others may be running low on feeds.

No matter the reason you are feeling harvest pressure, you must be mindful of the long-term effect of harvesting before the soil is adequately dry.

“The soil is highly sensitive to rut formation when it is saturated, and it is highly compactable when it is in the plastic state,” said Sjoerd Duiker, the Penn State University Extension specialist of soil management and applied soil physics. “If you question if your soil is in a plastic state, try molding a piece. If the piece is easily molded into a ball or a cylinder, it is in a plastic state.

“Ideally, harvest would be delayed until the soil is not in a plastic state, however, in certain cases you may not have time to wait due to crop quality or yield decrease.”

When you do decide to harvest, surface compaction may be unavoidable, and not a major concern like subsoil compaction.

“A long-term, multi-nation study found that subsoil compaction could reduce corn yields for up to 10 years after it had occurred,” said Duiker, “and when trying to avoid this deep, long-term type compaction, axle weights must be kept below 10 tons. When addressing surface compaction, the effects are often not long-lasting, but are usually more severe.”

The first key to reducing surface compaction is to keep contact pressure low, especially in compaction favorable conditions. This can be through using flotation tires at a low pressure (no higher than 35 psi, but 10 to 12 psi is optimal) or using tracks. Road tires are another major cause of compaction and rutting in farm fields during harvest. Tires which are inflated to 80 or 90 psi should not be used in fields.

“Increased aggregate stability is an important ally to manage compaction,” Duiker said.

Often no-till fields support more weight and have a “sponge” effect when traveled over. This is due to increased aggregate stability because it has not been tilled and turned for a period.

“Increased organic matter and macro-porosity found in no-till systems help resist compaction,” Duiker said.

A final tool for reducing and repairing soil compaction is to maintain living roots within the soil. Cover crop establishment should be as close to crop removal as possible. The roots serve as a filter that trap and hold nutrients, but also help to repair the damaged soil aggregates.

Justin Brackenrich is a Penn State agronomist with the Butler County Extension. To contact him, contact the Butler County Extension Office, 724-287-4761, or visit from 8:30 a.m. to 4:30 p.m. Monday through Friday at the office, 101 Motor Pool Way.