(December 2008) The key to minimizing soil compaction-related problems during planting is to avoid compacting the soil altogether, but that's easier said than done in a year when harvesting has been delayed throughout the upper half of the United States due to late planting and wet soils.

"Ideally, growers shouldn't be running heavy equipment through their fields in wet conditions, but the reality is that they have to get their corn out of the field before it falls over," explains Bob Schoper, AgriSolutions™ and CROPLAN GENETICS® brand agronomy services manager.

Soil compaction is generally broken down into two categories: surface compaction and deep compaction. Surface compaction occurs within the first 6 to 8 inches of topsoil and growers can address it by pulling a disk ripper through their fields in the fall.

"It doesn't need to be dry when you till your field, but it's something you don't want to do when soils are excessively wet," Schoper advises. "The deepest you'll want to go in moist conditions is 10 to 12 inches, but it's possible to go deeper under drier soil conditions."

Deep compaction is a result of heavy axle loads and occurs when the soil is compacted at a depth of 18 inches or more. It impacts water infiltration and root growth and development, and it's of particular concern right now as growers are leaving semis on the road, instead opting to use grain carts to haul the crop out of the field.

"If you fill a 1000-bushel grain cart to capacity before pulling it out of a field, you're putting a 28-ton load on a single axle," Schoper says. "That will cause serious, long-term deep compaction issues, because tillage won't help. Neither will freezing and thawing."

Schoper cites a study performed by the University of Minnesota - Waseca in which fields were subjected to axle loads of 5, 10 and 20 tons. Findings showed that the deep soil compaction that resulted impacted root growth and development as many as 10 years later.

One strategy to help prevent deep soil compaction is to dump the combine tank and grain cart more often, before they get too heavy, Schoper suggests. Another is to use a consistent path so not to damage the entire field.

"The bulk of compaction occurs on the first pass, so you're better off continuously using the same route," Schoper adds. "That way you're impacting only a small portion of your field."

And although no one generally wants to still be harvesting when the ground is frozen, a silver lining is that you're less likely to cause compaction issues on frozen soils.

The extra attention spent preventing soil compaction now can pay dividends over several years. For assistance in developing harvesting strategies, your local CROPLAN GENETICS® seed specialist has you covered. Turn to your local seed specialist and check out your local Answer Plot® location as a third-party source to help sort out the other brands and find the answers for your toughest field.