Every farmer knows equipment causes compaction. But results from a recent study show just how long that compaction lasts and how severe it really is.

Based on 20 years of compaction research, just one year of harvest traffic on clay soils can reduce corn yields by as much as 40 percent. And the impacts from compaction can persist for as many as eight years.

Rattan Lal, Ohio State University soil scientist, and his team made a one-time distribution with a single axle 20-ton grain cart and a single axle 10-ton grain cart across fields with two soil types -- clay ...