SOME WONDER WHETHER tracks reduce soil compaction over conventional farm tires or radials. Tracks and flotation tires may enable traffic on wetter soils, allowing more severe compaction, says Minnesota Regional Extension Educator Jodi DeJong-Hughes.

“An advantage of tracks is their large footprint and low ground-contact pressure. This footprint is spread front to back instead of side to side (as are duals or triples), so less of the field is compacted,” she says. “The disadvantages are that the weight of the tractor is on a given volume of soil for a longer period of time, and the vibration of the track may increase surface compaction.

“Some companies suggest that tracks reduce surface compaction over wheels. However, they may not reduce deep compaction. They may seem to have lower axle weights because the total weight of the tractor is spread over a larger area, but the guide wheels act as pressure points in the soil raising the track's average pressure on the soil to two to four times as high,” DeJong-Hughes says.

DUAL TIRES HAVE also been used as a method of spreading the load while maintaining constant axle loads. One study found that duals reduced the pressures by about 50% throughout the soil profile to a depth of 23 in. But duals' second tire increased the surface compaction.

“Duals essentially traffic twice the width of the vehicle track and, depending upon the crop and cropping system, may cause excessive surface compaction,” says Raper.

CONSIDER ADDING deep-rooted crops like alfalfa to your rotation.

VARY THE DEPTH of tillage. Continual tillage of the same depth can cause a very thin layer of soil immediately under the tillage tool caused by tillage implements, not wheel traffic.

FREEZE-THAW CYCLES do not remedy soil compaction caused by machinery deeper than 5 in. in the soil, according to nine years of university research at Lamberton, MN. Studies there also show compaction from wheel tracks extended down to 18 in., despite freeze-thaw cycles.