Don't work fields wet or expect soil compaction

In just a few weeks, many farmers will be out in their fields, tilling their soil and beginning to plant their cornfields. While the itch of spring may be too hard to resist for some farmers anxious to begin field work, don't yield to the temptation, warns Bob Frazee, University of Illinois Natural Resources Educator. If you begin field work too early, you run the risk of excessive soil compaction on soil that is still too wet. Substantial yield reduction due to compaction can be expected; compaction reduces drainage; causes denitrification; and limits the availability of oxygen to the roots.

According to Frazee, the most obvious preventative measure is to avoid, if at all possible, both heavy wheel traffic and tillage of soils that are too wet. In many years, the greatest amount of soil compaction is caused by the very first trip across the field in the spring, whether this may be applying pre-plant anhydrous ammonia or starting spring tillage. Although the soil surface is dry, and you may even see wind erosion occurring, usually only the top one-inch or so of the soil profile is dry. The rest of the soil profile is usually still saturated with water and is very susceptible to compaction. Allowing the soil to dry for just one or two more days can significantly minimize compaction problems for the rest of the season.

Twenty years ago when farmers tried to work in fields that were too wet, they got stuck! However, with today's high-powered tractors and large dual tires, farmers can actually run their equipment through some areas of their fields where water may still be standing. The resulting puddled soil, reduced infiltration and drainage, and poor plant growth are not necessarily the fault of the equipment, cautions Frazee, but the blame should probably go to the operator for operating the equipment when soil conditions are not fit.

Recent University of Illinois studies have shown that deep soil compaction, below the depth of tillage, persists for many years and is expensive and often impractical, if not impossible to remove. Thus preventing soil compaction from occurring is the key.

According to Frazee, the following recommendations should be considered in order to minimize the severity of compaction in a wet spring:

•Keep out of fields whenever they are wet!

•Reduce the number of tillage passes.

•Reduce surface pressure by using wide tires, duals, or tracks.

•Minimize tractor weight.

•Maintain minimum tire inflation.

•Space wheels to follow the same path by using a controlled traffic system.

•Avoid over-sized equipment.

•Keep wagons, trucks and other unnecessary equipment out of the fields.

•Combine field operations into one trip, such as applying herbicides and liquid fertilizer.

•Improve soil drainage by installing surface and sub-surface drainage systems.

•Consider adopting a long-term no-till farming system.