If you can't stay off wet fields, minimize compaction
The best way to manage soil compaction is to prevent it from happening. The old adage of "stay off the field until it's fit to work" still applies. However, the possible severe economic repercussions of delaying field operations may outweigh compaction damage or loss. The dilemma farmers face in a wet spring or fall is not easy to resolve.
Since farmers need to be in the field in less than ideal soil moisture conditions, minimizing or controlling compaction is the next best management option. This includes reducing axle load, proper inflation and size of tires, and band applying nutrients to maximize availability.
Your soil is your most important resource when growing a healthy and profitable crop. Preventing soil compaction will increase water infiltration and storage capacity, timeliness of field operations, decrease the stress on plant roots, and decrease diseases potential.
While large, heavy machinery is often blamed for soil compaction problems, it also offers opportunity to minimize compaction. Larger capacity machinery means fewer wheel tracks across the field because of wider working width. Approximately 80 percent of the compaction happens on the first pass. Subsequent passes cause additional, but progressively less, compaction.
Based on this concept, if wheel track spacing can be standardized among different pieces of equipment, soil compaction problems can be confined to certain traffic patterns and not throughout the entire field.
Compaction is managed, not eliminated. Controlled traffic is a method to manage soil compaction. All heavy traffic is confined to specific lanes through the crop, year after year. The lanes become compacted and the soil between the lanes is never driven on. Controlled traffic improves timeliness of planting, spraying, and harvesting while minimizing potential yield losses from compaction. Controlled traffic also results in beneficial compaction because the compacted soil under wheel tracks provide better flotation and improves traction when fields are wet.
Converting machinery to controlled traffic is not a simple change, but rather a transition that can take several years to complete. Therefore, consider controlled traffic in all major machinery buying decisions. Tire selection is very important with controlled traffic because minimizing the amount of area compacted is crucial: taller and narrower tires must be used.
If controlling all wheel traffic is not feasible, control the heaviest equipment like the grain cart. To reduce wheel traffic across the field, grain carts should use the previous combine tracks when possible. For example, after unloading the combine on-the-go, the grain cart should continue to the end of the field and take the headlands back to the field entrance. At all costs, avoid driving equipment across the field diagonally.
Jodi DeJong-Hughes is a crops educator with University of Minnesota Extension.